/**
+ * <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
+ * @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
+ */
+
+
+// All internals kept private for security reasons
+
+
+ /**
+ * Alias to native browser implementation of the JSON object if available.
+ *
+ * @property Native
+ * @type {Object}
+ * @private
+ */
+var _JSON = Y.config.win.JSON,
+ Native = (Object.prototype.toString.call(_JSON) === '[object JSON]' && _JSON),
+
+ /**
+ * 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
+ */
+ _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
+ _parse = function (s,reviver) {
+ 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, _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');
+ };
+
+Y.namespace('JSON').parse = function (s,reviver) {
+ return Native && Y.JSON.useNativeParse ?
+ Native.parse(s,reviver) : _parse(s,reviver);
+};
+
+/**
+ * Leverage native JSON parse if the browser has a native implementation.
+ * In general, this is a good idea. See the Known Issues section in the
+ * JSON user guide for caveats. The default value is true for browsers with
+ * native JSON support.
+ *
+ * @property useNativeParse
+ * @type Boolean
+ * @default true
+ * @static
+ */
+Y.JSON.useNativeParse = !!Native;
+