| /* |
| * Copyright 2006 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.json.client; |
| |
| import com.google.gwt.core.client.JavaScriptException; |
| import com.google.gwt.core.client.JavaScriptObject; |
| |
| /** |
| * Parses the string representation of a JSON object into a set of |
| * JSONValue-derived objects. |
| * |
| * @see com.google.gwt.json.client.JSONValue |
| */ |
| public class JSONParser { |
| |
| /** |
| * Given a jsonString, returns the JSONObject representation. For efficiency, |
| * parsing occurs lazily as the structure is requested. |
| * |
| * @param jsonString |
| * @return a JSONObject that has been built by parsing the JSON string |
| * @throws NullPointerException if <code>jsonString</code> is |
| * <code>null</code> |
| * @throws IllegalArgumentException if <code>jsonString</code> is empty |
| */ |
| public static JSONValue parse(String jsonString) { |
| // Create a JavaScriptObject from the JSON string. |
| // |
| if (jsonString == null) { |
| throw new NullPointerException(); |
| } |
| if (jsonString == "") { |
| throw new IllegalArgumentException("empty argument"); |
| } |
| try { |
| JavaScriptObject jsonObject = evaluate(jsonString); |
| return buildValue(jsonObject); |
| } catch (JavaScriptException ex) { |
| throw new JSONException(ex); |
| } |
| } |
| |
| /* |
| * Given a JavaScript object that could be an Object or a primitive JavaScript |
| * type, create the correct subtype of JSONValue and return it. |
| */ |
| static JSONValue buildValue(JavaScriptObject jsValue) throws JSONException { |
| if (isNull(jsValue)) { |
| return JSONNull.getInstance(); |
| } |
| if (isArray(jsValue)) { |
| return new JSONArray(jsValue); |
| } |
| Boolean bool = asBoolean(jsValue); |
| if (bool != null) { |
| return JSONBoolean.getInstance(bool.booleanValue()); |
| } |
| String str = asString(jsValue); |
| if (str != null) { |
| return new JSONString(str); |
| } |
| if (isDouble(jsValue)) { |
| return new JSONNumber(asDouble(jsValue)); |
| } |
| if (isJSONObject(jsValue)) { |
| return new JSONObject(jsValue); |
| } |
| throw new JSONException(toJavascriptString(jsValue)); |
| } |
| |
| /* |
| * Returns a Boolean representing the truth value of jsValue. Returns null if |
| * jsValue is not a boolean value. |
| */ |
| private static native Boolean asBoolean(JavaScriptObject jsValue) /*-{ |
| if (jsValue instanceof Boolean || ((typeof jsValue)=='boolean')) { |
| if(jsValue==true) { |
| return @java.lang.Boolean::TRUE; |
| } else { |
| return @java.lang.Boolean::FALSE; |
| } |
| } |
| return null; |
| }-*/; |
| |
| /* |
| * Returns the double represented by jsValue. |
| */ |
| private static native double asDouble(JavaScriptObject jsValue) /*-{ |
| return jsValue; |
| }-*/; |
| |
| /* |
| * converts the Javascript Object to a String. Returns null if the object is |
| * not a String. |
| */ |
| private static native String asString(JavaScriptObject jsValue) /*-{ |
| if (jsValue instanceof String || ((typeof jsValue)=='string')) { |
| return jsValue; |
| } |
| return null; |
| }-*/; |
| |
| /* |
| * This method converts the json string into a JavaScriptObject inside of JSNI |
| * method by simply evaluating the string in JavaScript. |
| */ |
| private static native JavaScriptObject evaluate(String jsonString) /*-{ |
| var x = eval('(' + jsonString + ')'); |
| if (typeof x == 'number' || typeof x == 'string' || typeof x == 'array' || typeof x == 'boolean') { |
| x = (Object(x)); |
| } |
| return x; |
| }-*/; |
| |
| private static native boolean isArray(JavaScriptObject jsValue) /*-{ |
| return (jsValue instanceof Array); |
| }-*/; |
| |
| /* |
| * Returns true if jsValue is a double. |
| */ |
| private static native boolean isDouble(JavaScriptObject jsValue) /*-{ |
| return (jsValue instanceof Number || ((typeof jsValue)=='number')); |
| }-*/; |
| |
| /* |
| * Given a JavaScriptObject build the corresponding JSONObject representation. |
| * Note it is assumed that the JavaScriptObject is a proper JSON object. This |
| * is done entirely in Javascript because the Javascript code to marshal it |
| * into a Java form would be about the same size. |
| */ |
| private static native boolean isJSONObject(JavaScriptObject jsObject) /*-{ |
| return (jsObject instanceof Object); |
| }-*/; |
| |
| private static native boolean isNull(JavaScriptObject o) /*-{ |
| return o == null; |
| }-*/; |
| |
| /* |
| * Returns the string value of jsValue. This is more informative than |
| * Object.toString(). |
| */ |
| private static native String toJavascriptString(JavaScriptObject jsValue) /*-{ |
| return jsValue.toString(); |
| }-*/; |
| |
| /** |
| * Not instantiable. |
| */ |
| private JSONParser() { |
| } |
| } |