json-stringify.js revision 34d05a0baa83aa231e5faed818bc6ab5112cf2bf
/**
* Provides Y.json.stringify method for converting objects to JSON strings.
* @module json
* @class Y.json
* @static
*/
YUI.add('json-stringify',function (Y) {
Y.json = Y.json || {};
Y.mix(Y.json,{
/**
* Regex used to replace special characters in strings for JSON
* stringification.
* @property _SPECIAL_CHARS
* @type {RegExp}
* @static
* @private
*/
_SPECIAL_CHARS : /["\\\x00-\x1f\x7f-\x9f]/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',
'"' : '\\"',
'\\': '\\\\'
},
/**
* 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"';
},
/**
* 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} (optional) whitelist of acceptable object keys to include
* @param d {number} (optional) depth limit to recurse objects/arrays (practical minimum 1)
* @return {string} JSON string representation of the input
* @static
* @public
*/
stringify : function (o,w,d) {
var m = Y.json._CHARS,
str_re = Y.json._SPECIAL_CHARS,
rep = typeof w === 'function' ? w : null,
pstack = []; // Processing stack used for cyclical ref protection
if (rep || typeof w !== 'object') {
w = undefined;
}
// escape encode special characters
var _char = function (c) {
if (!m[c]) {
var a = c.charCodeAt();
m[c] = '\\u00' + Math.floor(a / 16).toString(16) +
(a % 16).toString(16);
}
return m[c];
};
// Enclose the escaped string in double quotes
var _string = function (s) {
return '"' + s.replace(str_re, _char) + '"';
};
// Use the configured date conversion
var _date = Y.json.dateToString;
// Worker function. Fork behavior on data type and recurse objects and
// arrays per the configured depth.
var _stringify = function (h,key,d) {
var o = typeof rep === 'function' ? rep.call(h,key,h[key]) : h[key],
t = typeof o,
i,len,j, // array iteration
k,v, // object iteration
vt, // typeof v during iteration
a; // composition array for performance over string concat
// String
if (t === 'string') {
return _string(o);
}
// native boolean and Boolean instance
if (t === 'boolean' || o instanceof Boolean) {
return String(o);
}
// native number and Number instance
if (t === 'number' || o instanceof Number) {
return isFinite(o) ? String(o) : 'null';
}
// Date
if (o instanceof Date) {
return _date(o);
}
// Object types
if (t === 'object') {
if (!o) {
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 = [];
// Only recurse if we're above depth config
if (d > 0) {
// Array
if (Y.lang.isArray(o)) {
for (i = o.length - 1; i >= 0; --i) {
a[i] = _stringify(o,i,d-1) || 'null';
}
// remove the array from the stack
pstack.pop();
return '[' + a.join(',') + ']';
// Object
} else {
// If whitelist provided, take only those keys
w = Y.lang.isArray(w) ? w : Y.object.keys(w||o);
for (i = 0, j = 0, len = w.length; i < len; ++i) {
if (typeof w[i] === 'string') {
v = _stringify(o,w[i],d-1);
if (v) {
a[j++] = _string(w[i]) + ':' + v;
}
}
}
// Remove the object from processing stack
pstack.pop();
return '{' + a.join(',') + '}';
}
}
}
return undefined; // invalid input
};
// Default depth to POSITIVE_INFINITY
d = d >= 0 ? d : 1/0;
// process the input
return _stringify({'':o},'',d);
}
});
},'3.0.0');