8014785: Ability to extend global instance by binding properties of another object

Reviewed-by: attila, hannesw, jlaskey, lagergren

nashorn/src/jdk/nashorn/internal/objects/NativeObject.java

@@ -27,18 +27,24 @@ package jdk.nashorn.internal.objects;
 
 import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;
 import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;
+
+import java.lang.invoke.MethodHandle;
+import java.util.ArrayList;
 import jdk.nashorn.api.scripting.ScriptObjectMirror;
 import jdk.nashorn.internal.objects.annotations.Attribute;
 import jdk.nashorn.internal.objects.annotations.Constructor;
 import jdk.nashorn.internal.objects.annotations.Function;
 import jdk.nashorn.internal.objects.annotations.ScriptClass;
 import jdk.nashorn.internal.objects.annotations.Where;
+import jdk.nashorn.internal.runtime.AccessorProperty;
 import jdk.nashorn.internal.runtime.ECMAException;
 import jdk.nashorn.internal.runtime.JSType;
+import jdk.nashorn.internal.runtime.Property;
 import jdk.nashorn.internal.runtime.PropertyMap;
 import jdk.nashorn.internal.runtime.ScriptFunction;
 import jdk.nashorn.internal.runtime.ScriptObject;
 import jdk.nashorn.internal.runtime.ScriptRuntime;
+import jdk.nashorn.internal.runtime.linker.Bootstrap;
 import jdk.nashorn.internal.runtime.linker.InvokeByName;
 
 /**
@@ -471,4 +477,114 @@ public final class NativeObject {
 
         return false;
     }
+
+    /**
+     * Nashorn extension: Object.bindProperties
+     *
+     * Binds the source object's properties to the target object. Binding
+     * properties allows two-way read/write for the properties of the source object.
+     *
+     * Example:
+     * <pre>
+     * var obj = { x: 34, y: 100 };
+     * var foo = {}
+     *
+     * // bind properties of "obj" to "foo" object
+     * Object.bindProperties(foo, obj);
+     *
+     * // now, we can access/write on 'foo' properties
+     * print(foo.x); // prints obj.x which is 34
+     *
+     * // update obj.x via foo.x
+     * foo.x = "hello";
+     * print(obj.x); // prints "hello" now
+     *
+     * obj.x = 42;   // foo.x also becomes 42
+     * print(foo.x); // prints 42
+     * </pre>
+     * <p>
+     * The source object bound can be a ScriptObject or a ScriptOjectMirror.
+     * null or undefined source object results in TypeError being thrown.
+     * </p>
+     * Example:
+     * <pre>
+     * var obj = loadWithNewGlobal({
+     *    name: "test",
+     *    script: "obj = { x: 33, y: 'hello' }"
+     * });
+     *
+     * // bind 'obj's properties to global scope 'this'
+     * Object.bindProperties(this, obj);
+     * print(x);         // prints 33
+     * print(y);         // prints "hello"
+     * x = Math.PI;      // changes obj.x to Math.PI
+     * print(obj.x);     // prints Math.PI
+     * </pre>
+     *
+     * Limitations of property binding:
+     * <ul>
+     * <li> Only enumerable, immediate (not proto inherited) properties of the source object are bound.
+     * <li> If the target object already contains a property called "foo", the source's "foo" is skipped (not bound).
+     * <li> Properties added to the source object after binding to the target are not bound.
+     * <li> Property configuration changes on the source object (or on the target) is not propagated.
+     * <li> Delete of property on the target (or the source) is not propagated -
+     * only the property value is set to 'undefined' if the property happens to be a data property.
+     * </ul>
+     * <p>
+     * It is recommended that the bound properties be treated as non-configurable
+     * properties to avoid surprises.
+     * </p>
+     *
+     * @param self self reference
+     * @param target the target object to which the source object's properties are bound
+     * @param source the source object whose properties are bound to the target
+     * @return the target object after property binding
+     */
+    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
+    public static Object bindProperties(final Object self, final Object target, final Object source) {
+        // target object has to be a ScriptObject
+        Global.checkObject(target);
+        // check null or undefined source object
+        Global.checkObjectCoercible(source);
+
+        final ScriptObject targetObj = (ScriptObject)target;
+
+        if (source instanceof ScriptObject) {
+            final ScriptObject sourceObj = (ScriptObject)source;
+            final Property[] properties = sourceObj.getMap().getProperties();
+
+            // filter non-enumerable properties
+            final ArrayList<Property> propList = new ArrayList<>();
+            for (Property prop : properties) {
+                if (prop.isEnumerable()) {
+                    propList.add(prop);
+                }
+            }
+
+            if (! propList.isEmpty()) {
+                targetObj.addBoundProperties(sourceObj, propList.toArray(new Property[propList.size()]));
+            }
+        } else if (source instanceof ScriptObjectMirror) {
+            // get enumerable, immediate properties of mirror
+            final ScriptObjectMirror mirror = (ScriptObjectMirror)source;
+            final String[] keys = mirror.getOwnKeys(false);
+            if (keys.length == 0) {
+                // nothing to bind
+                return target;
+            }
+
+            // make accessor properties using dynamic invoker getters and setters
+            final AccessorProperty[] props = new AccessorProperty[keys.length];
+            for (int idx = 0; idx < keys.length; idx++) {
+                final String name = keys[idx];
+                final MethodHandle getter = Bootstrap.createDynamicInvoker("dyn:getMethod|getProp|getElem:" + name, Object.class, ScriptObjectMirror.class);
+                final MethodHandle setter = Bootstrap.createDynamicInvoker("dyn:setProp|setElem:" + name, Object.class, ScriptObjectMirror.class, Object.class);
+                props[idx] = (AccessorProperty.create(name, 0, getter, setter));
+            }
+
+            targetObj.addBoundProperties(source, props);
+        }
+
+        return target;
+    }
 }

nashorn/src/jdk/nashorn/internal/runtime/AccessorProperty.java

@@ -147,9 +147,9 @@ public class AccessorProperty extends Property {
      * and are thus rebound with that as receiver
      *
      * @param property  accessor property to rebind
-     * @param delegate  delegate script object to rebind receiver to
+     * @param delegate  delegate object to rebind receiver to
      */
-    public AccessorProperty(final AccessorProperty property, final ScriptObject delegate) {
+    public AccessorProperty(final AccessorProperty property, final Object delegate) {
         super(property);
 
         this.primitiveGetter = bindTo(property.primitiveGetter, delegate);

nashorn/src/jdk/nashorn/internal/runtime/Context.java

@@ -199,6 +199,7 @@ public final class Context {
 
     private static final ClassLoader myLoader = Context.class.getClassLoader();
     private static final StructureLoader sharedLoader;
+    private static final AccessControlContext NO_PERMISSIONS_CONTEXT;
 
     static {
         sharedLoader = AccessController.doPrivileged(new PrivilegedAction<StructureLoader>() {
@@ -207,6 +208,7 @@ public final class Context {
                 return new StructureLoader(myLoader, null);
             }
         });
+        NO_PERMISSIONS_CONTEXT = new AccessControlContext(new ProtectionDomain[] { new ProtectionDomain(null, new Permissions()) });
     }
 
     /**
@@ -564,7 +566,7 @@ public final class Context {
                         sm.checkPackageAccess(fullName.substring(0, index));
                         return null;
                     }
-                }, createNoPermissionsContext());
+                }, NO_PERMISSIONS_CONTEXT);
             }
         }
 
@@ -707,10 +709,6 @@ public final class Context {
         return (context != null) ? context : Context.getContextTrusted();
     }
 
-    private static AccessControlContext createNoPermissionsContext() {
-        return new AccessControlContext(new ProtectionDomain[] { new ProtectionDomain(null, new Permissions()) });
-    }
-
     private Object evaluateSource(final Source source, final ScriptObject scope, final ScriptObject thiz) {
         ScriptFunction script = null;
 

nashorn/src/jdk/nashorn/internal/runtime/PropertyMap.java

@@ -260,7 +260,7 @@ public final class PropertyMap implements Iterable<Object>, PropertyListener {
      *
      * @return New {@link PropertyMap} with {@link Property} added.
      */
-    PropertyMap addPropertyBind(final AccessorProperty property, final ScriptObject bindTo) {
+    PropertyMap addPropertyBind(final AccessorProperty property, final Object bindTo) {
         return addProperty(new AccessorProperty(property, bindTo));
     }
 

nashorn/src/jdk/nashorn/internal/runtime/ScriptObject.java

@@ -203,9 +203,19 @@ public abstract class ScriptObject extends PropertyListenerManager implements Pr
      * @param source The source object to copy from.
      */
     public void addBoundProperties(final ScriptObject source) {
+        addBoundProperties(source, source.getMap().getProperties());
+    }
+
+    /**
+     * Copy all properties from the array with their receiver bound to the source.
+     *
+     * @param source The source object to copy from.
+     * @param properties The array of properties to copy.
+     */
+    public void addBoundProperties(final ScriptObject source, final Property[] properties) {
         PropertyMap newMap = this.getMap();
 
-        for (final Property property : source.getMap().getProperties()) {
+        for (final Property property : properties) {
             final String key = property.getKey();
 
             if (newMap.findProperty(key) == null) {
@@ -221,6 +231,26 @@ public abstract class ScriptObject extends PropertyListenerManager implements Pr
         this.setMap(newMap);
     }
 
+    /**
+     * Copy all properties from the array with their receiver bound to the source.
+     *
+     * @param source The source object to copy from.
+     * @param properties The collection of accessor properties to copy.
+     */
+    public void addBoundProperties(final Object source, final AccessorProperty[] properties) {
+        PropertyMap newMap = this.getMap();
+
+        for (final AccessorProperty property : properties) {
+            final String key = property.getKey();
+
+            if (newMap.findProperty(key) == null) {
+                newMap = newMap.addPropertyBind(property, source);
+            }
+        }
+
+        this.setMap(newMap);
+    }
+
     /**
      * Bind the method handle to the specified receiver, while preserving its original type (it will just ignore the
      * first argument in lieu of the bound argument).

nashorn/src/jdk/nashorn/internal/runtime/linker/InvokeByName.java

@@ -83,7 +83,7 @@ public class InvokeByName {
      */
     public InvokeByName(final String name, final Class<?> targetClass, final Class<?> rtype, final Class<?>... ptypes) {
         this.name = name;
-        getter  = Bootstrap.createDynamicInvoker("dyn:getMethod|getProp|getItem:" + name, Object.class, targetClass);
+        getter  = Bootstrap.createDynamicInvoker("dyn:getMethod|getProp|getElem:" + name, Object.class, targetClass);
 
         final Class<?>[] finalPtypes;
         final int plength = ptypes.length;

nashorn/test/script/basic/JDK-8014785.js

+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * 
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ * 
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ * 
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * JDK-8014785: Ability to extend global instance by binding properties of another object
+ *
+ * @test
+ * @run
+ */
+
+var obj = { x: 34, y: 100 };
+var foo = {}
+
+// bind properties of "obj" to "foo" obj
+Object.bindProperties(foo, obj);
+
+// now we can access/write on foo properties
+print("foo.x = " + foo.x); // prints obj.x which is 34
+
+// update obj.x via foo.x
+foo.x = "hello";
+print("obj.x = " + obj.x); // prints "hello" now
+     
+obj.x = 42;   // foo.x also becomes 42
+print("obj.x = " + obj.x); // prints 42
+print("foo.x = " + foo.x); // prints 42
+
+// now bind a mirror object to an object
+var obj = loadWithNewGlobal({
+  name: "test",
+  script: "obj = { x: 33, y: 'hello' }"
+});
+
+Object.bindProperties(this, obj);
+print("x = " + x); // prints 33
+print("y = " + y); // prints "hello"
+
+x = Math.PI;               // changes obj.x to Math.PI
+print("obj.x = " +obj.x);  // prints Math.PI
+
+obj.y = 32;
+print("y = " + y);  // should print 32

nashorn/test/script/basic/JDK-8014785.js.EXPECTED

+foo.x = 34
+obj.x = hello
+obj.x = 42
+foo.x = 42
+x = 33
+y = hello
+obj.x = 3.141592653589793
+y = 32