/**
* Provides methods to parse JSON strings and convert objects to JSON strings.
* @module json
* @class JSON
* @static
*/
YAHOO.lang.JSON = (function () {
var l = YAHOO.lang,
/**
* 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 validation. 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 validation. 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 validation. 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*\[)+/g,
/**
* Final step in the validation. Regex used to test the string left after
* all previous replacements for invalid characters.
* @property _INVALID
* @type {RegExp}
* @static
* @private
*/
_INVALID = /^[\],:{}\s]*$/,
/**
* 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',
'"' : '\\"',
'\\': '\\\\'
};
/**
* 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;
}
/**
* Escapes a special character to a safe Unicode representation
* @method _char
* @param c {String} single character to escape
* @return {String} safe Unicode escape
*/
function _char(c) {
if (!_CHARS[c]) {
_CHARS[c] = '\\u'+('0000'+(+(c.charCodeAt(0))).toString(16)).slice(-4);
}
return _CHARS[c];
}
/**
* 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);
}
/**
* Four step determination whether a string is valid JSON. 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 _isValid
* @param str {String} JSON string to be tested
* @return {boolean} is the string safe for eval?
* @static
*/
function _isValid(str) {
return l.isString(str) &&
_INVALID.test(str.
replace(_ESCAPES,'@').
replace(_VALUES,']').
replace(_BRACKETS,''));
}
/**
* Enclose escaped strings in quotes
* @method _string
* @param s {String} string to wrap
* @return {String} '"'+s+'"' after s has had special characters escaped
* @private
*/
function _string(s) {
return '"' + s.replace(_SPECIAL_CHARS, _char) + '"';
}
/**
* Worker function used by public stringify.
* @method _stringify
* @param h {Object} object holding the key
* @param key {String} String key in object h to serialize
* @param depth {Number} depth to serialize
* @param w {Array|Function} array of whitelisted keys OR replacer function
* @param pstack {Array} used to protect against recursion
* @return {String} serialized version of o
*/
function _stringify(h,key,d,w,pstack) {
var o = typeof w === 'function' ? w.call(h,key,h[key]) : h[key],
i,len,j, // array iteration
k,v, // object iteration
isArray, // forking in typeof 'object'
a; // composition array for performance over string concat
if (o instanceof Date) {
o = l.JSON.dateToString(o);
} else if (o instanceof String || o instanceof Boolean || o instanceof Number) {
o = o.valueOf();
}
switch (typeof o) {
case 'string' : return _string(o);
case 'number' : return isFinite(o) ? String(o) : 'null';
case 'boolean': return String(o);
case 'object' :
// null
if (o === null) {
return 'null';
}
// Check for cyclical references
for (i = pstack.length - 1; i >= 0; --i) {
if (pstack[i] === o) {
return 'null';
}
}
// Add the object to the processing stack
pstack[pstack.length] = o;
a = [];
isArray = l.isArray(o);
// Only recurse if we're above depth config
if (d > 0) {
// Array
if (isArray) {
for (i = o.length - 1; i >= 0; --i) {
a[i] = _stringify(o,i,d-1,w,pstack) || 'null';
}
// Object
} else {
j = 0;
// Use whitelist keys if provided as an array
if (l.isArray(w)) {
for (i = 0, len = w.length; i < len; ++i) {
k = w[i];
v = _stringify(o,k,d-1,w,pstack);
if (v) {
a[j++] = _string(k) + ':' + v;
}
}
} else {
for (k in o) {
if (typeof k === 'string' && l.hasOwnProperty(o,k)) {
v = _stringify(o,k,d-1,w,pstack);
if (v) {
a[j++] = _string(k) + ':' + v;
}
}
}
}
// sort object keys for easier readability
a.sort();
}
}
// remove the object from the stack
pstack.pop();
return isArray ? '['+a.join(',')+']' : '{'+a.join(',')+'}';
}
return undefined; // invalid input
}
// Return the public API
return {
/**
* Four step determination whether a string is valid JSON. 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 isValid
* @param str {String} JSON string to be tested
* @return {boolean} is the string safe for eval?
* @static
*/
isValid : function (s) {
return _isValid(_prepare(s));
},
/**
* Parse a JSON string, returning the native JavaScript representation.
* Only minor modifications from http://www.json.org/json2.js.
* @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
*/
parse : function (s,reviver) {
// sanitize
s = _prepare(s);
// Ensure valid JSON
if (_isValid(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('parseJSON');
},
/**
* Converts an arbitrary value to a JSON string representation.
* Cyclical object or array references are replaced with null.
* If a whitelist is provided, only matching object keys will be included.
* If a depth limit is provided, objects and arrays at that depth will
* be stringified as empty.
* @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 d {number} (optional) depth limit to recurse objects/arrays (practical minimum 1)
* @return {string} JSON string representation of the input
* @static
*/
stringify : function (o,w,d) {
if (o !== undefined) {
// Ensure whitelist keys are unique (bug 2110391)
if (l.isArray(w)) {
w = (function (a) {
var uniq=[],map={},v,i,j,len;
for (i=0,j=0,len=a.length; i<len; ++i) {
v = a[i];
if (typeof v === 'string' && map[v] === undefined) {
uniq[(map[v] = j++)] = v;
}
}
return uniq;
})(w);
}
// Default depth to POSITIVE_INFINITY
d = d >= 0 ? d : 1/0;
// process the input
return _stringify({'':o},'',d,w,[]);
}
return undefined;
},
/**
* 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()) + ':' +
_zeroPad(d.getUTCMinutes()) + ':' +
_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) {
if (/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})Z$/.test(str)) {
var d = new Date();
d.setUTCFullYear(RegExp.$1, (RegExp.$2|0)-1, RegExp.$3);
d.setUTCHours(RegExp.$4, RegExp.$5, RegExp.$6);
return d;
}
return str;
}
};
})();