attributes.js

var DomUtils  = require("domutils"),
    hasAttrib = DomUtils.hasAttrib,
    getAttributeValue = DomUtils.getAttributeValue,
    falseFunc = require("boolbase").falseFunc;

//https://github.com/slevithan/XRegExp/blob/master/src/xregexp.js#L469
var reChars = /[-[\]{}()*+?.,\\^$|#\s]/g;

/*
	attribute selectors
*/

var attributeRules = {
	__proto__: null,
	equals: function(next, data){
		var name  = data.name,
		    value = data.value;

		if(data.ignoreCase){
			value = value.toLowerCase();

			return function equalsIC(elem){
				var attr = getAttributeValue(elem, name);
				return attr != null && attr.toLowerCase() === value && next(elem);
			};
		}

		return function equals(elem){
			return getAttributeValue(elem, name) === value && next(elem);
		};
	},
	hyphen: function(next, data){
		var name  = data.name,
		    value = data.value,
		    len = value.length;

		if(data.ignoreCase){
			value = value.toLowerCase();

			return function hyphenIC(elem){
				var attr = getAttributeValue(elem, name);
				return attr != null &&
						(attr.length === len || attr.charAt(len) === "-") &&
						attr.substr(0, len).toLowerCase() === value &&
						next(elem);
			};
		}

		return function hyphen(elem){
			var attr = getAttributeValue(elem, name);
			return attr != null &&
					attr.substr(0, len) === value &&
					(attr.length === len || attr.charAt(len) === "-") &&
					next(elem);
		};
	},
	element: function(next, data){
		var name = data.name,
		    value = data.value;

		if(/\s/.test(value)){
			return falseFunc;
		}

		value = value.replace(reChars, "\\$&");

		var pattern = "(?:^|\\s)" + value + "(?:$|\\s)",
		    flags = data.ignoreCase ? "i" : "",
		    regex = new RegExp(pattern, flags);

		return function element(elem){
			var attr = getAttributeValue(elem, name);
			return attr != null && regex.test(attr) && next(elem);
		};
	},
	exists: function(next, data){
		var name = data.name;
		return function exists(elem){
			return hasAttrib(elem, name) && next(elem);
		};
	},
	start: function(next, data){
		var name  = data.name,
		    value = data.value,
		    len = value.length;

		if(len === 0){
			return falseFunc;
		}
		
		if(data.ignoreCase){
			value = value.toLowerCase();

			return function startIC(elem){
				var attr = getAttributeValue(elem, name);
				return attr != null && attr.substr(0, len).toLowerCase() === value && next(elem);
			};
		}

		return function start(elem){
			var attr = getAttributeValue(elem, name);
			return attr != null && attr.substr(0, len) === value && next(elem);
		};
	},
	end: function(next, data){
		var name  = data.name,
		    value = data.value,
		    len   = -value.length;

		if(len === 0){
			return falseFunc;
		}

		if(data.ignoreCase){
			value = value.toLowerCase();

			return function endIC(elem){
				var attr = getAttributeValue(elem, name);
				return attr != null && attr.substr(len).toLowerCase() === value && next(elem);
			};
		}

		return function end(elem){
			var attr = getAttributeValue(elem, name);
			return attr != null && attr.substr(len) === value && next(elem);
		};
	},
	any: function(next, data){
		var name  = data.name,
		    value = data.value;

		if(value === ""){
			return falseFunc;
		}

		if(data.ignoreCase){
			var regex = new RegExp(value.replace(reChars, "\\$&"), "i");

			return function anyIC(elem){
				var attr = getAttributeValue(elem, name);
				return attr != null && regex.test(attr) && next(elem);
			};
		}

		return function any(elem){
			var attr = getAttributeValue(elem, name);
			return attr != null && attr.indexOf(value) >= 0 && next(elem);
		};
	},
	not: function(next, data){
		var name  = data.name,
		    value = data.value;

		if(value === ""){
			return function notEmpty(elem){
				return !!getAttributeValue(elem, name) && next(elem);
			};
		} else if(data.ignoreCase){
			value = value.toLowerCase();

			return function notIC(elem){
				var attr = getAttributeValue(elem, name);
				return attr != null && attr.toLowerCase() !== value && next(elem);
			};
		}

		return function not(elem){
			return getAttributeValue(elem, name) !== value && next(elem);
		};
	}
};

module.exports = {
	compile: function(next, data, options){
		if(options && options.strict && (
			data.ignoreCase || data.action === "not"
		)) throw SyntaxError("Unsupported attribute selector");
		return attributeRules[data.action](next, data);
	},
	rules: attributeRules
};