File: json/js/parse-shim.js
/**
* <p>The JSON module adds support for serializing JavaScript objects into
* JSON strings and parsing JavaScript objects from strings in JSON format.</p>
*
* <p>The JSON namespace is added to your YUI instance including static methods
* Y.JSON.parse(..) and Y.JSON.stringify(..).</p>
*
* <p>The functionality and method signatures follow the ECMAScript 5
* specification. In browsers with native JSON support, the native
* implementation is used.</p>
*
* <p>The <code>json</code> module is a rollup of <code>json-parse</code> and
* <code>json-stringify</code>.</p>
*
* <p>As their names suggest, <code>json-parse</code> adds support for parsing
* JSON data (Y.JSON.parse) and <code>json-stringify</code> for serializing
* JavaScript data into JSON strings (Y.JSON.stringify). You may choose to
* include either of the submodules individually if you don't need the
* complementary functionality, or include the rollup for both.</p>
*
* @module json
* @main json
* @class JSON
* @static
*/
/**
* Provides Y.JSON.parse method to accept JSON strings and return native
* JavaScript objects.
*
* @module json
* @submodule json-parse
* @for JSON
* @static
*/
/**
* Replace certain Unicode characters that JavaScript may handle incorrectly
* during eval--either by deleting them or treating them as line
* endings--with escape sequences.
* IMPORTANT NOTE: This regex will be used to modify the input if a match is
* found.
*
* @property _UNICODE_EXCEPTIONS
* @type {RegExp}
* @private
*/
var _UNICODE_EXCEPTIONS = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
/**
* First step in the safety evaluation. Regex used to replace all escape
* sequences (i.e. "\\", etc) with '@' characters (a non-JSON character).
*
* @property _ESCAPES
* @type {RegExp}
* @private
*/
_ESCAPES = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g,
/**
* Second step in the safety evaluation. Regex used to replace all simple
* values with ']' characters.
*
* @property _VALUES
* @type {RegExp}
* @private
*/
_VALUES = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g,
/**
* Third step in the safety evaluation. Regex used to remove all open
* square brackets following a colon, comma, or at the beginning of the
* string.
*
* @property _BRACKETS
* @type {RegExp}
* @private
*/
_BRACKETS = /(?:^|:|,)(?:\s*\[)+/g,
/**
* Final step in the safety evaluation. Regex used to test the string left
* after all previous replacements for invalid characters.
*
* @property _UNSAFE
* @type {RegExp}
* @private
*/
_UNSAFE = /[^\],:{}\s]/,
/**
* Replaces specific unicode characters with their appropriate \unnnn
* format. Some browsers ignore certain characters during eval.
*
* @method escapeException
* @param c {String} Unicode character
* @return {String} the \unnnn escapement of the character
* @private
*/
_escapeException = function (c) {
return '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
},
/**
* Traverses nested objects, applying a reviver function to each (key,value)
* from the scope if the key:value's containing object. The value returned
* from the function will replace the original value in the key:value pair.
* If the value returned is undefined, the key will be omitted from the
* returned object.
*
* @method _revive
* @param data {MIXED} Any JavaScript data
* @param reviver {Function} filter or mutation function
* @return {MIXED} The results of the filtered data
* @private
*/
_revive = function (data, reviver) {
var walk = function (o,key) {
var k,v,value = o[key];
if (value && typeof value === 'object') {
for (k in value) {
if (value.hasOwnProperty(k)) {
v = walk(value, k);
if (v === undefined) {
delete value[k];
} else {
value[k] = v;
}
}
}
}
return reviver.call(o,key,value);
};
return typeof reviver === 'function' ? walk({'':data},'') : data;
};
/**
* Parse a JSON string, returning the native JavaScript representation.
*
* @param s {string} JSON string data
* @param reviver {function} (optional) function(k,v) passed each key value
* pair of object literals, allowing pruning or altering values
* @return {MIXED} the native JavaScript representation of the JSON string
* @throws SyntaxError
* @method parse
* @static
*/
// JavaScript implementation in lieu of native browser support. Based on
// the json2.js library from http://json.org
Y.JSON.parse = function (s,reviver) {
if (typeof s !== 'string') {
s += '';
}
// Replace certain Unicode characters that are otherwise handled
// incorrectly by some browser implementations.
// NOTE: This modifies the input if such characters are found!
s = s.replace(_UNICODE_EXCEPTIONS, _escapeException);
// Test for any remaining invalid characters
if (!_UNSAFE.test(s.replace(_ESCAPES,'@').
replace(_VALUES,']').
replace(_BRACKETS,''))) {
// Eval the text into a JavaScript data structure, apply any
// reviver function, and return
return _revive(eval('(' + s + ')'), reviver);
}
throw new SyntaxError('JSON.parse');
};
// Property available for testing if the implementation being used
// is native or a shim
Y.JSON.parse.isShim = true;