397 lines
13 KiB
JavaScript
397 lines
13 KiB
JavaScript
/*
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Copyright (c) 2008, Yahoo! Inc. All rights reserved.
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Code licensed under the BSD License:
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http://developer.yahoo.net/yui/license.txt
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version: 2.6.0
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*/
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/**
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* Provides methods to parse JSON strings and convert objects to JSON strings.
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* @module json
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* @class JSON
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* @static
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*/
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YAHOO.lang.JSON = (function () {
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var l = YAHOO.lang,
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/**
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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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* found.
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* @property _UNICODE_EXCEPTIONS
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* @type {RegExp}
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* @private
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*/
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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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/**
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* First step in the validation. Regex used to replace all escape
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* sequences (i.e. "\\", etc) with '@' characters (a non-JSON character).
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* @property _ESCAPES
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* @type {RegExp}
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* @static
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* @private
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*/
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_ESCAPES = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g,
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/**
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* Second step in the validation. Regex used to replace all simple
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* values with ']' characters.
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* @property _VALUES
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* @type {RegExp}
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* @static
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* @private
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*/
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_VALUES = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g,
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/**
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* Third step in the validation. Regex used to remove all open square
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* brackets following a colon, comma, or at the beginning of the string.
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* @property _BRACKETS
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* @type {RegExp}
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* @static
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* @private
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*/
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_BRACKETS = /(?:^|:|,)(?:\s*\[)+/g,
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/**
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* Final step in the validation. Regex used to test the string left after
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* all previous replacements for invalid characters.
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* @property _INVALID
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* @type {RegExp}
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* @static
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* @private
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*/
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_INVALID = /^[\],:{}\s]*$/,
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/**
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* Regex used to replace special characters in strings for JSON
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* stringification.
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* @property _SPECIAL_CHARS
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* @type {RegExp}
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* @static
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* @private
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*/
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_SPECIAL_CHARS = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
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/**
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* Character substitution map for common escapes and special characters.
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* @property _CHARS
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* @type {Object}
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* @static
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* @private
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*/
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_CHARS = {
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'\b': '\\b',
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'\t': '\\t',
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'\n': '\\n',
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'\f': '\\f',
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'\r': '\\r',
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'"' : '\\"',
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'\\': '\\\\'
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};
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/**
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* Traverses nested objects, applying a filter or reviver function to
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* each value. The value returned from the function will replace the
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* original value in the key:value pair. If the value returned is
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* undefined, the key will be omitted from the returned object.
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* @method _revive
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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/mutated data structure
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* @private
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*/
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function _revive(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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for (k in value) {
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if (l.hasOwnProperty(value,k)) {
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v = walk(value, k);
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if (v === undefined) {
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delete value[k];
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} else {
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value[k] = v;
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}
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}
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}
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}
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return reviver.call(o,key,value);
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};
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return typeof reviver === 'function' ? walk({'':data},'') : data;
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}
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/**
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* Escapes a special character to a safe Unicode representation
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* @method _char
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* @param c {String} single character to escape
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* @return {String} safe Unicode escape
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*/
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function _char(c) {
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if (!_CHARS[c]) {
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_CHARS[c] = '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
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}
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return _CHARS[c];
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}
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/**
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* Replace certain Unicode characters that may be handled incorrectly by
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* some browser implementations.
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* @method _prepare
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* @param s {String} parse input
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* @return {String} sanitized JSON string ready to be validated/parsed
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* @private
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*/
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function _prepare(s) {
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return s.replace(_UNICODE_EXCEPTIONS, _char);
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}
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/**
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* Four step determination whether a string is valid JSON. In three steps,
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* escape sequences, safe values, and properly placed open square brackets
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* are replaced with placeholders or removed. Then in the final step, the
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* result of all these replacements is checked for invalid characters.
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* @method _isValid
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* @param str {String} JSON string to be tested
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* @return {boolean} is the string safe for eval?
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* @static
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*/
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function _isValid(str) {
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return l.isString(str) &&
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_INVALID.test(str.
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replace(_ESCAPES,'@').
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replace(_VALUES,']').
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replace(_BRACKETS,''));
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}
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/**
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* Enclose escaped strings in quotes
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* @method _string
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* @param s {String} string to wrap
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* @return {String} '"'+s+'"' after s has had special characters escaped
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* @private
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*/
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function _string(s) {
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return '"' + s.replace(_SPECIAL_CHARS, _char) + '"';
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}
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/**
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* Worker function used by public stringify.
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* @method _stringify
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* @param h {Object} object holding the key
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* @param key {String} String key in object h to serialize
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* @param depth {Number} depth to serialize
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* @param w {Array|Function} array of whitelisted keys OR replacer function
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* @param pstack {Array} used to protect against recursion
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* @return {String} serialized version of o
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*/
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function _stringify(h,key,d,w,pstack) {
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var o = typeof w === 'function' ? w.call(h,key,h[key]) : h[key],
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i,len,j, // array iteration
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k,v, // object iteration
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isArray, // forking in typeof 'object'
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a; // composition array for performance over string concat
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if (o instanceof Date) {
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o = l.JSON.dateToString(o);
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} else if (o instanceof String || o instanceof Boolean || o instanceof Number) {
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o = o.valueOf();
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}
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switch (typeof o) {
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case 'string' : return _string(o);
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case 'number' : return isFinite(o) ? String(o) : 'null';
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case 'boolean': return String(o);
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case 'object' :
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// null
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if (o === null) {
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return 'null';
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}
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// Check for cyclical references
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for (i = pstack.length - 1; i >= 0; --i) {
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if (pstack[i] === o) {
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return 'null';
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}
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}
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// Add the object to the processing stack
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pstack[pstack.length] = o;
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a = [];
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isArray = l.isArray(o);
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// Only recurse if we're above depth config
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if (d > 0) {
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// Array
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if (isArray) {
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for (i = o.length - 1; i >= 0; --i) {
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a[i] = _stringify(o,i,d-1,w,pstack) || 'null';
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}
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// Object
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} else {
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j = 0;
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// Use whitelist keys if provided as an array
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if (l.isArray(w)) {
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for (i = 0, len = w.length; i < len; ++i) {
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k = w[i];
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v = _stringify(o,k,d-1,w,pstack);
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if (v) {
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a[j++] = _string(k) + ':' + v;
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}
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}
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} else {
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for (k in o) {
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if (typeof k === 'string' && l.hasOwnProperty(o,k)) {
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v = _stringify(o,k,d-1,w,pstack);
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if (v) {
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a[j++] = _string(k) + ':' + v;
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}
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}
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}
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}
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// sort object keys for easier readability
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a.sort();
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}
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}
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// remove the object from the stack
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pstack.pop();
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return isArray ? '['+a.join(',')+']' : '{'+a.join(',')+'}';
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}
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return undefined; // invalid input
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}
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// Return the public API
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return {
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/**
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* Four step determination whether a string is valid JSON. In three steps,
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* escape sequences, safe values, and properly placed open square brackets
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* are replaced with placeholders or removed. Then in the final step, the
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* result of all these replacements is checked for invalid characters.
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* @method isValid
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* @param str {String} JSON string to be tested
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* @return {boolean} is the string safe for eval?
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* @static
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*/
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isValid : function (s) {
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return _isValid(_prepare(s));
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},
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/**
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* Parse a JSON string, returning the native JavaScript representation.
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* Only minor modifications from http://www.json.org/json2.js.
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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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* @method parse
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* @static
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*/
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parse : function (s,reviver) {
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// sanitize
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s = _prepare(s);
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// Ensure valid JSON
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if (_isValid(s)) {
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// Eval the text into a JavaScript data structure, apply the
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// reviver function if provided, and return
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return _revive( eval('(' + s + ')'), reviver );
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}
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// The text is not valid JSON
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throw new SyntaxError('parseJSON');
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},
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/**
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* Converts an arbitrary value to a JSON string representation.
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* Cyclical object or array references are replaced with null.
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* If a whitelist is provided, only matching object keys will be included.
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* If a depth limit is provided, objects and arrays at that depth will
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* be stringified as empty.
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* @method stringify
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* @param o {MIXED} any arbitrary object to convert to JSON string
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* @param w {Array|Function} (optional) whitelist of acceptable object keys to include OR a function(value,key) to alter values before serialization
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* @param d {number} (optional) depth limit to recurse objects/arrays (practical minimum 1)
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* @return {string} JSON string representation of the input
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* @static
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*/
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stringify : function (o,w,d) {
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if (o !== undefined) {
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// Ensure whitelist keys are unique (bug 2110391)
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if (l.isArray(w)) {
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w = (function (a) {
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var uniq=[],map={},v,i,j,len;
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for (i=0,j=0,len=a.length; i<len; ++i) {
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v = a[i];
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if (typeof v === 'string' && map[v] === undefined) {
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uniq[(map[v] = j++)] = v;
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}
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}
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return uniq;
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})(w);
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}
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// Default depth to POSITIVE_INFINITY
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d = d >= 0 ? d : 1/0;
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// process the input
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return _stringify({'':o},'',d,w,[]);
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}
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return undefined;
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},
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/**
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* Serializes a Date instance as a UTC date string. Used internally by
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* stringify. Override this method if you need Dates serialized in a
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* different format.
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* @method dateToString
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* @param d {Date} The Date to serialize
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* @return {String} stringified Date in UTC format YYYY-MM-DDTHH:mm:SSZ
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* @static
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*/
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dateToString : function (d) {
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function _zeroPad(v) {
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return v < 10 ? '0' + v : v;
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}
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return d.getUTCFullYear() + '-' +
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_zeroPad(d.getUTCMonth() + 1) + '-' +
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_zeroPad(d.getUTCDate()) + 'T' +
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_zeroPad(d.getUTCHours()) + ':' +
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_zeroPad(d.getUTCMinutes()) + ':' +
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_zeroPad(d.getUTCSeconds()) + 'Z';
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},
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/**
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* Reconstitute Date instances from the default JSON UTC serialization.
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* Reference this from a reviver function to rebuild Dates during the
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* parse operation.
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* @method stringToDate
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* @param str {String} String serialization of a Date
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* @return {Date}
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*/
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stringToDate : function (str) {
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if (/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})Z$/.test(str)) {
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var d = new Date();
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d.setUTCFullYear(RegExp.$1, (RegExp.$2|0)-1, RegExp.$3);
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d.setUTCHours(RegExp.$4, RegExp.$5, RegExp.$6);
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return d;
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}
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return str;
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}
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};
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})();
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YAHOO.register("json", YAHOO.lang.JSON, {version: "2.6.0", build: "1321"});
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