/**
* Provides methods to parse JSON strings and convert objects to JSON strings.
*
* @module json
* @class JSON
* @namespace YAHOO.lang
* @static
*/
(function () {
var l = YAHOO.lang,
isFunction = l.isFunction,
isObject = l.isObject,
isArray = l.isArray,
_toStr = Object.prototype.toString,
// 'this' is the global object. window in browser env. Keep
// the code env agnostic. Caja requies window, unfortunately.
Native = (YAHOO.env.ua.caja ? window : this).JSON,
/* Variables used by parse */
/**
* 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}
* @static
* @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}
* @static
* @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}
* @static
* @private
*/
_BRACKETS = /(?:^|:|,)(?:\s*\[)+/g,
/**
* Final step in the safety evaluation. Regex used to test the string left
* after all previous replacements for invalid characters.
*
* @property _UNSAFE
* @type {RegExp}
* @static
* @private
*/
_UNSAFE = /^[\],:{}\s]*$/,
/* Variables used by stringify */
/**
* Regex used to replace special characters in strings for JSON
* stringification.
*
* @property _SPECIAL_CHARS
* @type {RegExp}
* @static
* @private
*/
_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.
*
* @property _CHARS
* @type {Object}
* @static
* @private
*/
_CHARS = {
'\b': '\\b',
'\t': '\\t',
'\n': '\\n',
'\f': '\\f',
'\r': '\\r',
'"' : '\\"',
'\\': '\\\\'
},
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 = '"';
// Only accept JSON objects that report a [[Class]] of JSON
Native = _toStr.call(Native) === '[object JSON]' && Native;
// 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];
}
/* functions used by parse */
/**
* Traverses nested objects, applying a filter or reviver function to
* each value. 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/mutated data structure
* @private
*/
function _revive(data, reviver) {
var walk = function (o,key) {
var k,v,value = o[key];
if (value && typeof value === 'object') {
for (k in value) {
if (l.hasOwnProperty(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;
}
/**
* Replace certain Unicode characters that may be handled incorrectly by
* some browser implementations.
*
* @method _prepare
* @param s {String} parse input
* @return {String} sanitized JSON string ready to be validated/parsed
* @private
*/
function _prepare(s) {
return s.replace(_UNICODE_EXCEPTIONS, _char);
}
function _isSafe(str) {
return l.isString(str) &&
_UNSAFE.test(str.replace(_ESCAPES,'@').
replace(_VALUES,']').
replace(_BRACKETS,''));
}
function _parse(s,reviver) {
// sanitize
s = _prepare(s);
// Ensure valid JSON
if (_isSafe(s)) {
// Eval the text into a JavaScript data structure, apply the
// reviver function if provided, and return
return _revive( eval('(' + s + ')'), reviver );
}
// The text is not valid JSON
throw new SyntaxError('JSON.parse');
}
/* functions used by stringify */
// 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
}
// 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 = YAHOO.lang.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},'');
}
/* Public API */
YAHOO.lang.JSON = {
/**
* 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
*/
useNativeParse : !!Native,
/**
* 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 useNativeStringify
* @type Boolean
* @default true
* @static
*/
useNativeStringify : !!Native,
/**
* Four step determination whether a string is safe to eval. In three steps,
* escape sequences, safe values, and properly placed open square brackets
* are replaced with placeholders or removed. Then in the final step, the
* result of all these replacements is checked for invalid characters.
*
* @method isSafe
* @param str {String} JSON string to be tested
* @return {boolean} is the string safe for eval?
* @static
*/
isSafe : function (s) {
return _isSafe(_prepare(s));
},
/**
* <p>Parse a JSON string, returning the native JavaScript
* representation.</p>
*
* <p>When lang.JSON.useNativeParse is true, this will defer to the native
* JSON.parse if the browser has a native implementation. Otherwise, a
* JavaScript implementation based on http://www.json.org/json2.js
* is used.</p>
*
* @method parse
* @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
* @static
*/
parse : function (s,reviver) {
return Native && YAHOO.lang.JSON.useNativeParse ?
Native.parse(s,reviver) : _parse(s,reviver);
},
/**
* <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>
*
* <p>When lang.JSON.useNativeStringify is true, this will defer to the
* native JSON.stringify if the browser has a native implementation.
* Otherwise, a JavaScript implementation is used.</p>
*
* @method stringify
* @param o {MIXED} any arbitrary object to convert to JSON string
* @param w {Array|Function} (optional) whitelist of acceptable object keys
* to include OR a function(value,key) to alter values
* before serialization
* @param space {Number|String} (optional) indentation character(s) or
* depthy of spaces to format the output
* @return {string} JSON string representation of the input
* @throws Error
* @static
*/
stringify : function (o,w,space) {
return Native && YAHOO.lang.JSON.useNativeStringify ?
Native.stringify(o,w,space) : _stringify(o,w,space);
},
/**
* Serializes a Date instance as a UTC date string. Used internally by
* the JavaScript implementation of stringify. If you need a different
* Date serialization format, override this method. If you change this,
* you should also set useNativeStringify to false, since native JSON
* implementations serialize Dates per the ECMAScript 5 spec. You've been
* warned.
*
* @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';
},
/**
* Reconstitute Date instances from the default JSON UTC serialization.
* Reference this from a reviver function to rebuild Dates during the
* parse operation.
*
* @method stringToDate
* @param str {String} String serialization of a Date
* @return {Date}
*/
stringToDate : function (str) {
var m = str.match(/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(?:\.(\d{3}))?Z$/);
if (m) {
var d = new Date();
d.setUTCFullYear(m[1], m[2]-1, m[3]);
d.setUTCHours(m[4], m[5], m[6], (m[7] || 0));
return d;
}
return str;
}
};
/**
* <p>Four step determination whether a string is safe to eval. In three steps,
* escape sequences, safe values, and properly placed open square brackets
* are replaced with placeholders or removed. Then in the final step, the
* result of all these replacements is checked for invalid characters.</p>
*
* <p>This is an alias for isSafe.</p>
*
* @method isValid
* @param str {String} JSON string to be tested
* @return {boolean} is the string safe for eval?
* @static
* @deprecated use isSafe
*/
YAHOO.lang.JSON.isValid = YAHOO.lang.JSON.isSafe;
})();