lib/goog/json/json.js

1// Copyright 2006 The Closure Library Authors. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS-IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15/**
16 * @fileoverview JSON utility functions.
17 * @author arv@google.com (Erik Arvidsson)
18 */
19
20
21goog.provide('goog.json');
22goog.provide('goog.json.Replacer');
23goog.provide('goog.json.Reviver');
24goog.provide('goog.json.Serializer');
25
26
27/**
28 * @define {boolean} If true, use the native JSON parsing API.
29 * NOTE(ruilopes): EXPERIMENTAL, handle with care. Setting this to true might
30 * break your code. The default {@code goog.json.parse} implementation is able
31 * to handle invalid JSON, such as JSPB.
32 */
33goog.define('goog.json.USE_NATIVE_JSON', false);
34
35
36/**
37 * Tests if a string is an invalid JSON string. This only ensures that we are
38 * not using any invalid characters
39 * @param {string} s The string to test.
40 * @return {boolean} True if the input is a valid JSON string.
41 */
42goog.json.isValid = function(s) {
43 // All empty whitespace is not valid.
44 if (/^\s*$/.test(s)) {
45 return false;
46 }
47
48 // This is taken from http://www.json.org/json2.js which is released to the
49 // public domain.
50 // Changes: We dissallow \u2028 Line separator and \u2029 Paragraph separator
51 // inside strings. We also treat \u2028 and \u2029 as whitespace which they
52 // are in the RFC but IE and Safari does not match \s to these so we need to
53 // include them in the reg exps in all places where whitespace is allowed.
54 // We allowed \x7f inside strings because some tools don't escape it,
55 // e.g. http://www.json.org/java/org/json/JSONObject.java
56
57 // Parsing happens in three stages. In the first stage, we run the text
58 // against regular expressions that look for non-JSON patterns. We are
59 // especially concerned with '()' and 'new' because they can cause invocation,
60 // and '=' because it can cause mutation. But just to be safe, we want to
61 // reject all unexpected forms.
62
63 // We split the first stage into 4 regexp operations in order to work around
64 // crippling inefficiencies in IE's and Safari's regexp engines. First we
65 // replace all backslash pairs with '@' (a non-JSON character). Second, we
66 // replace all simple value tokens with ']' characters. Third, we delete all
67 // open brackets that follow a colon or comma or that begin the text. Finally,
68 // we look to see that the remaining characters are only whitespace or ']' or
69 // ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.
70
71 // Don't make these static since they have the global flag.
72 var backslashesRe = /\\["\\\/bfnrtu]/g;
73 var simpleValuesRe =
74 /"[^"\\\n\r\u2028\u2029\x00-\x08\x0a-\x1f]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g;
75 var openBracketsRe = /(?:^|:|,)(?:[\s\u2028\u2029]*\[)+/g;
76 var remainderRe = /^[\],:{}\s\u2028\u2029]*$/;
77
78 return remainderRe.test(s.replace(backslashesRe, '@').
79 replace(simpleValuesRe, ']').
80 replace(openBracketsRe, ''));
81};
82
83
84/**
85 * Parses a JSON string and returns the result. This throws an exception if
86 * the string is an invalid JSON string.
87 *
88 * Note that this is very slow on large strings. If you trust the source of
89 * the string then you should use unsafeParse instead.
90 *
91 * @param {*} s The JSON string to parse.
92 * @throws Error if s is invalid JSON.
93 * @return {Object} The object generated from the JSON string, or null.
94 */
95goog.json.parse = goog.json.USE_NATIVE_JSON ?
96 /** @type {function(*):Object} */ (goog.global['JSON']['parse']) :
97 function(s) {
98 var o = String(s);
99 if (goog.json.isValid(o)) {
100 /** @preserveTry */
101 try {
102 return /** @type {Object} */ (eval('(' + o + ')'));
103 } catch (ex) {
104 }
105 }
106 throw Error('Invalid JSON string: ' + o);
107 };
108
109
110/**
111 * Parses a JSON string and returns the result. This uses eval so it is open
112 * to security issues and it should only be used if you trust the source.
113 *
114 * @param {string} s The JSON string to parse.
115 * @return {Object} The object generated from the JSON string.
116 */
117goog.json.unsafeParse = goog.json.USE_NATIVE_JSON ?
118 /** @type {function(string):Object} */ (goog.global['JSON']['parse']) :
119 function(s) {
120 return /** @type {Object} */ (eval('(' + s + ')'));
121 };
122
123
124/**
125 * JSON replacer, as defined in Section 15.12.3 of the ES5 spec.
126 * @see http://ecma-international.org/ecma-262/5.1/#sec-15.12.3
127 *
128 * TODO(nicksantos): Array should also be a valid replacer.
129 *
130 * @typedef {function(this:Object, string, *): *}
131 */
132goog.json.Replacer;
133
134
135/**
136 * JSON reviver, as defined in Section 15.12.2 of the ES5 spec.
137 * @see http://ecma-international.org/ecma-262/5.1/#sec-15.12.3
138 *
139 * @typedef {function(this:Object, string, *): *}
140 */
141goog.json.Reviver;
142
143
144/**
145 * Serializes an object or a value to a JSON string.
146 *
147 * @param {*} object The object to serialize.
148 * @param {?goog.json.Replacer=} opt_replacer A replacer function
149 * called for each (key, value) pair that determines how the value
150 * should be serialized. By defult, this just returns the value
151 * and allows default serialization to kick in.
152 * @throws Error if there are loops in the object graph.
153 * @return {string} A JSON string representation of the input.
154 */
155goog.json.serialize = goog.json.USE_NATIVE_JSON ?
156 /** @type {function(*, ?goog.json.Replacer=):string} */
157 (goog.global['JSON']['stringify']) :
158 function(object, opt_replacer) {
159 // NOTE(nicksantos): Currently, we never use JSON.stringify.
160 //
161 // The last time I evaluated this, JSON.stringify had subtle bugs and
162 // behavior differences on all browsers, and the performance win was not
163 // large enough to justify all the issues. This may change in the future
164 // as browser implementations get better.
165 //
166 // assertSerialize in json_test contains if branches for the cases
167 // that fail.
168 return new goog.json.Serializer(opt_replacer).serialize(object);
169 };
170
171
172
173/**
174 * Class that is used to serialize JSON objects to a string.
175 * @param {?goog.json.Replacer=} opt_replacer Replacer.
176 * @constructor
177 */
178goog.json.Serializer = function(opt_replacer) {
179 /**
180 * @type {goog.json.Replacer|null|undefined}
181 * @private
182 */
183 this.replacer_ = opt_replacer;
184};
185
186
187/**
188 * Serializes an object or a value to a JSON string.
189 *
190 * @param {*} object The object to serialize.
191 * @throws Error if there are loops in the object graph.
192 * @return {string} A JSON string representation of the input.
193 */
194goog.json.Serializer.prototype.serialize = function(object) {
195 var sb = [];
196 this.serializeInternal(object, sb);
197 return sb.join('');
198};
199
200
201/**
202 * Serializes a generic value to a JSON string
203 * @protected
204 * @param {*} object The object to serialize.
205 * @param {Array<string>} sb Array used as a string builder.
206 * @throws Error if there are loops in the object graph.
207 */
208goog.json.Serializer.prototype.serializeInternal = function(object, sb) {
209 switch (typeof object) {
210 case 'string':
211 this.serializeString_(/** @type {string} */ (object), sb);
212 break;
213 case 'number':
214 this.serializeNumber_(/** @type {number} */ (object), sb);
215 break;
216 case 'boolean':
217 sb.push(object);
218 break;
219 case 'undefined':
220 sb.push('null');
221 break;
222 case 'object':
223 if (object == null) {
224 sb.push('null');
225 break;
226 }
227 if (goog.isArray(object)) {
228 this.serializeArray(/** @type {!Array<?>} */ (object), sb);
229 break;
230 }
231 // should we allow new String, new Number and new Boolean to be treated
232 // as string, number and boolean? Most implementations do not and the
233 // need is not very big
234 this.serializeObject_(/** @type {Object} */ (object), sb);
235 break;
236 case 'function':
237 // Skip functions.
238 // TODO(user) Should we return something here?
239 break;
240 default:
241 throw Error('Unknown type: ' + typeof object);
242 }
243};
244
245
246/**
247 * Character mappings used internally for goog.string.quote
248 * @private
249 * @type {!Object}
250 */
251goog.json.Serializer.charToJsonCharCache_ = {
252 '\"': '\\"',
253 '\\': '\\\\',
254 '/': '\\/',
255 '\b': '\\b',
256 '\f': '\\f',
257 '\n': '\\n',
258 '\r': '\\r',
259 '\t': '\\t',
260
261 '\x0B': '\\u000b' // '\v' is not supported in JScript
262};
263
264
265/**
266 * Regular expression used to match characters that need to be replaced.
267 * The S60 browser has a bug where unicode characters are not matched by
268 * regular expressions. The condition below detects such behaviour and
269 * adjusts the regular expression accordingly.
270 * @private
271 * @type {!RegExp}
272 */
273goog.json.Serializer.charsToReplace_ = /\uffff/.test('\uffff') ?
274 /[\\\"\x00-\x1f\x7f-\uffff]/g : /[\\\"\x00-\x1f\x7f-\xff]/g;
275
276
277/**
278 * Serializes a string to a JSON string
279 * @private
280 * @param {string} s The string to serialize.
281 * @param {Array<string>} sb Array used as a string builder.
282 */
283goog.json.Serializer.prototype.serializeString_ = function(s, sb) {
284 // The official JSON implementation does not work with international
285 // characters.
286 sb.push('"', s.replace(goog.json.Serializer.charsToReplace_, function(c) {
287 // caching the result improves performance by a factor 2-3
288 if (c in goog.json.Serializer.charToJsonCharCache_) {
289 return goog.json.Serializer.charToJsonCharCache_[c];
290 }
291
292 var cc = c.charCodeAt(0);
293 var rv = '\\u';
294 if (cc < 16) {
295 rv += '000';
296 } else if (cc < 256) {
297 rv += '00';
298 } else if (cc < 4096) { // \u1000
299 rv += '0';
300 }
301 return goog.json.Serializer.charToJsonCharCache_[c] = rv + cc.toString(16);
302 }), '"');
303};
304
305
306/**
307 * Serializes a number to a JSON string
308 * @private
309 * @param {number} n The number to serialize.
310 * @param {Array<string>} sb Array used as a string builder.
311 */
312goog.json.Serializer.prototype.serializeNumber_ = function(n, sb) {
313 sb.push(isFinite(n) && !isNaN(n) ? n : 'null');
314};
315
316
317/**
318 * Serializes an array to a JSON string
319 * @param {Array<string>} arr The array to serialize.
320 * @param {Array<string>} sb Array used as a string builder.
321 * @protected
322 */
323goog.json.Serializer.prototype.serializeArray = function(arr, sb) {
324 var l = arr.length;
325 sb.push('[');
326 var sep = '';
327 for (var i = 0; i < l; i++) {
328 sb.push(sep);
329
330 var value = arr[i];
331 this.serializeInternal(
332 this.replacer_ ? this.replacer_.call(arr, String(i), value) : value,
333 sb);
334
335 sep = ',';
336 }
337 sb.push(']');
338};
339
340
341/**
342 * Serializes an object to a JSON string
343 * @private
344 * @param {Object} obj The object to serialize.
345 * @param {Array<string>} sb Array used as a string builder.
346 */
347goog.json.Serializer.prototype.serializeObject_ = function(obj, sb) {
348 sb.push('{');
349 var sep = '';
350 for (var key in obj) {
351 if (Object.prototype.hasOwnProperty.call(obj, key)) {
352 var value = obj[key];
353 // Skip functions.
354 // TODO(ptucker) Should we return something for function properties?
355 if (typeof value != 'function') {
356 sb.push(sep);
357 this.serializeString_(key, sb);
358 sb.push(':');
359
360 this.serializeInternal(
361 this.replacer_ ? this.replacer_.call(obj, key, value) : value,
362 sb);
363
364 sep = ',';
365 }
366 }
367 }
368 sb.push('}');
369};