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Copyright 2012 Yahoo! Inc. All rights reserved.
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Licensed under the BSD License.
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http://yuilibrary.com/license/
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YUI.add('json-parse', function(Y) {
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* <p>The JSON module adds support for serializing JavaScript objects into
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* JSON strings and parsing JavaScript objects from strings in JSON format.</p>
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* <p>The JSON namespace is added to your YUI instance including static methods
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* Y.JSON.parse(..) and Y.JSON.stringify(..).</p>
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* <p>The functionality and method signatures follow the ECMAScript 5
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* specification. In browsers with native JSON support, the native
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* implementation is used.</p>
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* <p>The <code>json</code> module is a rollup of <code>json-parse</code> and
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* <code>json-stringify</code>.</p>
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* <p>As their names suggest, <code>json-parse</code> adds support for parsing
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* JSON data (Y.JSON.parse) and <code>json-stringify</code> for serializing
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* JavaScript data into JSON strings (Y.JSON.stringify). You may choose to
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* include either of the submodules individually if you don't need the
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* complementary functionality, or include the rollup for both.</p>
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* Provides Y.JSON.parse method to accept JSON strings and return native
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* @submodule json-parse
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// All internals kept private for security reasons
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function fromGlobal(ref) {
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return (Y.config.win || this || {})[ref];
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* Alias to native browser implementation of the JSON object if available.
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var _JSON = fromGlobal('JSON'),
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Native = (Object.prototype.toString.call(_JSON) === '[object JSON]' && _JSON),
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* Replace certain Unicode characters that JavaScript may handle incorrectly
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* during eval--either by deleting them or treating them as line
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* endings--with escape sequences.
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* IMPORTANT NOTE: This regex will be used to modify the input if a match is
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* @property _UNICODE_EXCEPTIONS
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_UNICODE_EXCEPTIONS = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
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* First step in the safety evaluation. Regex used to replace all escape
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* sequences (i.e. "\\", etc) with '@' characters (a non-JSON character).
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_ESCAPES = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g,
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* Second step in the safety evaluation. Regex used to replace all simple
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* values with ']' characters.
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_VALUES = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g,
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* Third step in the safety evaluation. Regex used to remove all open
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* square brackets following a colon, comma, or at the beginning of the
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* @property _BRACKETS
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_BRACKETS = /(?:^|:|,)(?:\s*\[)+/g,
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* Final step in the safety evaluation. Regex used to test the string left
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* after all previous replacements for invalid characters.
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_UNSAFE = /[^\],:{}\s]/,
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* Replaces specific unicode characters with their appropriate \unnnn
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* format. Some browsers ignore certain characters during eval.
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* @method escapeException
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* @param c {String} Unicode character
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* @return {String} the \unnnn escapement of the character
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_escapeException = function (c) {
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return '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
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* Traverses nested objects, applying a reviver function to each (key,value)
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* from the scope if the key:value's containing object. The value returned
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* from the function will replace the original value in the key:value pair.
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* If the value returned is undefined, the key will be omitted from the
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* @param data {MIXED} Any JavaScript data
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* @param reviver {Function} filter or mutation function
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* @return {MIXED} The results of the filtered data
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_revive = function (data, reviver) {
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var walk = function (o,key) {
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var k,v,value = o[key];
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if (value && typeof value === 'object') {
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if (value.hasOwnProperty(k)) {
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if (v === undefined) {
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return reviver.call(o,key,value);
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return typeof reviver === 'function' ? walk({'':data},'') : data;
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* Parse a JSON string, returning the native JavaScript representation.
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* @param s {string} JSON string data
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* @param reviver {function} (optional) function(k,v) passed each key value
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* pair of object literals, allowing pruning or altering values
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* @return {MIXED} the native JavaScript representation of the JSON string
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* @throws SyntaxError
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// JavaScript implementation in lieu of native browser support. Based on
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// the json2.js library from http://json.org
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_parse = function (s,reviver) {
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// Replace certain Unicode characters that are otherwise handled
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// incorrectly by some browser implementations.
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// NOTE: This modifies the input if such characters are found!
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s = s.replace(_UNICODE_EXCEPTIONS, _escapeException);
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// Test for any remaining invalid characters
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if (!_UNSAFE.test(s.replace(_ESCAPES,'@').
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replace(_VALUES,']').
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replace(_BRACKETS,''))) {
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// Eval the text into a JavaScript data structure, apply any
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// reviver function, and return
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return _revive( eval('(' + s + ')'), reviver );
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throw new SyntaxError('JSON.parse');
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Y.namespace('JSON').parse = function (s,reviver) {
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if (typeof s !== 'string') {
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return Native && Y.JSON.useNativeParse ?
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Native.parse(s,reviver) : _parse(s,reviver);
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function workingNative( k, v ) {
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return k === "ok" ? true : v;
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// Double check basic functionality. This is mainly to catch early broken
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// implementations of the JSON API in Firefox 3.1 beta1 and beta2
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useNative = ( Native.parse( '{"ok":false}', workingNative ) ).ok;
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* Leverage native JSON parse if the browser has a native implementation.
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* In general, this is a good idea. See the Known Issues section in the
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* JSON user guide for caveats. The default value is true for browsers with
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* native JSON support.
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* @property useNativeParse
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Y.JSON.useNativeParse = useNative;
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}, '3.5.1' ,{requires:['yui-base']});