/**
* Copyright 2010 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 org.waveprotocol.wave.communication.gwt;
import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.JavaScriptException;
import com.google.gwt.core.client.JavaScriptObject;
import org.waveprotocol.wave.communication.json.JsonException;
import org.waveprotocol.wave.communication.json.RawStringData;
/**
* Implementation of a JSON message.
* This is done by extending JavaScriptObject to minimise the size of the resulting code.
*
*/
public class JsonMessage extends JavaScriptObject {
private static final JsonSerializer serializer;
private static boolean registerToString = false;
static {
if (GWT.isClient() && BrowserAidedJsonSerailizer.hasBrowserSupport()) {
serializer = new BrowserAidedJsonSerailizer();
} else {
serializer = new JavascriptJsonSerializer();
}
}
/**
* Protected constructor. Instantiate via static create method.
*/
protected JsonMessage() {
}
/**
* @return a new empty JsonMessage.
*/
public static JsonMessage createJsonMessage() {
JsonMessage instance = JavaScriptObject.createObject().cast();
registerNativeJsonMessageToString(instance);
return instance;
}
/**
* Delete all existing properties on this object.
*/
public final native void clear() /*-{
for (var p in this) {
if (this.hasOwnProperty(p) && typeof this[p] != "function") {
delete p;
}
}
}-*/;
/**
* Copy the contents of an existing JsonMessage into this one.
* @param message
*/
public final native void copyFrom(JsonMessage message) /*-{
var clone = function (input) {
if (input === undefined || input === null) {
return null;
}
if (typeof input == 'object' && input.constructor === Array) {
var output = [];
for (var property = 0; property < input.length; ++property) {
output[property] = clone(input[property]);
}
return output;
}
if (typeof input == 'object') {
var output = {};
for (var property in input) {
if (input.hasOwnProperty(property)) {
output[property] = clone(input[property]);
}
}
return output;
}
return input;
};
// delete any existing properties
for (var property in this) {
if (this.hasOwnProperty(property) && typeof this[property] != "function") {
delete property;
}
}
// copy over new properties
for (var property in message) {
if (message.hasOwnProperty(property)) {
this[property] = clone(message[property]);
}
}
}-*/;
/**
* Convert this JsonMessage into a JSON String.
* @return a JSON string representation.
*/
public final String toJson() {
return serializer.serialize(this);
}
public static <T extends JsonMessage> T parse(String json) throws JsonException {
return createJsonMessage(json).<T>cast();
}
/**
* Create a JsonMessage object from the given json
* @param json The JSON String to load from.
* @return true if evaluation is successful, false otherwise.
*/
public static JsonMessage createJsonMessage(String json) throws JsonException {
try {
JsonMessage obj = (JsonMessage) serializer.parse(json);
registerNativeJsonMessageToString(obj);
return obj;
} catch (JavaScriptException e) {
throw new JsonException(e);
}
}
/**
* Create a JsonMessage object from the given json
* @param json The JSON String to load from.
* @return true if evaluation is successful, false otherwise.
*/
public static JsonMessage createJsonMessage(RawStringData data) throws JsonException {
try {
JsonMessage obj = (JsonMessage) serializer.parse(data.getBaseString());
JsonHelper.registerRawStringData(obj, data);
registerNativeJsonMessageToString(obj);
return obj;
} catch (JavaScriptException e) {
throw new JsonException(e);
}
}
/**
* JSON implementation of equals() since we can override it.
*
* TODO(user): Rename this to isEqualTo() once GWT compiler is fixed to
* not crash when another interface defines this method and is implemented by a subclass
* of JsonMessage.
*
* @return true if the other object is the same as this object.
*/
public final native boolean nativeIsEqualTo(Object toCompare) /*-{
var same = function (objectA, objectB) {
if (typeof objectA == "object" && typeof objectB == "object") {
// Check all A is in B
for (var property in objectA) {
if (objectA.hasOwnProperty(property) && typeof objectA[property] != "function") {
if (!same(objectA[property], objectB[property])) {
return false;
}
}
}
// Check all B is in A
for (var property in objectB) {
// Something in B we don't know in A.
if (objectB.hasOwnProperty(property) && typeof objectB[property] != "function" &&
!objectA.hasOwnProperty(property)) {
return false;
}
}
return true;
} else {
return objectA == objectB;
}
};
return same(this, toCompare);
}-*/;
/** Static version of toJson to allow us to call from JSNI */
@SuppressWarnings("unused") // Called from JSNI
private static final String jsonMessageToJson(JsonMessage instance) {
return instance.toJson();
}
/** Enables toString on JSOs */
public static void enableJsoToString() {
registerToString = true;
}
/** Disables toString on JSOs */
public static void disableJsoToString() {
registerToString = false;
}
protected static final void registerNativeJsonMessageToString(JsonMessage instance) {
if (registerToString) {
nativeRegisterNativeJsonMessageToString(instance);
}
}
/**
* Recursively registers a native toString function on the object.
* This toString method will be invoked from JavaScriptObject.toString(),
* allowing us to print JSON when toString() is called on a JsonMessage.
*/
private static final native void nativeRegisterNativeJsonMessageToString(JsonMessage instance)
/*-{
instance.toString = function () {
return (
@org.waveprotocol.wave.communication.gwt.JsonMessage::jsonMessageToJson(Lorg/waveprotocol/wave/communication/gwt/JsonMessage;)
(this));
}
// set toString on all sub objects.
for (var property in instance) {
if (instance.hasOwnProperty(property) && typeof instance[property] == "object") {
@org.waveprotocol.wave.communication.gwt.JsonMessage::registerNativeJsonMessageToString(Lorg/waveprotocol/wave/communication/gwt/JsonMessage;)
(instance[property]);
}
}
}-*/;
}