/**
+ * Provides Y.JSON.stringify method for converting objects to JSON strings.
+ *
+ * @module json
+ * @submodule json-stringify
+ * @for JSON
+ * @static
+ */
+var _JSON = Y.config.win.JSON,
+ Lang = Y.Lang,
+ isFunction= Lang.isFunction,
+ isObject = Lang.isObject,
+ isArray = Lang.isArray,
+ _toStr = Object.prototype.toString,
+ Native = (_toStr.call(_JSON) === '[object JSON]' && _JSON),
+ UNDEFINED = 'undefined',
+ OBJECT = 'object',
+ NULL = 'null',
+ STRING = 'string',
+ NUMBER = 'number',
+ BOOLEAN = 'boolean',
+ DATE = 'date',
+ _allowable= {
+ 'undefined' : UNDEFINED,
+ 'string' : STRING,
+ '[object String]' : STRING,
+ 'number' : NUMBER,
+ '[object Number]' : NUMBER,
+ 'boolean' : BOOLEAN,
+ '[object Boolean]' : BOOLEAN,
+ '[object Date]' : DATE,
+ '[object RegExp]' : OBJECT
+ },
+ EMPTY = '',
+ OPEN_O = '{',
+ CLOSE_O = '}',
+ OPEN_A = '[',
+ CLOSE_A = ']',
+ COMMA = ',',
+ COMMA_CR = ",\n",
+ CR = "\n",
+ COLON = ':',
+ COLON_SP = ': ',
+ QUOTE = '"',
+ // Regex used to capture characters that need escaping before enclosing
+ // their containing string in quotes.
+ _SPECIAL_CHARS = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
+ // Character substitution map for common escapes and special characters.
+ _CHARS = {
+ '\b': '\\b',
+ '\t': '\\t',
+ '\n': '\\n',
+ '\f': '\\f',
+ '\r': '\\r',
+ '"' : '\\"',
+ '\\': '\\\\'
+ };
+
+
+// Utility function used to determine how to serialize a variable.
+function _type(o) {
+ var t = typeof o;
+ return _allowable[t] || // number, string, boolean, undefined
+ _allowable[_toStr.call(o)] || // Number, String, Boolean, Date
+ (t === OBJECT ?
+ (o ? OBJECT : NULL) : // object, array, null, misc natives
+ UNDEFINED); // function, unknown
+}
+
+// Escapes a special character to a safe Unicode representation
+function _char(c) {
+ if (!_CHARS[c]) {
+ _CHARS[c] = '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
+ }
+ return _CHARS[c];
+}
+
+// Enclose escaped strings in quotes
+function _string(s) {
+ return QUOTE + s.replace(_SPECIAL_CHARS, _char) + QUOTE;
+}
+
+// Adds the provided space to the beginning of every line in the input string
+function _indent(s,space) {
+ return s.replace(/^/gm, space);
+}
+
+// JavaScript implementation of stringify (see API declaration of stringify)
+function _stringify(o,w,space) {
+ if (o === undefined) {
+ return undefined;
+ }
+
+ var replacer = isFunction(w) ? w : null,
+ format = _toStr.call(space).match(/String|Number/) || [],
+ _date = Y.JSON.dateToString,
+ stack = [],
+ tmp,i,len;
+
+ if (replacer || !isArray(w)) {
+ w = undefined;
+ }
+
+ // Ensure whitelist keys are unique (bug 2110391)
+ if (w) {
+ tmp = {};
+ for (i = 0, len = w.length; i < len; ++i) {
+ tmp[w[i]] = true;
+ }
+ w = tmp;
+ }
+
+ // Per the spec, strings are truncated to 10 characters and numbers
+ // are converted to that number of spaces (max 10)
+ space = format[0] === 'Number' ?
+ new Array(Math.min(Math.max(0,space),10)+1).join(" ") :
+ (space || EMPTY).slice(0,10);
+
+ function _serialize(h,key) {
+ var value = h[key],
+ t = _type(value),
+ a = [],
+ colon = space ? COLON_SP : COLON,
+ arr, i, keys, k, v;
+
+ // Per the ECMA 5 spec, toJSON is applied before the replacer is
+ // called. Also per the spec, Date.prototype.toJSON has been added, so
+ // Date instances should be serialized prior to exposure to the
+ // replacer. I disagree with this decision, but the spec is the spec.
+ if (isObject(value) && isFunction(value.toJSON)) {
+ value = value.toJSON(key);
+ } else if (t === DATE) {
+ value = _date(value);
+ }
+
+ if (isFunction(replacer)) {
+ value = replacer.call(h,key,value);
+ }
+
+ if (value !== h[key]) {
+ t = _type(value);
+ }
+
+ switch (t) {
+ case DATE : // intentional fallthrough. Pre-replacer Dates are
+ // serialized in the toJSON stage. Dates here would
+ // have been produced by the replacer.
+ case OBJECT : break;
+ case STRING : return _string(value);
+ case NUMBER : return isFinite(value) ? value+EMPTY : NULL;
+ case BOOLEAN : return value+EMPTY;
+ case NULL : return NULL;
+ default : return undefined;
+ }
+
+ // Check for cyclical references in nested objects
+ for (i = stack.length - 1; i >= 0; --i) {
+ if (stack[i] === value) {
+ throw new Error("JSON.stringify. Cyclical reference");
+ }
+ }
+
+ arr = isArray(value);
+
+ // Add the object to the processing stack
+ stack.push(value);
+
+ if (arr) { // Array
+ for (i = value.length - 1; i >= 0; --i) {
+ a[i] = _serialize(value, i) || NULL;
+ }
+ } else { // Object
+ // If whitelist provided, take only those keys
+ keys = w || value;
+ i = 0;
+
+ for (k in keys) {
+ if (keys.hasOwnProperty(k)) {
+ v = _serialize(value, k);
+ if (v) {
+ a[i++] = _string(k) + colon + v;
+ }
+ }
+ }
+ }
+
+ // remove the array from the stack
+ stack.pop();
+
+ if (space && a.length) {
+ return arr ?
+ OPEN_A + CR + _indent(a.join(COMMA_CR), space) + CR + CLOSE_A :
+ OPEN_O + CR + _indent(a.join(COMMA_CR), space) + CR + CLOSE_O;
+ } else {
+ return arr ?
+ OPEN_A + a.join(COMMA) + CLOSE_A :
+ OPEN_O + a.join(COMMA) + CLOSE_O;
+ }
+ }
+
+ // process the input
+ return _serialize({'':o},'');
+}
+
+Y.mix(Y.namespace('JSON'),{
+ /**
+ * Leverage native JSON stringify 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 JSON.useNativeStringify
+ * @type Boolean
+ * @default true
+ * @static
+ */
+ useNativeStringify : !!Native,
+
+ /**
+ * Serializes a Date instance as a UTC date string. Used internally by
+ * stringify. Override this method if you need Dates serialized in a
+ * different format.
+ *
+ * @method dateToString
+ * @param d {Date} The Date to serialize
+ * @return {String} stringified Date in UTC format YYYY-MM-DDTHH:mm:SSZ
+ * @static
+ */
+ dateToString : function (d) {
+ function _zeroPad(v) {
+ return v < 10 ? '0' + v : v;
+ }
+
+ return d.getUTCFullYear() + '-' +
+ _zeroPad(d.getUTCMonth() + 1) + '-' +
+ _zeroPad(d.getUTCDate()) + 'T' +
+ _zeroPad(d.getUTCHours()) + COLON +
+ _zeroPad(d.getUTCMinutes()) + COLON +
+ _zeroPad(d.getUTCSeconds()) + 'Z';
+ },
+
+ /**
+ * <p>Converts an arbitrary value to a JSON string representation.</p>
+ *
+ * <p>Objects with cyclical references will trigger an exception.</p>
+ *
+ * <p>If a whitelist is provided, only matching object keys will be
+ * included. Alternately, a replacer function may be passed as the
+ * second parameter. This function is executed on every value in the
+ * input, and its return value will be used in place of the original value.
+ * This is useful to serialize specialized objects or class instances.</p>
+ *
+ * <p>If a positive integer or non-empty string is passed as the third
+ * parameter, the output will be formatted with carriage returns and
+ * indentation for readability. If a String is passed (such as "\t") it
+ * will be used once for each indentation level. If a number is passed,
+ * that number of spaces will be used.</p>
+ *
+ * @method stringify
+ * @param o {MIXED} any arbitrary value to convert to JSON string
+ * @param w {Array|Function} (optional) whitelist of acceptable object
+ * keys to include, or a replacer function to modify the
+ * raw value before serialization
+ * @param ind {Number|String} (optional) indentation character or depth of
+ * spaces to format the output.
+ * @return {string} JSON string representation of the input
+ * @static
+ */
+ stringify : function (o,w,ind) {
+ return Native && Y.JSON.useNativeStringify ?
+ Native.stringify(o,w,ind) : _stringify(o,w,ind);
+ }
+});
+