/**
* The JSON Utility provides methods to serialize JavaScript objects into
* JSON strings and parse JavaScript objects from strings containing JSON data.
* Three modules are available for inclusion:
* <ol>
* <li>1. <code>json-parse</code> for parsing JSON strings into native JavaScript data</li>
* <li>2. <code>json-stringify</code> for stringification of JavaScript objects into JSON strings</li>
* <li>3. <code>json</code> for both parsing and stringification</li>
* </ol>
*
* Both <code>json-parse</code> and <code>json-stringify</code> create functions in a static JSON class under your YUI instance (e.g. Y.JSON.parse(..)).
* @module json
* @class JSON
* @static
*/
/**
* Provides Y.JSON.parse method to take JSON strings and return native
* JavaScript objects.
* @module json
* @submodule json-parse
* @for JSON
* @static
*/
Y.JSON = Y.JSON || {};
// All internals kept private for security reasons
/**
* Replace certain Unicode characters that JavaScript may handle incorrectly
* during eval--either by deleting them or treating them as line endings--with
* escae 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 validation. 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 validation. 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 validation. 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*\[)+/g,
/**
* Final step in the validation. Regex used to test the string left after
* all previous replacements for invalid characters.
* @property _INVALID
* @type {RegExp}
* @private
*/
_INVALID = /^[\],:{}\s]*$/,
has = Object.prototype.hasOwnProperty,
/**
* 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 (has.call(value,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
* @public
*/
Y.JSON.parse = function (s,reviver) {
// Ensure valid JSON
if (typeof s === 'string') {
// 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, function (c) {
return '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
});
// Test for validity
if (_INVALID.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 );
}
}
// The text is not JSON parsable
throw new SyntaxError('parseJSON');
};