/*!
 * Vue.js v2.5.8
 * (c) 2014-2017 Evan You
 * Released under the MIT License.
 */
/*  */

const emptyObject = Object.freeze({});

// these helpers produces better vm code in JS engines due to their
// explicitness and function inlining
function isUndef (v) {
  return v === undefined || v === null
}

function isDef (v) {
  return v !== undefined && v !== null
}

function isTrue (v) {
  return v === true
}

function isFalse (v) {
  return v === false
}

/**
 * Check if value is primitive
 */
function isPrimitive (value) {
  return (
    typeof value === 'string' ||
    typeof value === 'number' ||
    typeof value === 'boolean'
  )
}

/**
 * Quick object check - this is primarily used to tell
 * Objects from primitive values when we know the value
 * is a JSON-compliant type.
 */
function isObject (obj) {
  return obj !== null && typeof obj === 'object'
}

/**
 * Get the raw type string of a value e.g. [object Object]
 */
const _toString = Object.prototype.toString;

function toRawType (value) {
  return _toString.call(value).slice(8, -1)
}

/**
 * Strict object type check. Only returns true
 * for plain JavaScript objects.
 */
function isPlainObject (obj) {
  return _toString.call(obj) === '[object Object]'
}

function isRegExp (v) {
  return _toString.call(v) === '[object RegExp]'
}

/**
 * Check if val is a valid array index.
 */
function isValidArrayIndex (val) {
  const n = parseFloat(String(val));
  return n >= 0 && Math.floor(n) === n && isFinite(val)
}

/**
 * Convert a value to a string that is actually rendered.
 */
function toString (val) {
  return val == null
    ? ''
    : typeof val === 'object'
      ? JSON.stringify(val, null, 2)
      : String(val)
}

/**
 * Convert a input value to a number for persistence.
 * If the conversion fails, return original string.
 */
function toNumber (val) {
  const n = parseFloat(val);
  return isNaN(n) ? val : n
}

/**
 * Make a map and return a function for checking if a key
 * is in that map.
 */
function makeMap (
  str,
  expectsLowerCase
) {
  const map = Object.create(null);
  const list = str.split(',');
  for (let i = 0; i < list.length; i++) {
    map[list[i]] = true;
  }
  return expectsLowerCase
    ? val => map[val.toLowerCase()]
    : val => map[val]
}

/**
 * Check if a tag is a built-in tag.
 */
const isBuiltInTag = makeMap('slot,component', true);

/**
 * Check if a attribute is a reserved attribute.
 */
const isReservedAttribute = makeMap('key,ref,slot,slot-scope,is');

/**
 * Remove an item from an array
 */
function remove (arr, item) {
  if (arr.length) {
    const index = arr.indexOf(item);
    if (index > -1) {
      return arr.splice(index, 1)
    }
  }
}

/**
 * Check whether the object has the property.
 */
const hasOwnProperty = Object.prototype.hasOwnProperty;
function hasOwn (obj, key) {
  return hasOwnProperty.call(obj, key)
}

/**
 * Create a cached version of a pure function.
 */
function cached (fn) {
  const cache = Object.create(null);
  return (function cachedFn (str) {
    const hit = cache[str];
    return hit || (cache[str] = fn(str))
  })
}

/**
 * Camelize a hyphen-delimited string.
 */
const camelizeRE = /-(\w)/g;
const camelize = cached((str) => {
  return str.replace(camelizeRE, (_, c) => c ? c.toUpperCase() : '')
});

/**
 * Capitalize a string.
 */
const capitalize = cached((str) => {
  return str.charAt(0).toUpperCase() + str.slice(1)
});

/**
 * Hyphenate a camelCase string.
 */
const hyphenateRE = /\B([A-Z])/g;
const hyphenate = cached((str) => {
  return str.replace(hyphenateRE, '-$1').toLowerCase()
});

/**
 * Simple bind, faster than native
 */
function bind (fn, ctx) {
  function boundFn (a) {
    const l = arguments.length;
    return l
      ? l > 1
        ? fn.apply(ctx, arguments)
        : fn.call(ctx, a)
      : fn.call(ctx)
  }
  // record original fn length
  boundFn._length = fn.length;
  return boundFn
}

/**
 * Convert an Array-like object to a real Array.
 */
function toArray (list, start) {
  start = start || 0;
  let i = list.length - start;
  const ret = new Array(i);
  while (i--) {
    ret[i] = list[i + start];
  }
  return ret
}

/**
 * Mix properties into target object.
 */
function extend (to, _from) {
  for (const key in _from) {
    to[key] = _from[key];
  }
  return to
}

/**
 * Merge an Array of Objects into a single Object.
 */
function toObject (arr) {
  const res = {};
  for (let i = 0; i < arr.length; i++) {
    if (arr[i]) {
      extend(res, arr[i]);
    }
  }
  return res
}

/**
 * Perform no operation.
 * Stubbing args to make Flow happy without leaving useless transpiled code
 * with ...rest (https://flow.org/blog/2017/05/07/Strict-Function-Call-Arity/)
 */
function noop (a, b, c) {}

/**
 * Always return false.
 */
const no = (a, b, c) => false;

/**
 * Return same value
 */
const identity = (_) => _;

/**
 * Generate a static keys string from compiler modules.
 */
function genStaticKeys (modules) {
  return modules.reduce((keys, m) => {
    return keys.concat(m.staticKeys || [])
  }, []).join(',')
}

/**
 * Check if two values are loosely equal - that is,
 * if they are plain objects, do they have the same shape?
 */
function looseEqual (a, b) {
  if (a === b) return true
  const isObjectA = isObject(a);
  const isObjectB = isObject(b);
  if (isObjectA && isObjectB) {
    try {
      const isArrayA = Array.isArray(a);
      const isArrayB = Array.isArray(b);
      if (isArrayA && isArrayB) {
        return a.length === b.length && a.every((e, i) => {
          return looseEqual(e, b[i])
        })
      } else if (!isArrayA && !isArrayB) {
        const keysA = Object.keys(a);
        const keysB = Object.keys(b);
        return keysA.length === keysB.length && keysA.every(key => {
          return looseEqual(a[key], b[key])
        })
      } else {
        /* istanbul ignore next */
        return false
      }
    } catch (e) {
      /* istanbul ignore next */
      return false
    }
  } else if (!isObjectA && !isObjectB) {
    return String(a) === String(b)
  } else {
    return false
  }
}

function looseIndexOf (arr, val) {
  for (let i = 0; i < arr.length; i++) {
    if (looseEqual(arr[i], val)) return i
  }
  return -1
}

/**
 * Ensure a function is called only once.
 */
function once (fn) {
  let called = false;
  return function () {
    if (!called) {
      called = true;
      fn.apply(this, arguments);
    }
  }
}

const SSR_ATTR = 'data-server-rendered';

const ASSET_TYPES = [
  'component',
  'directive',
  'filter'
];

const LIFECYCLE_HOOKS = [
  'beforeCreate',
  'created',
  'beforeMount',
  'mounted',
  'beforeUpdate',
  'updated',
  'beforeDestroy',
  'destroyed',
  'activated',
  'deactivated',
  'errorCaptured'
];

/*  */

var config = ({
  /**
   * Option merge strategies (used in core/util/options)
   */
  optionMergeStrategies: Object.create(null),

  /**
   * Whether to suppress warnings.
   */
  silent: false,

  /**
   * Show production mode tip message on boot?
   */
  productionTip: "development" !== 'production',

  /**
   * Whether to enable devtools
   */
  devtools: "development" !== 'production',

  /**
   * Whether to record perf
   */
  performance: false,

  /**
   * Error handler for watcher errors
   */
  errorHandler: null,

  /**
   * Warn handler for watcher warns
   */
  warnHandler: null,

  /**
   * Ignore certain custom elements
   */
  ignoredElements: [],

  /**
   * Custom user key aliases for v-on
   */
  keyCodes: Object.create(null),

  /**
   * Check if a tag is reserved so that it cannot be registered as a
   * component. This is platform-dependent and may be overwritten.
   */
  isReservedTag: no,

  /**
   * Check if an attribute is reserved so that it cannot be used as a component
   * prop. This is platform-dependent and may be overwritten.
   */
  isReservedAttr: no,

  /**
   * Check if a tag is an unknown element.
   * Platform-dependent.
   */
  isUnknownElement: no,

  /**
   * Get the namespace of an element
   */
  getTagNamespace: noop,

  /**
   * Parse the real tag name for the specific platform.
   */
  parsePlatformTagName: identity,

  /**
   * Check if an attribute must be bound using property, e.g. value
   * Platform-dependent.
   */
  mustUseProp: no,

  /**
   * Exposed for legacy reasons
   */
  _lifecycleHooks: LIFECYCLE_HOOKS
});

/*  */

/**
 * Check if a string starts with $ or _
 */
function isReserved (str) {
  const c = (str + '').charCodeAt(0);
  return c === 0x24 || c === 0x5F
}

/**
 * Define a property.
 */
function def (obj, key, val, enumerable) {
  Object.defineProperty(obj, key, {
    value: val,
    enumerable: !!enumerable,
    writable: true,
    configurable: true
  });
}

/**
 * Parse simple path.
 */
const bailRE = /[^\w.$]/;
function parsePath (path) {
  if (bailRE.test(path)) {
    return
  }
  const segments = path.split('.');
  return function (obj) {
    for (let i = 0; i < segments.length; i++) {
      if (!obj) return
      obj = obj[segments[i]];
    }
    return obj
  }
}

/*  */


// can we use __proto__?
const hasProto = '__proto__' in {};

// Browser environment sniffing
const inBrowser = typeof window !== 'undefined';
const inWeex = typeof WXEnvironment !== 'undefined' && !!WXEnvironment.platform;
const weexPlatform = inWeex && WXEnvironment.platform.toLowerCase();
const UA = inBrowser && window.navigator.userAgent.toLowerCase();
const isIE = UA && /msie|trident/.test(UA);
const isIE9 = UA && UA.indexOf('msie 9.0') > 0;
const isEdge = UA && UA.indexOf('edge/') > 0;
const isAndroid = (UA && UA.indexOf('android') > 0) || (weexPlatform === 'android');
const isIOS = (UA && /iphone|ipad|ipod|ios/.test(UA)) || (weexPlatform === 'ios');
const isChrome = UA && /chrome\/\d+/.test(UA) && !isEdge;

// Firefox has a "watch" function on Object.prototype...
const nativeWatch = ({}).watch;

let supportsPassive = false;
if (inBrowser) {
  try {
    const opts = {};
    Object.defineProperty(opts, 'passive', ({
      get () {
        /* istanbul ignore next */
        supportsPassive = true;
      }
    })); // https://github.com/facebook/flow/issues/285
    window.addEventListener('test-passive', null, opts);
  } catch (e) {}
}

// this needs to be lazy-evaled because vue may be required before
// vue-server-renderer can set VUE_ENV
let _isServer;
const isServerRendering = () => {
  if (_isServer === undefined) {
    /* istanbul ignore if */
    if (!inBrowser && typeof global !== 'undefined') {
      // detect presence of vue-server-renderer and avoid
      // Webpack shimming the process
      _isServer = global['process'].env.VUE_ENV === 'server';
    } else {
      _isServer = false;
    }
  }
  return _isServer
};

// detect devtools
const devtools = inBrowser && window.__VUE_DEVTOOLS_GLOBAL_HOOK__;

/* istanbul ignore next */
function isNative (Ctor) {
  return typeof Ctor === 'function' && /native code/.test(Ctor.toString())
}

const hasSymbol =
  typeof Symbol !== 'undefined' && isNative(Symbol) &&
  typeof Reflect !== 'undefined' && isNative(Reflect.ownKeys);

let _Set;
/* istanbul ignore if */ // $flow-disable-line
if (typeof Set !== 'undefined' && isNative(Set)) {
  // use native Set when available.
  _Set = Set;
} else {
  // a non-standard Set polyfill that only works with primitive keys.
  _Set = class Set   {
    
    constructor () {
      this.set = Object.create(null);
    }
    has (key) {
      return this.set[key] === true
    }
    add (key) {
      this.set[key] = true;
    }
    clear () {
      this.set = Object.create(null);
    }
  };
}

/*  */

let warn = noop;
let tip = noop;
let generateComponentTrace = (noop); // work around flow check
let formatComponentName = (noop);

{
  const hasConsole = typeof console !== 'undefined';
  const classifyRE = /(?:^|[-_])(\w)/g;
  const classify = str => str
    .replace(classifyRE, c => c.toUpperCase())
    .replace(/[-_]/g, '');

  warn = (msg, vm) => {
    const trace = vm ? generateComponentTrace(vm) : '';

    if (config.warnHandler) {
      config.warnHandler.call(null, msg, vm, trace);
    } else if (hasConsole && (!config.silent)) {
      console.error(`[Vue warn]: ${msg}${trace}`);
    }
  };

  tip = (msg, vm) => {
    if (hasConsole && (!config.silent)) {
      console.warn(`[Vue tip]: ${msg}` + (
        vm ? generateComponentTrace(vm) : ''
      ));
    }
  };

  formatComponentName = (vm, includeFile) => {
    if (vm.$root === vm) {
      return '<Root>'
    }
    const options = typeof vm === 'function' && vm.cid != null
      ? vm.options
      : vm._isVue
        ? vm.$options || vm.constructor.options
        : vm || {};
    let name = options.name || options._componentTag;
    const file = options.__file;
    if (!name && file) {
      const match = file.match(/([^/\\]+)\.vue$/);
      name = match && match[1];
    }

    return (
      (name ? `<${classify(name)}>` : `<Anonymous>`) +
      (file && includeFile !== false ? ` at ${file}` : '')
    )
  };

  const repeat = (str, n) => {
    let res = '';
    while (n) {
      if (n % 2 === 1) res += str;
      if (n > 1) str += str;
      n >>= 1;
    }
    return res
  };

  generateComponentTrace = vm => {
    if (vm._isVue && vm.$parent) {
      const tree = [];
      let currentRecursiveSequence = 0;
      while (vm) {
        if (tree.length > 0) {
          const last = tree[tree.length - 1];
          if (last.constructor === vm.constructor) {
            currentRecursiveSequence++;
            vm = vm.$parent;
            continue
          } else if (currentRecursiveSequence > 0) {
            tree[tree.length - 1] = [last, currentRecursiveSequence];
            currentRecursiveSequence = 0;
          }
        }
        tree.push(vm);
        vm = vm.$parent;
      }
      return '\n\nfound in\n\n' + tree
        .map((vm, i) => `${
          i === 0 ? '---> ' : repeat(' ', 5 + i * 2)
        }${
          Array.isArray(vm)
            ? `${formatComponentName(vm[0])}... (${vm[1]} recursive calls)`
            : formatComponentName(vm)
        }`)
        .join('\n')
    } else {
      return `\n\n(found in ${formatComponentName(vm)})`
    }
  };
}

/*  */


let uid = 0;

/**
 * A dep is an observable that can have multiple
 * directives subscribing to it.
 */
class Dep {
  
  
  

  constructor () {
    this.id = uid++;
    this.subs = [];
  }

  addSub (sub) {
    this.subs.push(sub);
  }

  removeSub (sub) {
    remove(this.subs, sub);
  }

  depend () {
    if (Dep.target) {
      Dep.target.addDep(this);
    }
  }

  notify () {
    // stabilize the subscriber list first
    const subs = this.subs.slice();
    for (let i = 0, l = subs.length; i < l; i++) {
      subs[i].update();
    }
  }
}

// the current target watcher being evaluated.
// this is globally unique because there could be only one
// watcher being evaluated at any time.
Dep.target = null;
const targetStack = [];

function pushTarget (_target) {
  if (Dep.target) targetStack.push(Dep.target);
  Dep.target = _target;
}

function popTarget () {
  Dep.target = targetStack.pop();
}

/*  */

class VNode {
  
  
  
  
  
  
   // rendered in this component's scope
  
  
   // component instance
   // component placeholder node

  // strictly internal
   // contains raw HTML? (server only)
   // hoisted static node
   // necessary for enter transition check
   // empty comment placeholder?
   // is a cloned node?
   // is a v-once node?
   // async component factory function
  
  
  
   // real context vm for functional nodes
   // for SSR caching
   // functioanl scope id support

  constructor (
    tag,
    data,
    children,
    text,
    elm,
    context,
    componentOptions,
    asyncFactory
  ) {
    this.tag = tag;
    this.data = data;
    this.children = children;
    this.text = text;
    this.elm = elm;
    this.ns = undefined;
    this.context = context;
    this.functionalContext = undefined;
    this.functionalOptions = undefined;
    this.functionalScopeId = undefined;
    this.key = data && data.key;
    this.componentOptions = componentOptions;
    this.componentInstance = undefined;
    this.parent = undefined;
    this.raw = false;
    this.isStatic = false;
    this.isRootInsert = true;
    this.isComment = false;
    this.isCloned = false;
    this.isOnce = false;
    this.asyncFactory = asyncFactory;
    this.asyncMeta = undefined;
    this.isAsyncPlaceholder = false;
  }

  // DEPRECATED: alias for componentInstance for backwards compat.
  /* istanbul ignore next */
  get child () {
    return this.componentInstance
  }
}

const createEmptyVNode = (text = '') => {
  const node = new VNode();
  node.text = text;
  node.isComment = true;
  return node
};

function createTextVNode (val) {
  return new VNode(undefined, undefined, undefined, String(val))
}

// optimized shallow clone
// used for static nodes and slot nodes because they may be reused across
// multiple renders, cloning them avoids errors when DOM manipulations rely
// on their elm reference.
function cloneVNode (vnode, deep) {
  const componentOptions = vnode.componentOptions;
  const cloned = new VNode(
    vnode.tag,
    vnode.data,
    vnode.children,
    vnode.text,
    vnode.elm,
    vnode.context,
    componentOptions,
    vnode.asyncFactory
  );
  cloned.ns = vnode.ns;
  cloned.isStatic = vnode.isStatic;
  cloned.key = vnode.key;
  cloned.isComment = vnode.isComment;
  cloned.isCloned = true;
  if (deep) {
    if (vnode.children) {
      cloned.children = cloneVNodes(vnode.children, true);
    }
    if (componentOptions && componentOptions.children) {
      componentOptions.children = cloneVNodes(componentOptions.children, true);
    }
  }
  return cloned
}

function cloneVNodes (vnodes, deep) {
  const len = vnodes.length;
  const res = new Array(len);
  for (let i = 0; i < len; i++) {
    res[i] = cloneVNode(vnodes[i], deep);
  }
  return res
}

/*
 * not type checking this file because flow doesn't play well with
 * dynamically accessing methods on Array prototype
 */

const arrayProto = Array.prototype;
const arrayMethods = Object.create(arrayProto);[
  'push',
  'pop',
  'shift',
  'unshift',
  'splice',
  'sort',
  'reverse'
]
.forEach(function (method) {
  // cache original method
  const original = arrayProto[method];
  def(arrayMethods, method, function mutator (...args) {
    const result = original.apply(this, args);
    const ob = this.__ob__;
    let inserted;
    switch (method) {
      case 'push':
      case 'unshift':
        inserted = args;
        break
      case 'splice':
        inserted = args.slice(2);
        break
    }
    if (inserted) ob.observeArray(inserted);
    // notify change
    ob.dep.notify();
    return result
  });
});

/*  */

const arrayKeys = Object.getOwnPropertyNames(arrayMethods);

/**
 * By default, when a reactive property is set, the new value is
 * also converted to become reactive. However when passing down props,
 * we don't want to force conversion because the value may be a nested value
 * under a frozen data structure. Converting it would defeat the optimization.
 */
const observerState = {
  shouldConvert: true
};

/**
 * Observer class that are attached to each observed
 * object. Once attached, the observer converts target
 * object's property keys into getter/setters that
 * collect dependencies and dispatches updates.
 */
class Observer {
  
  
   // number of vms that has this object as root $data

  constructor (value) {
    this.value = value;
    this.dep = new Dep();
    this.vmCount = 0;
    def(value, '__ob__', this);
    if (Array.isArray(value)) {
      const augment = hasProto
        ? protoAugment
        : copyAugment;
      augment(value, arrayMethods, arrayKeys);
      this.observeArray(value);
    } else {
      this.walk(value);
    }
  }

  /**
   * Walk through each property and convert them into
   * getter/setters. This method should only be called when
   * value type is Object.
   */
  walk (obj) {
    const keys = Object.keys(obj);
    for (let i = 0; i < keys.length; i++) {
      defineReactive(obj, keys[i], obj[keys[i]]);
    }
  }

  /**
   * Observe a list of Array items.
   */
  observeArray (items) {
    for (let i = 0, l = items.length; i < l; i++) {
      observe(items[i]);
    }
  }
}

// helpers

/**
 * Augment an target Object or Array by intercepting
 * the prototype chain using __proto__
 */
function protoAugment (target, src, keys) {
  /* eslint-disable no-proto */
  target.__proto__ = src;
  /* eslint-enable no-proto */
}

/**
 * Augment an target Object or Array by defining
 * hidden properties.
 */
/* istanbul ignore next */
function copyAugment (target, src, keys) {
  for (let i = 0, l = keys.length; i < l; i++) {
    const key = keys[i];
    def(target, key, src[key]);
  }
}

/**
 * Attempt to create an observer instance for a value,
 * returns the new observer if successfully observed,
 * or the existing observer if the value already has one.
 */
function observe (value, asRootData) {
  if (!isObject(value) || value instanceof VNode) {
    return
  }
  let ob;
  if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
    ob = value.__ob__;
  } else if (
    observerState.shouldConvert &&
    !isServerRendering() &&
    (Array.isArray(value) || isPlainObject(value)) &&
    Object.isExtensible(value) &&
    !value._isVue
  ) {
    ob = new Observer(value);
  }
  if (asRootData && ob) {
    ob.vmCount++;
  }
  return ob
}

/**
 * Define a reactive property on an Object.
 */
function defineReactive (
  obj,
  key,
  val,
  customSetter,
  shallow
) {
  const dep = new Dep();

  const property = Object.getOwnPropertyDescriptor(obj, key);
  if (property && property.configurable === false) {
    return
  }

  // cater for pre-defined getter/setters
  const getter = property && property.get;
  const setter = property && property.set;

  let childOb = !shallow && observe(val);
  Object.defineProperty(obj, key, {
    enumerable: true,
    configurable: true,
    get: function reactiveGetter () {
      const value = getter ? getter.call(obj) : val;
      if (Dep.target) {
        dep.depend();
        if (childOb) {
          childOb.dep.depend();
          if (Array.isArray(value)) {
            dependArray(value);
          }
        }
      }
      return value
    },
    set: function reactiveSetter (newVal) {
      const value = getter ? getter.call(obj) : val;
      /* eslint-disable no-self-compare */
      if (newVal === value || (newVal !== newVal && value !== value)) {
        return
      }
      /* eslint-enable no-self-compare */
      if ("development" !== 'production' && customSetter) {
        customSetter();
      }
      if (setter) {
        setter.call(obj, newVal);
      } else {
        val = newVal;
      }
      childOb = !shallow && observe(newVal);
      dep.notify();
    }
  });
}

/**
 * Set a property on an object. Adds the new property and
 * triggers change notification if the property doesn't
 * already exist.
 */
function set (target, key, val) {
  if (Array.isArray(target) && isValidArrayIndex(key)) {
    target.length = Math.max(target.length, key);
    target.splice(key, 1, val);
    return val
  }
  if (key in target && !(key in Object.prototype)) {
    target[key] = val;
    return val
  }
  const ob = (target).__ob__;
  if (target._isVue || (ob && ob.vmCount)) {
    "development" !== 'production' && warn(
      'Avoid adding reactive properties to a Vue instance or its root $data ' +
      'at runtime - declare it upfront in the data option.'
    );
    return val
  }
  if (!ob) {
    target[key] = val;
    return val
  }
  defineReactive(ob.value, key, val);
  ob.dep.notify();
  return val
}

/**
 * Delete a property and trigger change if necessary.
 */
function del (target, key) {
  if (Array.isArray(target) && isValidArrayIndex(key)) {
    target.splice(key, 1);
    return
  }
  const ob = (target).__ob__;
  if (target._isVue || (ob && ob.vmCount)) {
    "development" !== 'production' && warn(
      'Avoid deleting properties on a Vue instance or its root $data ' +
      '- just set it to null.'
    );
    return
  }
  if (!hasOwn(target, key)) {
    return
  }
  delete target[key];
  if (!ob) {
    return
  }
  ob.dep.notify();
}

/**
 * Collect dependencies on array elements when the array is touched, since
 * we cannot intercept array element access like property getters.
 */
function dependArray (value) {
  for (let e, i = 0, l = value.length; i < l; i++) {
    e = value[i];
    e && e.__ob__ && e.__ob__.dep.depend();
    if (Array.isArray(e)) {
      dependArray(e);
    }
  }
}

/*  */

/**
 * Option overwriting strategies are functions that handle
 * how to merge a parent option value and a child option
 * value into the final value.
 */
const strats = config.optionMergeStrategies;

/**
 * Options with restrictions
 */
{
  strats.el = strats.propsData = function (parent, child, vm, key) {
    if (!vm) {
      warn(
        `option "${key}" can only be used during instance ` +
        'creation with the `new` keyword.'
      );
    }
    return defaultStrat(parent, child)
  };
}

/**
 * Helper that recursively merges two data objects together.
 */
function mergeData (to, from) {
  if (!from) return to
  let key, toVal, fromVal;
  const keys = Object.keys(from);
  for (let i = 0; i < keys.length; i++) {
    key = keys[i];
    toVal = to[key];
    fromVal = from[key];
    if (!hasOwn(to, key)) {
      set(to, key, fromVal);
    } else if (isPlainObject(toVal) && isPlainObject(fromVal)) {
      mergeData(toVal, fromVal);
    }
  }
  return to
}

/**
 * Data
 */
function mergeDataOrFn (
  parentVal,
  childVal,
  vm
) {
  if (!vm) {
    // in a Vue.extend merge, both should be functions
    if (!childVal) {
      return parentVal
    }
    if (!parentVal) {
      return childVal
    }
    // when parentVal & childVal are both present,
    // we need to return a function that returns the
    // merged result of both functions... no need to
    // check if parentVal is a function here because
    // it has to be a function to pass previous merges.
    return function mergedDataFn () {
      return mergeData(
        typeof childVal === 'function' ? childVal.call(this) : childVal,
        typeof parentVal === 'function' ? parentVal.call(this) : parentVal
      )
    }
  } else {
    return function mergedInstanceDataFn () {
      // instance merge
      const instanceData = typeof childVal === 'function'
        ? childVal.call(vm)
        : childVal;
      const defaultData = typeof parentVal === 'function'
        ? parentVal.call(vm)
        : parentVal;
      if (instanceData) {
        return mergeData(instanceData, defaultData)
      } else {
        return defaultData
      }
    }
  }
}

strats.data = function (
  parentVal,
  childVal,
  vm
) {
  if (!vm) {
    if (childVal && typeof childVal !== 'function') {
      "development" !== 'production' && warn(
        'The "data" option should be a function ' +
        'that returns a per-instance value in component ' +
        'definitions.',
        vm
      );

      return parentVal
    }
    return mergeDataOrFn(parentVal, childVal)
  }

  return mergeDataOrFn(parentVal, childVal, vm)
};

/**
 * Hooks and props are merged as arrays.
 */
function mergeHook (
  parentVal,
  childVal
) {
  return childVal
    ? parentVal
      ? parentVal.concat(childVal)
      : Array.isArray(childVal)
        ? childVal
        : [childVal]
    : parentVal
}

LIFECYCLE_HOOKS.forEach(hook => {
  strats[hook] = mergeHook;
});

/**
 * Assets
 *
 * When a vm is present (instance creation), we need to do
 * a three-way merge between constructor options, instance
 * options and parent options.
 */
function mergeAssets (
  parentVal,
  childVal,
  vm,
  key
) {
  const res = Object.create(parentVal || null);
  if (childVal) {
    "development" !== 'production' && assertObjectType(key, childVal, vm);
    return extend(res, childVal)
  } else {
    return res
  }
}

ASSET_TYPES.forEach(function (type) {
  strats[type + 's'] = mergeAssets;
});

/**
 * Watchers.
 *
 * Watchers hashes should not overwrite one
 * another, so we merge them as arrays.
 */
strats.watch = function (
  parentVal,
  childVal,
  vm,
  key
) {
  // work around Firefox's Object.prototype.watch...
  if (parentVal === nativeWatch) parentVal = undefined;
  if (childVal === nativeWatch) childVal = undefined;
  /* istanbul ignore if */
  if (!childVal) return Object.create(parentVal || null)
  {
    assertObjectType(key, childVal, vm);
  }
  if (!parentVal) return childVal
  const ret = {};
  extend(ret, parentVal);
  for (const key in childVal) {
    let parent = ret[key];
    const child = childVal[key];
    if (parent && !Array.isArray(parent)) {
      parent = [parent];
    }
    ret[key] = parent
      ? parent.concat(child)
      : Array.isArray(child) ? child : [child];
  }
  return ret
};

/**
 * Other object hashes.
 */
strats.props =
strats.methods =
strats.inject =
strats.computed = function (
  parentVal,
  childVal,
  vm,
  key
) {
  if (childVal && "development" !== 'production') {
    assertObjectType(key, childVal, vm);
  }
  if (!parentVal) return childVal
  const ret = Object.create(null);
  extend(ret, parentVal);
  if (childVal) extend(ret, childVal);
  return ret
};
strats.provide = mergeDataOrFn;

/**
 * Default strategy.
 */
const defaultStrat = function (parentVal, childVal) {
  return childVal === undefined
    ? parentVal
    : childVal
};

/**
 * Validate component names
 */
function checkComponents (options) {
  for (const key in options.components) {
    const lower = key.toLowerCase();
    if (isBuiltInTag(lower) || config.isReservedTag(lower)) {
      warn(
        'Do not use built-in or reserved HTML elements as component ' +
        'id: ' + key
      );
    }
  }
}

/**
 * Ensure all props option syntax are normalized into the
 * Object-based format.
 */
function normalizeProps (options, vm) {
  const props = options.props;
  if (!props) return
  const res = {};
  let i, val, name;
  if (Array.isArray(props)) {
    i = props.length;
    while (i--) {
      val = props[i];
      if (typeof val === 'string') {
        name = camelize(val);
        res[name] = { type: null };
      } else {
        warn('props must be strings when using array syntax.');
      }
    }
  } else if (isPlainObject(props)) {
    for (const key in props) {
      val = props[key];
      name = camelize(key);
      res[name] = isPlainObject(val)
        ? val
        : { type: val };
    }
  } else {
    warn(
      `Invalid value for option "props": expected an Array or an Object, ` +
      `but got ${toRawType(props)}.`,
      vm
    );
  }
  options.props = res;
}

/**
 * Normalize all injections into Object-based format
 */
function normalizeInject (options, vm) {
  const inject = options.inject;
  const normalized = options.inject = {};
  if (Array.isArray(inject)) {
    for (let i = 0; i < inject.length; i++) {
      normalized[inject[i]] = { from: inject[i] };
    }
  } else if (isPlainObject(inject)) {
    for (const key in inject) {
      const val = inject[key];
      normalized[key] = isPlainObject(val)
        ? extend({ from: key }, val)
        : { from: val };
    }
  } else if ("development" !== 'production' && inject) {
    warn(
      `Invalid value for option "inject": expected an Array or an Object, ` +
      `but got ${toRawType(inject)}.`,
      vm
    );
  }
}

/**
 * Normalize raw function directives into object format.
 */
function normalizeDirectives (options) {
  const dirs = options.directives;
  if (dirs) {
    for (const key in dirs) {
      const def = dirs[key];
      if (typeof def === 'function') {
        dirs[key] = { bind: def, update: def };
      }
    }
  }
}

function assertObjectType (name, value, vm) {
  if (!isPlainObject(value)) {
    warn(
      `Invalid value for option "${name}": expected an Object, ` +
      `but got ${toRawType(value)}.`,
      vm
    );
  }
}

/**
 * Merge two option objects into a new one.
 * Core utility used in both instantiation and inheritance.
 */
function mergeOptions (
  parent,
  child,
  vm
) {
  {
    checkComponents(child);
  }

  if (typeof child === 'function') {
    child = child.options;
  }

  normalizeProps(child, vm);
  normalizeInject(child, vm);
  normalizeDirectives(child);
  const extendsFrom = child.extends;
  if (extendsFrom) {
    parent = mergeOptions(parent, extendsFrom, vm);
  }
  if (child.mixins) {
    for (let i = 0, l = child.mixins.length; i < l; i++) {
      parent = mergeOptions(parent, child.mixins[i], vm);
    }
  }
  const options = {};
  let key;
  for (key in parent) {
    mergeField(key);
  }
  for (key in child) {
    if (!hasOwn(parent, key)) {
      mergeField(key);
    }
  }
  function mergeField (key) {
    const strat = strats[key] || defaultStrat;
    options[key] = strat(parent[key], child[key], vm, key);
  }
  return options
}

/**
 * Resolve an asset.
 * This function is used because child instances need access
 * to assets defined in its ancestor chain.
 */
function resolveAsset (
  options,
  type,
  id,
  warnMissing
) {
  /* istanbul ignore if */
  if (typeof id !== 'string') {
    return
  }
  const assets = options[type];
  // check local registration variations first
  if (hasOwn(assets, id)) return assets[id]
  const camelizedId = camelize(id);
  if (hasOwn(assets, camelizedId)) return assets[camelizedId]
  const PascalCaseId = capitalize(camelizedId);
  if (hasOwn(assets, PascalCaseId)) return assets[PascalCaseId]
  // fallback to prototype chain
  const res = assets[id] || assets[camelizedId] || assets[PascalCaseId];
  if ("development" !== 'production' && warnMissing && !res) {
    warn(
      'Failed to resolve ' + type.slice(0, -1) + ': ' + id,
      options
    );
  }
  return res
}

/*  */

function validateProp (
  key,
  propOptions,
  propsData,
  vm
) {
  const prop = propOptions[key];
  const absent = !hasOwn(propsData, key);
  let value = propsData[key];
  // handle boolean props
  if (isType(Boolean, prop.type)) {
    if (absent && !hasOwn(prop, 'default')) {
      value = false;
    } else if (!isType(String, prop.type) && (value === '' || value === hyphenate(key))) {
      value = true;
    }
  }
  // check default value
  if (value === undefined) {
    value = getPropDefaultValue(vm, prop, key);
    // since the default value is a fresh copy,
    // make sure to observe it.
    const prevShouldConvert = observerState.shouldConvert;
    observerState.shouldConvert = true;
    observe(value);
    observerState.shouldConvert = prevShouldConvert;
  }
  {
    assertProp(prop, key, value, vm, absent);
  }
  return value
}

/**
 * Get the default value of a prop.
 */
function getPropDefaultValue (vm, prop, key) {
  // no default, return undefined
  if (!hasOwn(prop, 'default')) {
    return undefined
  }
  const def = prop.default;
  // warn against non-factory defaults for Object & Array
  if ("development" !== 'production' && isObject(def)) {
    warn(
      'Invalid default value for prop "' + key + '": ' +
      'Props with type Object/Array must use a factory function ' +
      'to return the default value.',
      vm
    );
  }
  // the raw prop value was also undefined from previous render,
  // return previous default value to avoid unnecessary watcher trigger
  if (vm && vm.$options.propsData &&
    vm.$options.propsData[key] === undefined &&
    vm._props[key] !== undefined
  ) {
    return vm._props[key]
  }
  // call factory function for non-Function types
  // a value is Function if its prototype is function even across different execution context
  return typeof def === 'function' && getType(prop.type) !== 'Function'
    ? def.call(vm)
    : def
}

/**
 * Assert whether a prop is valid.
 */
function assertProp (
  prop,
  name,
  value,
  vm,
  absent
) {
  if (prop.required && absent) {
    warn(
      'Missing required prop: "' + name + '"',
      vm
    );
    return
  }
  if (value == null && !prop.required) {
    return
  }
  let type = prop.type;
  let valid = !type || type === true;
  const expectedTypes = [];
  if (type) {
    if (!Array.isArray(type)) {
      type = [type];
    }
    for (let i = 0; i < type.length && !valid; i++) {
      const assertedType = assertType(value, type[i]);
      expectedTypes.push(assertedType.expectedType || '');
      valid = assertedType.valid;
    }
  }
  if (!valid) {
    warn(
      `Invalid prop: type check failed for prop "${name}".` +
      ` Expected ${expectedTypes.map(capitalize).join(', ')}` +
      `, got ${toRawType(value)}.`,
      vm
    );
    return
  }
  const validator = prop.validator;
  if (validator) {
    if (!validator(value)) {
      warn(
        'Invalid prop: custom validator check failed for prop "' + name + '".',
        vm
      );
    }
  }
}

const simpleCheckRE = /^(String|Number|Boolean|Function|Symbol)$/;

function assertType (value, type) {
  let valid;
  const expectedType = getType(type);
  if (simpleCheckRE.test(expectedType)) {
    const t = typeof value;
    valid = t === expectedType.toLowerCase();
    // for primitive wrapper objects
    if (!valid && t === 'object') {
      valid = value instanceof type;
    }
  } else if (expectedType === 'Object') {
    valid = isPlainObject(value);
  } else if (expectedType === 'Array') {
    valid = Array.isArray(value);
  } else {
    valid = value instanceof type;
  }
  return {
    valid,
    expectedType
  }
}

/**
 * Use function string name to check built-in types,
 * because a simple equality check will fail when running
 * across different vms / iframes.
 */
function getType (fn) {
  const match = fn && fn.toString().match(/^\s*function (\w+)/);
  return match ? match[1] : ''
}

function isType (type, fn) {
  if (!Array.isArray(fn)) {
    return getType(fn) === getType(type)
  }
  for (let i = 0, len = fn.length; i < len; i++) {
    if (getType(fn[i]) === getType(type)) {
      return true
    }
  }
  /* istanbul ignore next */
  return false
}

/*  */

function handleError (err, vm, info) {
  if (vm) {
    let cur = vm;
    while ((cur = cur.$parent)) {
      const hooks = cur.$options.errorCaptured;
      if (hooks) {
        for (let i = 0; i < hooks.length; i++) {
          try {
            const capture = hooks[i].call(cur, err, vm, info) === false;
            if (capture) return
          } catch (e) {
            globalHandleError(e, cur, 'errorCaptured hook');
          }
        }
      }
    }
  }
  globalHandleError(err, vm, info);
}

function globalHandleError (err, vm, info) {
  if (config.errorHandler) {
    try {
      return config.errorHandler.call(null, err, vm, info)
    } catch (e) {
      logError(e, null, 'config.errorHandler');
    }
  }
  logError(err, vm, info);
}

function logError (err, vm, info) {
  {
    warn(`Error in ${info}: "${err.toString()}"`, vm);
  }
  /* istanbul ignore else */
  if ((inBrowser || inWeex) && typeof console !== 'undefined') {
    console.error(err);
  } else {
    throw err
  }
}

/*  */
/* globals MessageChannel */

const callbacks = [];
let pending = false;

function flushCallbacks () {
  pending = false;
  const copies = callbacks.slice(0);
  callbacks.length = 0;
  for (let i = 0; i < copies.length; i++) {
    copies[i]();
  }
}

// Here we have async deferring wrappers using both micro and macro tasks.
// In < 2.4 we used micro tasks everywhere, but there are some scenarios where
// micro tasks have too high a priority and fires in between supposedly
// sequential events (e.g. #4521, #6690) or even between bubbling of the same
// event (#6566). However, using macro tasks everywhere also has subtle problems
// when state is changed right before repaint (e.g. #6813, out-in transitions).
// Here we use micro task by default, but expose a way to force macro task when
// needed (e.g. in event handlers attached by v-on).
let microTimerFunc;
let macroTimerFunc;
let useMacroTask = false;

// Determine (macro) Task defer implementation.
// Technically setImmediate should be the ideal choice, but it's only available
// in IE. The only polyfill that consistently queues the callback after all DOM
// events triggered in the same loop is by using MessageChannel.
/* istanbul ignore if */
if (typeof setImmediate !== 'undefined' && isNative(setImmediate)) {
  macroTimerFunc = () => {
    setImmediate(flushCallbacks);
  };
} else if (typeof MessageChannel !== 'undefined' && (
  isNative(MessageChannel) ||
  // PhantomJS
  MessageChannel.toString() === '[object MessageChannelConstructor]'
)) {
  const channel = new MessageChannel();
  const port = channel.port2;
  channel.port1.onmessage = flushCallbacks;
  macroTimerFunc = () => {
    port.postMessage(1);
  };
} else {
  /* istanbul ignore next */
  macroTimerFunc = () => {
    setTimeout(flushCallbacks, 0);
  };
}

// Determine MicroTask defer implementation.
/* istanbul ignore next, $flow-disable-line */
if (typeof Promise !== 'undefined' && isNative(Promise)) {
  const p = Promise.resolve();
  microTimerFunc = () => {
    p.then(flushCallbacks);
    // in problematic UIWebViews, Promise.then doesn't completely break, but
    // it can get stuck in a weird state where callbacks are pushed into the
    // microtask queue but the queue isn't being flushed, until the browser
    // needs to do some other work, e.g. handle a timer. Therefore we can
    // "force" the microtask queue to be flushed by adding an empty timer.
    if (isIOS) setTimeout(noop);
  };
} else {
  // fallback to macro
  microTimerFunc = macroTimerFunc;
}

/**
 * Wrap a function so that if any code inside triggers state change,
 * the changes are queued using a Task instead of a MicroTask.
 */
function withMacroTask (fn) {
  return fn._withTask || (fn._withTask = function () {
    useMacroTask = true;
    const res = fn.apply(null, arguments);
    useMacroTask = false;
    return res
  })
}

function nextTick (cb, ctx) {
  let _resolve;
  callbacks.push(() => {
    if (cb) {
      try {
        cb.call(ctx);
      } catch (e) {
        handleError(e, ctx, 'nextTick');
      }
    } else if (_resolve) {
      _resolve(ctx);
    }
  });
  if (!pending) {
    pending = true;
    if (useMacroTask) {
      macroTimerFunc();
    } else {
      microTimerFunc();
    }
  }
  // $flow-disable-line
  if (!cb && typeof Promise !== 'undefined') {
    return new Promise(resolve => {
      _resolve = resolve;
    })
  }
}

/*  */

let mark;
let measure;

{
  const perf = inBrowser && window.performance;
  /* istanbul ignore if */
  if (
    perf &&
    perf.mark &&
    perf.measure &&
    perf.clearMarks &&
    perf.clearMeasures
  ) {
    mark = tag => perf.mark(tag);
    measure = (name, startTag, endTag) => {
      perf.measure(name, startTag, endTag);
      perf.clearMarks(startTag);
      perf.clearMarks(endTag);
      perf.clearMeasures(name);
    };
  }
}

/* not type checking this file because flow doesn't play well with Proxy */

let initProxy;

{
  const allowedGlobals = makeMap(
    'Infinity,undefined,NaN,isFinite,isNaN,' +
    'parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,' +
    'Math,Number,Date,Array,Object,Boolean,String,RegExp,Map,Set,JSON,Intl,' +
    'require' // for Webpack/Browserify
  );

  const warnNonPresent = (target, key) => {
    warn(
      `Property or method "${key}" is not defined on the instance but ` +
      'referenced during render. Make sure that this property is reactive, ' +
      'either in the data option, or for class-based components, by ' +
      'initializing the property. ' +
      'See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.',
      target
    );
  };

  const hasProxy =
    typeof Proxy !== 'undefined' &&
    Proxy.toString().match(/native code/);

  if (hasProxy) {
    const isBuiltInModifier = makeMap('stop,prevent,self,ctrl,shift,alt,meta,exact');
    config.keyCodes = new Proxy(config.keyCodes, {
      set (target, key, value) {
        if (isBuiltInModifier(key)) {
          warn(`Avoid overwriting built-in modifier in config.keyCodes: .${key}`);
          return false
        } else {
          target[key] = value;
          return true
        }
      }
    });
  }

  const hasHandler = {
    has (target, key) {
      const has = key in target;
      const isAllowed = allowedGlobals(key) || key.charAt(0) === '_';
      if (!has && !isAllowed) {
        warnNonPresent(target, key);
      }
      return has || !isAllowed
    }
  };

  const getHandler = {
    get (target, key) {
      if (typeof key === 'string' && !(key in target)) {
        warnNonPresent(target, key);
      }
      return target[key]
    }
  };

  initProxy = function initProxy (vm) {
    if (hasProxy) {
      // determine which proxy handler to use
      const options = vm.$options;
      const handlers = options.render && options.render._withStripped
        ? getHandler
        : hasHandler;
      vm._renderProxy = new Proxy(vm, handlers);
    } else {
      vm._renderProxy = vm;
    }
  };
}

/*  */

const seenObjects = new _Set();

/**
 * Recursively traverse an object to evoke all converted
 * getters, so that every nested property inside the object
 * is collected as a "deep" dependency.
 */
function traverse (val) {
  _traverse(val, seenObjects);
  seenObjects.clear();
}

function _traverse (val, seen) {
  let i, keys;
  const isA = Array.isArray(val);
  if ((!isA && !isObject(val)) || Object.isFrozen(val)) {
    return
  }
  if (val.__ob__) {
    const depId = val.__ob__.dep.id;
    if (seen.has(depId)) {
      return
    }
    seen.add(depId);
  }
  if (isA) {
    i = val.length;
    while (i--) _traverse(val[i], seen);
  } else {
    keys = Object.keys(val);
    i = keys.length;
    while (i--) _traverse(val[keys[i]], seen);
  }
}

/*  */

const normalizeEvent = cached((name) => {
  const passive = name.charAt(0) === '&';
  name = passive ? name.slice(1) : name;
  const once$$1 = name.charAt(0) === '~'; // Prefixed last, checked first
  name = once$$1 ? name.slice(1) : name;
  const capture = name.charAt(0) === '!';
  name = capture ? name.slice(1) : name;
  return {
    name,
    once: once$$1,
    capture,
    passive
  }
});

function createFnInvoker (fns) {
  function invoker () {
    const fns = invoker.fns;
    if (Array.isArray(fns)) {
      const cloned = fns.slice();
      for (let i = 0; i < cloned.length; i++) {
        cloned[i].apply(null, arguments);
      }
    } else {
      // return handler return value for single handlers
      return fns.apply(null, arguments)
    }
  }
  invoker.fns = fns;
  return invoker
}

function updateListeners (
  on,
  oldOn,
  add,
  remove$$1,
  vm
) {
  let name, cur, old, event;
  for (name in on) {
    cur = on[name];
    old = oldOn[name];
    event = normalizeEvent(name);
    if (isUndef(cur)) {
      "development" !== 'production' && warn(
        `Invalid handler for event "${event.name}": got ` + String(cur),
        vm
      );
    } else if (isUndef(old)) {
      if (isUndef(cur.fns)) {
        cur = on[name] = createFnInvoker(cur);
      }
      add(event.name, cur, event.once, event.capture, event.passive);
    } else if (cur !== old) {
      old.fns = cur;
      on[name] = old;
    }
  }
  for (name in oldOn) {
    if (isUndef(on[name])) {
      event = normalizeEvent(name);
      remove$$1(event.name, oldOn[name], event.capture);
    }
  }
}

/*  */

function mergeVNodeHook (def, hookKey, hook) {
  if (def instanceof VNode) {
    def = def.data.hook || (def.data.hook = {});
  }
  let invoker;
  const oldHook = def[hookKey];

  function wrappedHook () {
    hook.apply(this, arguments);
    // important: remove merged hook to ensure it's called only once
    // and prevent memory leak
    remove(invoker.fns, wrappedHook);
  }

  if (isUndef(oldHook)) {
    // no existing hook
    invoker = createFnInvoker([wrappedHook]);
  } else {
    /* istanbul ignore if */
    if (isDef(oldHook.fns) && isTrue(oldHook.merged)) {
      // already a merged invoker
      invoker = oldHook;
      invoker.fns.push(wrappedHook);
    } else {
      // existing plain hook
      invoker = createFnInvoker([oldHook, wrappedHook]);
    }
  }

  invoker.merged = true;
  def[hookKey] = invoker;
}

/*  */

function extractPropsFromVNodeData (
  data,
  Ctor,
  tag
) {
  // we are only extracting raw values here.
  // validation and default values are handled in the child
  // component itself.
  const propOptions = Ctor.options.props;
  if (isUndef(propOptions)) {
    return
  }
  const res = {};
  const { attrs, props } = data;
  if (isDef(attrs) || isDef(props)) {
    for (const key in propOptions) {
      const altKey = hyphenate(key);
      {
        const keyInLowerCase = key.toLowerCase();
        if (
          key !== keyInLowerCase &&
          attrs && hasOwn(attrs, keyInLowerCase)
        ) {
          tip(
            `Prop "${keyInLowerCase}" is passed to component ` +
            `${formatComponentName(tag || Ctor)}, but the declared prop name is` +
            ` "${key}". ` +
            `Note that HTML attributes are case-insensitive and camelCased ` +
            `props need to use their kebab-case equivalents when using in-DOM ` +
            `templates. You should probably use "${altKey}" instead of "${key}".`
          );
        }
      }
      checkProp(res, props, key, altKey, true) ||
      checkProp(res, attrs, key, altKey, false);
    }
  }
  return res
}

function checkProp (
  res,
  hash,
  key,
  altKey,
  preserve
) {
  if (isDef(hash)) {
    if (hasOwn(hash, key)) {
      res[key] = hash[key];
      if (!preserve) {
        delete hash[key];
      }
      return true
    } else if (hasOwn(hash, altKey)) {
      res[key] = hash[altKey];
      if (!preserve) {
        delete hash[altKey];
      }
      return true
    }
  }
  return false
}

/*  */

// The template compiler attempts to minimize the need for normalization by
// statically analyzing the template at compile time.
//
// For plain HTML markup, normalization can be completely skipped because the
// generated render function is guaranteed to return Array<VNode>. There are
// two cases where extra normalization is needed:

// 1. When the children contains components - because a functional component
// may return an Array instead of a single root. In this case, just a simple
// normalization is needed - if any child is an Array, we flatten the whole
// thing with Array.prototype.concat. It is guaranteed to be only 1-level deep
// because functional components already normalize their own children.
function simpleNormalizeChildren (children) {
  for (let i = 0; i < children.length; i++) {
    if (Array.isArray(children[i])) {
      return Array.prototype.concat.apply([], children)
    }
  }
  return children
}

// 2. When the children contains constructs that always generated nested Arrays,
// e.g. <template>, <slot>, v-for, or when the children is provided by user
// with hand-written render functions / JSX. In such cases a full normalization
// is needed to cater to all possible types of children values.
function normalizeChildren (children) {
  return isPrimitive(children)
    ? [createTextVNode(children)]
    : Array.isArray(children)
      ? normalizeArrayChildren(children)
      : undefined
}

function isTextNode (node) {
  return isDef(node) && isDef(node.text) && isFalse(node.isComment)
}

function normalizeArrayChildren (children, nestedIndex) {
  const res = [];
  let i, c, lastIndex, last;
  for (i = 0; i < children.length; i++) {
    c = children[i];
    if (isUndef(c) || typeof c === 'boolean') continue
    lastIndex = res.length - 1;
    last = res[lastIndex];
    //  nested
    if (Array.isArray(c)) {
      if (c.length > 0) {
        c = normalizeArrayChildren(c, `${nestedIndex || ''}_${i}`);
        // merge adjacent text nodes
        if (isTextNode(c[0]) && isTextNode(last)) {
          res[lastIndex] = createTextVNode(last.text + (c[0]).text);
          c.shift();
        }
        res.push.apply(res, c);
      }
    } else if (isPrimitive(c)) {
      if (isTextNode(last)) {
        // merge adjacent text nodes
        // this is necessary for SSR hydration because text nodes are
        // essentially merged when rendered to HTML strings
        res[lastIndex] = createTextVNode(last.text + c);
      } else if (c !== '') {
        // convert primitive to vnode
        res.push(createTextVNode(c));
      }
    } else {
      if (isTextNode(c) && isTextNode(last)) {
        // merge adjacent text nodes
        res[lastIndex] = createTextVNode(last.text + c.text);
      } else {
        // default key for nested array children (likely generated by v-for)
        if (isTrue(children._isVList) &&
          isDef(c.tag) &&
          isUndef(c.key) &&
          isDef(nestedIndex)) {
          c.key = `__vlist${nestedIndex}_${i}__`;
        }
        res.push(c);
      }
    }
  }
  return res
}

/*  */

function ensureCtor (comp, base) {
  if (
    comp.__esModule ||
    (hasSymbol && comp[Symbol.toStringTag] === 'Module')
  ) {
    comp = comp.default;
  }
  return isObject(comp)
    ? base.extend(comp)
    : comp
}

function createAsyncPlaceholder (
  factory,
  data,
  context,
  children,
  tag
) {
  const node = createEmptyVNode();
  node.asyncFactory = factory;
  node.asyncMeta = { data, context, children, tag };
  return node
}

function resolveAsyncComponent (
  factory,
  baseCtor,
  context
) {
  if (isTrue(factory.error) && isDef(factory.errorComp)) {
    return factory.errorComp
  }

  if (isDef(factory.resolved)) {
    return factory.resolved
  }

  if (isTrue(factory.loading) && isDef(factory.loadingComp)) {
    return factory.loadingComp
  }

  if (isDef(factory.contexts)) {
    // already pending
    factory.contexts.push(context);
  } else {
    const contexts = factory.contexts = [context];
    let sync = true;

    const forceRender = () => {
      for (let i = 0, l = contexts.length; i < l; i++) {
        contexts[i].$forceUpdate();
      }
    };

    const resolve = once((res) => {
      // cache resolved
      factory.resolved = ensureCtor(res, baseCtor);
      // invoke callbacks only if this is not a synchronous resolve
      // (async resolves are shimmed as synchronous during SSR)
      if (!sync) {
        forceRender();
      }
    });

    const reject = once(reason => {
      "development" !== 'production' && warn(
        `Failed to resolve async component: ${String(factory)}` +
        (reason ? `\nReason: ${reason}` : '')
      );
      if (isDef(factory.errorComp)) {
        factory.error = true;
        forceRender();
      }
    });

    const res = factory(resolve, reject);

    if (isObject(res)) {
      if (typeof res.then === 'function') {
        // () => Promise
        if (isUndef(factory.resolved)) {
          res.then(resolve, reject);
        }
      } else if (isDef(res.component) && typeof res.component.then === 'function') {
        res.component.then(resolve, reject);

        if (isDef(res.error)) {
          factory.errorComp = ensureCtor(res.error, baseCtor);
        }

        if (isDef(res.loading)) {
          factory.loadingComp = ensureCtor(res.loading, baseCtor);
          if (res.delay === 0) {
            factory.loading = true;
          } else {
            setTimeout(() => {
              if (isUndef(factory.resolved) && isUndef(factory.error)) {
                factory.loading = true;
                forceRender();
              }
            }, res.delay || 200);
          }
        }

        if (isDef(res.timeout)) {
          setTimeout(() => {
            if (isUndef(factory.resolved)) {
              reject(
                `timeout (${res.timeout}ms)`
              );
            }
          }, res.timeout);
        }
      }
    }

    sync = false;
    // return in case resolved synchronously
    return factory.loading
      ? factory.loadingComp
      : factory.resolved
  }
}

/*  */

function isAsyncPlaceholder (node) {
  return node.isComment && node.asyncFactory
}

/*  */

function getFirstComponentChild (children) {
  if (Array.isArray(children)) {
    for (let i = 0; i < children.length; i++) {
      const c = children[i];
      if (isDef(c) && (isDef(c.componentOptions) || isAsyncPlaceholder(c))) {
        return c
      }
    }
  }
}

/*  */

/*  */

function initEvents (vm) {
  vm._events = Object.create(null);
  vm._hasHookEvent = false;
  // init parent attached events
  const listeners = vm.$options._parentListeners;
  if (listeners) {
    updateComponentListeners(vm, listeners);
  }
}

let target;

function add (event, fn, once) {
  if (once) {
    target.$once(event, fn);
  } else {
    target.$on(event, fn);
  }
}

function remove$1 (event, fn) {
  target.$off(event, fn);
}

function updateComponentListeners (
  vm,
  listeners,
  oldListeners
) {
  target = vm;
  updateListeners(listeners, oldListeners || {}, add, remove$1, vm);
  target = undefined;
}

function eventsMixin (Vue) {
  const hookRE = /^hook:/;
  Vue.prototype.$on = function (event, fn) {
    const vm = this;
    if (Array.isArray(event)) {
      for (let i = 0, l = event.length; i < l; i++) {
        this.$on(event[i], fn);
      }
    } else {
      (vm._events[event] || (vm._events[event] = [])).push(fn);
      // optimize hook:event cost by using a boolean flag marked at registration
      // instead of a hash lookup
      if (hookRE.test(event)) {
        vm._hasHookEvent = true;
      }
    }
    return vm
  };

  Vue.prototype.$once = function (event, fn) {
    const vm = this;
    function on () {
      vm.$off(event, on);
      fn.apply(vm, arguments);
    }
    on.fn = fn;
    vm.$on(event, on);
    return vm
  };

  Vue.prototype.$off = function (event, fn) {
    const vm = this;
    // all
    if (!arguments.length) {
      vm._events = Object.create(null);
      return vm
    }
    // array of events
    if (Array.isArray(event)) {
      for (let i = 0, l = event.length; i < l; i++) {
        this.$off(event[i], fn);
      }
      return vm
    }
    // specific event
    const cbs = vm._events[event];
    if (!cbs) {
      return vm
    }
    if (!fn) {
      vm._events[event] = null;
      return vm
    }
    if (fn) {
      // specific handler
      let cb;
      let i = cbs.length;
      while (i--) {
        cb = cbs[i];
        if (cb === fn || cb.fn === fn) {
          cbs.splice(i, 1);
          break
        }
      }
    }
    return vm
  };

  Vue.prototype.$emit = function (event) {
    const vm = this;
    {
      const lowerCaseEvent = event.toLowerCase();
      if (lowerCaseEvent !== event && vm._events[lowerCaseEvent]) {
        tip(
          `Event "${lowerCaseEvent}" is emitted in component ` +
          `${formatComponentName(vm)} but the handler is registered for "${event}". ` +
          `Note that HTML attributes are case-insensitive and you cannot use ` +
          `v-on to listen to camelCase events when using in-DOM templates. ` +
          `You should probably use "${hyphenate(event)}" instead of "${event}".`
        );
      }
    }
    let cbs = vm._events[event];
    if (cbs) {
      cbs = cbs.length > 1 ? toArray(cbs) : cbs;
      const args = toArray(arguments, 1);
      for (let i = 0, l = cbs.length; i < l; i++) {
        try {
          cbs[i].apply(vm, args);
        } catch (e) {
          handleError(e, vm, `event handler for "${event}"`);
        }
      }
    }
    return vm
  };
}

/*  */

/**
 * Runtime helper for resolving raw children VNodes into a slot object.
 */
function resolveSlots (
  children,
  context
) {
  const slots = {};
  if (!children) {
    return slots
  }
  for (let i = 0, l = children.length; i < l; i++) {
    const child = children[i];
    const data = child.data;
    // remove slot attribute if the node is resolved as a Vue slot node
    if (data && data.attrs && data.attrs.slot) {
      delete data.attrs.slot;
    }
    // named slots should only be respected if the vnode was rendered in the
    // same context.
    if ((child.context === context || child.functionalContext === context) &&
      data && data.slot != null
    ) {
      const name = child.data.slot;
      const slot = (slots[name] || (slots[name] = []));
      if (child.tag === 'template') {
        slot.push.apply(slot, child.children);
      } else {
        slot.push(child);
      }
    } else {
      (slots.default || (slots.default = [])).push(child);
    }
  }
  // ignore slots that contains only whitespace
  for (const name in slots) {
    if (slots[name].every(isWhitespace)) {
      delete slots[name];
    }
  }
  return slots
}

function isWhitespace (node) {
  return (node.isComment && !node.asyncFactory) || node.text === ' '
}

function resolveScopedSlots (
  fns, // see flow/vnode
  res
) {
  res = res || {};
  for (let i = 0; i < fns.length; i++) {
    if (Array.isArray(fns[i])) {
      resolveScopedSlots(fns[i], res);
    } else {
      res[fns[i].key] = fns[i].fn;
    }
  }
  return res
}

/*  */

let activeInstance = null;
let isUpdatingChildComponent = false;

function initLifecycle (vm) {
  const options = vm.$options;

  // locate first non-abstract parent
  let parent = options.parent;
  if (parent && !options.abstract) {
    while (parent.$options.abstract && parent.$parent) {
      parent = parent.$parent;
    }
    parent.$children.push(vm);
  }

  vm.$parent = parent;
  vm.$root = parent ? parent.$root : vm;

  vm.$children = [];
  vm.$refs = {};

  vm._watcher = null;
  vm._inactive = null;
  vm._directInactive = false;
  vm._isMounted = false;
  vm._isDestroyed = false;
  vm._isBeingDestroyed = false;
}

function lifecycleMixin (Vue) {
  Vue.prototype._update = function (vnode, hydrating) {
    const vm = this;
    if (vm._isMounted) {
      callHook(vm, 'beforeUpdate');
    }
    const prevEl = vm.$el;
    const prevVnode = vm._vnode;
    const prevActiveInstance = activeInstance;
    activeInstance = vm;
    vm._vnode = vnode;
    // Vue.prototype.__patch__ is injected in entry points
    // based on the rendering backend used.
    if (!prevVnode) {
      // initial render
      vm.$el = vm.__patch__(
        vm.$el, vnode, hydrating, false /* removeOnly */,
        vm.$options._parentElm,
        vm.$options._refElm
      );
      // no need for the ref nodes after initial patch
      // this prevents keeping a detached DOM tree in memory (#5851)
      vm.$options._parentElm = vm.$options._refElm = null;
    } else {
      // updates
      vm.$el = vm.__patch__(prevVnode, vnode);
    }
    activeInstance = prevActiveInstance;
    // update __vue__ reference
    if (prevEl) {
      prevEl.__vue__ = null;
    }
    if (vm.$el) {
      vm.$el.__vue__ = vm;
    }
    // if parent is an HOC, update its $el as well
    if (vm.$vnode && vm.$parent && vm.$vnode === vm.$parent._vnode) {
      vm.$parent.$el = vm.$el;
    }
    // updated hook is called by the scheduler to ensure that children are
    // updated in a parent's updated hook.
  };

  Vue.prototype.$forceUpdate = function () {
    const vm = this;
    if (vm._watcher) {
      vm._watcher.update();
    }
  };

  Vue.prototype.$destroy = function () {
    const vm = this;
    if (vm._isBeingDestroyed) {
      return
    }
    callHook(vm, 'beforeDestroy');
    vm._isBeingDestroyed = true;
    // remove self from parent
    const parent = vm.$parent;
    if (parent && !parent._isBeingDestroyed && !vm.$options.abstract) {
      remove(parent.$children, vm);
    }
    // teardown watchers
    if (vm._watcher) {
      vm._watcher.teardown();
    }
    let i = vm._watchers.length;
    while (i--) {
      vm._watchers[i].teardown();
    }
    // remove reference from data ob
    // frozen object may not have observer.
    if (vm._data.__ob__) {
      vm._data.__ob__.vmCount--;
    }
    // call the last hook...
    vm._isDestroyed = true;
    // invoke destroy hooks on current rendered tree
    vm.__patch__(vm._vnode, null);
    // fire destroyed hook
    callHook(vm, 'destroyed');
    // turn off all instance listeners.
    vm.$off();
    // remove __vue__ reference
    if (vm.$el) {
      vm.$el.__vue__ = null;
    }
    // release circular reference (#6759)
    if (vm.$vnode) {
      vm.$vnode.parent = null;
    }
  };
}

function mountComponent (
  vm,
  el,
  hydrating
) {
  vm.$el = el;
  if (!vm.$options.render) {
    vm.$options.render = createEmptyVNode;
    {
      /* istanbul ignore if */
      if ((vm.$options.template && vm.$options.template.charAt(0) !== '#') ||
        vm.$options.el || el) {
        warn(
          'You are using the runtime-only build of Vue where the template ' +
          'compiler is not available. Either pre-compile the templates into ' +
          'render functions, or use the compiler-included build.',
          vm
        );
      } else {
        warn(
          'Failed to mount component: template or render function not defined.',
          vm
        );
      }
    }
  }
  callHook(vm, 'beforeMount');

  let updateComponent;
  /* istanbul ignore if */
  if ("development" !== 'production' && config.performance && mark) {
    updateComponent = () => {
      const name = vm._name;
      const id = vm._uid;
      const startTag = `vue-perf-start:${id}`;
      const endTag = `vue-perf-end:${id}`;

      mark(startTag);
      const vnode = vm._render();
      mark(endTag);
      measure(`vue ${name} render`, startTag, endTag);

      mark(startTag);
      vm._update(vnode, hydrating);
      mark(endTag);
      measure(`vue ${name} patch`, startTag, endTag);
    };
  } else {
    updateComponent = () => {
      vm._update(vm._render(), hydrating);
    };
  }

  vm._watcher = new Watcher(vm, updateComponent, noop);
  hydrating = false;

  // manually mounted instance, call mounted on self
  // mounted is called for render-created child components in its inserted hook
  if (vm.$vnode == null) {
    vm._isMounted = true;
    callHook(vm, 'mounted');
  }
  return vm
}

function updateChildComponent (
  vm,
  propsData,
  listeners,
  parentVnode,
  renderChildren
) {
  {
    isUpdatingChildComponent = true;
  }

  // determine whether component has slot children
  // we need to do this before overwriting $options._renderChildren
  const hasChildren = !!(
    renderChildren ||               // has new static slots
    vm.$options._renderChildren ||  // has old static slots
    parentVnode.data.scopedSlots || // has new scoped slots
    vm.$scopedSlots !== emptyObject // has old scoped slots
  );

  vm.$options._parentVnode = parentVnode;
  vm.$vnode = parentVnode; // update vm's placeholder node without re-render

  if (vm._vnode) { // update child tree's parent
    vm._vnode.parent = parentVnode;
  }
  vm.$options._renderChildren = renderChildren;

  // update $attrs and $listeners hash
  // these are also reactive so they may trigger child update if the child
  // used them during render
  vm.$attrs = (parentVnode.data && parentVnode.data.attrs) || emptyObject;
  vm.$listeners = listeners || emptyObject;

  // update props
  if (propsData && vm.$options.props) {
    observerState.shouldConvert = false;
    const props = vm._props;
    const propKeys = vm.$options._propKeys || [];
    for (let i = 0; i < propKeys.length; i++) {
      const key = propKeys[i];
      props[key] = validateProp(key, vm.$options.props, propsData, vm);
    }
    observerState.shouldConvert = true;
    // keep a copy of raw propsData
    vm.$options.propsData = propsData;
  }

  // update listeners
  if (listeners) {
    const oldListeners = vm.$options._parentListeners;
    vm.$options._parentListeners = listeners;
    updateComponentListeners(vm, listeners, oldListeners);
  }
  // resolve slots + force update if has children
  if (hasChildren) {
    vm.$slots = resolveSlots(renderChildren, parentVnode.context);
    vm.$forceUpdate();
  }

  {
    isUpdatingChildComponent = false;
  }
}

function isInInactiveTree (vm) {
  while (vm && (vm = vm.$parent)) {
    if (vm._inactive) return true
  }
  return false
}

function activateChildComponent (vm, direct) {
  if (direct) {
    vm._directInactive = false;
    if (isInInactiveTree(vm)) {
      return
    }
  } else if (vm._directInactive) {
    return
  }
  if (vm._inactive || vm._inactive === null) {
    vm._inactive = false;
    for (let i = 0; i < vm.$children.length; i++) {
      activateChildComponent(vm.$children[i]);
    }
    callHook(vm, 'activated');
  }
}

function deactivateChildComponent (vm, direct) {
  if (direct) {
    vm._directInactive = true;
    if (isInInactiveTree(vm)) {
      return
    }
  }
  if (!vm._inactive) {
    vm._inactive = true;
    for (let i = 0; i < vm.$children.length; i++) {
      deactivateChildComponent(vm.$children[i]);
    }
    callHook(vm, 'deactivated');
  }
}

function callHook (vm, hook) {
  const handlers = vm.$options[hook];
  if (handlers) {
    for (let i = 0, j = handlers.length; i < j; i++) {
      try {
        handlers[i].call(vm);
      } catch (e) {
        handleError(e, vm, `${hook} hook`);
      }
    }
  }
  if (vm._hasHookEvent) {
    vm.$emit('hook:' + hook);
  }
}

/*  */


const MAX_UPDATE_COUNT = 100;

const queue = [];
const activatedChildren = [];
let has = {};
let circular = {};
let waiting = false;
let flushing = false;
let index = 0;

/**
 * Reset the scheduler's state.
 */
function resetSchedulerState () {
  index = queue.length = activatedChildren.length = 0;
  has = {};
  {
    circular = {};
  }
  waiting = flushing = false;
}

/**
 * Flush both queues and run the watchers.
 */
function flushSchedulerQueue () {
  flushing = true;
  let watcher, id;

  // Sort queue before flush.
  // This ensures that:
  // 1. Components are updated from parent to child. (because parent is always
  //    created before the child)
  // 2. A component's user watchers are run before its render watcher (because
  //    user watchers are created before the render watcher)
  // 3. If a component is destroyed during a parent component's watcher run,
  //    its watchers can be skipped.
  queue.sort((a, b) => a.id - b.id);

  // do not cache length because more watchers might be pushed
  // as we run existing watchers
  for (index = 0; index < queue.length; index++) {
    watcher = queue[index];
    id = watcher.id;
    has[id] = null;
    watcher.run();
    // in dev build, check and stop circular updates.
    if ("development" !== 'production' && has[id] != null) {
      circular[id] = (circular[id] || 0) + 1;
      if (circular[id] > MAX_UPDATE_COUNT) {
        warn(
          'You may have an infinite update loop ' + (
            watcher.user
              ? `in watcher with expression "${watcher.expression}"`
              : `in a component render function.`
          ),
          watcher.vm
        );
        break
      }
    }
  }

  // keep copies of post queues before resetting state
  const activatedQueue = activatedChildren.slice();
  const updatedQueue = queue.slice();

  resetSchedulerState();

  // call component updated and activated hooks
  callActivatedHooks(activatedQueue);
  callUpdatedHooks(updatedQueue);

  // devtool hook
  /* istanbul ignore if */
  if (devtools && config.devtools) {
    devtools.emit('flush');
  }
}

function callUpdatedHooks (queue) {
  let i = queue.length;
  while (i--) {
    const watcher = queue[i];
    const vm = watcher.vm;
    if (vm._watcher === watcher && vm._isMounted) {
      callHook(vm, 'updated');
    }
  }
}

/**
 * Queue a kept-alive component that was activated during patch.
 * The queue will be processed after the entire tree has been patched.
 */
function queueActivatedComponent (vm) {
  // setting _inactive to false here so that a render function can
  // rely on checking whether it's in an inactive tree (e.g. router-view)
  vm._inactive = false;
  activatedChildren.push(vm);
}

function callActivatedHooks (queue) {
  for (let i = 0; i < queue.length; i++) {
    queue[i]._inactive = true;
    activateChildComponent(queue[i], true /* true */);
  }
}

/**
 * Push a watcher into the watcher queue.
 * Jobs with duplicate IDs will be skipped unless it's
 * pushed when the queue is being flushed.
 */
function queueWatcher (watcher) {
  const id = watcher.id;
  if (has[id] == null) {
    has[id] = true;
    if (!flushing) {
      queue.push(watcher);
    } else {
      // if already flushing, splice the watcher based on its id
      // if already past its id, it will be run next immediately.
      let i = queue.length - 1;
      while (i > index && queue[i].id > watcher.id) {
        i--;
      }
      queue.splice(i + 1, 0, watcher);
    }
    // queue the flush
    if (!waiting) {
      waiting = true;
      nextTick(flushSchedulerQueue);
    }
  }
}

/*  */

let uid$2 = 0;

/**
 * A watcher parses an expression, collects dependencies,
 * and fires callback when the expression value changes.
 * This is used for both the $watch() api and directives.
 */
class Watcher {
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  constructor (
    vm,
    expOrFn,
    cb,
    options
  ) {
    this.vm = vm;
    vm._watchers.push(this);
    // options
    if (options) {
      this.deep = !!options.deep;
      this.user = !!options.user;
      this.lazy = !!options.lazy;
      this.sync = !!options.sync;
    } else {
      this.deep = this.user = this.lazy = this.sync = false;
    }
    this.cb = cb;
    this.id = ++uid$2; // uid for batching
    this.active = true;
    this.dirty = this.lazy; // for lazy watchers
    this.deps = [];
    this.newDeps = [];
    this.depIds = new _Set();
    this.newDepIds = new _Set();
    this.expression = expOrFn.toString();
    // parse expression for getter
    if (typeof expOrFn === 'function') {
      this.getter = expOrFn;
    } else {
      this.getter = parsePath(expOrFn);
      if (!this.getter) {
        this.getter = function () {};
        "development" !== 'production' && warn(
          `Failed watching path: "${expOrFn}" ` +
          'Watcher only accepts simple dot-delimited paths. ' +
          'For full control, use a function instead.',
          vm
        );
      }
    }
    this.value = this.lazy
      ? undefined
      : this.get();
  }

  /**
   * Evaluate the getter, and re-collect dependencies.
   */
  get () {
    pushTarget(this);
    let value;
    const vm = this.vm;
    try {
      value = this.getter.call(vm, vm);
    } catch (e) {
      if (this.user) {
        handleError(e, vm, `getter for watcher "${this.expression}"`);
      } else {
        throw e
      }
    } finally {
      // "touch" every property so they are all tracked as
      // dependencies for deep watching
      if (this.deep) {
        traverse(value);
      }
      popTarget();
      this.cleanupDeps();
    }
    return value
  }

  /**
   * Add a dependency to this directive.
   */
  addDep (dep) {
    const id = dep.id;
    if (!this.newDepIds.has(id)) {
      this.newDepIds.add(id);
      this.newDeps.push(dep);
      if (!this.depIds.has(id)) {
        dep.addSub(this);
      }
    }
  }

  /**
   * Clean up for dependency collection.
   */
  cleanupDeps () {
    let i = this.deps.length;
    while (i--) {
      const dep = this.deps[i];
      if (!this.newDepIds.has(dep.id)) {
        dep.removeSub(this);
      }
    }
    let tmp = this.depIds;
    this.depIds = this.newDepIds;
    this.newDepIds = tmp;
    this.newDepIds.clear();
    tmp = this.deps;
    this.deps = this.newDeps;
    this.newDeps = tmp;
    this.newDeps.length = 0;
  }

  /**
   * Subscriber interface.
   * Will be called when a dependency changes.
   */
  update () {
    /* istanbul ignore else */
    if (this.lazy) {
      this.dirty = true;
    } else if (this.sync) {
      this.run();
    } else {
      queueWatcher(this);
    }
  }

  /**
   * Scheduler job interface.
   * Will be called by the scheduler.
   */
  run () {
    if (this.active) {
      const value = this.get();
      if (
        value !== this.value ||
        // Deep watchers and watchers on Object/Arrays should fire even
        // when the value is the same, because the value may
        // have mutated.
        isObject(value) ||
        this.deep
      ) {
        // set new value
        const oldValue = this.value;
        this.value = value;
        if (this.user) {
          try {
            this.cb.call(this.vm, value, oldValue);
          } catch (e) {
            handleError(e, this.vm, `callback for watcher "${this.expression}"`);
          }
        } else {
          this.cb.call(this.vm, value, oldValue);
        }
      }
    }
  }

  /**
   * Evaluate the value of the watcher.
   * This only gets called for lazy watchers.
   */
  evaluate () {
    this.value = this.get();
    this.dirty = false;
  }

  /**
   * Depend on all deps collected by this watcher.
   */
  depend () {
    let i = this.deps.length;
    while (i--) {
      this.deps[i].depend();
    }
  }

  /**
   * Remove self from all dependencies' subscriber list.
   */
  teardown () {
    if (this.active) {
      // remove self from vm's watcher list
      // this is a somewhat expensive operation so we skip it
      // if the vm is being destroyed.
      if (!this.vm._isBeingDestroyed) {
        remove(this.vm._watchers, this);
      }
      let i = this.deps.length;
      while (i--) {
        this.deps[i].removeSub(this);
      }
      this.active = false;
    }
  }
}

/*  */

const sharedPropertyDefinition = {
  enumerable: true,
  configurable: true,
  get: noop,
  set: noop
};

function proxy (target, sourceKey, key) {
  sharedPropertyDefinition.get = function proxyGetter () {
    return this[sourceKey][key]
  };
  sharedPropertyDefinition.set = function proxySetter (val) {
    this[sourceKey][key] = val;
  };
  Object.defineProperty(target, key, sharedPropertyDefinition);
}

function initState (vm) {
  vm._watchers = [];
  const opts = vm.$options;
  if (opts.props) initProps(vm, opts.props);
  if (opts.methods) initMethods(vm, opts.methods);
  if (opts.data) {
    initData(vm);
  } else {
    observe(vm._data = {}, true /* asRootData */);
  }
  if (opts.computed) initComputed(vm, opts.computed);
  if (opts.watch && opts.watch !== nativeWatch) {
    initWatch(vm, opts.watch);
  }
}

function initProps (vm, propsOptions) {
  const propsData = vm.$options.propsData || {};
  const props = vm._props = {};
  // cache prop keys so that future props updates can iterate using Array
  // instead of dynamic object key enumeration.
  const keys = vm.$options._propKeys = [];
  const isRoot = !vm.$parent;
  // root instance props should be converted
  observerState.shouldConvert = isRoot;
  for (const key in propsOptions) {
    keys.push(key);
    const value = validateProp(key, propsOptions, propsData, vm);
    /* istanbul ignore else */
    {
      const hyphenatedKey = hyphenate(key);
      if (isReservedAttribute(hyphenatedKey) ||
          config.isReservedAttr(hyphenatedKey)) {
        warn(
          `"${hyphenatedKey}" is a reserved attribute and cannot be used as component prop.`,
          vm
        );
      }
      defineReactive(props, key, value, () => {
        if (vm.$parent && !isUpdatingChildComponent) {
          warn(
            `Avoid mutating a prop directly since the value will be ` +
            `overwritten whenever the parent component re-renders. ` +
            `Instead, use a data or computed property based on the prop's ` +
            `value. Prop being mutated: "${key}"`,
            vm
          );
        }
      });
    }
    // static props are already proxied on the component's prototype
    // during Vue.extend(). We only need to proxy props defined at
    // instantiation here.
    if (!(key in vm)) {
      proxy(vm, `_props`, key);
    }
  }
  observerState.shouldConvert = true;
}

function initData (vm) {
  let data = vm.$options.data;
  data = vm._data = typeof data === 'function'
    ? getData(data, vm)
    : data || {};
  if (!isPlainObject(data)) {
    data = {};
    "development" !== 'production' && warn(
      'data functions should return an object:\n' +
      'https://vuejs.org/v2/guide/components.html#data-Must-Be-a-Function',
      vm
    );
  }
  // proxy data on instance
  const keys = Object.keys(data);
  const props = vm.$options.props;
  const methods = vm.$options.methods;
  let i = keys.length;
  while (i--) {
    const key = keys[i];
    {
      if (methods && hasOwn(methods, key)) {
        warn(
          `Method "${key}" has already been defined as a data property.`,
          vm
        );
      }
    }
    if (props && hasOwn(props, key)) {
      "development" !== 'production' && warn(
        `The data property "${key}" is already declared as a prop. ` +
        `Use prop default value instead.`,
        vm
      );
    } else if (!isReserved(key)) {
      proxy(vm, `_data`, key);
    }
  }
  // observe data
  observe(data, true /* asRootData */);
}

function getData (data, vm) {
  try {
    return data.call(vm, vm)
  } catch (e) {
    handleError(e, vm, `data()`);
    return {}
  }
}

const computedWatcherOptions = { lazy: true };

function initComputed (vm, computed) {
  const watchers = vm._computedWatchers = Object.create(null);
  // computed properties are just getters during SSR
  const isSSR = isServerRendering();

  for (const key in computed) {
    const userDef = computed[key];
    const getter = typeof userDef === 'function' ? userDef : userDef.get;
    if ("development" !== 'production' && getter == null) {
      warn(
        `Getter is missing for computed property "${key}".`,
        vm
      );
    }

    if (!isSSR) {
      // create internal watcher for the computed property.
      watchers[key] = new Watcher(
        vm,
        getter || noop,
        noop,
        computedWatcherOptions
      );
    }

    // component-defined computed properties are already defined on the
    // component prototype. We only need to define computed properties defined
    // at instantiation here.
    if (!(key in vm)) {
      defineComputed(vm, key, userDef);
    } else {
      if (key in vm.$data) {
        warn(`The computed property "${key}" is already defined in data.`, vm);
      } else if (vm.$options.props && key in vm.$options.props) {
        warn(`The computed property "${key}" is already defined as a prop.`, vm);
      }
    }
  }
}

function defineComputed (
  target,
  key,
  userDef
) {
  const shouldCache = !isServerRendering();
  if (typeof userDef === 'function') {
    sharedPropertyDefinition.get = shouldCache
      ? createComputedGetter(key)
      : userDef;
    sharedPropertyDefinition.set = noop;
  } else {
    sharedPropertyDefinition.get = userDef.get
      ? shouldCache && userDef.cache !== false
        ? createComputedGetter(key)
        : userDef.get
      : noop;
    sharedPropertyDefinition.set = userDef.set
      ? userDef.set
      : noop;
  }
  if ("development" !== 'production' &&
      sharedPropertyDefinition.set === noop) {
    sharedPropertyDefinition.set = function () {
      warn(
        `Computed property "${key}" was assigned to but it has no setter.`,
        this
      );
    };
  }
  Object.defineProperty(target, key, sharedPropertyDefinition);
}

function createComputedGetter (key) {
  return function computedGetter () {
    const watcher = this._computedWatchers && this._computedWatchers[key];
    if (watcher) {
      if (watcher.dirty) {
        watcher.evaluate();
      }
      if (Dep.target) {
        watcher.depend();
      }
      return watcher.value
    }
  }
}

function initMethods (vm, methods) {
  const props = vm.$options.props;
  for (const key in methods) {
    {
      if (methods[key] == null) {
        warn(
          `Method "${key}" has an undefined value in the component definition. ` +
          `Did you reference the function correctly?`,
          vm
        );
      }
      if (props && hasOwn(props, key)) {
        warn(
          `Method "${key}" has already been defined as a prop.`,
          vm
        );
      }
      if ((key in vm) && isReserved(key)) {
        warn(
          `Method "${key}" conflicts with an existing Vue instance method. ` +
          `Avoid defining component methods that start with _ or $.`
        );
      }
    }
    vm[key] = methods[key] == null ? noop : bind(methods[key], vm);
  }
}

function initWatch (vm, watch) {
  for (const key in watch) {
    const handler = watch[key];
    if (Array.isArray(handler)) {
      for (let i = 0; i < handler.length; i++) {
        createWatcher(vm, key, handler[i]);
      }
    } else {
      createWatcher(vm, key, handler);
    }
  }
}

function createWatcher (
  vm,
  keyOrFn,
  handler,
  options
) {
  if (isPlainObject(handler)) {
    options = handler;
    handler = handler.handler;
  }
  if (typeof handler === 'string') {
    handler = vm[handler];
  }
  return vm.$watch(keyOrFn, handler, options)
}

function stateMixin (Vue) {
  // flow somehow has problems with directly declared definition object
  // when using Object.defineProperty, so we have to procedurally build up
  // the object here.
  const dataDef = {};
  dataDef.get = function () { return this._data };
  const propsDef = {};
  propsDef.get = function () { return this._props };
  {
    dataDef.set = function (newData) {
      warn(
        'Avoid replacing instance root $data. ' +
        'Use nested data properties instead.',
        this
      );
    };
    propsDef.set = function () {
      warn(`$props is readonly.`, this);
    };
  }
  Object.defineProperty(Vue.prototype, '$data', dataDef);
  Object.defineProperty(Vue.prototype, '$props', propsDef);

  Vue.prototype.$set = set;
  Vue.prototype.$delete = del;

  Vue.prototype.$watch = function (
    expOrFn,
    cb,
    options
  ) {
    const vm = this;
    if (isPlainObject(cb)) {
      return createWatcher(vm, expOrFn, cb, options)
    }
    options = options || {};
    options.user = true;
    const watcher = new Watcher(vm, expOrFn, cb, options);
    if (options.immediate) {
      cb.call(vm, watcher.value);
    }
    return function unwatchFn () {
      watcher.teardown();
    }
  };
}

/*  */

function initProvide (vm) {
  const provide = vm.$options.provide;
  if (provide) {
    vm._provided = typeof provide === 'function'
      ? provide.call(vm)
      : provide;
  }
}

function initInjections (vm) {
  const result = resolveInject(vm.$options.inject, vm);
  if (result) {
    observerState.shouldConvert = false;
    Object.keys(result).forEach(key => {
      /* istanbul ignore else */
      {
        defineReactive(vm, key, result[key], () => {
          warn(
            `Avoid mutating an injected value directly since the changes will be ` +
            `overwritten whenever the provided component re-renders. ` +
            `injection being mutated: "${key}"`,
            vm
          );
        });
      }
    });
    observerState.shouldConvert = true;
  }
}

function resolveInject (inject, vm) {
  if (inject) {
    // inject is :any because flow is not smart enough to figure out cached
    const result = Object.create(null);
    const keys = hasSymbol
        ? Reflect.ownKeys(inject).filter(key => {
          /* istanbul ignore next */
          return Object.getOwnPropertyDescriptor(inject, key).enumerable
        })
        : Object.keys(inject);

    for (let i = 0; i < keys.length; i++) {
      const key = keys[i];
      const provideKey = inject[key].from;
      let source = vm;
      while (source) {
        if (source._provided && provideKey in source._provided) {
          result[key] = source._provided[provideKey];
          break
        }
        source = source.$parent;
      }
      if (!source) {
        if ('default' in inject[key]) {
          const provideDefault = inject[key].default;
          result[key] = typeof provideDefault === 'function'
            ? provideDefault.call(vm)
            : provideDefault;
        } else {
          warn(`Injection "${key}" not found`, vm);
        }
      }
    }
    return result
  }
}

/*  */

/**
 * Runtime helper for rendering v-for lists.
 */
function renderList (
  val,
  render
) {
  let ret, i, l, keys, key;
  if (Array.isArray(val) || typeof val === 'string') {
    ret = new Array(val.length);
    for (i = 0, l = val.length; i < l; i++) {
      ret[i] = render(val[i], i);
    }
  } else if (typeof val === 'number') {
    ret = new Array(val);
    for (i = 0; i < val; i++) {
      ret[i] = render(i + 1, i);
    }
  } else if (isObject(val)) {
    keys = Object.keys(val);
    ret = new Array(keys.length);
    for (i = 0, l = keys.length; i < l; i++) {
      key = keys[i];
      ret[i] = render(val[key], key, i);
    }
  }
  if (isDef(ret)) {
    (ret)._isVList = true;
  }
  return ret
}

/*  */

/**
 * Runtime helper for rendering <slot>
 */
function renderSlot (
  name,
  fallback,
  props,
  bindObject
) {
  const scopedSlotFn = this.$scopedSlots[name];
  let nodes;
  if (scopedSlotFn) { // scoped slot
    props = props || {};
    if (bindObject) {
      if ("development" !== 'production' && !isObject(bindObject)) {
        warn(
          'slot v-bind without argument expects an Object',
          this
        );
      }
      props = extend(extend({}, bindObject), props);
    }
    nodes = scopedSlotFn(props) || fallback;
  } else {
    const slotNodes = this.$slots[name];
    // warn duplicate slot usage
    if (slotNodes) {
      if ("development" !== 'production' && slotNodes._rendered) {
        warn(
          `Duplicate presence of slot "${name}" found in the same render tree ` +
          `- this will likely cause render errors.`,
          this
        );
      }
      slotNodes._rendered = true;
    }
    nodes = slotNodes || fallback;
  }

  const target = props && props.slot;
  if (target) {
    return this.$createElement('template', { slot: target }, nodes)
  } else {
    return nodes
  }
}

/*  */

/**
 * Runtime helper for resolving filters
 */
function resolveFilter (id) {
  return resolveAsset(this.$options, 'filters', id, true) || identity
}

/*  */

/**
 * Runtime helper for checking keyCodes from config.
 * exposed as Vue.prototype._k
 * passing in eventKeyName as last argument separately for backwards compat
 */
function checkKeyCodes (
  eventKeyCode,
  key,
  builtInAlias,
  eventKeyName
) {
  const keyCodes = config.keyCodes[key] || builtInAlias;
  if (keyCodes) {
    if (Array.isArray(keyCodes)) {
      return keyCodes.indexOf(eventKeyCode) === -1
    } else {
      return keyCodes !== eventKeyCode
    }
  } else if (eventKeyName) {
    return hyphenate(eventKeyName) !== key
  }
}

/*  */

/**
 * Runtime helper for merging v-bind="object" into a VNode's data.
 */
function bindObjectProps (
  data,
  tag,
  value,
  asProp,
  isSync
) {
  if (value) {
    if (!isObject(value)) {
      "development" !== 'production' && warn(
        'v-bind without argument expects an Object or Array value',
        this
      );
    } else {
      if (Array.isArray(value)) {
        value = toObject(value);
      }
      let hash;
      for (const key in value) {
        if (
          key === 'class' ||
          key === 'style' ||
          isReservedAttribute(key)
        ) {
          hash = data;
        } else {
          const type = data.attrs && data.attrs.type;
          hash = asProp || config.mustUseProp(tag, type, key)
            ? data.domProps || (data.domProps = {})
            : data.attrs || (data.attrs = {});
        }
        if (!(key in hash)) {
          hash[key] = value[key];

          if (isSync) {
            const on = data.on || (data.on = {});
            on[`update:${key}`] = function ($event) {
              value[key] = $event;
            };
          }
        }
      }
    }
  }
  return data
}

/*  */

/**
 * Runtime helper for rendering static trees.
 */
function renderStatic (
  index,
  isInFor,
  isOnce
) {
  // render fns generated by compiler < 2.5.4 does not provide v-once
  // information to runtime so be conservative
  const isOldVersion = arguments.length < 3;
  // if a static tree is generated by v-once, it is cached on the instance;
  // otherwise it is purely static and can be cached on the shared options
  // across all instances.
  const renderFns = this.$options.staticRenderFns;
  const cached = isOldVersion || isOnce
    ? (this._staticTrees || (this._staticTrees = []))
    : (renderFns.cached || (renderFns.cached = []));
  let tree = cached[index];
  // if has already-rendered static tree and not inside v-for,
  // we can reuse the same tree by doing a shallow clone.
  if (tree && !isInFor) {
    return Array.isArray(tree)
      ? cloneVNodes(tree)
      : cloneVNode(tree)
  }
  // otherwise, render a fresh tree.
  tree = cached[index] = renderFns[index].call(this._renderProxy, null, this);
  markStatic(tree, `__static__${index}`, false);
  return tree
}

/**
 * Runtime helper for v-once.
 * Effectively it means marking the node as static with a unique key.
 */
function markOnce (
  tree,
  index,
  key
) {
  markStatic(tree, `__once__${index}${key ? `_${key}` : ``}`, true);
  return tree
}

function markStatic (
  tree,
  key,
  isOnce
) {
  if (Array.isArray(tree)) {
    for (let i = 0; i < tree.length; i++) {
      if (tree[i] && typeof tree[i] !== 'string') {
        markStaticNode(tree[i], `${key}_${i}`, isOnce);
      }
    }
  } else {
    markStaticNode(tree, key, isOnce);
  }
}

function markStaticNode (node, key, isOnce) {
  node.isStatic = true;
  node.key = key;
  node.isOnce = isOnce;
}

/*  */

function bindObjectListeners (data, value) {
  if (value) {
    if (!isPlainObject(value)) {
      "development" !== 'production' && warn(
        'v-on without argument expects an Object value',
        this
      );
    } else {
      const on = data.on = data.on ? extend({}, data.on) : {};
      for (const key in value) {
        const existing = on[key];
        const ours = value[key];
        on[key] = existing ? [].concat(existing, ours) : ours;
      }
    }
  }
  return data
}

/*  */

function installRenderHelpers (target) {
  target._o = markOnce;
  target._n = toNumber;
  target._s = toString;
  target._l = renderList;
  target._t = renderSlot;
  target._q = looseEqual;
  target._i = looseIndexOf;
  target._m = renderStatic;
  target._f = resolveFilter;
  target._k = checkKeyCodes;
  target._b = bindObjectProps;
  target._v = createTextVNode;
  target._e = createEmptyVNode;
  target._u = resolveScopedSlots;
  target._g = bindObjectListeners;
}

/*  */

function FunctionalRenderContext (
  data,
  props,
  children,
  parent,
  Ctor
) {
  const options = Ctor.options;
  this.data = data;
  this.props = props;
  this.children = children;
  this.parent = parent;
  this.listeners = data.on || emptyObject;
  this.injections = resolveInject(options.inject, parent);
  this.slots = () => resolveSlots(children, parent);

  // ensure the createElement function in functional components
  // gets a unique context - this is necessary for correct named slot check
  const contextVm = Object.create(parent);
  const isCompiled = isTrue(options._compiled);
  const needNormalization = !isCompiled;

  // support for compiled functional template
  if (isCompiled) {
    // exposing $options for renderStatic()
    this.$options = options;
    // pre-resolve slots for renderSlot()
    this.$slots = this.slots();
    this.$scopedSlots = data.scopedSlots || emptyObject;
  }

  if (options._scopeId) {
    this._c = (a, b, c, d) => {
      const vnode = createElement(contextVm, a, b, c, d, needNormalization);
      if (vnode) {
        vnode.functionalScopeId = options._scopeId;
        vnode.functionalContext = parent;
      }
      return vnode
    };
  } else {
    this._c = (a, b, c, d) => createElement(contextVm, a, b, c, d, needNormalization);
  }
}

installRenderHelpers(FunctionalRenderContext.prototype);

function createFunctionalComponent (
  Ctor,
  propsData,
  data,
  contextVm,
  children
) {
  const options = Ctor.options;
  const props = {};
  const propOptions = options.props;
  if (isDef(propOptions)) {
    for (const key in propOptions) {
      props[key] = validateProp(key, propOptions, propsData || emptyObject);
    }
  } else {
    if (isDef(data.attrs)) mergeProps(props, data.attrs);
    if (isDef(data.props)) mergeProps(props, data.props);
  }

  const renderContext = new FunctionalRenderContext(
    data,
    props,
    children,
    contextVm,
    Ctor
  );

  const vnode = options.render.call(null, renderContext._c, renderContext);

  if (vnode instanceof VNode) {
    vnode.functionalContext = contextVm;
    vnode.functionalOptions = options;
    if (data.slot) {
      (vnode.data || (vnode.data = {})).slot = data.slot;
    }
  }

  return vnode
}

function mergeProps (to, from) {
  for (const key in from) {
    to[camelize(key)] = from[key];
  }
}

/*  */

// hooks to be invoked on component VNodes during patch
const componentVNodeHooks = {
  init (
    vnode,
    hydrating,
    parentElm,
    refElm
  ) {
    if (!vnode.componentInstance || vnode.componentInstance._isDestroyed) {
      const child = vnode.componentInstance = createComponentInstanceForVnode(
        vnode,
        activeInstance,
        parentElm,
        refElm
      );
      child.$mount(hydrating ? vnode.elm : undefined, hydrating);
    } else if (vnode.data.keepAlive) {
      // kept-alive components, treat as a patch
      const mountedNode = vnode; // work around flow
      componentVNodeHooks.prepatch(mountedNode, mountedNode);
    }
  },

  prepatch (oldVnode, vnode) {
    const options = vnode.componentOptions;
    const child = vnode.componentInstance = oldVnode.componentInstance;
    updateChildComponent(
      child,
      options.propsData, // updated props
      options.listeners, // updated listeners
      vnode, // new parent vnode
      options.children // new children
    );
  },

  insert (vnode) {
    const { context, componentInstance } = vnode;
    if (!componentInstance._isMounted) {
      componentInstance._isMounted = true;
      callHook(componentInstance, 'mounted');
    }
    if (vnode.data.keepAlive) {
      if (context._isMounted) {
        // vue-router#1212
        // During updates, a kept-alive component's child components may
        // change, so directly walking the tree here may call activated hooks
        // on incorrect children. Instead we push them into a queue which will
        // be processed after the whole patch process ended.
        queueActivatedComponent(componentInstance);
      } else {
        activateChildComponent(componentInstance, true /* direct */);
      }
    }
  },

  destroy (vnode) {
    const { componentInstance } = vnode;
    if (!componentInstance._isDestroyed) {
      if (!vnode.data.keepAlive) {
        componentInstance.$destroy();
      } else {
        deactivateChildComponent(componentInstance, true /* direct */);
      }
    }
  }
};

const hooksToMerge = Object.keys(componentVNodeHooks);

function createComponent (
  Ctor,
  data,
  context,
  children,
  tag
) {
  if (isUndef(Ctor)) {
    return
  }

  const baseCtor = context.$options._base;

  // plain options object: turn it into a constructor
  if (isObject(Ctor)) {
    Ctor = baseCtor.extend(Ctor);
  }

  // if at this stage it's not a constructor or an async component factory,
  // reject.
  if (typeof Ctor !== 'function') {
    {
      warn(`Invalid Component definition: ${String(Ctor)}`, context);
    }
    return
  }

  // async component
  let asyncFactory;
  if (isUndef(Ctor.cid)) {
    asyncFactory = Ctor;
    Ctor = resolveAsyncComponent(asyncFactory, baseCtor, context);
    if (Ctor === undefined) {
      // return a placeholder node for async component, which is rendered
      // as a comment node but preserves all the raw information for the node.
      // the information will be used for async server-rendering and hydration.
      return createAsyncPlaceholder(
        asyncFactory,
        data,
        context,
        children,
        tag
      )
    }
  }

  data = data || {};

  // resolve constructor options in case global mixins are applied after
  // component constructor creation
  resolveConstructorOptions(Ctor);

  // transform component v-model data into props & events
  if (isDef(data.model)) {
    transformModel(Ctor.options, data);
  }

  // extract props
  const propsData = extractPropsFromVNodeData(data, Ctor, tag);

  // functional component
  if (isTrue(Ctor.options.functional)) {
    return createFunctionalComponent(Ctor, propsData, data, context, children)
  }

  // extract listeners, since these needs to be treated as
  // child component listeners instead of DOM listeners
  const listeners = data.on;
  // replace with listeners with .native modifier
  // so it gets processed during parent component patch.
  data.on = data.nativeOn;

  if (isTrue(Ctor.options.abstract)) {
    // abstract components do not keep anything
    // other than props & listeners & slot

    // work around flow
    const slot = data.slot;
    data = {};
    if (slot) {
      data.slot = slot;
    }
  }

  // merge component management hooks onto the placeholder node
  mergeHooks(data);

  // return a placeholder vnode
  const name = Ctor.options.name || tag;
  const vnode = new VNode(
    `vue-component-${Ctor.cid}${name ? `-${name}` : ''}`,
    data, undefined, undefined, undefined, context,
    { Ctor, propsData, listeners, tag, children },
    asyncFactory
  );
  return vnode
}

function createComponentInstanceForVnode (
  vnode, // we know it's MountedComponentVNode but flow doesn't
  parent, // activeInstance in lifecycle state
  parentElm,
  refElm
) {
  const vnodeComponentOptions = vnode.componentOptions;
  const options = {
    _isComponent: true,
    parent,
    propsData: vnodeComponentOptions.propsData,
    _componentTag: vnodeComponentOptions.tag,
    _parentVnode: vnode,
    _parentListeners: vnodeComponentOptions.listeners,
    _renderChildren: vnodeComponentOptions.children,
    _parentElm: parentElm || null,
    _refElm: refElm || null
  };
  // check inline-template render functions
  const inlineTemplate = vnode.data.inlineTemplate;
  if (isDef(inlineTemplate)) {
    options.render = inlineTemplate.render;
    options.staticRenderFns = inlineTemplate.staticRenderFns;
  }
  return new vnodeComponentOptions.Ctor(options)
}

function mergeHooks (data) {
  if (!data.hook) {
    data.hook = {};
  }
  for (let i = 0; i < hooksToMerge.length; i++) {
    const key = hooksToMerge[i];
    const fromParent = data.hook[key];
    const ours = componentVNodeHooks[key];
    data.hook[key] = fromParent ? mergeHook$1(ours, fromParent) : ours;
  }
}

function mergeHook$1 (one, two) {
  return function (a, b, c, d) {
    one(a, b, c, d);
    two(a, b, c, d);
  }
}

// transform component v-model info (value and callback) into
// prop and event handler respectively.
function transformModel (options, data) {
  const prop = (options.model && options.model.prop) || 'value';
  const event = (options.model && options.model.event) || 'input';(data.props || (data.props = {}))[prop] = data.model.value;
  const on = data.on || (data.on = {});
  if (isDef(on[event])) {
    on[event] = [data.model.callback].concat(on[event]);
  } else {
    on[event] = data.model.callback;
  }
}

/*  */

const SIMPLE_NORMALIZE = 1;
const ALWAYS_NORMALIZE = 2;

// wrapper function for providing a more flexible interface
// without getting yelled at by flow
function createElement (
  context,
  tag,
  data,
  children,
  normalizationType,
  alwaysNormalize
) {
  if (Array.isArray(data) || isPrimitive(data)) {
    normalizationType = children;
    children = data;
    data = undefined;
  }
  if (isTrue(alwaysNormalize)) {
    normalizationType = ALWAYS_NORMALIZE;
  }
  return _createElement(context, tag, data, children, normalizationType)
}

function _createElement (
  context,
  tag,
  data,
  children,
  normalizationType
) {
  if (isDef(data) && isDef((data).__ob__)) {
    "development" !== 'production' && warn(
      `Avoid using observed data object as vnode data: ${JSON.stringify(data)}\n` +
      'Always create fresh vnode data objects in each render!',
      context
    );
    return createEmptyVNode()
  }
  // object syntax in v-bind
  if (isDef(data) && isDef(data.is)) {
    tag = data.is;
  }
  if (!tag) {
    // in case of component :is set to falsy value
    return createEmptyVNode()
  }
  // warn against non-primitive key
  if ("development" !== 'production' &&
    isDef(data) && isDef(data.key) && !isPrimitive(data.key)
  ) {
    warn(
      'Avoid using non-primitive value as key, ' +
      'use string/number value instead.',
      context
    );
  }
  // support single function children as default scoped slot
  if (Array.isArray(children) &&
    typeof children[0] === 'function'
  ) {
    data = data || {};
    data.scopedSlots = { default: children[0] };
    children.length = 0;
  }
  if (normalizationType === ALWAYS_NORMALIZE) {
    children = normalizeChildren(children);
  } else if (normalizationType === SIMPLE_NORMALIZE) {
    children = simpleNormalizeChildren(children);
  }
  let vnode, ns;
  if (typeof tag === 'string') {
    let Ctor;
    ns = (context.$vnode && context.$vnode.ns) || config.getTagNamespace(tag);
    if (config.isReservedTag(tag)) {
      // platform built-in elements
      vnode = new VNode(
        config.parsePlatformTagName(tag), data, children,
        undefined, undefined, context
      );
    } else if (isDef(Ctor = resolveAsset(context.$options, 'components', tag))) {
      // component
      vnode = createComponent(Ctor, data, context, children, tag);
    } else {
      // unknown or unlisted namespaced elements
      // check at runtime because it may get assigned a namespace when its
      // parent normalizes children
      vnode = new VNode(
        tag, data, children,
        undefined, undefined, context
      );
    }
  } else {
    // direct component options / constructor
    vnode = createComponent(tag, data, context, children);
  }
  if (isDef(vnode)) {
    if (ns) applyNS(vnode, ns);
    return vnode
  } else {
    return createEmptyVNode()
  }
}

function applyNS (vnode, ns, force) {
  vnode.ns = ns;
  if (vnode.tag === 'foreignObject') {
    // use default namespace inside foreignObject
    ns = undefined;
    force = true;
  }
  if (isDef(vnode.children)) {
    for (let i = 0, l = vnode.children.length; i < l; i++) {
      const child = vnode.children[i];
      if (isDef(child.tag) && (isUndef(child.ns) || isTrue(force))) {
        applyNS(child, ns, force);
      }
    }
  }
}

/*  */

function initRender (vm) {
  vm._vnode = null; // the root of the child tree
  vm._staticTrees = null; // v-once cached trees
  const options = vm.$options;
  const parentVnode = vm.$vnode = options._parentVnode; // the placeholder node in parent tree
  const renderContext = parentVnode && parentVnode.context;
  vm.$slots = resolveSlots(options._renderChildren, renderContext);
  vm.$scopedSlots = emptyObject;
  // bind the createElement fn to this instance
  // so that we get proper render context inside it.
  // args order: tag, data, children, normalizationType, alwaysNormalize
  // internal version is used by render functions compiled from templates
  vm._c = (a, b, c, d) => createElement(vm, a, b, c, d, false);
  // normalization is always applied for the public version, used in
  // user-written render functions.
  vm.$createElement = (a, b, c, d) => createElement(vm, a, b, c, d, true);

  // $attrs & $listeners are exposed for easier HOC creation.
  // they need to be reactive so that HOCs using them are always updated
  const parentData = parentVnode && parentVnode.data;

  /* istanbul ignore else */
  {
    defineReactive(vm, '$attrs', parentData && parentData.attrs || emptyObject, () => {
      !isUpdatingChildComponent && warn(`$attrs is readonly.`, vm);
    }, true);
    defineReactive(vm, '$listeners', options._parentListeners || emptyObject, () => {
      !isUpdatingChildComponent && warn(`$listeners is readonly.`, vm);
    }, true);
  }
}

function renderMixin (Vue) {
  // install runtime convenience helpers
  installRenderHelpers(Vue.prototype);

  Vue.prototype.$nextTick = function (fn) {
    return nextTick(fn, this)
  };

  Vue.prototype._render = function () {
    const vm = this;
    const { render, _parentVnode } = vm.$options;

    if (vm._isMounted) {
      // if the parent didn't update, the slot nodes will be the ones from
      // last render. They need to be cloned to ensure "freshness" for this render.
      for (const key in vm.$slots) {
        const slot = vm.$slots[key];
        // _rendered is a flag added by renderSlot, but may not be present
        // if the slot is passed from manually written render functions
        if (slot._rendered || (slot[0] && slot[0].elm)) {
          vm.$slots[key] = cloneVNodes(slot, true /* deep */);
        }
      }
    }

    vm.$scopedSlots = (_parentVnode && _parentVnode.data.scopedSlots) || emptyObject;

    // set parent vnode. this allows render functions to have access
    // to the data on the placeholder node.
    vm.$vnode = _parentVnode;
    // render self
    let vnode;
    try {
      vnode = render.call(vm._renderProxy, vm.$createElement);
    } catch (e) {
      handleError(e, vm, `render`);
      // return error render result,
      // or previous vnode to prevent render error causing blank component
      /* istanbul ignore else */
      {
        if (vm.$options.renderError) {
          try {
            vnode = vm.$options.renderError.call(vm._renderProxy, vm.$createElement, e);
          } catch (e) {
            handleError(e, vm, `renderError`);
            vnode = vm._vnode;
          }
        } else {
          vnode = vm._vnode;
        }
      }
    }
    // return empty vnode in case the render function errored out
    if (!(vnode instanceof VNode)) {
      if ("development" !== 'production' && Array.isArray(vnode)) {
        warn(
          'Multiple root nodes returned from render function. Render function ' +
          'should return a single root node.',
          vm
        );
      }
      vnode = createEmptyVNode();
    }
    // set parent
    vnode.parent = _parentVnode;
    return vnode
  };
}

/*  */

let uid$1 = 0;

function initMixin (Vue) {
  Vue.prototype._init = function (options) {
    const vm = this;
    // a uid
    vm._uid = uid$1++;

    let startTag, endTag;
    /* istanbul ignore if */
    if ("development" !== 'production' && config.performance && mark) {
      startTag = `vue-perf-start:${vm._uid}`;
      endTag = `vue-perf-end:${vm._uid}`;
      mark(startTag);
    }

    // a flag to avoid this being observed
    vm._isVue = true;
    // merge options
    if (options && options._isComponent) {
      // optimize internal component instantiation
      // since dynamic options merging is pretty slow, and none of the
      // internal component options needs special treatment.
      initInternalComponent(vm, options);
    } else {
      vm.$options = mergeOptions(
        resolveConstructorOptions(vm.constructor),
        options || {},
        vm
      );
    }
    /* istanbul ignore else */
    {
      initProxy(vm);
    }
    // expose real self
    vm._self = vm;
    initLifecycle(vm);
    initEvents(vm);
    initRender(vm);
    callHook(vm, 'beforeCreate');
    initInjections(vm); // resolve injections before data/props
    initState(vm);
    initProvide(vm); // resolve provide after data/props
    callHook(vm, 'created');

    /* istanbul ignore if */
    if ("development" !== 'production' && config.performance && mark) {
      vm._name = formatComponentName(vm, false);
      mark(endTag);
      measure(`vue ${vm._name} init`, startTag, endTag);
    }

    if (vm.$options.el) {
      vm.$mount(vm.$options.el);
    }
  };
}

function initInternalComponent (vm, options) {
  const opts = vm.$options = Object.create(vm.constructor.options);
  // doing this because it's faster than dynamic enumeration.
  opts.parent = options.parent;
  opts.propsData = options.propsData;
  opts._parentVnode = options._parentVnode;
  opts._parentListeners = options._parentListeners;
  opts._renderChildren = options._renderChildren;
  opts._componentTag = options._componentTag;
  opts._parentElm = options._parentElm;
  opts._refElm = options._refElm;
  if (options.render) {
    opts.render = options.render;
    opts.staticRenderFns = options.staticRenderFns;
  }
}

function resolveConstructorOptions (Ctor) {
  let options = Ctor.options;
  if (Ctor.super) {
    const superOptions = resolveConstructorOptions(Ctor.super);
    const cachedSuperOptions = Ctor.superOptions;
    if (superOptions !== cachedSuperOptions) {
      // super option changed,
      // need to resolve new options.
      Ctor.superOptions = superOptions;
      // check if there are any late-modified/attached options (#4976)
      const modifiedOptions = resolveModifiedOptions(Ctor);
      // update base extend options
      if (modifiedOptions) {
        extend(Ctor.extendOptions, modifiedOptions);
      }
      options = Ctor.options = mergeOptions(superOptions, Ctor.extendOptions);
      if (options.name) {
        options.components[options.name] = Ctor;
      }
    }
  }
  return options
}

function resolveModifiedOptions (Ctor) {
  let modified;
  const latest = Ctor.options;
  const extended = Ctor.extendOptions;
  const sealed = Ctor.sealedOptions;
  for (const key in latest) {
    if (latest[key] !== sealed[key]) {
      if (!modified) modified = {};
      modified[key] = dedupe(latest[key], extended[key], sealed[key]);
    }
  }
  return modified
}

function dedupe (latest, extended, sealed) {
  // compare latest and sealed to ensure lifecycle hooks won't be duplicated
  // between merges
  if (Array.isArray(latest)) {
    const res = [];
    sealed = Array.isArray(sealed) ? sealed : [sealed];
    extended = Array.isArray(extended) ? extended : [extended];
    for (let i = 0; i < latest.length; i++) {
      // push original options and not sealed options to exclude duplicated options
      if (extended.indexOf(latest[i]) >= 0 || sealed.indexOf(latest[i]) < 0) {
        res.push(latest[i]);
      }
    }
    return res
  } else {
    return latest
  }
}

function Vue$3 (options) {
  if ("development" !== 'production' &&
    !(this instanceof Vue$3)
  ) {
    warn('Vue is a constructor and should be called with the `new` keyword');
  }
  this._init(options);
}

initMixin(Vue$3);
stateMixin(Vue$3);
eventsMixin(Vue$3);
lifecycleMixin(Vue$3);
renderMixin(Vue$3);

/*  */

function initUse (Vue) {
  Vue.use = function (plugin) {
    const installedPlugins = (this._installedPlugins || (this._installedPlugins = []));
    if (installedPlugins.indexOf(plugin) > -1) {
      return this
    }

    // additional parameters
    const args = toArray(arguments, 1);
    args.unshift(this);
    if (typeof plugin.install === 'function') {
      plugin.install.apply(plugin, args);
    } else if (typeof plugin === 'function') {
      plugin.apply(null, args);
    }
    installedPlugins.push(plugin);
    return this
  };
}

/*  */

function initMixin$1 (Vue) {
  Vue.mixin = function (mixin) {
    this.options = mergeOptions(this.options, mixin);
    return this
  };
}

/*  */

function initExtend (Vue) {
  /**
   * Each instance constructor, including Vue, has a unique
   * cid. This enables us to create wrapped "child
   * constructors" for prototypal inheritance and cache them.
   */
  Vue.cid = 0;
  let cid = 1;

  /**
   * Class inheritance
   */
  Vue.extend = function (extendOptions) {
    extendOptions = extendOptions || {};
    const Super = this;
    const SuperId = Super.cid;
    const cachedCtors = extendOptions._Ctor || (extendOptions._Ctor = {});
    if (cachedCtors[SuperId]) {
      return cachedCtors[SuperId]
    }

    const name = extendOptions.name || Super.options.name;
    {
      if (!/^[a-zA-Z][\w-]*$/.test(name)) {
        warn(
          'Invalid component name: "' + name + '". Component names ' +
          'can only contain alphanumeric characters and the hyphen, ' +
          'and must start with a letter.'
        );
      }
    }

    const Sub = function VueComponent (options) {
      this._init(options);
    };
    Sub.prototype = Object.create(Super.prototype);
    Sub.prototype.constructor = Sub;
    Sub.cid = cid++;
    Sub.options = mergeOptions(
      Super.options,
      extendOptions
    );
    Sub['super'] = Super;

    // For props and computed properties, we define the proxy getters on
    // the Vue instances at extension time, on the extended prototype. This
    // avoids Object.defineProperty calls for each instance created.
    if (Sub.options.props) {
      initProps$1(Sub);
    }
    if (Sub.options.computed) {
      initComputed$1(Sub);
    }

    // allow further extension/mixin/plugin usage
    Sub.extend = Super.extend;
    Sub.mixin = Super.mixin;
    Sub.use = Super.use;

    // create asset registers, so extended classes
    // can have their private assets too.
    ASSET_TYPES.forEach(function (type) {
      Sub[type] = Super[type];
    });
    // enable recursive self-lookup
    if (name) {
      Sub.options.components[name] = Sub;
    }

    // keep a reference to the super options at extension time.
    // later at instantiation we can check if Super's options have
    // been updated.
    Sub.superOptions = Super.options;
    Sub.extendOptions = extendOptions;
    Sub.sealedOptions = extend({}, Sub.options);

    // cache constructor
    cachedCtors[SuperId] = Sub;
    return Sub
  };
}

function initProps$1 (Comp) {
  const props = Comp.options.props;
  for (const key in props) {
    proxy(Comp.prototype, `_props`, key);
  }
}

function initComputed$1 (Comp) {
  const computed = Comp.options.computed;
  for (const key in computed) {
    defineComputed(Comp.prototype, key, computed[key]);
  }
}

/*  */

function initAssetRegisters (Vue) {
  /**
   * Create asset registration methods.
   */
  ASSET_TYPES.forEach(type => {
    Vue[type] = function (
      id,
      definition
    ) {
      if (!definition) {
        return this.options[type + 's'][id]
      } else {
        /* istanbul ignore if */
        {
          if (type === 'component' && config.isReservedTag(id)) {
            warn(
              'Do not use built-in or reserved HTML elements as component ' +
              'id: ' + id
            );
          }
        }
        if (type === 'component' && isPlainObject(definition)) {
          definition.name = definition.name || id;
          definition = this.options._base.extend(definition);
        }
        if (type === 'directive' && typeof definition === 'function') {
          definition = { bind: definition, update: definition };
        }
        this.options[type + 's'][id] = definition;
        return definition
      }
    };
  });
}

/*  */

function getComponentName (opts) {
  return opts && (opts.Ctor.options.name || opts.tag)
}

function matches (pattern, name) {
  if (Array.isArray(pattern)) {
    return pattern.indexOf(name) > -1
  } else if (typeof pattern === 'string') {
    return pattern.split(',').indexOf(name) > -1
  } else if (isRegExp(pattern)) {
    return pattern.test(name)
  }
  /* istanbul ignore next */
  return false
}

function pruneCache (keepAliveInstance, filter) {
  const { cache, keys, _vnode } = keepAliveInstance;
  for (const key in cache) {
    const cachedNode = cache[key];
    if (cachedNode) {
      const name = getComponentName(cachedNode.componentOptions);
      if (name && !filter(name)) {
        pruneCacheEntry(cache, key, keys, _vnode);
      }
    }
  }
}

function pruneCacheEntry (
  cache,
  key,
  keys,
  current
) {
  const cached$$1 = cache[key];
  if (cached$$1 && cached$$1 !== current) {
    cached$$1.componentInstance.$destroy();
  }
  cache[key] = null;
  remove(keys, key);
}

const patternTypes = [String, RegExp, Array];

var KeepAlive = {
  name: 'keep-alive',
  abstract: true,

  props: {
    include: patternTypes,
    exclude: patternTypes,
    max: [String, Number]
  },

  created () {
    this.cache = Object.create(null);
    this.keys = [];
  },

  destroyed () {
    for (const key in this.cache) {
      pruneCacheEntry(this.cache, key, this.keys);
    }
  },

  watch: {
    include (val) {
      pruneCache(this, name => matches(val, name));
    },
    exclude (val) {
      pruneCache(this, name => !matches(val, name));
    }
  },

  render () {
    const slot = this.$slots.default;
    const vnode = getFirstComponentChild(slot);
    const componentOptions = vnode && vnode.componentOptions;
    if (componentOptions) {
      // check pattern
      const name = getComponentName(componentOptions);
      const { include, exclude } = this;
      if (
        // not included
        (include && (!name || !matches(include, name))) ||
        // excluded
        (exclude && name && matches(exclude, name))
      ) {
        return vnode
      }

      const { cache, keys } = this;
      const key = vnode.key == null
        // same constructor may get registered as different local components
        // so cid alone is not enough (#3269)
        ? componentOptions.Ctor.cid + (componentOptions.tag ? `::${componentOptions.tag}` : '')
        : vnode.key;
      if (cache[key]) {
        vnode.componentInstance = cache[key].componentInstance;
        // make current key freshest
        remove(keys, key);
        keys.push(key);
      } else {
        cache[key] = vnode;
        keys.push(key);
        // prune oldest entry
        if (this.max && keys.length > parseInt(this.max)) {
          pruneCacheEntry(cache, keys[0], keys, this._vnode);
        }
      }

      vnode.data.keepAlive = true;
    }
    return vnode || (slot && slot[0])
  }
};

var builtInComponents = {
  KeepAlive
};

/*  */

function initGlobalAPI (Vue) {
  // config
  const configDef = {};
  configDef.get = () => config;
  {
    configDef.set = () => {
      warn(
        'Do not replace the Vue.config object, set individual fields instead.'
      );
    };
  }
  Object.defineProperty(Vue, 'config', configDef);

  // exposed util methods.
  // NOTE: these are not considered part of the public API - avoid relying on
  // them unless you are aware of the risk.
  Vue.util = {
    warn,
    extend,
    mergeOptions,
    defineReactive
  };

  Vue.set = set;
  Vue.delete = del;
  Vue.nextTick = nextTick;

  Vue.options = Object.create(null);
  ASSET_TYPES.forEach(type => {
    Vue.options[type + 's'] = Object.create(null);
  });

  // this is used to identify the "base" constructor to extend all plain-object
  // components with in Weex's multi-instance scenarios.
  Vue.options._base = Vue;

  extend(Vue.options.components, builtInComponents);

  initUse(Vue);
  initMixin$1(Vue);
  initExtend(Vue);
  initAssetRegisters(Vue);
}

initGlobalAPI(Vue$3);

Object.defineProperty(Vue$3.prototype, '$isServer', {
  get: isServerRendering
});

Object.defineProperty(Vue$3.prototype, '$ssrContext', {
  get () {
    /* istanbul ignore next */
    return this.$vnode && this.$vnode.ssrContext
  }
});

Vue$3.version = '2.5.8';

/*  */

// these are reserved for web because they are directly compiled away
// during template compilation
const isReservedAttr = makeMap('style,class');

// attributes that should be using props for binding
const acceptValue = makeMap('input,textarea,option,select,progress');
const mustUseProp = (tag, type, attr) => {
  return (
    (attr === 'value' && acceptValue(tag)) && type !== 'button' ||
    (attr === 'selected' && tag === 'option') ||
    (attr === 'checked' && tag === 'input') ||
    (attr === 'muted' && tag === 'video')
  )
};

const isEnumeratedAttr = makeMap('contenteditable,draggable,spellcheck');

const isBooleanAttr = makeMap(
  'allowfullscreen,async,autofocus,autoplay,checked,compact,controls,declare,' +
  'default,defaultchecked,defaultmuted,defaultselected,defer,disabled,' +
  'enabled,formnovalidate,hidden,indeterminate,inert,ismap,itemscope,loop,multiple,' +
  'muted,nohref,noresize,noshade,novalidate,nowrap,open,pauseonexit,readonly,' +
  'required,reversed,scoped,seamless,selected,sortable,translate,' +
  'truespeed,typemustmatch,visible'
);

const xlinkNS = 'http://www.w3.org/1999/xlink';

const isXlink = (name) => {
  return name.charAt(5) === ':' && name.slice(0, 5) === 'xlink'
};

const getXlinkProp = (name) => {
  return isXlink(name) ? name.slice(6, name.length) : ''
};

const isFalsyAttrValue = (val) => {
  return val == null || val === false
};

/*  */

function genClassForVnode (vnode) {
  let data = vnode.data;
  let parentNode = vnode;
  let childNode = vnode;
  while (isDef(childNode.componentInstance)) {
    childNode = childNode.componentInstance._vnode;
    if (childNode.data) {
      data = mergeClassData(childNode.data, data);
    }
  }
  while (isDef(parentNode = parentNode.parent)) {
    if (parentNode.data) {
      data = mergeClassData(data, parentNode.data);
    }
  }
  return renderClass(data.staticClass, data.class)
}

function mergeClassData (child, parent) {
  return {
    staticClass: concat(child.staticClass, parent.staticClass),
    class: isDef(child.class)
      ? [child.class, parent.class]
      : parent.class
  }
}

function renderClass (
  staticClass,
  dynamicClass
) {
  if (isDef(staticClass) || isDef(dynamicClass)) {
    return concat(staticClass, stringifyClass(dynamicClass))
  }
  /* istanbul ignore next */
  return ''
}

function concat (a, b) {
  return a ? b ? (a + ' ' + b) : a : (b || '')
}

function stringifyClass (value) {
  if (Array.isArray(value)) {
    return stringifyArray(value)
  }
  if (isObject(value)) {
    return stringifyObject(value)
  }
  if (typeof value === 'string') {
    return value
  }
  /* istanbul ignore next */
  return ''
}

function stringifyArray (value) {
  let res = '';
  let stringified;
  for (let i = 0, l = value.length; i < l; i++) {
    if (isDef(stringified = stringifyClass(value[i])) && stringified !== '') {
      if (res) res += ' ';
      res += stringified;
    }
  }
  return res
}

function stringifyObject (value) {
  let res = '';
  for (const key in value) {
    if (value[key]) {
      if (res) res += ' ';
      res += key;
    }
  }
  return res
}

/*  */

const namespaceMap = {
  svg: 'http://www.w3.org/2000/svg',
  math: 'http://www.w3.org/1998/Math/MathML'
};

const isHTMLTag = makeMap(
  'html,body,base,head,link,meta,style,title,' +
  'address,article,aside,footer,header,h1,h2,h3,h4,h5,h6,hgroup,nav,section,' +
  'div,dd,dl,dt,figcaption,figure,picture,hr,img,li,main,ol,p,pre,ul,' +
  'a,b,abbr,bdi,bdo,br,cite,code,data,dfn,em,i,kbd,mark,q,rp,rt,rtc,ruby,' +
  's,samp,small,span,strong,sub,sup,time,u,var,wbr,area,audio,map,track,video,' +
  'embed,object,param,source,canvas,script,noscript,del,ins,' +
  'caption,col,colgroup,table,thead,tbody,td,th,tr,' +
  'button,datalist,fieldset,form,input,label,legend,meter,optgroup,option,' +
  'output,progress,select,textarea,' +
  'details,dialog,menu,menuitem,summary,' +
  'content,element,shadow,template,blockquote,iframe,tfoot'
);

// this map is intentionally selective, only covering SVG elements that may
// contain child elements.
const isSVG = makeMap(
  'svg,animate,circle,clippath,cursor,defs,desc,ellipse,filter,font-face,' +
  'foreignObject,g,glyph,image,line,marker,mask,missing-glyph,path,pattern,' +
  'polygon,polyline,rect,switch,symbol,text,textpath,tspan,use,view',
  true
);

const isPreTag = (tag) => tag === 'pre';

const isReservedTag = (tag) => {
  return isHTMLTag(tag) || isSVG(tag)
};

function getTagNamespace (tag) {
  if (isSVG(tag)) {
    return 'svg'
  }
  // basic support for MathML
  // note it doesn't support other MathML elements being component roots
  if (tag === 'math') {
    return 'math'
  }
}

const unknownElementCache = Object.create(null);
function isUnknownElement (tag) {
  /* istanbul ignore if */
  if (!inBrowser) {
    return true
  }
  if (isReservedTag(tag)) {
    return false
  }
  tag = tag.toLowerCase();
  /* istanbul ignore if */
  if (unknownElementCache[tag] != null) {
    return unknownElementCache[tag]
  }
  const el = document.createElement(tag);
  if (tag.indexOf('-') > -1) {
    // http://stackoverflow.com/a/28210364/1070244
    return (unknownElementCache[tag] = (
      el.constructor === window.HTMLUnknownElement ||
      el.constructor === window.HTMLElement
    ))
  } else {
    return (unknownElementCache[tag] = /HTMLUnknownElement/.test(el.toString()))
  }
}

const isTextInputType = makeMap('text,number,password,search,email,tel,url');

/*  */

/**
 * Query an element selector if it's not an element already.
 */
function query (el) {
  if (typeof el === 'string') {
    const selected = document.querySelector(el);
    if (!selected) {
      "development" !== 'production' && warn(
        'Cannot find element: ' + el
      );
      return document.createElement('div')
    }
    return selected
  } else {
    return el
  }
}

/*  */

function createElement$1 (tagName, vnode) {
  const elm = document.createElement(tagName);
  if (tagName !== 'select') {
    return elm
  }
  // false or null will remove the attribute but undefined will not
  if (vnode.data && vnode.data.attrs && vnode.data.attrs.multiple !== undefined) {
    elm.setAttribute('multiple', 'multiple');
  }
  return elm
}

function createElementNS (namespace, tagName) {
  return document.createElementNS(namespaceMap[namespace], tagName)
}

function createTextNode (text) {
  return document.createTextNode(text)
}

function createComment (text) {
  return document.createComment(text)
}

function insertBefore (parentNode, newNode, referenceNode) {
  parentNode.insertBefore(newNode, referenceNode);
}

function removeChild (node, child) {
  node.removeChild(child);
}

function appendChild (node, child) {
  node.appendChild(child);
}

function parentNode (node) {
  return node.parentNode
}

function nextSibling (node) {
  return node.nextSibling
}

function tagName (node) {
  return node.tagName
}

function setTextContent (node, text) {
  node.textContent = text;
}

function setAttribute (node, key, val) {
  node.setAttribute(key, val);
}


var nodeOps = Object.freeze({
	createElement: createElement$1,
	createElementNS: createElementNS,
	createTextNode: createTextNode,
	createComment: createComment,
	insertBefore: insertBefore,
	removeChild: removeChild,
	appendChild: appendChild,
	parentNode: parentNode,
	nextSibling: nextSibling,
	tagName: tagName,
	setTextContent: setTextContent,
	setAttribute: setAttribute
});

/*  */

var ref = {
  create (_, vnode) {
    registerRef(vnode);
  },
  update (oldVnode, vnode) {
    if (oldVnode.data.ref !== vnode.data.ref) {
      registerRef(oldVnode, true);
      registerRef(vnode);
    }
  },
  destroy (vnode) {
    registerRef(vnode, true);
  }
};

function registerRef (vnode, isRemoval) {
  const key = vnode.data.ref;
  if (!key) return

  const vm = vnode.context;
  const ref = vnode.componentInstance || vnode.elm;
  const refs = vm.$refs;
  if (isRemoval) {
    if (Array.isArray(refs[key])) {
      remove(refs[key], ref);
    } else if (refs[key] === ref) {
      refs[key] = undefined;
    }
  } else {
    if (vnode.data.refInFor) {
      if (!Array.isArray(refs[key])) {
        refs[key] = [ref];
      } else if (refs[key].indexOf(ref) < 0) {
        // $flow-disable-line
        refs[key].push(ref);
      }
    } else {
      refs[key] = ref;
    }
  }
}

/**
 * Virtual DOM patching algorithm based on Snabbdom by
 * Simon Friis Vindum (@paldepind)
 * Licensed under the MIT License
 * https://github.com/paldepind/snabbdom/blob/master/LICENSE
 *
 * modified by Evan You (@yyx990803)
 *
 * Not type-checking this because this file is perf-critical and the cost
 * of making flow understand it is not worth it.
 */

const emptyNode = new VNode('', {}, []);

const hooks = ['create', 'activate', 'update', 'remove', 'destroy'];

function sameVnode (a, b) {
  return (
    a.key === b.key && (
      (
        a.tag === b.tag &&
        a.isComment === b.isComment &&
        isDef(a.data) === isDef(b.data) &&
        sameInputType(a, b)
      ) || (
        isTrue(a.isAsyncPlaceholder) &&
        a.asyncFactory === b.asyncFactory &&
        isUndef(b.asyncFactory.error)
      )
    )
  )
}

function sameInputType (a, b) {
  if (a.tag !== 'input') return true
  let i;
  const typeA = isDef(i = a.data) && isDef(i = i.attrs) && i.type;
  const typeB = isDef(i = b.data) && isDef(i = i.attrs) && i.type;
  return typeA === typeB || isTextInputType(typeA) && isTextInputType(typeB)
}

function createKeyToOldIdx (children, beginIdx, endIdx) {
  let i, key;
  const map = {};
  for (i = beginIdx; i <= endIdx; ++i) {
    key = children[i].key;
    if (isDef(key)) map[key] = i;
  }
  return map
}

function createPatchFunction (backend) {
  let i, j;
  const cbs = {};

  const { modules, nodeOps } = backend;

  for (i = 0; i < hooks.length; ++i) {
    cbs[hooks[i]] = [];
    for (j = 0; j < modules.length; ++j) {
      if (isDef(modules[j][hooks[i]])) {
        cbs[hooks[i]].push(modules[j][hooks[i]]);
      }
    }
  }

  function emptyNodeAt (elm) {
    return new VNode(nodeOps.tagName(elm).toLowerCase(), {}, [], undefined, elm)
  }

  function createRmCb (childElm, listeners) {
    function remove () {
      if (--remove.listeners === 0) {
        removeNode(childElm);
      }
    }
    remove.listeners = listeners;
    return remove
  }

  function removeNode (el) {
    const parent = nodeOps.parentNode(el);
    // element may have already been removed due to v-html / v-text
    if (isDef(parent)) {
      nodeOps.removeChild(parent, el);
    }
  }

  function isUnknownElement$$1 (vnode, inVPre) {
    return (
      !inVPre &&
      !vnode.ns &&
      !(
        config.ignoredElements.length &&
        config.ignoredElements.some(ignore => {
          return isRegExp(ignore)
            ? ignore.test(vnode.tag)
            : ignore === vnode.tag
        })
      ) &&
      config.isUnknownElement(vnode.tag)
    )
  }

  let creatingElmInVPre = 0;
  function createElm (vnode, insertedVnodeQueue, parentElm, refElm, nested) {
    vnode.isRootInsert = !nested; // for transition enter check
    if (createComponent(vnode, insertedVnodeQueue, parentElm, refElm)) {
      return
    }

    const data = vnode.data;
    const children = vnode.children;
    const tag = vnode.tag;
    if (isDef(tag)) {
      {
        if (data && data.pre) {
          creatingElmInVPre++;
        }
        if (isUnknownElement$$1(vnode, creatingElmInVPre)) {
          warn(
            'Unknown custom element: <' + tag + '> - did you ' +
            'register the component correctly? For recursive components, ' +
            'make sure to provide the "name" option.',
            vnode.context
          );
        }
      }
      vnode.elm = vnode.ns
        ? nodeOps.createElementNS(vnode.ns, tag)
        : nodeOps.createElement(tag, vnode);
      setScope(vnode);

      /* istanbul ignore if */
      {
        createChildren(vnode, children, insertedVnodeQueue);
        if (isDef(data)) {
          invokeCreateHooks(vnode, insertedVnodeQueue);
        }
        insert(parentElm, vnode.elm, refElm);
      }

      if ("development" !== 'production' && data && data.pre) {
        creatingElmInVPre--;
      }
    } else if (isTrue(vnode.isComment)) {
      vnode.elm = nodeOps.createComment(vnode.text);
      insert(parentElm, vnode.elm, refElm);
    } else {
      vnode.elm = nodeOps.createTextNode(vnode.text);
      insert(parentElm, vnode.elm, refElm);
    }
  }

  function createComponent (vnode, insertedVnodeQueue, parentElm, refElm) {
    let i = vnode.data;
    if (isDef(i)) {
      const isReactivated = isDef(vnode.componentInstance) && i.keepAlive;
      if (isDef(i = i.hook) && isDef(i = i.init)) {
        i(vnode, false /* hydrating */, parentElm, refElm);
      }
      // after calling the init hook, if the vnode is a child component
      // it should've created a child instance and mounted it. the child
      // component also has set the placeholder vnode's elm.
      // in that case we can just return the element and be done.
      if (isDef(vnode.componentInstance)) {
        initComponent(vnode, insertedVnodeQueue);
        if (isTrue(isReactivated)) {
          reactivateComponent(vnode, insertedVnodeQueue, parentElm, refElm);
        }
        return true
      }
    }
  }

  function initComponent (vnode, insertedVnodeQueue) {
    if (isDef(vnode.data.pendingInsert)) {
      insertedVnodeQueue.push.apply(insertedVnodeQueue, vnode.data.pendingInsert);
      vnode.data.pendingInsert = null;
    }
    vnode.elm = vnode.componentInstance.$el;
    if (isPatchable(vnode)) {
      invokeCreateHooks(vnode, insertedVnodeQueue);
      setScope(vnode);
    } else {
      // empty component root.
      // skip all element-related modules except for ref (#3455)
      registerRef(vnode);
      // make sure to invoke the insert hook
      insertedVnodeQueue.push(vnode);
    }
  }

  function reactivateComponent (vnode, insertedVnodeQueue, parentElm, refElm) {
    let i;
    // hack for #4339: a reactivated component with inner transition
    // does not trigger because the inner node's created hooks are not called
    // again. It's not ideal to involve module-specific logic in here but
    // there doesn't seem to be a better way to do it.
    let innerNode = vnode;
    while (innerNode.componentInstance) {
      innerNode = innerNode.componentInstance._vnode;
      if (isDef(i = innerNode.data) && isDef(i = i.transition)) {
        for (i = 0; i < cbs.activate.length; ++i) {
          cbs.activate[i](emptyNode, innerNode);
        }
        insertedVnodeQueue.push(innerNode);
        break
      }
    }
    // unlike a newly created component,
    // a reactivated keep-alive component doesn't insert itself
    insert(parentElm, vnode.elm, refElm);
  }

  function insert (parent, elm, ref$$1) {
    if (isDef(parent)) {
      if (isDef(ref$$1)) {
        if (ref$$1.parentNode === parent) {
          nodeOps.insertBefore(parent, elm, ref$$1);
        }
      } else {
        nodeOps.appendChild(parent, elm);
      }
    }
  }

  function createChildren (vnode, children, insertedVnodeQueue) {
    if (Array.isArray(children)) {
      for (let i = 0; i < children.length; ++i) {
        createElm(children[i], insertedVnodeQueue, vnode.elm, null, true);
      }
    } else if (isPrimitive(vnode.text)) {
      nodeOps.appendChild(vnode.elm, nodeOps.createTextNode(vnode.text));
    }
  }

  function isPatchable (vnode) {
    while (vnode.componentInstance) {
      vnode = vnode.componentInstance._vnode;
    }
    return isDef(vnode.tag)
  }

  function invokeCreateHooks (vnode, insertedVnodeQueue) {
    for (let i = 0; i < cbs.create.length; ++i) {
      cbs.create[i](emptyNode, vnode);
    }
    i = vnode.data.hook; // Reuse variable
    if (isDef(i)) {
      if (isDef(i.create)) i.create(emptyNode, vnode);
      if (isDef(i.insert)) insertedVnodeQueue.push(vnode);
    }
  }

  // set scope id attribute for scoped CSS.
  // this is implemented as a special case to avoid the overhead
  // of going through the normal attribute patching process.
  function setScope (vnode) {
    let i;
    if (isDef(i = vnode.functionalScopeId)) {
      nodeOps.setAttribute(vnode.elm, i, '');
    } else {
      let ancestor = vnode;
      while (ancestor) {
        if (isDef(i = ancestor.context) && isDef(i = i.$options._scopeId)) {
          nodeOps.setAttribute(vnode.elm, i, '');
        }
        ancestor = ancestor.parent;
      }
    }
    // for slot content they should also get the scopeId from the host instance.
    if (isDef(i = activeInstance) &&
      i !== vnode.context &&
      i !== vnode.functionalContext &&
      isDef(i = i.$options._scopeId)
    ) {
      nodeOps.setAttribute(vnode.elm, i, '');
    }
  }

  function addVnodes (parentElm, refElm, vnodes, startIdx, endIdx, insertedVnodeQueue) {
    for (; startIdx <= endIdx; ++startIdx) {
      createElm(vnodes[startIdx], insertedVnodeQueue, parentElm, refElm);
    }
  }

  function invokeDestroyHook (vnode) {
    let i, j;
    const data = vnode.data;
    if (isDef(data)) {
      if (isDef(i = data.hook) && isDef(i = i.destroy)) i(vnode);
      for (i = 0; i < cbs.destroy.length; ++i) cbs.destroy[i](vnode);
    }
    if (isDef(i = vnode.children)) {
      for (j = 0; j < vnode.children.length; ++j) {
        invokeDestroyHook(vnode.children[j]);
      }
    }
  }

  function removeVnodes (parentElm, vnodes, startIdx, endIdx) {
    for (; startIdx <= endIdx; ++startIdx) {
      const ch = vnodes[startIdx];
      if (isDef(ch)) {
        if (isDef(ch.tag)) {
          removeAndInvokeRemoveHook(ch);
          invokeDestroyHook(ch);
        } else { // Text node
          removeNode(ch.elm);
        }
      }
    }
  }

  function removeAndInvokeRemoveHook (vnode, rm) {
    if (isDef(rm) || isDef(vnode.data)) {
      let i;
      const listeners = cbs.remove.length + 1;
      if (isDef(rm)) {
        // we have a recursively passed down rm callback
        // increase the listeners count
        rm.listeners += listeners;
      } else {
        // directly removing
        rm = createRmCb(vnode.elm, listeners);
      }
      // recursively invoke hooks on child component root node
      if (isDef(i = vnode.componentInstance) && isDef(i = i._vnode) && isDef(i.data)) {
        removeAndInvokeRemoveHook(i, rm);
      }
      for (i = 0; i < cbs.remove.length; ++i) {
        cbs.remove[i](vnode, rm);
      }
      if (isDef(i = vnode.data.hook) && isDef(i = i.remove)) {
        i(vnode, rm);
      } else {
        rm();
      }
    } else {
      removeNode(vnode.elm);
    }
  }

  function updateChildren (parentElm, oldCh, newCh, insertedVnodeQueue, removeOnly) {
    let oldStartIdx = 0;
    let newStartIdx = 0;
    let oldEndIdx = oldCh.length - 1;
    let oldStartVnode = oldCh[0];
    let oldEndVnode = oldCh[oldEndIdx];
    let newEndIdx = newCh.length - 1;
    let newStartVnode = newCh[0];
    let newEndVnode = newCh[newEndIdx];
    let oldKeyToIdx, idxInOld, vnodeToMove, refElm;

    // removeOnly is a special flag used only by <transition-group>
    // to ensure removed elements stay in correct relative positions
    // during leaving transitions
    const canMove = !removeOnly;

    while (oldStartIdx <= oldEndIdx && newStartIdx <= newEndIdx) {
      if (isUndef(oldStartVnode)) {
        oldStartVnode = oldCh[++oldStartIdx]; // Vnode has been moved left
      } else if (isUndef(oldEndVnode)) {
        oldEndVnode = oldCh[--oldEndIdx];
      } else if (sameVnode(oldStartVnode, newStartVnode)) {
        patchVnode(oldStartVnode, newStartVnode, insertedVnodeQueue);
        oldStartVnode = oldCh[++oldStartIdx];
        newStartVnode = newCh[++newStartIdx];
      } else if (sameVnode(oldEndVnode, newEndVnode)) {
        patchVnode(oldEndVnode, newEndVnode, insertedVnodeQueue);
        oldEndVnode = oldCh[--oldEndIdx];
        newEndVnode = newCh[--newEndIdx];
      } else if (sameVnode(oldStartVnode, newEndVnode)) { // Vnode moved right
        patchVnode(oldStartVnode, newEndVnode, insertedVnodeQueue);
        canMove && nodeOps.insertBefore(parentElm, oldStartVnode.elm, nodeOps.nextSibling(oldEndVnode.elm));
        oldStartVnode = oldCh[++oldStartIdx];
        newEndVnode = newCh[--newEndIdx];
      } else if (sameVnode(oldEndVnode, newStartVnode)) { // Vnode moved left
        patchVnode(oldEndVnode, newStartVnode, insertedVnodeQueue);
        canMove && nodeOps.insertBefore(parentElm, oldEndVnode.elm, oldStartVnode.elm);
        oldEndVnode = oldCh[--oldEndIdx];
        newStartVnode = newCh[++newStartIdx];
      } else {
        if (isUndef(oldKeyToIdx)) oldKeyToIdx = createKeyToOldIdx(oldCh, oldStartIdx, oldEndIdx);
        idxInOld = isDef(newStartVnode.key)
          ? oldKeyToIdx[newStartVnode.key]
          : findIdxInOld(newStartVnode, oldCh, oldStartIdx, oldEndIdx);
        if (isUndef(idxInOld)) { // New element
          createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm);
        } else {
          vnodeToMove = oldCh[idxInOld];
          /* istanbul ignore if */
          if ("development" !== 'production' && !vnodeToMove) {
            warn(
              'It seems there are duplicate keys that is causing an update error. ' +
              'Make sure each v-for item has a unique key.'
            );
          }
          if (sameVnode(vnodeToMove, newStartVnode)) {
            patchVnode(vnodeToMove, newStartVnode, insertedVnodeQueue);
            oldCh[idxInOld] = undefined;
            canMove && nodeOps.insertBefore(parentElm, vnodeToMove.elm, oldStartVnode.elm);
          } else {
            // same key but different element. treat as new element
            createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm);
          }
        }
        newStartVnode = newCh[++newStartIdx];
      }
    }
    if (oldStartIdx > oldEndIdx) {
      refElm = isUndef(newCh[newEndIdx + 1]) ? null : newCh[newEndIdx + 1].elm;
      addVnodes(parentElm, refElm, newCh, newStartIdx, newEndIdx, insertedVnodeQueue);
    } else if (newStartIdx > newEndIdx) {
      removeVnodes(parentElm, oldCh, oldStartIdx, oldEndIdx);
    }
  }

  function findIdxInOld (node, oldCh, start, end) {
    for (let i = start; i < end; i++) {
      const c = oldCh[i];
      if (isDef(c) && sameVnode(node, c)) return i
    }
  }

  function patchVnode (oldVnode, vnode, insertedVnodeQueue, removeOnly) {
    if (oldVnode === vnode) {
      return
    }

    const elm = vnode.elm = oldVnode.elm;

    if (isTrue(oldVnode.isAsyncPlaceholder)) {
      if (isDef(vnode.asyncFactory.resolved)) {
        hydrate(oldVnode.elm, vnode, insertedVnodeQueue);
      } else {
        vnode.isAsyncPlaceholder = true;
      }
      return
    }

    // reuse element for static trees.
    // note we only do this if the vnode is cloned -
    // if the new node is not cloned it means the render functions have been
    // reset by the hot-reload-api and we need to do a proper re-render.
    if (isTrue(vnode.isStatic) &&
      isTrue(oldVnode.isStatic) &&
      vnode.key === oldVnode.key &&
      (isTrue(vnode.isCloned) || isTrue(vnode.isOnce))
    ) {
      vnode.componentInstance = oldVnode.componentInstance;
      return
    }

    let i;
    const data = vnode.data;
    if (isDef(data) && isDef(i = data.hook) && isDef(i = i.prepatch)) {
      i(oldVnode, vnode);
    }

    const oldCh = oldVnode.children;
    const ch = vnode.children;
    if (isDef(data) && isPatchable(vnode)) {
      for (i = 0; i < cbs.update.length; ++i) cbs.update[i](oldVnode, vnode);
      if (isDef(i = data.hook) && isDef(i = i.update)) i(oldVnode, vnode);
    }
    if (isUndef(vnode.text)) {
      if (isDef(oldCh) && isDef(ch)) {
        if (oldCh !== ch) updateChildren(elm, oldCh, ch, insertedVnodeQueue, removeOnly);
      } else if (isDef(ch)) {
        if (isDef(oldVnode.text)) nodeOps.setTextContent(elm, '');
        addVnodes(elm, null, ch, 0, ch.length - 1, insertedVnodeQueue);
      } else if (isDef(oldCh)) {
        removeVnodes(elm, oldCh, 0, oldCh.length - 1);
      } else if (isDef(oldVnode.text)) {
        nodeOps.setTextContent(elm, '');
      }
    } else if (oldVnode.text !== vnode.text) {
      nodeOps.setTextContent(elm, vnode.text);
    }
    if (isDef(data)) {
      if (isDef(i = data.hook) && isDef(i = i.postpatch)) i(oldVnode, vnode);
    }
  }

  function invokeInsertHook (vnode, queue, initial) {
    // delay insert hooks for component root nodes, invoke them after the
    // element is really inserted
    if (isTrue(initial) && isDef(vnode.parent)) {
      vnode.parent.data.pendingInsert = queue;
    } else {
      for (let i = 0; i < queue.length; ++i) {
        queue[i].data.hook.insert(queue[i]);
      }
    }
  }

  let hydrationBailed = false;
  // list of modules that can skip create hook during hydration because they
  // are already rendered on the client or has no need for initialization
  // Note: style is excluded because it relies on initial clone for future
  // deep updates (#7063).
  const isRenderedModule = makeMap('attrs,class,staticClass,staticStyle,key');

  // Note: this is a browser-only function so we can assume elms are DOM nodes.
  function hydrate (elm, vnode, insertedVnodeQueue, inVPre) {
    let i;
    const { tag, data, children } = vnode;
    inVPre = inVPre || (data && data.pre);
    vnode.elm = elm;

    if (isTrue(vnode.isComment) && isDef(vnode.asyncFactory)) {
      vnode.isAsyncPlaceholder = true;
      return true
    }
    // assert node match
    {
      if (!assertNodeMatch(elm, vnode, inVPre)) {
        return false
      }
    }
    if (isDef(data)) {
      if (isDef(i = data.hook) && isDef(i = i.init)) i(vnode, true /* hydrating */);
      if (isDef(i = vnode.componentInstance)) {
        // child component. it should have hydrated its own tree.
        initComponent(vnode, insertedVnodeQueue);
        return true
      }
    }
    if (isDef(tag)) {
      if (isDef(children)) {
        // empty element, allow client to pick up and populate children
        if (!elm.hasChildNodes()) {
          createChildren(vnode, children, insertedVnodeQueue);
        } else {
          // v-html and domProps: innerHTML
          if (isDef(i = data) && isDef(i = i.domProps) && isDef(i = i.innerHTML)) {
            if (i !== elm.innerHTML) {
              /* istanbul ignore if */
              if ("development" !== 'production' &&
                typeof console !== 'undefined' &&
                !hydrationBailed
              ) {
                hydrationBailed = true;
                console.warn('Parent: ', elm);
                console.warn('server innerHTML: ', i);
                console.warn('client innerHTML: ', elm.innerHTML);
              }
              return false
            }
          } else {
            // iterate and compare children lists
            let childrenMatch = true;
            let childNode = elm.firstChild;
            for (let i = 0; i < children.length; i++) {
              if (!childNode || !hydrate(childNode, children[i], insertedVnodeQueue, inVPre)) {
                childrenMatch = false;
                break
              }
              childNode = childNode.nextSibling;
            }
            // if childNode is not null, it means the actual childNodes list is
            // longer than the virtual children list.
            if (!childrenMatch || childNode) {
              /* istanbul ignore if */
              if ("development" !== 'production' &&
                typeof console !== 'undefined' &&
                !hydrationBailed
              ) {
                hydrationBailed = true;
                console.warn('Parent: ', elm);
                console.warn('Mismatching childNodes vs. VNodes: ', elm.childNodes, children);
              }
              return false
            }
          }
        }
      }
      if (isDef(data)) {
        let fullInvoke = false;
        for (const key in data) {
          if (!isRenderedModule(key)) {
            fullInvoke = true;
            invokeCreateHooks(vnode, insertedVnodeQueue);
            break
          }
        }
        if (!fullInvoke && data['class']) {
          // ensure collecting deps for deep class bindings for future updates
          traverse(data['class']);
        }
      }
    } else if (elm.data !== vnode.text) {
      elm.data = vnode.text;
    }
    return true
  }

  function assertNodeMatch (node, vnode, inVPre) {
    if (isDef(vnode.tag)) {
      return vnode.tag.indexOf('vue-component') === 0 || (
        !isUnknownElement$$1(vnode, inVPre) &&
        vnode.tag.toLowerCase() === (node.tagName && node.tagName.toLowerCase())
      )
    } else {
      return node.nodeType === (vnode.isComment ? 8 : 3)
    }
  }

  return function patch (oldVnode, vnode, hydrating, removeOnly, parentElm, refElm) {
    if (isUndef(vnode)) {
      if (isDef(oldVnode)) invokeDestroyHook(oldVnode);
      return
    }

    let isInitialPatch = false;
    const insertedVnodeQueue = [];

    if (isUndef(oldVnode)) {
      // empty mount (likely as component), create new root element
      isInitialPatch = true;
      createElm(vnode, insertedVnodeQueue, parentElm, refElm);
    } else {
      const isRealElement = isDef(oldVnode.nodeType);
      if (!isRealElement && sameVnode(oldVnode, vnode)) {
        // patch existing root node
        patchVnode(oldVnode, vnode, insertedVnodeQueue, removeOnly);
      } else {
        if (isRealElement) {
          // mounting to a real element
          // check if this is server-rendered content and if we can perform
          // a successful hydration.
          if (oldVnode.nodeType === 1 && oldVnode.hasAttribute(SSR_ATTR)) {
            oldVnode.removeAttribute(SSR_ATTR);
            hydrating = true;
          }
          if (isTrue(hydrating)) {
            if (hydrate(oldVnode, vnode, insertedVnodeQueue)) {
              invokeInsertHook(vnode, insertedVnodeQueue, true);
              return oldVnode
            } else {
              warn(
                'The client-side rendered virtual DOM tree is not matching ' +
                'server-rendered content. This is likely caused by incorrect ' +
                'HTML markup, for example nesting block-level elements inside ' +
                '<p>, or missing <tbody>. Bailing hydration and performing ' +
                'full client-side render.'
              );
            }
          }
          // either not server-rendered, or hydration failed.
          // create an empty node and replace it
          oldVnode = emptyNodeAt(oldVnode);
        }

        // replacing existing element
        const oldElm = oldVnode.elm;
        const parentElm = nodeOps.parentNode(oldElm);

        // create new node
        createElm(
          vnode,
          insertedVnodeQueue,
          // extremely rare edge case: do not insert if old element is in a
          // leaving transition. Only happens when combining transition +
          // keep-alive + HOCs. (#4590)
          oldElm._leaveCb ? null : parentElm,
          nodeOps.nextSibling(oldElm)
        );

        // update parent placeholder node element, recursively
        if (isDef(vnode.parent)) {
          let ancestor = vnode.parent;
          const patchable = isPatchable(vnode);
          while (ancestor) {
            for (let i = 0; i < cbs.destroy.length; ++i) {
              cbs.destroy[i](ancestor);
            }
            ancestor.elm = vnode.elm;
            if (patchable) {
              for (let i = 0; i < cbs.create.length; ++i) {
                cbs.create[i](emptyNode, ancestor);
              }
              // #6513
              // invoke insert hooks that may have been merged by create hooks.
              // e.g. for directives that uses the "inserted" hook.
              const insert = ancestor.data.hook.insert;
              if (insert.merged) {
                // start at index 1 to avoid re-invoking component mounted hook
                for (let i = 1; i < insert.fns.length; i++) {
                  insert.fns[i]();
                }
              }
            } else {
              registerRef(ancestor);
            }
            ancestor = ancestor.parent;
          }
        }

        // destroy old node
        if (isDef(parentElm)) {
          removeVnodes(parentElm, [oldVnode], 0, 0);
        } else if (isDef(oldVnode.tag)) {
          invokeDestroyHook(oldVnode);
        }
      }
    }

    invokeInsertHook(vnode, insertedVnodeQueue, isInitialPatch);
    return vnode.elm
  }
}

/*  */

var directives = {
  create: updateDirectives,
  update: updateDirectives,
  destroy: function unbindDirectives (vnode) {
    updateDirectives(vnode, emptyNode);
  }
};

function updateDirectives (oldVnode, vnode) {
  if (oldVnode.data.directives || vnode.data.directives) {
    _update(oldVnode, vnode);
  }
}

function _update (oldVnode, vnode) {
  const isCreate = oldVnode === emptyNode;
  const isDestroy = vnode === emptyNode;
  const oldDirs = normalizeDirectives$1(oldVnode.data.directives, oldVnode.context);
  const newDirs = normalizeDirectives$1(vnode.data.directives, vnode.context);

  const dirsWithInsert = [];
  const dirsWithPostpatch = [];

  let key, oldDir, dir;
  for (key in newDirs) {
    oldDir = oldDirs[key];
    dir = newDirs[key];
    if (!oldDir) {
      // new directive, bind
      callHook$1(dir, 'bind', vnode, oldVnode);
      if (dir.def && dir.def.inserted) {
        dirsWithInsert.push(dir);
      }
    } else {
      // existing directive, update
      dir.oldValue = oldDir.value;
      callHook$1(dir, 'update', vnode, oldVnode);
      if (dir.def && dir.def.componentUpdated) {
        dirsWithPostpatch.push(dir);
      }
    }
  }

  if (dirsWithInsert.length) {
    const callInsert = () => {
      for (let i = 0; i < dirsWithInsert.length; i++) {
        callHook$1(dirsWithInsert[i], 'inserted', vnode, oldVnode);
      }
    };
    if (isCreate) {
      mergeVNodeHook(vnode, 'insert', callInsert);
    } else {
      callInsert();
    }
  }

  if (dirsWithPostpatch.length) {
    mergeVNodeHook(vnode, 'postpatch', () => {
      for (let i = 0; i < dirsWithPostpatch.length; i++) {
        callHook$1(dirsWithPostpatch[i], 'componentUpdated', vnode, oldVnode);
      }
    });
  }

  if (!isCreate) {
    for (key in oldDirs) {
      if (!newDirs[key]) {
        // no longer present, unbind
        callHook$1(oldDirs[key], 'unbind', oldVnode, oldVnode, isDestroy);
      }
    }
  }
}

const emptyModifiers = Object.create(null);

function normalizeDirectives$1 (
  dirs,
  vm
) {
  const res = Object.create(null);
  if (!dirs) {
    return res
  }
  let i, dir;
  for (i = 0; i < dirs.length; i++) {
    dir = dirs[i];
    if (!dir.modifiers) {
      dir.modifiers = emptyModifiers;
    }
    res[getRawDirName(dir)] = dir;
    dir.def = resolveAsset(vm.$options, 'directives', dir.name, true);
  }
  return res
}

function getRawDirName (dir) {
  return dir.rawName || `${dir.name}.${Object.keys(dir.modifiers || {}).join('.')}`
}

function callHook$1 (dir, hook, vnode, oldVnode, isDestroy) {
  const fn = dir.def && dir.def[hook];
  if (fn) {
    try {
      fn(vnode.elm, dir, vnode, oldVnode, isDestroy);
    } catch (e) {
      handleError(e, vnode.context, `directive ${dir.name} ${hook} hook`);
    }
  }
}

var baseModules = [
  ref,
  directives
];

/*  */

function updateAttrs (oldVnode, vnode) {
  const opts = vnode.componentOptions;
  if (isDef(opts) && opts.Ctor.options.inheritAttrs === false) {
    return
  }
  if (isUndef(oldVnode.data.attrs) && isUndef(vnode.data.attrs)) {
    return
  }
  let key, cur, old;
  const elm = vnode.elm;
  const oldAttrs = oldVnode.data.attrs || {};
  let attrs = vnode.data.attrs || {};
  // clone observed objects, as the user probably wants to mutate it
  if (isDef(attrs.__ob__)) {
    attrs = vnode.data.attrs = extend({}, attrs);
  }

  for (key in attrs) {
    cur = attrs[key];
    old = oldAttrs[key];
    if (old !== cur) {
      setAttr(elm, key, cur);
    }
  }
  // #4391: in IE9, setting type can reset value for input[type=radio]
  // #6666: IE/Edge forces progress value down to 1 before setting a max
  /* istanbul ignore if */
  if ((isIE9 || isEdge) && attrs.value !== oldAttrs.value) {
    setAttr(elm, 'value', attrs.value);
  }
  for (key in oldAttrs) {
    if (isUndef(attrs[key])) {
      if (isXlink(key)) {
        elm.removeAttributeNS(xlinkNS, getXlinkProp(key));
      } else if (!isEnumeratedAttr(key)) {
        elm.removeAttribute(key);
      }
    }
  }
}

function setAttr (el, key, value) {
  if (isBooleanAttr(key)) {
    // set attribute for blank value
    // e.g. <option disabled>Select one</option>
    if (isFalsyAttrValue(value)) {
      el.removeAttribute(key);
    } else {
      // technically allowfullscreen is a boolean attribute for <iframe>,
      // but Flash expects a value of "true" when used on <embed> tag
      value = key === 'allowfullscreen' && el.tagName === 'EMBED'
        ? 'true'
        : key;
      el.setAttribute(key, value);
    }
  } else if (isEnumeratedAttr(key)) {
    el.setAttribute(key, isFalsyAttrValue(value) || value === 'false' ? 'false' : 'true');
  } else if (isXlink(key)) {
    if (isFalsyAttrValue(value)) {
      el.removeAttributeNS(xlinkNS, getXlinkProp(key));
    } else {
      el.setAttributeNS(xlinkNS, key, value);
    }
  } else {
    if (isFalsyAttrValue(value)) {
      el.removeAttribute(key);
    } else {
      el.setAttribute(key, value);
    }
  }
}

var attrs = {
  create: updateAttrs,
  update: updateAttrs
};

/*  */

function updateClass (oldVnode, vnode) {
  const el = vnode.elm;
  const data = vnode.data;
  const oldData = oldVnode.data;
  if (
    isUndef(data.staticClass) &&
    isUndef(data.class) && (
      isUndef(oldData) || (
        isUndef(oldData.staticClass) &&
        isUndef(oldData.class)
      )
    )
  ) {
    return
  }

  let cls = genClassForVnode(vnode);

  // handle transition classes
  const transitionClass = el._transitionClasses;
  if (isDef(transitionClass)) {
    cls = concat(cls, stringifyClass(transitionClass));
  }

  // set the class
  if (cls !== el._prevClass) {
    el.setAttribute('class', cls);
    el._prevClass = cls;
  }
}

var klass = {
  create: updateClass,
  update: updateClass
};

/*  */

const validDivisionCharRE = /[\w).+\-_$\]]/;

function parseFilters (exp) {
  let inSingle = false;
  let inDouble = false;
  let inTemplateString = false;
  let inRegex = false;
  let curly = 0;
  let square = 0;
  let paren = 0;
  let lastFilterIndex = 0;
  let c, prev, i, expression, filters;

  for (i = 0; i < exp.length; i++) {
    prev = c;
    c = exp.charCodeAt(i);
    if (inSingle) {
      if (c === 0x27 && prev !== 0x5C) inSingle = false;
    } else if (inDouble) {
      if (c === 0x22 && prev !== 0x5C) inDouble = false;
    } else if (inTemplateString) {
      if (c === 0x60 && prev !== 0x5C) inTemplateString = false;
    } else if (inRegex) {
      if (c === 0x2f && prev !== 0x5C) inRegex = false;
    } else if (
      c === 0x7C && // pipe
      exp.charCodeAt(i + 1) !== 0x7C &&
      exp.charCodeAt(i - 1) !== 0x7C &&
      !curly && !square && !paren
    ) {
      if (expression === undefined) {
        // first filter, end of expression
        lastFilterIndex = i + 1;
        expression = exp.slice(0, i).trim();
      } else {
        pushFilter();
      }
    } else {
      switch (c) {
        case 0x22: inDouble = true; break         // "
        case 0x27: inSingle = true; break         // '
        case 0x60: inTemplateString = true; break // `
        case 0x28: paren++; break                 // (
        case 0x29: paren--; break                 // )
        case 0x5B: square++; break                // [
        case 0x5D: square--; break                // ]
        case 0x7B: curly++; break                 // {
        case 0x7D: curly--; break                 // }
      }
      if (c === 0x2f) { // /
        let j = i - 1;
        let p;
        // find first non-whitespace prev char
        for (; j >= 0; j--) {
          p = exp.charAt(j);
          if (p !== ' ') break
        }
        if (!p || !validDivisionCharRE.test(p)) {
          inRegex = true;
        }
      }
    }
  }

  if (expression === undefined) {
    expression = exp.slice(0, i).trim();
  } else if (lastFilterIndex !== 0) {
    pushFilter();
  }

  function pushFilter () {
    (filters || (filters = [])).push(exp.slice(lastFilterIndex, i).trim());
    lastFilterIndex = i + 1;
  }

  if (filters) {
    for (i = 0; i < filters.length; i++) {
      expression = wrapFilter(expression, filters[i]);
    }
  }

  return expression
}

function wrapFilter (exp, filter) {
  const i = filter.indexOf('(');
  if (i < 0) {
    // _f: resolveFilter
    return `_f("${filter}")(${exp})`
  } else {
    const name = filter.slice(0, i);
    const args = filter.slice(i + 1);
    return `_f("${name}")(${exp},${args}`
  }
}

/*  */

function baseWarn (msg) {
  console.error(`[Vue compiler]: ${msg}`);
}

function pluckModuleFunction (
  modules,
  key
) {
  return modules
    ? modules.map(m => m[key]).filter(_ => _)
    : []
}

function addProp (el, name, value) {
  (el.props || (el.props = [])).push({ name, value });
}

function addAttr (el, name, value) {
  (el.attrs || (el.attrs = [])).push({ name, value });
}

function addDirective (
  el,
  name,
  rawName,
  value,
  arg,
  modifiers
) {
  (el.directives || (el.directives = [])).push({ name, rawName, value, arg, modifiers });
}

function addHandler (
  el,
  name,
  value,
  modifiers,
  important,
  warn
) {
  modifiers = modifiers || emptyObject;
  // warn prevent and passive modifier
  /* istanbul ignore if */
  if (
    "development" !== 'production' && warn &&
    modifiers.prevent && modifiers.passive
  ) {
    warn(
      'passive and prevent can\'t be used together. ' +
      'Passive handler can\'t prevent default event.'
    );
  }

  // check capture modifier
  if (modifiers.capture) {
    delete modifiers.capture;
    name = '!' + name; // mark the event as captured
  }
  if (modifiers.once) {
    delete modifiers.once;
    name = '~' + name; // mark the event as once
  }
  /* istanbul ignore if */
  if (modifiers.passive) {
    delete modifiers.passive;
    name = '&' + name; // mark the event as passive
  }

  // normalize click.right and click.middle since they don't actually fire
  // this is technically browser-specific, but at least for now browsers are
  // the only target envs that have right/middle clicks.
  if (name === 'click') {
    if (modifiers.right) {
      name = 'contextmenu';
      delete modifiers.right;
    } else if (modifiers.middle) {
      name = 'mouseup';
    }
  }

  let events;
  if (modifiers.native) {
    delete modifiers.native;
    events = el.nativeEvents || (el.nativeEvents = {});
  } else {
    events = el.events || (el.events = {});
  }

  const newHandler = { value };
  if (modifiers !== emptyObject) {
    newHandler.modifiers = modifiers;
  }

  const handlers = events[name];
  /* istanbul ignore if */
  if (Array.isArray(handlers)) {
    important ? handlers.unshift(newHandler) : handlers.push(newHandler);
  } else if (handlers) {
    events[name] = important ? [newHandler, handlers] : [handlers, newHandler];
  } else {
    events[name] = newHandler;
  }
}

function getBindingAttr (
  el,
  name,
  getStatic
) {
  const dynamicValue =
    getAndRemoveAttr(el, ':' + name) ||
    getAndRemoveAttr(el, 'v-bind:' + name);
  if (dynamicValue != null) {
    return parseFilters(dynamicValue)
  } else if (getStatic !== false) {
    const staticValue = getAndRemoveAttr(el, name);
    if (staticValue != null) {
      return JSON.stringify(staticValue)
    }
  }
}

// note: this only removes the attr from the Array (attrsList) so that it
// doesn't get processed by processAttrs.
// By default it does NOT remove it from the map (attrsMap) because the map is
// needed during codegen.
function getAndRemoveAttr (
  el,
  name,
  removeFromMap
) {
  let val;
  if ((val = el.attrsMap[name]) != null) {
    const list = el.attrsList;
    for (let i = 0, l = list.length; i < l; i++) {
      if (list[i].name === name) {
        list.splice(i, 1);
        break
      }
    }
  }
  if (removeFromMap) {
    delete el.attrsMap[name];
  }
  return val
}

/*  */

/**
 * Cross-platform code generation for component v-model
 */
function genComponentModel (
  el,
  value,
  modifiers
) {
  const { number, trim } = modifiers || {};

  const baseValueExpression = '$$v';
  let valueExpression = baseValueExpression;
  if (trim) {
    valueExpression =
      `(typeof ${baseValueExpression} === 'string'` +
        `? ${baseValueExpression}.trim()` +
        `: ${baseValueExpression})`;
  }
  if (number) {
    valueExpression = `_n(${valueExpression})`;
  }
  const assignment = genAssignmentCode(value, valueExpression);

  el.model = {
    value: `(${value})`,
    expression: `"${value}"`,
    callback: `function (${baseValueExpression}) {${assignment}}`
  };
}

/**
 * Cross-platform codegen helper for generating v-model value assignment code.
 */
function genAssignmentCode (
  value,
  assignment
) {
  const res = parseModel(value);
  if (res.key === null) {
    return `${value}=${assignment}`
  } else {
    return `$set(${res.exp}, ${res.key}, ${assignment})`
  }
}

/**
 * Parse a v-model expression into a base path and a final key segment.
 * Handles both dot-path and possible square brackets.
 *
 * Possible cases:
 *
 * - test
 * - test[key]
 * - test[test1[key]]
 * - test["a"][key]
 * - xxx.test[a[a].test1[key]]
 * - test.xxx.a["asa"][test1[key]]
 *
 */

let len;
let str;
let chr;
let index$1;
let expressionPos;
let expressionEndPos;



function parseModel (val) {
  len = val.length;

  if (val.indexOf('[') < 0 || val.lastIndexOf(']') < len - 1) {
    index$1 = val.lastIndexOf('.');
    if (index$1 > -1) {
      return {
        exp: val.slice(0, index$1),
        key: '"' + val.slice(index$1 + 1) + '"'
      }
    } else {
      return {
        exp: val,
        key: null
      }
    }
  }

  str = val;
  index$1 = expressionPos = expressionEndPos = 0;

  while (!eof()) {
    chr = next();
    /* istanbul ignore if */
    if (isStringStart(chr)) {
      parseString(chr);
    } else if (chr === 0x5B) {
      parseBracket(chr);
    }
  }

  return {
    exp: val.slice(0, expressionPos),
    key: val.slice(expressionPos + 1, expressionEndPos)
  }
}

function next () {
  return str.charCodeAt(++index$1)
}

function eof () {
  return index$1 >= len
}

function isStringStart (chr) {
  return chr === 0x22 || chr === 0x27
}

function parseBracket (chr) {
  let inBracket = 1;
  expressionPos = index$1;
  while (!eof()) {
    chr = next();
    if (isStringStart(chr)) {
      parseString(chr);
      continue
    }
    if (chr === 0x5B) inBracket++;
    if (chr === 0x5D) inBracket--;
    if (inBracket === 0) {
      expressionEndPos = index$1;
      break
    }
  }
}

function parseString (chr) {
  const stringQuote = chr;
  while (!eof()) {
    chr = next();
    if (chr === stringQuote) {
      break
    }
  }
}

/*  */

let warn$1;

// in some cases, the event used has to be determined at runtime
// so we used some reserved tokens during compile.
const RANGE_TOKEN = '__r';
const CHECKBOX_RADIO_TOKEN = '__c';

function model (
  el,
  dir,
  _warn
) {
  warn$1 = _warn;
  const value = dir.value;
  const modifiers = dir.modifiers;
  const tag = el.tag;
  const type = el.attrsMap.type;

  {
    // inputs with type="file" are read only and setting the input's
    // value will throw an error.
    if (tag === 'input' && type === 'file') {
      warn$1(
        `<${el.tag} v-model="${value}" type="file">:\n` +
        `File inputs are read only. Use a v-on:change listener instead.`
      );
    }
  }

  if (el.component) {
    genComponentModel(el, value, modifiers);
    // component v-model doesn't need extra runtime
    return false
  } else if (tag === 'select') {
    genSelect(el, value, modifiers);
  } else if (tag === 'input' && type === 'checkbox') {
    genCheckboxModel(el, value, modifiers);
  } else if (tag === 'input' && type === 'radio') {
    genRadioModel(el, value, modifiers);
  } else if (tag === 'input' || tag === 'textarea') {
    genDefaultModel(el, value, modifiers);
  } else if (!config.isReservedTag(tag)) {
    genComponentModel(el, value, modifiers);
    // component v-model doesn't need extra runtime
    return false
  } else {
    warn$1(
      `<${el.tag} v-model="${value}">: ` +
      `v-model is not supported on this element type. ` +
      'If you are working with contenteditable, it\'s recommended to ' +
      'wrap a library dedicated for that purpose inside a custom component.'
    );
  }

  // ensure runtime directive metadata
  return true
}

function genCheckboxModel (
  el,
  value,
  modifiers
) {
  const number = modifiers && modifiers.number;
  const valueBinding = getBindingAttr(el, 'value') || 'null';
  const trueValueBinding = getBindingAttr(el, 'true-value') || 'true';
  const falseValueBinding = getBindingAttr(el, 'false-value') || 'false';
  addProp(el, 'checked',
    `Array.isArray(${value})` +
      `?_i(${value},${valueBinding})>-1` + (
        trueValueBinding === 'true'
          ? `:(${value})`
          : `:_q(${value},${trueValueBinding})`
      )
  );
  addHandler(el, 'change',
    `var $$a=${value},` +
        '$$el=$event.target,' +
        `$$c=$$el.checked?(${trueValueBinding}):(${falseValueBinding});` +
    'if(Array.isArray($$a)){' +
      `var $$v=${number ? '_n(' + valueBinding + ')' : valueBinding},` +
          '$$i=_i($$a,$$v);' +
      `if($$el.checked){$$i<0&&(${value}=$$a.concat([$$v]))}` +
      `else{$$i>-1&&(${value}=$$a.slice(0,$$i).concat($$a.slice($$i+1)))}` +
    `}else{${genAssignmentCode(value, '$$c')}}`,
    null, true
  );
}

function genRadioModel (
    el,
    value,
    modifiers
) {
  const number = modifiers && modifiers.number;
  let valueBinding = getBindingAttr(el, 'value') || 'null';
  valueBinding = number ? `_n(${valueBinding})` : valueBinding;
  addProp(el, 'checked', `_q(${value},${valueBinding})`);
  addHandler(el, 'change', genAssignmentCode(value, valueBinding), null, true);
}

function genSelect (
    el,
    value,
    modifiers
) {
  const number = modifiers && modifiers.number;
  const selectedVal = `Array.prototype.filter` +
    `.call($event.target.options,function(o){return o.selected})` +
    `.map(function(o){var val = "_value" in o ? o._value : o.value;` +
    `return ${number ? '_n(val)' : 'val'}})`;

  const assignment = '$event.target.multiple ? $$selectedVal : $$selectedVal[0]';
  let code = `var $$selectedVal = ${selectedVal};`;
  code = `${code} ${genAssignmentCode(value, assignment)}`;
  addHandler(el, 'change', code, null, true);
}

function genDefaultModel (
  el,
  value,
  modifiers
) {
  const type = el.attrsMap.type;

  // warn if v-bind:value conflicts with v-model
  {
    const value = el.attrsMap['v-bind:value'] || el.attrsMap[':value'];
    if (value) {
      const binding = el.attrsMap['v-bind:value'] ? 'v-bind:value' : ':value';
      warn$1(
        `${binding}="${value}" conflicts with v-model on the same element ` +
        'because the latter already expands to a value binding internally'
      );
    }
  }

  const { lazy, number, trim } = modifiers || {};
  const needCompositionGuard = !lazy && type !== 'range';
  const event = lazy
    ? 'change'
    : type === 'range'
      ? RANGE_TOKEN
      : 'input';

  let valueExpression = '$event.target.value';
  if (trim) {
    valueExpression = `$event.target.value.trim()`;
  }
  if (number) {
    valueExpression = `_n(${valueExpression})`;
  }

  let code = genAssignmentCode(value, valueExpression);
  if (needCompositionGuard) {
    code = `if($event.target.composing)return;${code}`;
  }

  addProp(el, 'value', `(${value})`);
  addHandler(el, event, code, null, true);
  if (trim || number) {
    addHandler(el, 'blur', '$forceUpdate()');
  }
}

/*  */

// normalize v-model event tokens that can only be determined at runtime.
// it's important to place the event as the first in the array because
// the whole point is ensuring the v-model callback gets called before
// user-attached handlers.
function normalizeEvents (on) {
  /* istanbul ignore if */
  if (isDef(on[RANGE_TOKEN])) {
    // IE input[type=range] only supports `change` event
    const event = isIE ? 'change' : 'input';
    on[event] = [].concat(on[RANGE_TOKEN], on[event] || []);
    delete on[RANGE_TOKEN];
  }
  // This was originally intended to fix #4521 but no longer necessary
  // after 2.5. Keeping it for backwards compat with generated code from < 2.4
  /* istanbul ignore if */
  if (isDef(on[CHECKBOX_RADIO_TOKEN])) {
    on.change = [].concat(on[CHECKBOX_RADIO_TOKEN], on.change || []);
    delete on[CHECKBOX_RADIO_TOKEN];
  }
}

let target$1;

function createOnceHandler (handler, event, capture) {
  const _target = target$1; // save current target element in closure
  return function onceHandler () {
    const res = handler.apply(null, arguments);
    if (res !== null) {
      remove$2(event, onceHandler, capture, _target);
    }
  }
}

function add$1 (
  event,
  handler,
  once$$1,
  capture,
  passive
) {
  handler = withMacroTask(handler);
  if (once$$1) handler = createOnceHandler(handler, event, capture);
  target$1.addEventListener(
    event,
    handler,
    supportsPassive
      ? { capture, passive }
      : capture
  );
}

function remove$2 (
  event,
  handler,
  capture,
  _target
) {
  (_target || target$1).removeEventListener(
    event,
    handler._withTask || handler,
    capture
  );
}

function updateDOMListeners (oldVnode, vnode) {
  if (isUndef(oldVnode.data.on) && isUndef(vnode.data.on)) {
    return
  }
  const on = vnode.data.on || {};
  const oldOn = oldVnode.data.on || {};
  target$1 = vnode.elm;
  normalizeEvents(on);
  updateListeners(on, oldOn, add$1, remove$2, vnode.context);
  target$1 = undefined;
}

var events = {
  create: updateDOMListeners,
  update: updateDOMListeners
};

/*  */

function updateDOMProps (oldVnode, vnode) {
  if (isUndef(oldVnode.data.domProps) && isUndef(vnode.data.domProps)) {
    return
  }
  let key, cur;
  const elm = vnode.elm;
  const oldProps = oldVnode.data.domProps || {};
  let props = vnode.data.domProps || {};
  // clone observed objects, as the user probably wants to mutate it
  if (isDef(props.__ob__)) {
    props = vnode.data.domProps = extend({}, props);
  }

  for (key in oldProps) {
    if (isUndef(props[key])) {
      elm[key] = '';
    }
  }
  for (key in props) {
    cur = props[key];
    // ignore children if the node has textContent or innerHTML,
    // as these will throw away existing DOM nodes and cause removal errors
    // on subsequent patches (#3360)
    if (key === 'textContent' || key === 'innerHTML') {
      if (vnode.children) vnode.children.length = 0;
      if (cur === oldProps[key]) continue
      // #6601 work around Chrome version <= 55 bug where single textNode
      // replaced by innerHTML/textContent retains its parentNode property
      if (elm.childNodes.length === 1) {
        elm.removeChild(elm.childNodes[0]);
      }
    }

    if (key === 'value') {
      // store value as _value as well since
      // non-string values will be stringified
      elm._value = cur;
      // avoid resetting cursor position when value is the same
      const strCur = isUndef(cur) ? '' : String(cur);
      if (shouldUpdateValue(elm, strCur)) {
        elm.value = strCur;
      }
    } else {
      elm[key] = cur;
    }
  }
}

// check platforms/web/util/attrs.js acceptValue


function shouldUpdateValue (elm, checkVal) {
  return (!elm.composing && (
    elm.tagName === 'OPTION' ||
    isDirty(elm, checkVal) ||
    isInputChanged(elm, checkVal)
  ))
}

function isDirty (elm, checkVal) {
  // return true when textbox (.number and .trim) loses focus and its value is
  // not equal to the updated value
  let notInFocus = true;
  // #6157
  // work around IE bug when accessing document.activeElement in an iframe
  try { notInFocus = document.activeElement !== elm; } catch (e) {}
  return notInFocus && elm.value !== checkVal
}

function isInputChanged (elm, newVal) {
  const value = elm.value;
  const modifiers = elm._vModifiers; // injected by v-model runtime
  if (isDef(modifiers) && modifiers.number) {
    return toNumber(value) !== toNumber(newVal)
  }
  if (isDef(modifiers) && modifiers.trim) {
    return value.trim() !== newVal.trim()
  }
  return value !== newVal
}

var domProps = {
  create: updateDOMProps,
  update: updateDOMProps
};

/*  */

const parseStyleText = cached(function (cssText) {
  const res = {};
  const listDelimiter = /;(?![^(]*\))/g;
  const propertyDelimiter = /:(.+)/;
  cssText.split(listDelimiter).forEach(function (item) {
    if (item) {
      var tmp = item.split(propertyDelimiter);
      tmp.length > 1 && (res[tmp[0].trim()] = tmp[1].trim());
    }
  });
  return res
});

// merge static and dynamic style data on the same vnode
function normalizeStyleData (data) {
  const style = normalizeStyleBinding(data.style);
  // static style is pre-processed into an object during compilation
  // and is always a fresh object, so it's safe to merge into it
  return data.staticStyle
    ? extend(data.staticStyle, style)
    : style
}

// normalize possible array / string values into Object
function normalizeStyleBinding (bindingStyle) {
  if (Array.isArray(bindingStyle)) {
    return toObject(bindingStyle)
  }
  if (typeof bindingStyle === 'string') {
    return parseStyleText(bindingStyle)
  }
  return bindingStyle
}

/**
 * parent component style should be after child's
 * so that parent component's style could override it
 */
function getStyle (vnode, checkChild) {
  const res = {};
  let styleData;

  if (checkChild) {
    let childNode = vnode;
    while (childNode.componentInstance) {
      childNode = childNode.componentInstance._vnode;
      if (childNode.data && (styleData = normalizeStyleData(childNode.data))) {
        extend(res, styleData);
      }
    }
  }

  if ((styleData = normalizeStyleData(vnode.data))) {
    extend(res, styleData);
  }

  let parentNode = vnode;
  while ((parentNode = parentNode.parent)) {
    if (parentNode.data && (styleData = normalizeStyleData(parentNode.data))) {
      extend(res, styleData);
    }
  }
  return res
}

/*  */

const cssVarRE = /^--/;
const importantRE = /\s*!important$/;
const setProp = (el, name, val) => {
  /* istanbul ignore if */
  if (cssVarRE.test(name)) {
    el.style.setProperty(name, val);
  } else if (importantRE.test(val)) {
    el.style.setProperty(name, val.replace(importantRE, ''), 'important');
  } else {
    const normalizedName = normalize(name);
    if (Array.isArray(val)) {
      // Support values array created by autoprefixer, e.g.
      // {display: ["-webkit-box", "-ms-flexbox", "flex"]}
      // Set them one by one, and the browser will only set those it can recognize
      for (let i = 0, len = val.length; i < len; i++) {
        el.style[normalizedName] = val[i];
      }
    } else {
      el.style[normalizedName] = val;
    }
  }
};

const vendorNames = ['Webkit', 'Moz', 'ms'];

let emptyStyle;
const normalize = cached(function (prop) {
  emptyStyle = emptyStyle || document.createElement('div').style;
  prop = camelize(prop);
  if (prop !== 'filter' && (prop in emptyStyle)) {
    return prop
  }
  const capName = prop.charAt(0).toUpperCase() + prop.slice(1);
  for (let i = 0; i < vendorNames.length; i++) {
    const name = vendorNames[i] + capName;
    if (name in emptyStyle) {
      return name
    }
  }
});

function updateStyle (oldVnode, vnode) {
  const data = vnode.data;
  const oldData = oldVnode.data;

  if (isUndef(data.staticStyle) && isUndef(data.style) &&
    isUndef(oldData.staticStyle) && isUndef(oldData.style)
  ) {
    return
  }

  let cur, name;
  const el = vnode.elm;
  const oldStaticStyle = oldData.staticStyle;
  const oldStyleBinding = oldData.normalizedStyle || oldData.style || {};

  // if static style exists, stylebinding already merged into it when doing normalizeStyleData
  const oldStyle = oldStaticStyle || oldStyleBinding;

  const style = normalizeStyleBinding(vnode.data.style) || {};

  // store normalized style under a different key for next diff
  // make sure to clone it if it's reactive, since the user likely wants
  // to mutate it.
  vnode.data.normalizedStyle = isDef(style.__ob__)
    ? extend({}, style)
    : style;

  const newStyle = getStyle(vnode, true);

  for (name in oldStyle) {
    if (isUndef(newStyle[name])) {
      setProp(el, name, '');
    }
  }
  for (name in newStyle) {
    cur = newStyle[name];
    if (cur !== oldStyle[name]) {
      // ie9 setting to null has no effect, must use empty string
      setProp(el, name, cur == null ? '' : cur);
    }
  }
}

var style = {
  create: updateStyle,
  update: updateStyle
};

/*  */

/**
 * Add class with compatibility for SVG since classList is not supported on
 * SVG elements in IE
 */
function addClass (el, cls) {
  /* istanbul ignore if */
  if (!cls || !(cls = cls.trim())) {
    return
  }

  /* istanbul ignore else */
  if (el.classList) {
    if (cls.indexOf(' ') > -1) {
      cls.split(/\s+/).forEach(c => el.classList.add(c));
    } else {
      el.classList.add(cls);
    }
  } else {
    const cur = ` ${el.getAttribute('class') || ''} `;
    if (cur.indexOf(' ' + cls + ' ') < 0) {
      el.setAttribute('class', (cur + cls).trim());
    }
  }
}

/**
 * Remove class with compatibility for SVG since classList is not supported on
 * SVG elements in IE
 */
function removeClass (el, cls) {
  /* istanbul ignore if */
  if (!cls || !(cls = cls.trim())) {
    return
  }

  /* istanbul ignore else */
  if (el.classList) {
    if (cls.indexOf(' ') > -1) {
      cls.split(/\s+/).forEach(c => el.classList.remove(c));
    } else {
      el.classList.remove(cls);
    }
    if (!el.classList.length) {
      el.removeAttribute('class');
    }
  } else {
    let cur = ` ${el.getAttribute('class') || ''} `;
    const tar = ' ' + cls + ' ';
    while (cur.indexOf(tar) >= 0) {
      cur = cur.replace(tar, ' ');
    }
    cur = cur.trim();
    if (cur) {
      el.setAttribute('class', cur);
    } else {
      el.removeAttribute('class');
    }
  }
}

/*  */

function resolveTransition (def) {
  if (!def) {
    return
  }
  /* istanbul ignore else */
  if (typeof def === 'object') {
    const res = {};
    if (def.css !== false) {
      extend(res, autoCssTransition(def.name || 'v'));
    }
    extend(res, def);
    return res
  } else if (typeof def === 'string') {
    return autoCssTransition(def)
  }
}

const autoCssTransition = cached(name => {
  return {
    enterClass: `${name}-enter`,
    enterToClass: `${name}-enter-to`,
    enterActiveClass: `${name}-enter-active`,
    leaveClass: `${name}-leave`,
    leaveToClass: `${name}-leave-to`,
    leaveActiveClass: `${name}-leave-active`
  }
});

const hasTransition = inBrowser && !isIE9;
const TRANSITION = 'transition';
const ANIMATION = 'animation';

// Transition property/event sniffing
let transitionProp = 'transition';
let transitionEndEvent = 'transitionend';
let animationProp = 'animation';
let animationEndEvent = 'animationend';
if (hasTransition) {
  /* istanbul ignore if */
  if (window.ontransitionend === undefined &&
    window.onwebkittransitionend !== undefined
  ) {
    transitionProp = 'WebkitTransition';
    transitionEndEvent = 'webkitTransitionEnd';
  }
  if (window.onanimationend === undefined &&
    window.onwebkitanimationend !== undefined
  ) {
    animationProp = 'WebkitAnimation';
    animationEndEvent = 'webkitAnimationEnd';
  }
}

// binding to window is necessary to make hot reload work in IE in strict mode
const raf = inBrowser
  ? window.requestAnimationFrame
    ? window.requestAnimationFrame.bind(window)
    : setTimeout
  : /* istanbul ignore next */ fn => fn();

function nextFrame (fn) {
  raf(() => {
    raf(fn);
  });
}

function addTransitionClass (el, cls) {
  const transitionClasses = el._transitionClasses || (el._transitionClasses = []);
  if (transitionClasses.indexOf(cls) < 0) {
    transitionClasses.push(cls);
    addClass(el, cls);
  }
}

function removeTransitionClass (el, cls) {
  if (el._transitionClasses) {
    remove(el._transitionClasses, cls);
  }
  removeClass(el, cls);
}

function whenTransitionEnds (
  el,
  expectedType,
  cb
) {
  const { type, timeout, propCount } = getTransitionInfo(el, expectedType);
  if (!type) return cb()
  const event = type === TRANSITION ? transitionEndEvent : animationEndEvent;
  let ended = 0;
  const end = () => {
    el.removeEventListener(event, onEnd);
    cb();
  };
  const onEnd = e => {
    if (e.target === el) {
      if (++ended >= propCount) {
        end();
      }
    }
  };
  setTimeout(() => {
    if (ended < propCount) {
      end();
    }
  }, timeout + 1);
  el.addEventListener(event, onEnd);
}

const transformRE = /\b(transform|all)(,|$)/;

function getTransitionInfo (el, expectedType) {
  const styles = window.getComputedStyle(el);
  const transitionDelays = styles[transitionProp + 'Delay'].split(', ');
  const transitionDurations = styles[transitionProp + 'Duration'].split(', ');
  const transitionTimeout = getTimeout(transitionDelays, transitionDurations);
  const animationDelays = styles[animationProp + 'Delay'].split(', ');
  const animationDurations = styles[animationProp + 'Duration'].split(', ');
  const animationTimeout = getTimeout(animationDelays, animationDurations);

  let type;
  let timeout = 0;
  let propCount = 0;
  /* istanbul ignore if */
  if (expectedType === TRANSITION) {
    if (transitionTimeout > 0) {
      type = TRANSITION;
      timeout = transitionTimeout;
      propCount = transitionDurations.length;
    }
  } else if (expectedType === ANIMATION) {
    if (animationTimeout > 0) {
      type = ANIMATION;
      timeout = animationTimeout;
      propCount = animationDurations.length;
    }
  } else {
    timeout = Math.max(transitionTimeout, animationTimeout);
    type = timeout > 0
      ? transitionTimeout > animationTimeout
        ? TRANSITION
        : ANIMATION
      : null;
    propCount = type
      ? type === TRANSITION
        ? transitionDurations.length
        : animationDurations.length
      : 0;
  }
  const hasTransform =
    type === TRANSITION &&
    transformRE.test(styles[transitionProp + 'Property']);
  return {
    type,
    timeout,
    propCount,
    hasTransform
  }
}

function getTimeout (delays, durations) {
  /* istanbul ignore next */
  while (delays.length < durations.length) {
    delays = delays.concat(delays);
  }

  return Math.max.apply(null, durations.map((d, i) => {
    return toMs(d) + toMs(delays[i])
  }))
}

function toMs (s) {
  return Number(s.slice(0, -1)) * 1000
}

/*  */

function enter (vnode, toggleDisplay) {
  const el = vnode.elm;

  // call leave callback now
  if (isDef(el._leaveCb)) {
    el._leaveCb.cancelled = true;
    el._leaveCb();
  }

  const data = resolveTransition(vnode.data.transition);
  if (isUndef(data)) {
    return
  }

  /* istanbul ignore if */
  if (isDef(el._enterCb) || el.nodeType !== 1) {
    return
  }

  const {
    css,
    type,
    enterClass,
    enterToClass,
    enterActiveClass,
    appearClass,
    appearToClass,
    appearActiveClass,
    beforeEnter,
    enter,
    afterEnter,
    enterCancelled,
    beforeAppear,
    appear,
    afterAppear,
    appearCancelled,
    duration
  } = data;

  // activeInstance will always be the <transition> component managing this
  // transition. One edge case to check is when the <transition> is placed
  // as the root node of a child component. In that case we need to check
  // <transition>'s parent for appear check.
  let context = activeInstance;
  let transitionNode = activeInstance.$vnode;
  while (transitionNode && transitionNode.parent) {
    transitionNode = transitionNode.parent;
    context = transitionNode.context;
  }

  const isAppear = !context._isMounted || !vnode.isRootInsert;

  if (isAppear && !appear && appear !== '') {
    return
  }

  const startClass = isAppear && appearClass
    ? appearClass
    : enterClass;
  const activeClass = isAppear && appearActiveClass
    ? appearActiveClass
    : enterActiveClass;
  const toClass = isAppear && appearToClass
    ? appearToClass
    : enterToClass;

  const beforeEnterHook = isAppear
    ? (beforeAppear || beforeEnter)
    : beforeEnter;
  const enterHook = isAppear
    ? (typeof appear === 'function' ? appear : enter)
    : enter;
  const afterEnterHook = isAppear
    ? (afterAppear || afterEnter)
    : afterEnter;
  const enterCancelledHook = isAppear
    ? (appearCancelled || enterCancelled)
    : enterCancelled;

  const explicitEnterDuration = toNumber(
    isObject(duration)
      ? duration.enter
      : duration
  );

  if ("development" !== 'production' && explicitEnterDuration != null) {
    checkDuration(explicitEnterDuration, 'enter', vnode);
  }

  const expectsCSS = css !== false && !isIE9;
  const userWantsControl = getHookArgumentsLength(enterHook);

  const cb = el._enterCb = once(() => {
    if (expectsCSS) {
      removeTransitionClass(el, toClass);
      removeTransitionClass(el, activeClass);
    }
    if (cb.cancelled) {
      if (expectsCSS) {
        removeTransitionClass(el, startClass);
      }
      enterCancelledHook && enterCancelledHook(el);
    } else {
      afterEnterHook && afterEnterHook(el);
    }
    el._enterCb = null;
  });

  if (!vnode.data.show) {
    // remove pending leave element on enter by injecting an insert hook
    mergeVNodeHook(vnode, 'insert', () => {
      const parent = el.parentNode;
      const pendingNode = parent && parent._pending && parent._pending[vnode.key];
      if (pendingNode &&
        pendingNode.tag === vnode.tag &&
        pendingNode.elm._leaveCb
      ) {
        pendingNode.elm._leaveCb();
      }
      enterHook && enterHook(el, cb);
    });
  }

  // start enter transition
  beforeEnterHook && beforeEnterHook(el);
  if (expectsCSS) {
    addTransitionClass(el, startClass);
    addTransitionClass(el, activeClass);
    nextFrame(() => {
      addTransitionClass(el, toClass);
      removeTransitionClass(el, startClass);
      if (!cb.cancelled && !userWantsControl) {
        if (isValidDuration(explicitEnterDuration)) {
          setTimeout(cb, explicitEnterDuration);
        } else {
          whenTransitionEnds(el, type, cb);
        }
      }
    });
  }

  if (vnode.data.show) {
    toggleDisplay && toggleDisplay();
    enterHook && enterHook(el, cb);
  }

  if (!expectsCSS && !userWantsControl) {
    cb();
  }
}

function leave (vnode, rm) {
  const el = vnode.elm;

  // call enter callback now
  if (isDef(el._enterCb)) {
    el._enterCb.cancelled = true;
    el._enterCb();
  }

  const data = resolveTransition(vnode.data.transition);
  if (isUndef(data) || el.nodeType !== 1) {
    return rm()
  }

  /* istanbul ignore if */
  if (isDef(el._leaveCb)) {
    return
  }

  const {
    css,
    type,
    leaveClass,
    leaveToClass,
    leaveActiveClass,
    beforeLeave,
    leave,
    afterLeave,
    leaveCancelled,
    delayLeave,
    duration
  } = data;

  const expectsCSS = css !== false && !isIE9;
  const userWantsControl = getHookArgumentsLength(leave);

  const explicitLeaveDuration = toNumber(
    isObject(duration)
      ? duration.leave
      : duration
  );

  if ("development" !== 'production' && isDef(explicitLeaveDuration)) {
    checkDuration(explicitLeaveDuration, 'leave', vnode);
  }

  const cb = el._leaveCb = once(() => {
    if (el.parentNode && el.parentNode._pending) {
      el.parentNode._pending[vnode.key] = null;
    }
    if (expectsCSS) {
      removeTransitionClass(el, leaveToClass);
      removeTransitionClass(el, leaveActiveClass);
    }
    if (cb.cancelled) {
      if (expectsCSS) {
        removeTransitionClass(el, leaveClass);
      }
      leaveCancelled && leaveCancelled(el);
    } else {
      rm();
      afterLeave && afterLeave(el);
    }
    el._leaveCb = null;
  });

  if (delayLeave) {
    delayLeave(performLeave);
  } else {
    performLeave();
  }

  function performLeave () {
    // the delayed leave may have already been cancelled
    if (cb.cancelled) {
      return
    }
    // record leaving element
    if (!vnode.data.show) {
      (el.parentNode._pending || (el.parentNode._pending = {}))[(vnode.key)] = vnode;
    }
    beforeLeave && beforeLeave(el);
    if (expectsCSS) {
      addTransitionClass(el, leaveClass);
      addTransitionClass(el, leaveActiveClass);
      nextFrame(() => {
        addTransitionClass(el, leaveToClass);
        removeTransitionClass(el, leaveClass);
        if (!cb.cancelled && !userWantsControl) {
          if (isValidDuration(explicitLeaveDuration)) {
            setTimeout(cb, explicitLeaveDuration);
          } else {
            whenTransitionEnds(el, type, cb);
          }
        }
      });
    }
    leave && leave(el, cb);
    if (!expectsCSS && !userWantsControl) {
      cb();
    }
  }
}

// only used in dev mode
function checkDuration (val, name, vnode) {
  if (typeof val !== 'number') {
    warn(
      `<transition> explicit ${name} duration is not a valid number - ` +
      `got ${JSON.stringify(val)}.`,
      vnode.context
    );
  } else if (isNaN(val)) {
    warn(
      `<transition> explicit ${name} duration is NaN - ` +
      'the duration expression might be incorrect.',
      vnode.context
    );
  }
}

function isValidDuration (val) {
  return typeof val === 'number' && !isNaN(val)
}

/**
 * Normalize a transition hook's argument length. The hook may be:
 * - a merged hook (invoker) with the original in .fns
 * - a wrapped component method (check ._length)
 * - a plain function (.length)
 */
function getHookArgumentsLength (fn) {
  if (isUndef(fn)) {
    return false
  }
  const invokerFns = fn.fns;
  if (isDef(invokerFns)) {
    // invoker
    return getHookArgumentsLength(
      Array.isArray(invokerFns)
        ? invokerFns[0]
        : invokerFns
    )
  } else {
    return (fn._length || fn.length) > 1
  }
}

function _enter (_, vnode) {
  if (vnode.data.show !== true) {
    enter(vnode);
  }
}

var transition = inBrowser ? {
  create: _enter,
  activate: _enter,
  remove (vnode, rm) {
    /* istanbul ignore else */
    if (vnode.data.show !== true) {
      leave(vnode, rm);
    } else {
      rm();
    }
  }
} : {};

var platformModules = [
  attrs,
  klass,
  events,
  domProps,
  style,
  transition
];

/*  */

// the directive module should be applied last, after all
// built-in modules have been applied.
const modules = platformModules.concat(baseModules);

const patch = createPatchFunction({ nodeOps, modules });

/**
 * Not type checking this file because flow doesn't like attaching
 * properties to Elements.
 */

/* istanbul ignore if */
if (isIE9) {
  // http://www.matts411.com/post/internet-explorer-9-oninput/
  document.addEventListener('selectionchange', () => {
    const el = document.activeElement;
    if (el && el.vmodel) {
      trigger(el, 'input');
    }
  });
}

const directive = {
  inserted (el, binding, vnode, oldVnode) {
    if (vnode.tag === 'select') {
      // #6903
      if (oldVnode.elm && !oldVnode.elm._vOptions) {
        mergeVNodeHook(vnode, 'postpatch', () => {
          directive.componentUpdated(el, binding, vnode);
        });
      } else {
        setSelected(el, binding, vnode.context);
      }
      el._vOptions = [].map.call(el.options, getValue);
    } else if (vnode.tag === 'textarea' || isTextInputType(el.type)) {
      el._vModifiers = binding.modifiers;
      if (!binding.modifiers.lazy) {
        // Safari < 10.2 & UIWebView doesn't fire compositionend when
        // switching focus before confirming composition choice
        // this also fixes the issue where some browsers e.g. iOS Chrome
        // fires "change" instead of "input" on autocomplete.
        el.addEventListener('change', onCompositionEnd);
        if (!isAndroid) {
          el.addEventListener('compositionstart', onCompositionStart);
          el.addEventListener('compositionend', onCompositionEnd);
        }
        /* istanbul ignore if */
        if (isIE9) {
          el.vmodel = true;
        }
      }
    }
  },

  componentUpdated (el, binding, vnode) {
    if (vnode.tag === 'select') {
      setSelected(el, binding, vnode.context);
      // in case the options rendered by v-for have changed,
      // it's possible that the value is out-of-sync with the rendered options.
      // detect such cases and filter out values that no longer has a matching
      // option in the DOM.
      const prevOptions = el._vOptions;
      const curOptions = el._vOptions = [].map.call(el.options, getValue);
      if (curOptions.some((o, i) => !looseEqual(o, prevOptions[i]))) {
        // trigger change event if
        // no matching option found for at least one value
        const needReset = el.multiple
          ? binding.value.some(v => hasNoMatchingOption(v, curOptions))
          : binding.value !== binding.oldValue && hasNoMatchingOption(binding.value, curOptions);
        if (needReset) {
          trigger(el, 'change');
        }
      }
    }
  }
};

function setSelected (el, binding, vm) {
  actuallySetSelected(el, binding, vm);
  /* istanbul ignore if */
  if (isIE || isEdge) {
    setTimeout(() => {
      actuallySetSelected(el, binding, vm);
    }, 0);
  }
}

function actuallySetSelected (el, binding, vm) {
  const value = binding.value;
  const isMultiple = el.multiple;
  if (isMultiple && !Array.isArray(value)) {
    "development" !== 'production' && warn(
      `<select multiple v-model="${binding.expression}"> ` +
      `expects an Array value for its binding, but got ${
        Object.prototype.toString.call(value).slice(8, -1)
      }`,
      vm
    );
    return
  }
  let selected, option;
  for (let i = 0, l = el.options.length; i < l; i++) {
    option = el.options[i];
    if (isMultiple) {
      selected = looseIndexOf(value, getValue(option)) > -1;
      if (option.selected !== selected) {
        option.selected = selected;
      }
    } else {
      if (looseEqual(getValue(option), value)) {
        if (el.selectedIndex !== i) {
          el.selectedIndex = i;
        }
        return
      }
    }
  }
  if (!isMultiple) {
    el.selectedIndex = -1;
  }
}

function hasNoMatchingOption (value, options) {
  return options.every(o => !looseEqual(o, value))
}

function getValue (option) {
  return '_value' in option
    ? option._value
    : option.value
}

function onCompositionStart (e) {
  e.target.composing = true;
}

function onCompositionEnd (e) {
  // prevent triggering an input event for no reason
  if (!e.target.composing) return
  e.target.composing = false;
  trigger(e.target, 'input');
}

function trigger (el, type) {
  const e = document.createEvent('HTMLEvents');
  e.initEvent(type, true, true);
  el.dispatchEvent(e);
}

/*  */

// recursively search for possible transition defined inside the component root
function locateNode (vnode) {
  return vnode.componentInstance && (!vnode.data || !vnode.data.transition)
    ? locateNode(vnode.componentInstance._vnode)
    : vnode
}

var show = {
  bind (el, { value }, vnode) {
    vnode = locateNode(vnode);
    const transition$$1 = vnode.data && vnode.data.transition;
    const originalDisplay = el.__vOriginalDisplay =
      el.style.display === 'none' ? '' : el.style.display;
    if (value && transition$$1) {
      vnode.data.show = true;
      enter(vnode, () => {
        el.style.display = originalDisplay;
      });
    } else {
      el.style.display = value ? originalDisplay : 'none';
    }
  },

  update (el, { value, oldValue }, vnode) {
    /* istanbul ignore if */
    if (value === oldValue) return
    vnode = locateNode(vnode);
    const transition$$1 = vnode.data && vnode.data.transition;
    if (transition$$1) {
      vnode.data.show = true;
      if (value) {
        enter(vnode, () => {
          el.style.display = el.__vOriginalDisplay;
        });
      } else {
        leave(vnode, () => {
          el.style.display = 'none';
        });
      }
    } else {
      el.style.display = value ? el.__vOriginalDisplay : 'none';
    }
  },

  unbind (
    el,
    binding,
    vnode,
    oldVnode,
    isDestroy
  ) {
    if (!isDestroy) {
      el.style.display = el.__vOriginalDisplay;
    }
  }
};

var platformDirectives = {
  model: directive,
  show
};

/*  */

// Provides transition support for a single element/component.
// supports transition mode (out-in / in-out)

const transitionProps = {
  name: String,
  appear: Boolean,
  css: Boolean,
  mode: String,
  type: String,
  enterClass: String,
  leaveClass: String,
  enterToClass: String,
  leaveToClass: String,
  enterActiveClass: String,
  leaveActiveClass: String,
  appearClass: String,
  appearActiveClass: String,
  appearToClass: String,
  duration: [Number, String, Object]
};

// in case the child is also an abstract component, e.g. <keep-alive>
// we want to recursively retrieve the real component to be rendered
function getRealChild (vnode) {
  const compOptions = vnode && vnode.componentOptions;
  if (compOptions && compOptions.Ctor.options.abstract) {
    return getRealChild(getFirstComponentChild(compOptions.children))
  } else {
    return vnode
  }
}

function extractTransitionData (comp) {
  const data = {};
  const options = comp.$options;
  // props
  for (const key in options.propsData) {
    data[key] = comp[key];
  }
  // events.
  // extract listeners and pass them directly to the transition methods
  const listeners = options._parentListeners;
  for (const key in listeners) {
    data[camelize(key)] = listeners[key];
  }
  return data
}

function placeholder (h, rawChild) {
  if (/\d-keep-alive$/.test(rawChild.tag)) {
    return h('keep-alive', {
      props: rawChild.componentOptions.propsData
    })
  }
}

function hasParentTransition (vnode) {
  while ((vnode = vnode.parent)) {
    if (vnode.data.transition) {
      return true
    }
  }
}

function isSameChild (child, oldChild) {
  return oldChild.key === child.key && oldChild.tag === child.tag
}

var Transition = {
  name: 'transition',
  props: transitionProps,
  abstract: true,

  render (h) {
    let children = this.$slots.default;
    if (!children) {
      return
    }

    // filter out text nodes (possible whitespaces)
    children = children.filter((c) => c.tag || isAsyncPlaceholder(c));
    /* istanbul ignore if */
    if (!children.length) {
      return
    }

    // warn multiple elements
    if ("development" !== 'production' && children.length > 1) {
      warn(
        '<transition> can only be used on a single element. Use ' +
        '<transition-group> for lists.',
        this.$parent
      );
    }

    const mode = this.mode;

    // warn invalid mode
    if ("development" !== 'production' &&
      mode && mode !== 'in-out' && mode !== 'out-in'
    ) {
      warn(
        'invalid <transition> mode: ' + mode,
        this.$parent
      );
    }

    const rawChild = children[0];

    // if this is a component root node and the component's
    // parent container node also has transition, skip.
    if (hasParentTransition(this.$vnode)) {
      return rawChild
    }

    // apply transition data to child
    // use getRealChild() to ignore abstract components e.g. keep-alive
    const child = getRealChild(rawChild);
    /* istanbul ignore if */
    if (!child) {
      return rawChild
    }

    if (this._leaving) {
      return placeholder(h, rawChild)
    }

    // ensure a key that is unique to the vnode type and to this transition
    // component instance. This key will be used to remove pending leaving nodes
    // during entering.
    const id = `__transition-${this._uid}-`;
    child.key = child.key == null
      ? child.isComment
        ? id + 'comment'
        : id + child.tag
      : isPrimitive(child.key)
        ? (String(child.key).indexOf(id) === 0 ? child.key : id + child.key)
        : child.key;

    const data = (child.data || (child.data = {})).transition = extractTransitionData(this);
    const oldRawChild = this._vnode;
    const oldChild = getRealChild(oldRawChild);

    // mark v-show
    // so that the transition module can hand over the control to the directive
    if (child.data.directives && child.data.directives.some(d => d.name === 'show')) {
      child.data.show = true;
    }

    if (
      oldChild &&
      oldChild.data &&
      !isSameChild(child, oldChild) &&
      !isAsyncPlaceholder(oldChild) &&
      // #6687 component root is a comment node
      !(oldChild.componentInstance && oldChild.componentInstance._vnode.isComment)
    ) {
      // replace old child transition data with fresh one
      // important for dynamic transitions!
      const oldData = oldChild.data.transition = extend({}, data);
      // handle transition mode
      if (mode === 'out-in') {
        // return placeholder node and queue update when leave finishes
        this._leaving = true;
        mergeVNodeHook(oldData, 'afterLeave', () => {
          this._leaving = false;
          this.$forceUpdate();
        });
        return placeholder(h, rawChild)
      } else if (mode === 'in-out') {
        if (isAsyncPlaceholder(child)) {
          return oldRawChild
        }
        let delayedLeave;
        const performLeave = () => { delayedLeave(); };
        mergeVNodeHook(data, 'afterEnter', performLeave);
        mergeVNodeHook(data, 'enterCancelled', performLeave);
        mergeVNodeHook(oldData, 'delayLeave', leave => { delayedLeave = leave; });
      }
    }

    return rawChild
  }
};

/*  */

// Provides transition support for list items.
// supports move transitions using the FLIP technique.

// Because the vdom's children update algorithm is "unstable" - i.e.
// it doesn't guarantee the relative positioning of removed elements,
// we force transition-group to update its children into two passes:
// in the first pass, we remove all nodes that need to be removed,
// triggering their leaving transition; in the second pass, we insert/move
// into the final desired state. This way in the second pass removed
// nodes will remain where they should be.

const props = extend({
  tag: String,
  moveClass: String
}, transitionProps);

delete props.mode;

var TransitionGroup = {
  props,

  render (h) {
    const tag = this.tag || this.$vnode.data.tag || 'span';
    const map = Object.create(null);
    const prevChildren = this.prevChildren = this.children;
    const rawChildren = this.$slots.default || [];
    const children = this.children = [];
    const transitionData = extractTransitionData(this);

    for (let i = 0; i < rawChildren.length; i++) {
      const c = rawChildren[i];
      if (c.tag) {
        if (c.key != null && String(c.key).indexOf('__vlist') !== 0) {
          children.push(c);
          map[c.key] = c
          ;(c.data || (c.data = {})).transition = transitionData;
        } else {
          const opts = c.componentOptions;
          const name = opts ? (opts.Ctor.options.name || opts.tag || '') : c.tag;
          warn(`<transition-group> children must be keyed: <${name}>`);
        }
      }
    }

    if (prevChildren) {
      const kept = [];
      const removed = [];
      for (let i = 0; i < prevChildren.length; i++) {
        const c = prevChildren[i];
        c.data.transition = transitionData;
        c.data.pos = c.elm.getBoundingClientRect();
        if (map[c.key]) {
          kept.push(c);
        } else {
          removed.push(c);
        }
      }
      this.kept = h(tag, null, kept);
      this.removed = removed;
    }

    return h(tag, null, children)
  },

  beforeUpdate () {
    // force removing pass
    this.__patch__(
      this._vnode,
      this.kept,
      false, // hydrating
      true // removeOnly (!important, avoids unnecessary moves)
    );
    this._vnode = this.kept;
  },

  updated () {
    const children = this.prevChildren;
    const moveClass = this.moveClass || ((this.name || 'v') + '-move');
    if (!children.length || !this.hasMove(children[0].elm, moveClass)) {
      return
    }

    // we divide the work into three loops to avoid mixing DOM reads and writes
    // in each iteration - which helps prevent layout thrashing.
    children.forEach(callPendingCbs);
    children.forEach(recordPosition);
    children.forEach(applyTranslation);

    // force reflow to put everything in position
    // assign to this to avoid being removed in tree-shaking
    // $flow-disable-line
    this._reflow = document.body.offsetHeight;

    children.forEach((c) => {
      if (c.data.moved) {
        var el = c.elm;
        var s = el.style;
        addTransitionClass(el, moveClass);
        s.transform = s.WebkitTransform = s.transitionDuration = '';
        el.addEventListener(transitionEndEvent, el._moveCb = function cb (e) {
          if (!e || /transform$/.test(e.propertyName)) {
            el.removeEventListener(transitionEndEvent, cb);
            el._moveCb = null;
            removeTransitionClass(el, moveClass);
          }
        });
      }
    });
  },

  methods: {
    hasMove (el, moveClass) {
      /* istanbul ignore if */
      if (!hasTransition) {
        return false
      }
      /* istanbul ignore if */
      if (this._hasMove) {
        return this._hasMove
      }
      // Detect whether an element with the move class applied has
      // CSS transitions. Since the element may be inside an entering
      // transition at this very moment, we make a clone of it and remove
      // all other transition classes applied to ensure only the move class
      // is applied.
      const clone = el.cloneNode();
      if (el._transitionClasses) {
        el._transitionClasses.forEach((cls) => { removeClass(clone, cls); });
      }
      addClass(clone, moveClass);
      clone.style.display = 'none';
      this.$el.appendChild(clone);
      const info = getTransitionInfo(clone);
      this.$el.removeChild(clone);
      return (this._hasMove = info.hasTransform)
    }
  }
};

function callPendingCbs (c) {
  /* istanbul ignore if */
  if (c.elm._moveCb) {
    c.elm._moveCb();
  }
  /* istanbul ignore if */
  if (c.elm._enterCb) {
    c.elm._enterCb();
  }
}

function recordPosition (c) {
  c.data.newPos = c.elm.getBoundingClientRect();
}

function applyTranslation (c) {
  const oldPos = c.data.pos;
  const newPos = c.data.newPos;
  const dx = oldPos.left - newPos.left;
  const dy = oldPos.top - newPos.top;
  if (dx || dy) {
    c.data.moved = true;
    const s = c.elm.style;
    s.transform = s.WebkitTransform = `translate(${dx}px,${dy}px)`;
    s.transitionDuration = '0s';
  }
}

var platformComponents = {
  Transition,
  TransitionGroup
};

/*  */

// install platform specific utils
Vue$3.config.mustUseProp = mustUseProp;
Vue$3.config.isReservedTag = isReservedTag;
Vue$3.config.isReservedAttr = isReservedAttr;
Vue$3.config.getTagNamespace = getTagNamespace;
Vue$3.config.isUnknownElement = isUnknownElement;

// install platform runtime directives & components
extend(Vue$3.options.directives, platformDirectives);
extend(Vue$3.options.components, platformComponents);

// install platform patch function
Vue$3.prototype.__patch__ = inBrowser ? patch : noop;

// public mount method
Vue$3.prototype.$mount = function (
  el,
  hydrating
) {
  el = el && inBrowser ? query(el) : undefined;
  return mountComponent(this, el, hydrating)
};

// devtools global hook
/* istanbul ignore next */
Vue$3.nextTick(() => {
  if (config.devtools) {
    if (devtools) {
      devtools.emit('init', Vue$3);
    } else if ("development" !== 'production' && isChrome) {
      console[console.info ? 'info' : 'log'](
        'Download the Vue Devtools extension for a better development experience:\n' +
        'https://github.com/vuejs/vue-devtools'
      );
    }
  }
  if ("development" !== 'production' &&
    config.productionTip !== false &&
    inBrowser && typeof console !== 'undefined'
  ) {
    console[console.info ? 'info' : 'log'](
      `You are running Vue in development mode.\n` +
      `Make sure to turn on production mode when deploying for production.\n` +
      `See more tips at https://vuejs.org/guide/deployment.html`
    );
  }
}, 0);

/*  */

const defaultTagRE = /\{\{((?:.|\n)+?)\}\}/g;
const regexEscapeRE = /[-.*+?^${}()|[\]\/\\]/g;

const buildRegex = cached(delimiters => {
  const open = delimiters[0].replace(regexEscapeRE, '\\$&');
  const close = delimiters[1].replace(regexEscapeRE, '\\$&');
  return new RegExp(open + '((?:.|\\n)+?)' + close, 'g')
});

function parseText (
  text,
  delimiters
) {
  const tagRE = delimiters ? buildRegex(delimiters) : defaultTagRE;
  if (!tagRE.test(text)) {
    return
  }
  const tokens = [];
  let lastIndex = tagRE.lastIndex = 0;
  let match, index;
  while ((match = tagRE.exec(text))) {
    index = match.index;
    // push text token
    if (index > lastIndex) {
      tokens.push(JSON.stringify(text.slice(lastIndex, index)));
    }
    // tag token
    const exp = parseFilters(match[1].trim());
    tokens.push(`_s(${exp})`);
    lastIndex = index + match[0].length;
  }
  if (lastIndex < text.length) {
    tokens.push(JSON.stringify(text.slice(lastIndex)));
  }
  return tokens.join('+')
}

/*  */

function transformNode (el, options) {
  const warn = options.warn || baseWarn;
  const staticClass = getAndRemoveAttr(el, 'class');
  if ("development" !== 'production' && staticClass) {
    const expression = parseText(staticClass, options.delimiters);
    if (expression) {
      warn(
        `class="${staticClass}": ` +
        'Interpolation inside attributes has been removed. ' +
        'Use v-bind or the colon shorthand instead. For example, ' +
        'instead of <div class="{{ val }}">, use <div :class="val">.'
      );
    }
  }
  if (staticClass) {
    el.staticClass = JSON.stringify(staticClass);
  }
  const classBinding = getBindingAttr(el, 'class', false /* getStatic */);
  if (classBinding) {
    el.classBinding = classBinding;
  }
}

function genData (el) {
  let data = '';
  if (el.staticClass) {
    data += `staticClass:${el.staticClass},`;
  }
  if (el.classBinding) {
    data += `class:${el.classBinding},`;
  }
  return data
}

var klass$1 = {
  staticKeys: ['staticClass'],
  transformNode,
  genData
};

/*  */

function transformNode$1 (el, options) {
  const warn = options.warn || baseWarn;
  const staticStyle = getAndRemoveAttr(el, 'style');
  if (staticStyle) {
    /* istanbul ignore if */
    {
      const expression = parseText(staticStyle, options.delimiters);
      if (expression) {
        warn(
          `style="${staticStyle}": ` +
          'Interpolation inside attributes has been removed. ' +
          'Use v-bind or the colon shorthand instead. For example, ' +
          'instead of <div style="{{ val }}">, use <div :style="val">.'
        );
      }
    }
    el.staticStyle = JSON.stringify(parseStyleText(staticStyle));
  }

  const styleBinding = getBindingAttr(el, 'style', false /* getStatic */);
  if (styleBinding) {
    el.styleBinding = styleBinding;
  }
}

function genData$1 (el) {
  let data = '';
  if (el.staticStyle) {
    data += `staticStyle:${el.staticStyle},`;
  }
  if (el.styleBinding) {
    data += `style:(${el.styleBinding}),`;
  }
  return data
}

var style$1 = {
  staticKeys: ['staticStyle'],
  transformNode: transformNode$1,
  genData: genData$1
};

/*  */

let decoder;

var he = {
  decode (html) {
    decoder = decoder || document.createElement('div');
    decoder.innerHTML = html;
    return decoder.textContent
  }
};

/*  */

const isUnaryTag = makeMap(
  'area,base,br,col,embed,frame,hr,img,input,isindex,keygen,' +
  'link,meta,param,source,track,wbr'
);

// Elements that you can, intentionally, leave open
// (and which close themselves)
const canBeLeftOpenTag = makeMap(
  'colgroup,dd,dt,li,options,p,td,tfoot,th,thead,tr,source'
);

// HTML5 tags https://html.spec.whatwg.org/multipage/indices.html#elements-3
// Phrasing Content https://html.spec.whatwg.org/multipage/dom.html#phrasing-content
const isNonPhrasingTag = makeMap(
  'address,article,aside,base,blockquote,body,caption,col,colgroup,dd,' +
  'details,dialog,div,dl,dt,fieldset,figcaption,figure,footer,form,' +
  'h1,h2,h3,h4,h5,h6,head,header,hgroup,hr,html,legend,li,menuitem,meta,' +
  'optgroup,option,param,rp,rt,source,style,summary,tbody,td,tfoot,th,thead,' +
  'title,tr,track'
);

/**
 * Not type-checking this file because it's mostly vendor code.
 */

/*!
 * HTML Parser By John Resig (ejohn.org)
 * Modified by Juriy "kangax" Zaytsev
 * Original code by Erik Arvidsson, Mozilla Public License
 * http://erik.eae.net/simplehtmlparser/simplehtmlparser.js
 */

// Regular Expressions for parsing tags and attributes
const attribute = /^\s*([^\s"'<>\/=]+)(?:\s*(=)\s*(?:"([^"]*)"+|'([^']*)'+|([^\s"'=<>`]+)))?/;
// could use https://www.w3.org/TR/1999/REC-xml-names-19990114/#NT-QName
// but for Vue templates we can enforce a simple charset
const ncname = '[a-zA-Z_][\\w\\-\\.]*';
const qnameCapture = `((?:${ncname}\\:)?${ncname})`;
const startTagOpen = new RegExp(`^<${qnameCapture}`);
const startTagClose = /^\s*(\/?)>/;
const endTag = new RegExp(`^<\\/${qnameCapture}[^>]*>`);
const doctype = /^<!DOCTYPE [^>]+>/i;
const comment = /^<!--/;
const conditionalComment = /^<!\[/;

let IS_REGEX_CAPTURING_BROKEN = false;
'x'.replace(/x(.)?/g, function (m, g) {
  IS_REGEX_CAPTURING_BROKEN = g === '';
});

// Special Elements (can contain anything)
const isPlainTextElement = makeMap('script,style,textarea', true);
const reCache = {};

const decodingMap = {
  '&lt;': '<',
  '&gt;': '>',
  '&quot;': '"',
  '&amp;': '&',
  '&#10;': '\n',
  '&#9;': '\t'
};
const encodedAttr = /&(?:lt|gt|quot|amp);/g;
const encodedAttrWithNewLines = /&(?:lt|gt|quot|amp|#10|#9);/g;

// #5992
const isIgnoreNewlineTag = makeMap('pre,textarea', true);
const shouldIgnoreFirstNewline = (tag, html) => tag && isIgnoreNewlineTag(tag) && html[0] === '\n';

function decodeAttr (value, shouldDecodeNewlines) {
  const re = shouldDecodeNewlines ? encodedAttrWithNewLines : encodedAttr;
  return value.replace(re, match => decodingMap[match])
}

function parseHTML (html, options) {
  const stack = [];
  const expectHTML = options.expectHTML;
  const isUnaryTag$$1 = options.isUnaryTag || no;
  const canBeLeftOpenTag$$1 = options.canBeLeftOpenTag || no;
  let index = 0;
  let last, lastTag;
  while (html) {
    last = html;
    // Make sure we're not in a plaintext content element like script/style
    if (!lastTag || !isPlainTextElement(lastTag)) {
      let textEnd = html.indexOf('<');
      if (textEnd === 0) {
        // Comment:
        if (comment.test(html)) {
          const commentEnd = html.indexOf('-->');

          if (commentEnd >= 0) {
            if (options.shouldKeepComment) {
              options.comment(html.substring(4, commentEnd));
            }
            advance(commentEnd + 3);
            continue
          }
        }

        // http://en.wikipedia.org/wiki/Conditional_comment#Downlevel-revealed_conditional_comment
        if (conditionalComment.test(html)) {
          const conditionalEnd = html.indexOf(']>');

          if (conditionalEnd >= 0) {
            advance(conditionalEnd + 2);
            continue
          }
        }

        // Doctype:
        const doctypeMatch = html.match(doctype);
        if (doctypeMatch) {
          advance(doctypeMatch[0].length);
          continue
        }

        // End tag:
        const endTagMatch = html.match(endTag);
        if (endTagMatch) {
          const curIndex = index;
          advance(endTagMatch[0].length);
          parseEndTag(endTagMatch[1], curIndex, index);
          continue
        }

        // Start tag:
        const startTagMatch = parseStartTag();
        if (startTagMatch) {
          handleStartTag(startTagMatch);
          if (shouldIgnoreFirstNewline(lastTag, html)) {
            advance(1);
          }
          continue
        }
      }

      let text, rest, next;
      if (textEnd >= 0) {
        rest = html.slice(textEnd);
        while (
          !endTag.test(rest) &&
          !startTagOpen.test(rest) &&
          !comment.test(rest) &&
          !conditionalComment.test(rest)
        ) {
          // < in plain text, be forgiving and treat it as text
          next = rest.indexOf('<', 1);
          if (next < 0) break
          textEnd += next;
          rest = html.slice(textEnd);
        }
        text = html.substring(0, textEnd);
        advance(textEnd);
      }

      if (textEnd < 0) {
        text = html;
        html = '';
      }

      if (options.chars && text) {
        options.chars(text);
      }
    } else {
      let endTagLength = 0;
      const stackedTag = lastTag.toLowerCase();
      const reStackedTag = reCache[stackedTag] || (reCache[stackedTag] = new RegExp('([\\s\\S]*?)(</' + stackedTag + '[^>]*>)', 'i'));
      const rest = html.replace(reStackedTag, function (all, text, endTag) {
        endTagLength = endTag.length;
        if (!isPlainTextElement(stackedTag) && stackedTag !== 'noscript') {
          text = text
            .replace(/<!--([\s\S]*?)-->/g, '$1')
            .replace(/<!\[CDATA\[([\s\S]*?)]]>/g, '$1');
        }
        if (shouldIgnoreFirstNewline(stackedTag, text)) {
          text = text.slice(1);
        }
        if (options.chars) {
          options.chars(text);
        }
        return ''
      });
      index += html.length - rest.length;
      html = rest;
      parseEndTag(stackedTag, index - endTagLength, index);
    }

    if (html === last) {
      options.chars && options.chars(html);
      if ("development" !== 'production' && !stack.length && options.warn) {
        options.warn(`Mal-formatted tag at end of template: "${html}"`);
      }
      break
    }
  }

  // Clean up any remaining tags
  parseEndTag();

  function advance (n) {
    index += n;
    html = html.substring(n);
  }

  function parseStartTag () {
    const start = html.match(startTagOpen);
    if (start) {
      const match = {
        tagName: start[1],
        attrs: [],
        start: index
      };
      advance(start[0].length);
      let end, attr;
      while (!(end = html.match(startTagClose)) && (attr = html.match(attribute))) {
        advance(attr[0].length);
        match.attrs.push(attr);
      }
      if (end) {
        match.unarySlash = end[1];
        advance(end[0].length);
        match.end = index;
        return match
      }
    }
  }

  function handleStartTag (match) {
    const tagName = match.tagName;
    const unarySlash = match.unarySlash;

    if (expectHTML) {
      if (lastTag === 'p' && isNonPhrasingTag(tagName)) {
        parseEndTag(lastTag);
      }
      if (canBeLeftOpenTag$$1(tagName) && lastTag === tagName) {
        parseEndTag(tagName);
      }
    }

    const unary = isUnaryTag$$1(tagName) || !!unarySlash;

    const l = match.attrs.length;
    const attrs = new Array(l);
    for (let i = 0; i < l; i++) {
      const args = match.attrs[i];
      // hackish work around FF bug https://bugzilla.mozilla.org/show_bug.cgi?id=369778
      if (IS_REGEX_CAPTURING_BROKEN && args[0].indexOf('""') === -1) {
        if (args[3] === '') { delete args[3]; }
        if (args[4] === '') { delete args[4]; }
        if (args[5] === '') { delete args[5]; }
      }
      const value = args[3] || args[4] || args[5] || '';
      const shouldDecodeNewlines = tagName === 'a' && args[1] === 'href'
        ? options.shouldDecodeNewlinesForHref
        : options.shouldDecodeNewlines;
      attrs[i] = {
        name: args[1],
        value: decodeAttr(value, shouldDecodeNewlines)
      };
    }

    if (!unary) {
      stack.push({ tag: tagName, lowerCasedTag: tagName.toLowerCase(), attrs: attrs });
      lastTag = tagName;
    }

    if (options.start) {
      options.start(tagName, attrs, unary, match.start, match.end);
    }
  }

  function parseEndTag (tagName, start, end) {
    let pos, lowerCasedTagName;
    if (start == null) start = index;
    if (end == null) end = index;

    if (tagName) {
      lowerCasedTagName = tagName.toLowerCase();
    }

    // Find the closest opened tag of the same type
    if (tagName) {
      for (pos = stack.length - 1; pos >= 0; pos--) {
        if (stack[pos].lowerCasedTag === lowerCasedTagName) {
          break
        }
      }
    } else {
      // If no tag name is provided, clean shop
      pos = 0;
    }

    if (pos >= 0) {
      // Close all the open elements, up the stack
      for (let i = stack.length - 1; i >= pos; i--) {
        if ("development" !== 'production' &&
          (i > pos || !tagName) &&
          options.warn
        ) {
          options.warn(
            `tag <${stack[i].tag}> has no matching end tag.`
          );
        }
        if (options.end) {
          options.end(stack[i].tag, start, end);
        }
      }

      // Remove the open elements from the stack
      stack.length = pos;
      lastTag = pos && stack[pos - 1].tag;
    } else if (lowerCasedTagName === 'br') {
      if (options.start) {
        options.start(tagName, [], true, start, end);
      }
    } else if (lowerCasedTagName === 'p') {
      if (options.start) {
        options.start(tagName, [], false, start, end);
      }
      if (options.end) {
        options.end(tagName, start, end);
      }
    }
  }
}

/*  */

const onRE = /^@|^v-on:/;
const dirRE = /^v-|^@|^:/;
const forAliasRE = /(.*?)\s+(?:in|of)\s+(.*)/;
const forIteratorRE = /\((\{[^}]*\}|[^,]*),([^,]*)(?:,([^,]*))?\)/;

const argRE = /:(.*)$/;
const bindRE = /^:|^v-bind:/;
const modifierRE = /\.[^.]+/g;

const decodeHTMLCached = cached(he.decode);

// configurable state
let warn$2;
let delimiters;
let transforms;
let preTransforms;
let postTransforms;
let platformIsPreTag;
let platformMustUseProp;
let platformGetTagNamespace;



function createASTElement (
  tag,
  attrs,
  parent
) {
  return {
    type: 1,
    tag,
    attrsList: attrs,
    attrsMap: makeAttrsMap(attrs),
    parent,
    children: []
  }
}

/**
 * Convert HTML string to AST.
 */
function parse (
  template,
  options
) {
  warn$2 = options.warn || baseWarn;

  platformIsPreTag = options.isPreTag || no;
  platformMustUseProp = options.mustUseProp || no;
  platformGetTagNamespace = options.getTagNamespace || no;

  transforms = pluckModuleFunction(options.modules, 'transformNode');
  preTransforms = pluckModuleFunction(options.modules, 'preTransformNode');
  postTransforms = pluckModuleFunction(options.modules, 'postTransformNode');

  delimiters = options.delimiters;

  const stack = [];
  const preserveWhitespace = options.preserveWhitespace !== false;
  let root;
  let currentParent;
  let inVPre = false;
  let inPre = false;
  let warned = false;

  function warnOnce (msg) {
    if (!warned) {
      warned = true;
      warn$2(msg);
    }
  }

  function endPre (element) {
    // check pre state
    if (element.pre) {
      inVPre = false;
    }
    if (platformIsPreTag(element.tag)) {
      inPre = false;
    }
  }

  parseHTML(template, {
    warn: warn$2,
    expectHTML: options.expectHTML,
    isUnaryTag: options.isUnaryTag,
    canBeLeftOpenTag: options.canBeLeftOpenTag,
    shouldDecodeNewlines: options.shouldDecodeNewlines,
    shouldDecodeNewlinesForHref: options.shouldDecodeNewlinesForHref,
    shouldKeepComment: options.comments,
    start (tag, attrs, unary) {
      // check namespace.
      // inherit parent ns if there is one
      const ns = (currentParent && currentParent.ns) || platformGetTagNamespace(tag);

      // handle IE svg bug
      /* istanbul ignore if */
      if (isIE && ns === 'svg') {
        attrs = guardIESVGBug(attrs);
      }

      let element = createASTElement(tag, attrs, currentParent);
      if (ns) {
        element.ns = ns;
      }

      if (isForbiddenTag(element) && !isServerRendering()) {
        element.forbidden = true;
        "development" !== 'production' && warn$2(
          'Templates should only be responsible for mapping the state to the ' +
          'UI. Avoid placing tags with side-effects in your templates, such as ' +
          `<${tag}>` + ', as they will not be parsed.'
        );
      }

      // apply pre-transforms
      for (let i = 0; i < preTransforms.length; i++) {
        element = preTransforms[i](element, options) || element;
      }

      if (!inVPre) {
        processPre(element);
        if (element.pre) {
          inVPre = true;
        }
      }
      if (platformIsPreTag(element.tag)) {
        inPre = true;
      }
      if (inVPre) {
        processRawAttrs(element);
      } else if (!element.processed) {
        // structural directives
        processFor(element);
        processIf(element);
        processOnce(element);
        // element-scope stuff
        processElement(element, options);
      }

      function checkRootConstraints (el) {
        {
          if (el.tag === 'slot' || el.tag === 'template') {
            warnOnce(
              `Cannot use <${el.tag}> as component root element because it may ` +
              'contain multiple nodes.'
            );
          }
          if (el.attrsMap.hasOwnProperty('v-for')) {
            warnOnce(
              'Cannot use v-for on stateful component root element because ' +
              'it renders multiple elements.'
            );
          }
        }
      }

      // tree management
      if (!root) {
        root = element;
        checkRootConstraints(root);
      } else if (!stack.length) {
        // allow root elements with v-if, v-else-if and v-else
        if (root.if && (element.elseif || element.else)) {
          checkRootConstraints(element);
          addIfCondition(root, {
            exp: element.elseif,
            block: element
          });
        } else {
          warnOnce(
            `Component template should contain exactly one root element. ` +
            `If you are using v-if on multiple elements, ` +
            `use v-else-if to chain them instead.`
          );
        }
      }
      if (currentParent && !element.forbidden) {
        if (element.elseif || element.else) {
          processIfConditions(element, currentParent);
        } else if (element.slotScope) { // scoped slot
          currentParent.plain = false;
          const name = element.slotTarget || '"default"';(currentParent.scopedSlots || (currentParent.scopedSlots = {}))[name] = element;
        } else {
          currentParent.children.push(element);
          element.parent = currentParent;
        }
      }
      if (!unary) {
        currentParent = element;
        stack.push(element);
      } else {
        endPre(element);
      }
      // apply post-transforms
      for (let i = 0; i < postTransforms.length; i++) {
        postTransforms[i](element, options);
      }
    },

    end () {
      // remove trailing whitespace
      const element = stack[stack.length - 1];
      const lastNode = element.children[element.children.length - 1];
      if (lastNode && lastNode.type === 3 && lastNode.text === ' ' && !inPre) {
        element.children.pop();
      }
      // pop stack
      stack.length -= 1;
      currentParent = stack[stack.length - 1];
      endPre(element);
    },

    chars (text) {
      if (!currentParent) {
        {
          if (text === template) {
            warnOnce(
              'Component template requires a root element, rather than just text.'
            );
          } else if ((text = text.trim())) {
            warnOnce(
              `text "${text}" outside root element will be ignored.`
            );
          }
        }
        return
      }
      // IE textarea placeholder bug
      /* istanbul ignore if */
      if (isIE &&
        currentParent.tag === 'textarea' &&
        currentParent.attrsMap.placeholder === text
      ) {
        return
      }
      const children = currentParent.children;
      text = inPre || text.trim()
        ? isTextTag(currentParent) ? text : decodeHTMLCached(text)
        // only preserve whitespace if its not right after a starting tag
        : preserveWhitespace && children.length ? ' ' : '';
      if (text) {
        let expression;
        if (!inVPre && text !== ' ' && (expression = parseText(text, delimiters))) {
          children.push({
            type: 2,
            expression,
            text
          });
        } else if (text !== ' ' || !children.length || children[children.length - 1].text !== ' ') {
          children.push({
            type: 3,
            text
          });
        }
      }
    },
    comment (text) {
      currentParent.children.push({
        type: 3,
        text,
        isComment: true
      });
    }
  });
  return root
}

function processPre (el) {
  if (getAndRemoveAttr(el, 'v-pre') != null) {
    el.pre = true;
  }
}

function processRawAttrs (el) {
  const l = el.attrsList.length;
  if (l) {
    const attrs = el.attrs = new Array(l);
    for (let i = 0; i < l; i++) {
      attrs[i] = {
        name: el.attrsList[i].name,
        value: JSON.stringify(el.attrsList[i].value)
      };
    }
  } else if (!el.pre) {
    // non root node in pre blocks with no attributes
    el.plain = true;
  }
}

function processElement (element, options) {
  processKey(element);

  // determine whether this is a plain element after
  // removing structural attributes
  element.plain = !element.key && !element.attrsList.length;

  processRef(element);
  processSlot(element);
  processComponent(element);
  for (let i = 0; i < transforms.length; i++) {
    element = transforms[i](element, options) || element;
  }
  processAttrs(element);
}

function processKey (el) {
  const exp = getBindingAttr(el, 'key');
  if (exp) {
    if ("development" !== 'production' && el.tag === 'template') {
      warn$2(`<template> cannot be keyed. Place the key on real elements instead.`);
    }
    el.key = exp;
  }
}

function processRef (el) {
  const ref = getBindingAttr(el, 'ref');
  if (ref) {
    el.ref = ref;
    el.refInFor = checkInFor(el);
  }
}

function processFor (el) {
  let exp;
  if ((exp = getAndRemoveAttr(el, 'v-for'))) {
    const inMatch = exp.match(forAliasRE);
    if (!inMatch) {
      "development" !== 'production' && warn$2(
        `Invalid v-for expression: ${exp}`
      );
      return
    }
    el.for = inMatch[2].trim();
    const alias = inMatch[1].trim();
    const iteratorMatch = alias.match(forIteratorRE);
    if (iteratorMatch) {
      el.alias = iteratorMatch[1].trim();
      el.iterator1 = iteratorMatch[2].trim();
      if (iteratorMatch[3]) {
        el.iterator2 = iteratorMatch[3].trim();
      }
    } else {
      el.alias = alias;
    }
  }
}

function processIf (el) {
  const exp = getAndRemoveAttr(el, 'v-if');
  if (exp) {
    el.if = exp;
    addIfCondition(el, {
      exp: exp,
      block: el
    });
  } else {
    if (getAndRemoveAttr(el, 'v-else') != null) {
      el.else = true;
    }
    const elseif = getAndRemoveAttr(el, 'v-else-if');
    if (elseif) {
      el.elseif = elseif;
    }
  }
}

function processIfConditions (el, parent) {
  const prev = findPrevElement(parent.children);
  if (prev && prev.if) {
    addIfCondition(prev, {
      exp: el.elseif,
      block: el
    });
  } else {
    warn$2(
      `v-${el.elseif ? ('else-if="' + el.elseif + '"') : 'else'} ` +
      `used on element <${el.tag}> without corresponding v-if.`
    );
  }
}

function findPrevElement (children) {
  let i = children.length;
  while (i--) {
    if (children[i].type === 1) {
      return children[i]
    } else {
      if ("development" !== 'production' && children[i].text !== ' ') {
        warn$2(
          `text "${children[i].text.trim()}" between v-if and v-else(-if) ` +
          `will be ignored.`
        );
      }
      children.pop();
    }
  }
}

function addIfCondition (el, condition) {
  if (!el.ifConditions) {
    el.ifConditions = [];
  }
  el.ifConditions.push(condition);
}

function processOnce (el) {
  const once$$1 = getAndRemoveAttr(el, 'v-once');
  if (once$$1 != null) {
    el.once = true;
  }
}

function processSlot (el) {
  if (el.tag === 'slot') {
    el.slotName = getBindingAttr(el, 'name');
    if ("development" !== 'production' && el.key) {
      warn$2(
        `\`key\` does not work on <slot> because slots are abstract outlets ` +
        `and can possibly expand into multiple elements. ` +
        `Use the key on a wrapping element instead.`
      );
    }
  } else {
    let slotScope;
    if (el.tag === 'template') {
      slotScope = getAndRemoveAttr(el, 'scope');
      /* istanbul ignore if */
      if ("development" !== 'production' && slotScope) {
        warn$2(
          `the "scope" attribute for scoped slots have been deprecated and ` +
          `replaced by "slot-scope" since 2.5. The new "slot-scope" attribute ` +
          `can also be used on plain elements in addition to <template> to ` +
          `denote scoped slots.`,
          true
        );
      }
      el.slotScope = slotScope || getAndRemoveAttr(el, 'slot-scope');
    } else if ((slotScope = getAndRemoveAttr(el, 'slot-scope'))) {
      /* istanbul ignore if */
      if ("development" !== 'production' && el.attrsMap['v-for']) {
        warn$2(
          `Ambiguous combined usage of slot-scope and v-for on <${el.tag}> ` +
          `(v-for takes higher priority). Use a wrapper <template> for the ` +
          `scoped slot to make it clearer.`,
          true
        );
      }
      el.slotScope = slotScope;
    }
    const slotTarget = getBindingAttr(el, 'slot');
    if (slotTarget) {
      el.slotTarget = slotTarget === '""' ? '"default"' : slotTarget;
      // preserve slot as an attribute for native shadow DOM compat
      // only for non-scoped slots.
      if (el.tag !== 'template' && !el.slotScope) {
        addAttr(el, 'slot', slotTarget);
      }
    }
  }
}

function processComponent (el) {
  let binding;
  if ((binding = getBindingAttr(el, 'is'))) {
    el.component = binding;
  }
  if (getAndRemoveAttr(el, 'inline-template') != null) {
    el.inlineTemplate = true;
  }
}

function processAttrs (el) {
  const list = el.attrsList;
  let i, l, name, rawName, value, modifiers, isProp;
  for (i = 0, l = list.length; i < l; i++) {
    name = rawName = list[i].name;
    value = list[i].value;
    if (dirRE.test(name)) {
      // mark element as dynamic
      el.hasBindings = true;
      // modifiers
      modifiers = parseModifiers(name);
      if (modifiers) {
        name = name.replace(modifierRE, '');
      }
      if (bindRE.test(name)) { // v-bind
        name = name.replace(bindRE, '');
        value = parseFilters(value);
        isProp = false;
        if (modifiers) {
          if (modifiers.prop) {
            isProp = true;
            name = camelize(name);
            if (name === 'innerHtml') name = 'innerHTML';
          }
          if (modifiers.camel) {
            name = camelize(name);
          }
          if (modifiers.sync) {
            addHandler(
              el,
              `update:${camelize(name)}`,
              genAssignmentCode(value, `$event`)
            );
          }
        }
        if (isProp || (
          !el.component && platformMustUseProp(el.tag, el.attrsMap.type, name)
        )) {
          addProp(el, name, value);
        } else {
          addAttr(el, name, value);
        }
      } else if (onRE.test(name)) { // v-on
        name = name.replace(onRE, '');
        addHandler(el, name, value, modifiers, false, warn$2);
      } else { // normal directives
        name = name.replace(dirRE, '');
        // parse arg
        const argMatch = name.match(argRE);
        const arg = argMatch && argMatch[1];
        if (arg) {
          name = name.slice(0, -(arg.length + 1));
        }
        addDirective(el, name, rawName, value, arg, modifiers);
        if ("development" !== 'production' && name === 'model') {
          checkForAliasModel(el, value);
        }
      }
    } else {
      // literal attribute
      {
        const expression = parseText(value, delimiters);
        if (expression) {
          warn$2(
            `${name}="${value}": ` +
            'Interpolation inside attributes has been removed. ' +
            'Use v-bind or the colon shorthand instead. For example, ' +
            'instead of <div id="{{ val }}">, use <div :id="val">.'
          );
        }
      }
      addAttr(el, name, JSON.stringify(value));
      // #6887 firefox doesn't update muted state if set via attribute
      // even immediately after element creation
      if (!el.component &&
          name === 'muted' &&
          platformMustUseProp(el.tag, el.attrsMap.type, name)) {
        addProp(el, name, 'true');
      }
    }
  }
}

function checkInFor (el) {
  let parent = el;
  while (parent) {
    if (parent.for !== undefined) {
      return true
    }
    parent = parent.parent;
  }
  return false
}

function parseModifiers (name) {
  const match = name.match(modifierRE);
  if (match) {
    const ret = {};
    match.forEach(m => { ret[m.slice(1)] = true; });
    return ret
  }
}

function makeAttrsMap (attrs) {
  const map = {};
  for (let i = 0, l = attrs.length; i < l; i++) {
    if (
      "development" !== 'production' &&
      map[attrs[i].name] && !isIE && !isEdge
    ) {
      warn$2('duplicate attribute: ' + attrs[i].name);
    }
    map[attrs[i].name] = attrs[i].value;
  }
  return map
}

// for script (e.g. type="x/template") or style, do not decode content
function isTextTag (el) {
  return el.tag === 'script' || el.tag === 'style'
}

function isForbiddenTag (el) {
  return (
    el.tag === 'style' ||
    (el.tag === 'script' && (
      !el.attrsMap.type ||
      el.attrsMap.type === 'text/javascript'
    ))
  )
}

const ieNSBug = /^xmlns:NS\d+/;
const ieNSPrefix = /^NS\d+:/;

/* istanbul ignore next */
function guardIESVGBug (attrs) {
  const res = [];
  for (let i = 0; i < attrs.length; i++) {
    const attr = attrs[i];
    if (!ieNSBug.test(attr.name)) {
      attr.name = attr.name.replace(ieNSPrefix, '');
      res.push(attr);
    }
  }
  return res
}

function checkForAliasModel (el, value) {
  let _el = el;
  while (_el) {
    if (_el.for && _el.alias === value) {
      warn$2(
        `<${el.tag} v-model="${value}">: ` +
        `You are binding v-model directly to a v-for iteration alias. ` +
        `This will not be able to modify the v-for source array because ` +
        `writing to the alias is like modifying a function local variable. ` +
        `Consider using an array of objects and use v-model on an object property instead.`
      );
    }
    _el = _el.parent;
  }
}

/*  */

/**
 * Expand input[v-model] with dyanmic type bindings into v-if-else chains
 * Turn this:
 *   <input v-model="data[type]" :type="type">
 * into this:
 *   <input v-if="type === 'checkbox'" type="checkbox" v-model="data[type]">
 *   <input v-else-if="type === 'radio'" type="radio" v-model="data[type]">
 *   <input v-else :type="type" v-model="data[type]">
 */

function preTransformNode (el, options) {
  if (el.tag === 'input') {
    const map = el.attrsMap;
    if (map['v-model'] && (map['v-bind:type'] || map[':type'])) {
      const typeBinding = getBindingAttr(el, 'type');
      const ifCondition = getAndRemoveAttr(el, 'v-if', true);
      const ifConditionExtra = ifCondition ? `&&(${ifCondition})` : ``;
      const hasElse = getAndRemoveAttr(el, 'v-else', true) != null;
      const elseIfCondition = getAndRemoveAttr(el, 'v-else-if', true);
      // 1. checkbox
      const branch0 = cloneASTElement(el);
      // process for on the main node
      processFor(branch0);
      addRawAttr(branch0, 'type', 'checkbox');
      processElement(branch0, options);
      branch0.processed = true; // prevent it from double-processed
      branch0.if = `(${typeBinding})==='checkbox'` + ifConditionExtra;
      addIfCondition(branch0, {
        exp: branch0.if,
        block: branch0
      });
      // 2. add radio else-if condition
      const branch1 = cloneASTElement(el);
      getAndRemoveAttr(branch1, 'v-for', true);
      addRawAttr(branch1, 'type', 'radio');
      processElement(branch1, options);
      addIfCondition(branch0, {
        exp: `(${typeBinding})==='radio'` + ifConditionExtra,
        block: branch1
      });
      // 3. other
      const branch2 = cloneASTElement(el);
      getAndRemoveAttr(branch2, 'v-for', true);
      addRawAttr(branch2, ':type', typeBinding);
      processElement(branch2, options);
      addIfCondition(branch0, {
        exp: ifCondition,
        block: branch2
      });

      if (hasElse) {
        branch0.else = true;
      } else if (elseIfCondition) {
        branch0.elseif = elseIfCondition;
      }

      return branch0
    }
  }
}

function cloneASTElement (el) {
  return createASTElement(el.tag, el.attrsList.slice(), el.parent)
}

function addRawAttr (el, name, value) {
  el.attrsMap[name] = value;
  el.attrsList.push({ name, value });
}

var model$2 = {
  preTransformNode
};

var modules$1 = [
  klass$1,
  style$1,
  model$2
];

/*  */

function text (el, dir) {
  if (dir.value) {
    addProp(el, 'textContent', `_s(${dir.value})`);
  }
}

/*  */

function html (el, dir) {
  if (dir.value) {
    addProp(el, 'innerHTML', `_s(${dir.value})`);
  }
}

var directives$1 = {
  model,
  text,
  html
};

/*  */

const baseOptions = {
  expectHTML: true,
  modules: modules$1,
  directives: directives$1,
  isPreTag,
  isUnaryTag,
  mustUseProp,
  canBeLeftOpenTag,
  isReservedTag,
  getTagNamespace,
  staticKeys: genStaticKeys(modules$1)
};

/*  */

let isStaticKey;
let isPlatformReservedTag;

const genStaticKeysCached = cached(genStaticKeys$1);

/**
 * Goal of the optimizer: walk the generated template AST tree
 * and detect sub-trees that are purely static, i.e. parts of
 * the DOM that never needs to change.
 *
 * Once we detect these sub-trees, we can:
 *
 * 1. Hoist them into constants, so that we no longer need to
 *    create fresh nodes for them on each re-render;
 * 2. Completely skip them in the patching process.
 */
function optimize (root, options) {
  if (!root) return
  isStaticKey = genStaticKeysCached(options.staticKeys || '');
  isPlatformReservedTag = options.isReservedTag || no;
  // first pass: mark all non-static nodes.
  markStatic$1(root);
  // second pass: mark static roots.
  markStaticRoots(root, false);
}

function genStaticKeys$1 (keys) {
  return makeMap(
    'type,tag,attrsList,attrsMap,plain,parent,children,attrs' +
    (keys ? ',' + keys : '')
  )
}

function markStatic$1 (node) {
  node.static = isStatic(node);
  if (node.type === 1) {
    // do not make component slot content static. this avoids
    // 1. components not able to mutate slot nodes
    // 2. static slot content fails for hot-reloading
    if (
      !isPlatformReservedTag(node.tag) &&
      node.tag !== 'slot' &&
      node.attrsMap['inline-template'] == null
    ) {
      return
    }
    for (let i = 0, l = node.children.length; i < l; i++) {
      const child = node.children[i];
      markStatic$1(child);
      if (!child.static) {
        node.static = false;
      }
    }
    if (node.ifConditions) {
      for (let i = 1, l = node.ifConditions.length; i < l; i++) {
        const block = node.ifConditions[i].block;
        markStatic$1(block);
        if (!block.static) {
          node.static = false;
        }
      }
    }
  }
}

function markStaticRoots (node, isInFor) {
  if (node.type === 1) {
    if (node.static || node.once) {
      node.staticInFor = isInFor;
    }
    // For a node to qualify as a static root, it should have children that
    // are not just static text. Otherwise the cost of hoisting out will
    // outweigh the benefits and it's better off to just always render it fresh.
    if (node.static && node.children.length && !(
      node.children.length === 1 &&
      node.children[0].type === 3
    )) {
      node.staticRoot = true;
      return
    } else {
      node.staticRoot = false;
    }
    if (node.children) {
      for (let i = 0, l = node.children.length; i < l; i++) {
        markStaticRoots(node.children[i], isInFor || !!node.for);
      }
    }
    if (node.ifConditions) {
      for (let i = 1, l = node.ifConditions.length; i < l; i++) {
        markStaticRoots(node.ifConditions[i].block, isInFor);
      }
    }
  }
}

function isStatic (node) {
  if (node.type === 2) { // expression
    return false
  }
  if (node.type === 3) { // text
    return true
  }
  return !!(node.pre || (
    !node.hasBindings && // no dynamic bindings
    !node.if && !node.for && // not v-if or v-for or v-else
    !isBuiltInTag(node.tag) && // not a built-in
    isPlatformReservedTag(node.tag) && // not a component
    !isDirectChildOfTemplateFor(node) &&
    Object.keys(node).every(isStaticKey)
  ))
}

function isDirectChildOfTemplateFor (node) {
  while (node.parent) {
    node = node.parent;
    if (node.tag !== 'template') {
      return false
    }
    if (node.for) {
      return true
    }
  }
  return false
}

/*  */

const fnExpRE = /^\s*([\w$_]+|\([^)]*?\))\s*=>|^function\s*\(/;
const simplePathRE = /^\s*[A-Za-z_$][\w$]*(?:\.[A-Za-z_$][\w$]*|\['.*?']|\[".*?"]|\[\d+]|\[[A-Za-z_$][\w$]*])*\s*$/;

// keyCode aliases
const keyCodes = {
  esc: 27,
  tab: 9,
  enter: 13,
  space: 32,
  up: 38,
  left: 37,
  right: 39,
  down: 40,
  'delete': [8, 46]
};

// #4868: modifiers that prevent the execution of the listener
// need to explicitly return null so that we can determine whether to remove
// the listener for .once
const genGuard = condition => `if(${condition})return null;`;

const modifierCode = {
  stop: '$event.stopPropagation();',
  prevent: '$event.preventDefault();',
  self: genGuard(`$event.target !== $event.currentTarget`),
  ctrl: genGuard(`!$event.ctrlKey`),
  shift: genGuard(`!$event.shiftKey`),
  alt: genGuard(`!$event.altKey`),
  meta: genGuard(`!$event.metaKey`),
  left: genGuard(`'button' in $event && $event.button !== 0`),
  middle: genGuard(`'button' in $event && $event.button !== 1`),
  right: genGuard(`'button' in $event && $event.button !== 2`)
};

function genHandlers (
  events,
  isNative,
  warn
) {
  let res = isNative ? 'nativeOn:{' : 'on:{';
  for (const name in events) {
    res += `"${name}":${genHandler(name, events[name])},`;
  }
  return res.slice(0, -1) + '}'
}

function genHandler (
  name,
  handler
) {
  if (!handler) {
    return 'function(){}'
  }

  if (Array.isArray(handler)) {
    return `[${handler.map(handler => genHandler(name, handler)).join(',')}]`
  }

  const isMethodPath = simplePathRE.test(handler.value);
  const isFunctionExpression = fnExpRE.test(handler.value);

  if (!handler.modifiers) {
    return isMethodPath || isFunctionExpression
      ? handler.value
      : `function($event){${handler.value}}` // inline statement
  } else {
    let code = '';
    let genModifierCode = '';
    const keys = [];
    for (const key in handler.modifiers) {
      if (modifierCode[key]) {
        genModifierCode += modifierCode[key];
        // left/right
        if (keyCodes[key]) {
          keys.push(key);
        }
      } else if (key === 'exact') {
        const modifiers = (handler.modifiers);
        genModifierCode += genGuard(
          ['ctrl', 'shift', 'alt', 'meta']
            .filter(keyModifier => !modifiers[keyModifier])
            .map(keyModifier => `$event.${keyModifier}Key`)
            .join('||')
        );
      } else {
        keys.push(key);
      }
    }
    if (keys.length) {
      code += genKeyFilter(keys);
    }
    // Make sure modifiers like prevent and stop get executed after key filtering
    if (genModifierCode) {
      code += genModifierCode;
    }
    const handlerCode = isMethodPath
      ? handler.value + '($event)'
      : isFunctionExpression
        ? `(${handler.value})($event)`
        : handler.value;
    return `function($event){${code}${handlerCode}}`
  }
}

function genKeyFilter (keys) {
  return `if(!('button' in $event)&&${keys.map(genFilterCode).join('&&')})return null;`
}

function genFilterCode (key) {
  const keyVal = parseInt(key, 10);
  if (keyVal) {
    return `$event.keyCode!==${keyVal}`
  }
  const code = keyCodes[key];
  return (
    `_k($event.keyCode,` +
    `${JSON.stringify(key)},` +
    `${JSON.stringify(code)},` +
    `$event.key)`
  )
}

/*  */

function on (el, dir) {
  if ("development" !== 'production' && dir.modifiers) {
    warn(`v-on without argument does not support modifiers.`);
  }
  el.wrapListeners = (code) => `_g(${code},${dir.value})`;
}

/*  */

function bind$1 (el, dir) {
  el.wrapData = (code) => {
    return `_b(${code},'${el.tag}',${dir.value},${
      dir.modifiers && dir.modifiers.prop ? 'true' : 'false'
    }${
      dir.modifiers && dir.modifiers.sync ? ',true' : ''
    })`
  };
}

/*  */

var baseDirectives = {
  on,
  bind: bind$1,
  cloak: noop
};

/*  */

class CodegenState {
  
  
  
  
  
  
  
  

  constructor (options) {
    this.options = options;
    this.warn = options.warn || baseWarn;
    this.transforms = pluckModuleFunction(options.modules, 'transformCode');
    this.dataGenFns = pluckModuleFunction(options.modules, 'genData');
    this.directives = extend(extend({}, baseDirectives), options.directives);
    const isReservedTag = options.isReservedTag || no;
    this.maybeComponent = (el) => !isReservedTag(el.tag);
    this.onceId = 0;
    this.staticRenderFns = [];
  }
}



function generate (
  ast,
  options
) {
  const state = new CodegenState(options);
  const code = ast ? genElement(ast, state) : '_c("div")';
  return {
    render: `with(this){return ${code}}`,
    staticRenderFns: state.staticRenderFns
  }
}

function genElement (el, state) {
  if (el.staticRoot && !el.staticProcessed) {
    return genStatic(el, state)
  } else if (el.once && !el.onceProcessed) {
    return genOnce(el, state)
  } else if (el.for && !el.forProcessed) {
    return genFor(el, state)
  } else if (el.if && !el.ifProcessed) {
    return genIf(el, state)
  } else if (el.tag === 'template' && !el.slotTarget) {
    return genChildren(el, state) || 'void 0'
  } else if (el.tag === 'slot') {
    return genSlot(el, state)
  } else {
    // component or element
    let code;
    if (el.component) {
      code = genComponent(el.component, el, state);
    } else {
      const data = el.plain ? undefined : genData$2(el, state);

      const children = el.inlineTemplate ? null : genChildren(el, state, true);
      code = `_c('${el.tag}'${
        data ? `,${data}` : '' // data
      }${
        children ? `,${children}` : '' // children
      })`;
    }
    // module transforms
    for (let i = 0; i < state.transforms.length; i++) {
      code = state.transforms[i](el, code);
    }
    return code
  }
}

// hoist static sub-trees out
function genStatic (el, state, once$$1) {
  el.staticProcessed = true;
  state.staticRenderFns.push(`with(this){return ${genElement(el, state)}}`);
  return `_m(${
    state.staticRenderFns.length - 1
  },${
    el.staticInFor ? 'true' : 'false'
  },${
    once$$1 ? 'true' : 'false'
  })`
}

// v-once
function genOnce (el, state) {
  el.onceProcessed = true;
  if (el.if && !el.ifProcessed) {
    return genIf(el, state)
  } else if (el.staticInFor) {
    let key = '';
    let parent = el.parent;
    while (parent) {
      if (parent.for) {
        key = parent.key;
        break
      }
      parent = parent.parent;
    }
    if (!key) {
      "development" !== 'production' && state.warn(
        `v-once can only be used inside v-for that is keyed. `
      );
      return genElement(el, state)
    }
    return `_o(${genElement(el, state)},${state.onceId++},${key})`
  } else {
    return genStatic(el, state, true)
  }
}

function genIf (
  el,
  state,
  altGen,
  altEmpty
) {
  el.ifProcessed = true; // avoid recursion
  return genIfConditions(el.ifConditions.slice(), state, altGen, altEmpty)
}

function genIfConditions (
  conditions,
  state,
  altGen,
  altEmpty
) {
  if (!conditions.length) {
    return altEmpty || '_e()'
  }

  const condition = conditions.shift();
  if (condition.exp) {
    return `(${condition.exp})?${
      genTernaryExp(condition.block)
    }:${
      genIfConditions(conditions, state, altGen, altEmpty)
    }`
  } else {
    return `${genTernaryExp(condition.block)}`
  }

  // v-if with v-once should generate code like (a)?_m(0):_m(1)
  function genTernaryExp (el) {
    return altGen
      ? altGen(el, state)
      : el.once
        ? genOnce(el, state)
        : genElement(el, state)
  }
}

function genFor (
  el,
  state,
  altGen,
  altHelper
) {
  const exp = el.for;
  const alias = el.alias;
  const iterator1 = el.iterator1 ? `,${el.iterator1}` : '';
  const iterator2 = el.iterator2 ? `,${el.iterator2}` : '';

  if ("development" !== 'production' &&
    state.maybeComponent(el) &&
    el.tag !== 'slot' &&
    el.tag !== 'template' &&
    !el.key
  ) {
    state.warn(
      `<${el.tag} v-for="${alias} in ${exp}">: component lists rendered with ` +
      `v-for should have explicit keys. ` +
      `See https://vuejs.org/guide/list.html#key for more info.`,
      true /* tip */
    );
  }

  el.forProcessed = true; // avoid recursion
  return `${altHelper || '_l'}((${exp}),` +
    `function(${alias}${iterator1}${iterator2}){` +
      `return ${(altGen || genElement)(el, state)}` +
    '})'
}

function genData$2 (el, state) {
  let data = '{';

  // directives first.
  // directives may mutate the el's other properties before they are generated.
  const dirs = genDirectives(el, state);
  if (dirs) data += dirs + ',';

  // key
  if (el.key) {
    data += `key:${el.key},`;
  }
  // ref
  if (el.ref) {
    data += `ref:${el.ref},`;
  }
  if (el.refInFor) {
    data += `refInFor:true,`;
  }
  // pre
  if (el.pre) {
    data += `pre:true,`;
  }
  // record original tag name for components using "is" attribute
  if (el.component) {
    data += `tag:"${el.tag}",`;
  }
  // module data generation functions
  for (let i = 0; i < state.dataGenFns.length; i++) {
    data += state.dataGenFns[i](el);
  }
  // attributes
  if (el.attrs) {
    data += `attrs:{${genProps(el.attrs)}},`;
  }
  // DOM props
  if (el.props) {
    data += `domProps:{${genProps(el.props)}},`;
  }
  // event handlers
  if (el.events) {
    data += `${genHandlers(el.events, false, state.warn)},`;
  }
  if (el.nativeEvents) {
    data += `${genHandlers(el.nativeEvents, true, state.warn)},`;
  }
  // slot target
  // only for non-scoped slots
  if (el.slotTarget && !el.slotScope) {
    data += `slot:${el.slotTarget},`;
  }
  // scoped slots
  if (el.scopedSlots) {
    data += `${genScopedSlots(el.scopedSlots, state)},`;
  }
  // component v-model
  if (el.model) {
    data += `model:{value:${
      el.model.value
    },callback:${
      el.model.callback
    },expression:${
      el.model.expression
    }},`;
  }
  // inline-template
  if (el.inlineTemplate) {
    const inlineTemplate = genInlineTemplate(el, state);
    if (inlineTemplate) {
      data += `${inlineTemplate},`;
    }
  }
  data = data.replace(/,$/, '') + '}';
  // v-bind data wrap
  if (el.wrapData) {
    data = el.wrapData(data);
  }
  // v-on data wrap
  if (el.wrapListeners) {
    data = el.wrapListeners(data);
  }
  return data
}

function genDirectives (el, state) {
  const dirs = el.directives;
  if (!dirs) return
  let res = 'directives:[';
  let hasRuntime = false;
  let i, l, dir, needRuntime;
  for (i = 0, l = dirs.length; i < l; i++) {
    dir = dirs[i];
    needRuntime = true;
    const gen = state.directives[dir.name];
    if (gen) {
      // compile-time directive that manipulates AST.
      // returns true if it also needs a runtime counterpart.
      needRuntime = !!gen(el, dir, state.warn);
    }
    if (needRuntime) {
      hasRuntime = true;
      res += `{name:"${dir.name}",rawName:"${dir.rawName}"${
        dir.value ? `,value:(${dir.value}),expression:${JSON.stringify(dir.value)}` : ''
      }${
        dir.arg ? `,arg:"${dir.arg}"` : ''
      }${
        dir.modifiers ? `,modifiers:${JSON.stringify(dir.modifiers)}` : ''
      }},`;
    }
  }
  if (hasRuntime) {
    return res.slice(0, -1) + ']'
  }
}

function genInlineTemplate (el, state) {
  const ast = el.children[0];
  if ("development" !== 'production' && (
    el.children.length !== 1 || ast.type !== 1
  )) {
    state.warn('Inline-template components must have exactly one child element.');
  }
  if (ast.type === 1) {
    const inlineRenderFns = generate(ast, state.options);
    return `inlineTemplate:{render:function(){${
      inlineRenderFns.render
    }},staticRenderFns:[${
      inlineRenderFns.staticRenderFns.map(code => `function(){${code}}`).join(',')
    }]}`
  }
}

function genScopedSlots (
  slots,
  state
) {
  return `scopedSlots:_u([${
    Object.keys(slots).map(key => {
      return genScopedSlot(key, slots[key], state)
    }).join(',')
  }])`
}

function genScopedSlot (
  key,
  el,
  state
) {
  if (el.for && !el.forProcessed) {
    return genForScopedSlot(key, el, state)
  }
  const fn = `function(${String(el.slotScope)}){` +
    `return ${el.tag === 'template'
      ? el.if
        ? `${el.if}?${genChildren(el, state) || 'undefined'}:undefined`
        : genChildren(el, state) || 'undefined'
      : genElement(el, state)
  }}`;
  return `{key:${key},fn:${fn}}`
}

function genForScopedSlot (
  key,
  el,
  state
) {
  const exp = el.for;
  const alias = el.alias;
  const iterator1 = el.iterator1 ? `,${el.iterator1}` : '';
  const iterator2 = el.iterator2 ? `,${el.iterator2}` : '';
  el.forProcessed = true; // avoid recursion
  return `_l((${exp}),` +
    `function(${alias}${iterator1}${iterator2}){` +
      `return ${genScopedSlot(key, el, state)}` +
    '})'
}

function genChildren (
  el,
  state,
  checkSkip,
  altGenElement,
  altGenNode
) {
  const children = el.children;
  if (children.length) {
    const el = children[0];
    // optimize single v-for
    if (children.length === 1 &&
      el.for &&
      el.tag !== 'template' &&
      el.tag !== 'slot'
    ) {
      return (altGenElement || genElement)(el, state)
    }
    const normalizationType = checkSkip
      ? getNormalizationType(children, state.maybeComponent)
      : 0;
    const gen = altGenNode || genNode;
    return `[${children.map(c => gen(c, state)).join(',')}]${
      normalizationType ? `,${normalizationType}` : ''
    }`
  }
}

// determine the normalization needed for the children array.
// 0: no normalization needed
// 1: simple normalization needed (possible 1-level deep nested array)
// 2: full normalization needed
function getNormalizationType (
  children,
  maybeComponent
) {
  let res = 0;
  for (let i = 0; i < children.length; i++) {
    const el = children[i];
    if (el.type !== 1) {
      continue
    }
    if (needsNormalization(el) ||
        (el.ifConditions && el.ifConditions.some(c => needsNormalization(c.block)))) {
      res = 2;
      break
    }
    if (maybeComponent(el) ||
        (el.ifConditions && el.ifConditions.some(c => maybeComponent(c.block)))) {
      res = 1;
    }
  }
  return res
}

function needsNormalization (el) {
  return el.for !== undefined || el.tag === 'template' || el.tag === 'slot'
}

function genNode (node, state) {
  if (node.type === 1) {
    return genElement(node, state)
  } if (node.type === 3 && node.isComment) {
    return genComment(node)
  } else {
    return genText(node)
  }
}

function genText (text) {
  return `_v(${text.type === 2
    ? text.expression // no need for () because already wrapped in _s()
    : transformSpecialNewlines(JSON.stringify(text.text))
  })`
}

function genComment (comment) {
  return `_e(${JSON.stringify(comment.text)})`
}

function genSlot (el, state) {
  const slotName = el.slotName || '"default"';
  const children = genChildren(el, state);
  let res = `_t(${slotName}${children ? `,${children}` : ''}`;
  const attrs = el.attrs && `{${el.attrs.map(a => `${camelize(a.name)}:${a.value}`).join(',')}}`;
  const bind$$1 = el.attrsMap['v-bind'];
  if ((attrs || bind$$1) && !children) {
    res += `,null`;
  }
  if (attrs) {
    res += `,${attrs}`;
  }
  if (bind$$1) {
    res += `${attrs ? '' : ',null'},${bind$$1}`;
  }
  return res + ')'
}

// componentName is el.component, take it as argument to shun flow's pessimistic refinement
function genComponent (
  componentName,
  el,
  state
) {
  const children = el.inlineTemplate ? null : genChildren(el, state, true);
  return `_c(${componentName},${genData$2(el, state)}${
    children ? `,${children}` : ''
  })`
}

function genProps (props) {
  let res = '';
  for (let i = 0; i < props.length; i++) {
    const prop = props[i];
    res += `"${prop.name}":${transformSpecialNewlines(prop.value)},`;
  }
  return res.slice(0, -1)
}

// #3895, #4268
function transformSpecialNewlines (text) {
  return text
    .replace(/\u2028/g, '\\u2028')
    .replace(/\u2029/g, '\\u2029')
}

/*  */

// these keywords should not appear inside expressions, but operators like
// typeof, instanceof and in are allowed
const prohibitedKeywordRE = new RegExp('\\b' + (
  'do,if,for,let,new,try,var,case,else,with,await,break,catch,class,const,' +
  'super,throw,while,yield,delete,export,import,return,switch,default,' +
  'extends,finally,continue,debugger,function,arguments'
).split(',').join('\\b|\\b') + '\\b');

// these unary operators should not be used as property/method names
const unaryOperatorsRE = new RegExp('\\b' + (
  'delete,typeof,void'
).split(',').join('\\s*\\([^\\)]*\\)|\\b') + '\\s*\\([^\\)]*\\)');

// strip strings in expressions
const stripStringRE = /'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*"|`(?:[^`\\]|\\.)*\$\{|\}(?:[^`\\]|\\.)*`|`(?:[^`\\]|\\.)*`/g;

// detect problematic expressions in a template
function detectErrors (ast) {
  const errors = [];
  if (ast) {
    checkNode(ast, errors);
  }
  return errors
}

function checkNode (node, errors) {
  if (node.type === 1) {
    for (const name in node.attrsMap) {
      if (dirRE.test(name)) {
        const value = node.attrsMap[name];
        if (value) {
          if (name === 'v-for') {
            checkFor(node, `v-for="${value}"`, errors);
          } else if (onRE.test(name)) {
            checkEvent(value, `${name}="${value}"`, errors);
          } else {
            checkExpression(value, `${name}="${value}"`, errors);
          }
        }
      }
    }
    if (node.children) {
      for (let i = 0; i < node.children.length; i++) {
        checkNode(node.children[i], errors);
      }
    }
  } else if (node.type === 2) {
    checkExpression(node.expression, node.text, errors);
  }
}

function checkEvent (exp, text, errors) {
  const stipped = exp.replace(stripStringRE, '');
  const keywordMatch = stipped.match(unaryOperatorsRE);
  if (keywordMatch && stipped.charAt(keywordMatch.index - 1) !== '$') {
    errors.push(
      `avoid using JavaScript unary operator as property name: ` +
      `"${keywordMatch[0]}" in expression ${text.trim()}`
    );
  }
  checkExpression(exp, text, errors);
}

function checkFor (node, text, errors) {
  checkExpression(node.for || '', text, errors);
  checkIdentifier(node.alias, 'v-for alias', text, errors);
  checkIdentifier(node.iterator1, 'v-for iterator', text, errors);
  checkIdentifier(node.iterator2, 'v-for iterator', text, errors);
}

function checkIdentifier (
  ident,
  type,
  text,
  errors
) {
  if (typeof ident === 'string') {
    try {
      new Function(`var ${ident}=_`);
    } catch (e) {
      errors.push(`invalid ${type} "${ident}" in expression: ${text.trim()}`);
    }
  }
}

function checkExpression (exp, text, errors) {
  try {
    new Function(`return ${exp}`);
  } catch (e) {
    const keywordMatch = exp.replace(stripStringRE, '').match(prohibitedKeywordRE);
    if (keywordMatch) {
      errors.push(
        `avoid using JavaScript keyword as property name: ` +
        `"${keywordMatch[0]}"\n  Raw expression: ${text.trim()}`
      );
    } else {
      errors.push(
        `invalid expression: ${e.message} in\n\n` +
        `    ${exp}\n\n` +
        `  Raw expression: ${text.trim()}\n`
      );
    }
  }
}

/*  */

function createFunction (code, errors) {
  try {
    return new Function(code)
  } catch (err) {
    errors.push({ err, code });
    return noop
  }
}

function createCompileToFunctionFn (compile) {
  const cache = Object.create(null);

  return function compileToFunctions (
    template,
    options,
    vm
  ) {
    options = extend({}, options);
    const warn$$1 = options.warn || warn;
    delete options.warn;

    /* istanbul ignore if */
    {
      // detect possible CSP restriction
      try {
        new Function('return 1');
      } catch (e) {
        if (e.toString().match(/unsafe-eval|CSP/)) {
          warn$$1(
            'It seems you are using the standalone build of Vue.js in an ' +
            'environment with Content Security Policy that prohibits unsafe-eval. ' +
            'The template compiler cannot work in this environment. Consider ' +
            'relaxing the policy to allow unsafe-eval or pre-compiling your ' +
            'templates into render functions.'
          );
        }
      }
    }

    // check cache
    const key = options.delimiters
      ? String(options.delimiters) + template
      : template;
    if (cache[key]) {
      return cache[key]
    }

    // compile
    const compiled = compile(template, options);

    // check compilation errors/tips
    {
      if (compiled.errors && compiled.errors.length) {
        warn$$1(
          `Error compiling template:\n\n${template}\n\n` +
          compiled.errors.map(e => `- ${e}`).join('\n') + '\n',
          vm
        );
      }
      if (compiled.tips && compiled.tips.length) {
        compiled.tips.forEach(msg => tip(msg, vm));
      }
    }

    // turn code into functions
    const res = {};
    const fnGenErrors = [];
    res.render = createFunction(compiled.render, fnGenErrors);
    res.staticRenderFns = compiled.staticRenderFns.map(code => {
      return createFunction(code, fnGenErrors)
    });

    // check function generation errors.
    // this should only happen if there is a bug in the compiler itself.
    // mostly for codegen development use
    /* istanbul ignore if */
    {
      if ((!compiled.errors || !compiled.errors.length) && fnGenErrors.length) {
        warn$$1(
          `Failed to generate render function:\n\n` +
          fnGenErrors.map(({ err, code }) => `${err.toString()} in\n\n${code}\n`).join('\n'),
          vm
        );
      }
    }

    return (cache[key] = res)
  }
}

/*  */

function createCompilerCreator (baseCompile) {
  return function createCompiler (baseOptions) {
    function compile (
      template,
      options
    ) {
      const finalOptions = Object.create(baseOptions);
      const errors = [];
      const tips = [];
      finalOptions.warn = (msg, tip) => {
        (tip ? tips : errors).push(msg);
      };

      if (options) {
        // merge custom modules
        if (options.modules) {
          finalOptions.modules =
            (baseOptions.modules || []).concat(options.modules);
        }
        // merge custom directives
        if (options.directives) {
          finalOptions.directives = extend(
            Object.create(baseOptions.directives),
            options.directives
          );
        }
        // copy other options
        for (const key in options) {
          if (key !== 'modules' && key !== 'directives') {
            finalOptions[key] = options[key];
          }
        }
      }

      const compiled = baseCompile(template, finalOptions);
      {
        errors.push.apply(errors, detectErrors(compiled.ast));
      }
      compiled.errors = errors;
      compiled.tips = tips;
      return compiled
    }

    return {
      compile,
      compileToFunctions: createCompileToFunctionFn(compile)
    }
  }
}

/*  */

// `createCompilerCreator` allows creating compilers that use alternative
// parser/optimizer/codegen, e.g the SSR optimizing compiler.
// Here we just export a default compiler using the default parts.
const createCompiler = createCompilerCreator(function baseCompile (
  template,
  options
) {
  const ast = parse(template.trim(), options);
  optimize(ast, options);
  const code = generate(ast, options);
  return {
    ast,
    render: code.render,
    staticRenderFns: code.staticRenderFns
  }
});

/*  */

const { compile, compileToFunctions } = createCompiler(baseOptions);

/*  */

// check whether current browser encodes a char inside attribute values
let div;
function getShouldDecode (href) {
  div = div || document.createElement('div');
  div.innerHTML = href ? `<a href="\n"/>` : `<div a="\n"/>`;
  return div.innerHTML.indexOf('&#10;') > 0
}

// #3663: IE encodes newlines inside attribute values while other browsers don't
const shouldDecodeNewlines = inBrowser ? getShouldDecode(false) : false;
// #6828: chrome encodes content in a[href]
const shouldDecodeNewlinesForHref = inBrowser ? getShouldDecode(true) : false;

/*  */

const idToTemplate = cached(id => {
  const el = query(id);
  return el && el.innerHTML
});

const mount = Vue$3.prototype.$mount;
Vue$3.prototype.$mount = function (
  el,
  hydrating
) {
  el = el && query(el);

  /* istanbul ignore if */
  if (el === document.body || el === document.documentElement) {
    "development" !== 'production' && warn(
      `Do not mount Vue to <html> or <body> - mount to normal elements instead.`
    );
    return this
  }

  const options = this.$options;
  // resolve template/el and convert to render function
  if (!options.render) {
    let template = options.template;
    if (template) {
      if (typeof template === 'string') {
        if (template.charAt(0) === '#') {
          template = idToTemplate(template);
          /* istanbul ignore if */
          if ("development" !== 'production' && !template) {
            warn(
              `Template element not found or is empty: ${options.template}`,
              this
            );
          }
        }
      } else if (template.nodeType) {
        template = template.innerHTML;
      } else {
        {
          warn('invalid template option:' + template, this);
        }
        return this
      }
    } else if (el) {
      template = getOuterHTML(el);
    }
    if (template) {
      /* istanbul ignore if */
      if ("development" !== 'production' && config.performance && mark) {
        mark('compile');
      }

      const { render, staticRenderFns } = compileToFunctions(template, {
        shouldDecodeNewlines,
        shouldDecodeNewlinesForHref,
        delimiters: options.delimiters,
        comments: options.comments
      }, this);
      options.render = render;
      options.staticRenderFns = staticRenderFns;

      /* istanbul ignore if */
      if ("development" !== 'production' && config.performance && mark) {
        mark('compile end');
        measure(`vue ${this._name} compile`, 'compile', 'compile end');
      }
    }
  }
  return mount.call(this, el, hydrating)
};

/**
 * Get outerHTML of elements, taking care
 * of SVG elements in IE as well.
 */
function getOuterHTML (el) {
  if (el.outerHTML) {
    return el.outerHTML
  } else {
    const container = document.createElement('div');
    container.appendChild(el.cloneNode(true));
    return container.innerHTML
  }
}

Vue$3.compile = compileToFunctions;

export default Vue$3;
