2 Copyright (c) 2009, Yahoo! Inc. All rights reserved.
3 Code licensed under the BSD License:
4 http://developer.yahoo.net/yui/license.txt
8 YUI.add('json-parse', function(Y) {
11 * <p>The JSON module adds support for serializing JavaScript objects into
12 * JSON strings and parsing JavaScript objects from strings in JSON format.</p>
14 * <p>The JSON namespace is added to your YUI instance including static methods
15 * Y.JSON.parse(..) and Y.JSON.stringify(..).</p>
17 * <p>The functionality and method signatures follow the ECMAScript 5
18 * specification. In browsers with native JSON support, the native
19 * implementation is used.</p>
21 * <p>The <code>json</code> module is a rollup of <code>json-parse</code> and
22 * <code>json-stringify</code>.</p>
24 * <p>As their names suggest, <code>json-parse</code> adds support for parsing
25 * JSON data (Y.JSON.parse) and <code>json-stringify</code> for serializing
26 * JavaScript data into JSON strings (Y.JSON.stringify). You may choose to
27 * include either of the submodules individually if you don't need the
28 * complementary functionality, or include the rollup for both.</p>
36 * Provides Y.JSON.parse method to accept JSON strings and return native
40 * @submodule json-parse
46 // All internals kept private for security reasons
50 * Alias to native browser implementation of the JSON object if available.
56 var _JSON = Y.config.win.JSON,
57 Native = (Object.prototype.toString.call(_JSON) === '[object JSON]' && _JSON),
60 * Replace certain Unicode characters that JavaScript may handle incorrectly
61 * during eval--either by deleting them or treating them as line
62 * endings--with escape sequences.
63 * IMPORTANT NOTE: This regex will be used to modify the input if a match is
66 * @property _UNICODE_EXCEPTIONS
70 _UNICODE_EXCEPTIONS = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
74 * First step in the safety evaluation. Regex used to replace all escape
75 * sequences (i.e. "\\", etc) with '@' characters (a non-JSON character).
81 _ESCAPES = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g,
84 * Second step in the safety evaluation. Regex used to replace all simple
85 * values with ']' characters.
91 _VALUES = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g,
94 * Third step in the safety evaluation. Regex used to remove all open
95 * square brackets following a colon, comma, or at the beginning of the
102 _BRACKETS = /(?:^|:|,)(?:\s*\[)+/g,
105 * Final step in the safety evaluation. Regex used to test the string left
106 * after all previous replacements for invalid characters.
112 _UNSAFE = /[^\],:{}\s]/,
115 * Replaces specific unicode characters with their appropriate \unnnn
116 * format. Some browsers ignore certain characters during eval.
118 * @method escapeException
119 * @param c {String} Unicode character
120 * @return {String} the \unnnn escapement of the character
123 _escapeException = function (c) {
124 return '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
128 * Traverses nested objects, applying a reviver function to each (key,value)
129 * from the scope if the key:value's containing object. The value returned
130 * from the function will replace the original value in the key:value pair.
131 * If the value returned is undefined, the key will be omitted from the
135 * @param data {MIXED} Any JavaScript data
136 * @param reviver {Function} filter or mutation function
137 * @return {MIXED} The results of the filtered data
140 _revive = function (data, reviver) {
141 var walk = function (o,key) {
142 var k,v,value = o[key];
143 if (value && typeof value === 'object') {
145 if (value.hasOwnProperty(k)) {
147 if (v === undefined) {
155 return reviver.call(o,key,value);
158 return typeof reviver === 'function' ? walk({'':data},'') : data;
162 * Parse a JSON string, returning the native JavaScript representation.
164 * @param s {string} JSON string data
165 * @param reviver {function} (optional) function(k,v) passed each key value
166 * pair of object literals, allowing pruning or altering values
167 * @return {MIXED} the native JavaScript representation of the JSON string
168 * @throws SyntaxError
172 // JavaScript implementation in lieu of native browser support. Based on
173 // the json2.js library from http://json.org
174 _parse = function (s,reviver) {
175 if (typeof s === 'string') {
176 // Replace certain Unicode characters that are otherwise handled
177 // incorrectly by some browser implementations.
178 // NOTE: This modifies the input if such characters are found!
179 s = s.replace(_UNICODE_EXCEPTIONS, _escapeException);
181 // Test for any remaining invalid characters
182 if (!_UNSAFE.test(s.replace(_ESCAPES,'@').
183 replace(_VALUES,']').
184 replace(_BRACKETS,''))) {
186 // Eval the text into a JavaScript data structure, apply any
187 // reviver function, and return
188 return _revive( eval('(' + s + ')'), reviver );
192 throw new SyntaxError('JSON.parse');
195 Y.namespace('JSON').parse = function (s,reviver) {
196 return Native && Y.JSON.useNativeParse ?
197 Native.parse(s,reviver) : _parse(s,reviver);
201 * Leverage native JSON parse if the browser has a native implementation.
202 * In general, this is a good idea. See the Known Issues section in the
203 * JSON user guide for caveats. The default value is true for browsers with
204 * native JSON support.
206 * @property useNativeParse
211 Y.JSON.useNativeParse = !!Native;