com.google.gwt.core.client.JavaScriptObject Maven / Gradle / Ivy
/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.core.client;
/**
* An opaque handle to a native JavaScript object. A
* JavaScriptObject cannot be created directly.
* JavaScriptObject should be declared as the return type of a
* JSNI method that returns native (non-Java) objects. A
* JavaScriptObject passed back into JSNI from Java becomes the
* original object, and can be accessed in JavaScript as expected.
*/
public class JavaScriptObject {
/**
* Returns a new array.
*/
public static native JavaScriptObject createArray() /*-{
return [];
}-*/;
/**
* Returns a new array with a given size.
*
* Consider using this method in performance critical code instead of using
* {@link #createArray()}, since this gives more hints to the underlying
* JavaScript VM for optimizations.
*/
public static native JavaScriptObject createArray(int size) /*-{
return new Array(size);
}-*/;
/**
* Returns an empty function.
*/
public static native JavaScriptObject createFunction() /*-{
return function() {
};
}-*/;
/**
* Returns a new object.
*/
public static native JavaScriptObject createObject() /*-{
return {};
}-*/;
/**
* Helper for {@link #toString()}, for lighter "more production" code.
*/
private static native String toStringSimple(JavaScriptObject obj) /*-{
return obj.toString ? obj.toString() : '[JavaScriptObject]';
}-*/;
/**
* Helper for {@link #toString()}, when Development Mode or assertions are on.
*/
private static native String toStringVerbose(JavaScriptObject obj) /*-{
var defined = function(m) { return typeof m != 'undefined'; };
var strip = function(s) { return s.replace(/\r\n/g, ""); };
// Output nodes that have outerHTML
if (defined(obj.outerHTML))
return strip(obj.outerHTML);
// Output nodes that have innerHTML
if (defined(obj.innerHTML) && obj.cloneNode) {
$doc.createElement('div').appendChild(obj.cloneNode(true)).innerHTML;
}
// Output text nodes
if (defined(obj.nodeType) && obj.nodeType == 3) {
return "'" +
obj.data.replace(/ /g, "\u25ab").replace(/\u00A0/, "\u25aa") +
"'";
}
// Output IE's TextRange (this code specific to IE7)
if (typeof defined(obj.htmlText) && obj.collapse) {
var html = obj.htmlText;
if (html) {
return 'IETextRange [' + strip(html) + ']';
} else {
// NOTE: using pasteHTML to place a | where the range is collapsed
// if *very* useful when debugging. It also, however, in certain very
// subtle circumstances change the range being toStringed! If you
// see different behaviour in debug vs. release builds (or if logging
// ranges changes the behaviour, comment out the 4 of the 6 lines
// below containing dup.
var dup = obj.duplicate();
dup.pasteHTML('|');
var out = 'IETextRange ' + strip(obj.parentElement().outerHTML);
dup.moveStart('character', -1);
dup.pasteHTML('');
return out;
}
}
return obj.toString ? obj.toString() : '[JavaScriptObject]';
}-*/;
/**
* Not directly instantiable. All subclasses must also define a protected,
* empty, no-arg constructor.
*/
protected JavaScriptObject() {
}
/**
* A helper method to enable cross-casting from any {@link JavaScriptObject}
* type to any other {@link JavaScriptObject} type.
*
* @param the target type
* @return this object as a different type
*/
@SuppressWarnings("unchecked")
public final T cast() {
return (T) this;
}
/**
* Calls a native JS equals method if any, otherwise
* returns true if the objects are JavaScript identical
* (triple-equals).
*/
@Override
public final boolean equals(Object other) {
if (!GWT.isClient()) {
return super.equals(other);
}
return hasEquals(this) ? callEquals(this, other) : super.equals(other);
}
/**
* Calls a native JS hashCode method if any, otherwise
* uses a monotonically increasing counter to assign a hash code to the
* underlying JavaScript object. Do not call this method on non-modifiable
* JavaScript objects.
*
* @return the hash code of the object
*/
@Override
public final int hashCode() {
if (!GWT.isClient()) {
return super.hashCode();
}
return hasHashCode(this) ? callHashCode(this) : super.hashCode();
};
/**
* Call the toSource() on the JSO.
*/
public native String toSource() /*-{
this.toSource ? this.toSource() : "NO SOURCE";
}-*/;
/**
* Makes a best-effort attempt to get a useful debugging string describing the
* given JavaScriptObject. In Production Mode with assertions disabled, this
* will either call and return the JSO's toString() if one exists, or just
* return "[JavaScriptObject]". In Development Mode, or with assertions
* enabled, some stronger effort is made to represent other types of JSOs,
* including inspecting for document nodes' outerHTML and innerHTML, etc.
*/
@Override
public final String toString() {
return JavaScriptObject.class.desiredAssertionStatus() ?
toStringVerbose(this) : toStringSimple(this);
}
private static native boolean hasEquals(Object object) /*-{
return !!object && !!object.equals;
}-*/;
private static native boolean hasHashCode(Object object) /*-{
return !!object && !!object.hashCode;
}-*/;
private static native boolean callEquals(Object thisObject, Object thatObject) /*-{
return thisObject.equals(thatObject);
}-*/;
private static native int callHashCode(Object object) /*-{
return object.hashCode();
}-*/;
}