/*
cycle.js
2013-02-19
Public Domain.
NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
This code should be minified before deployment.
See http://javascript.crockford.com/jsmin.html
USE YOUR OWN COPY. IT IS EXTREMELY UNWISE TO LOAD CODE FROM SERVERS YOU DO
NOT CONTROL.
*/
/*jslint evil: true, regexp: true */
/*members $ref, apply, call, decycle, hasOwnProperty, length, prototype, push,
retrocycle, stringify, test, toString
*/
if (typeof JSON.decycle !== 'function') {
JSON.decycle = function decycle(object) {
'use strict';
// Make a deep copy of an object or array, assuring that there is at most
// one instance of each object or array in the resulting structure. The
// duplicate references (which might be forming cycles) are replaced with
// an object of the form
// {$ref: PATH}
// where the PATH is a JSONPath string that locates the first occurance.
// So,
// var a = [];
// a[0] = a;
// return JSON.stringify(JSON.decycle(a));
// produces the string '[{"$ref":"$"}]'.
// JSONPath is used to locate the unique object. $ indicates the top level of
// the object or array. [NUMBER] or [STRING] indicates a child member or
// property.
var objects = [], // Keep a reference to each unique object or array
paths = []; // Keep the path to each unique object or array
return (function derez(value, path) {
// The derez recurses through the object, producing the deep copy.
var i, // The loop counter
name, // Property name
nu; // The new object or array
// typeof null === 'object', so go on if this value is really an object but not
// one of the weird builtin objects.
if (typeof value === 'object' && value !== null &&
!(value instanceof Boolean) &&
!(value instanceof Date) &&
!(value instanceof Number) &&
!(value instanceof RegExp) &&
!(value instanceof String)) {
// If the value is an object or array, look to see if we have already
// encountered it. If so, return a $ref/path object. This is a hard way,
// linear search that will get slower as the number of unique objects grows.
for (i = 0; i < objects.length; i += 1) {
if (objects[i] === value) {
return {$ref: paths[i]};
}
}
// Otherwise, accumulate the unique value and its path.
objects.push(value);
paths.push(path);
// If it is an array, replicate the array.
if (Object.prototype.toString.apply(value) === '[object Array]') {
nu = [];
for (i = 0; i < value.length; i += 1) {
nu[i] = derez(value[i], path + '[' + i + ']');
}
} else {
// If it is an object, replicate the object.
nu = {};
for (name in value) {
if (Object.prototype.hasOwnProperty.call(value, name)) {
nu[name] = derez(value[name],
path + '[' + JSON.stringify(name) + ']');
}
}
}
return nu;
}
return value;
}(object, '$'));
};
}
if (typeof JSON.retrocycle !== 'function') {
JSON.retrocycle = function retrocycle($) {
'use strict';
// Restore an object that was reduced by decycle. Members whose values are
// objects of the form
// {$ref: PATH}
// are replaced with references to the value found by the PATH. This will
// restore cycles. The object will be mutated.
// The eval function is used to locate the values described by a PATH. The
// root object is kept in a $ variable. A regular expression is used to
// assure that the PATH is extremely well formed. The regexp contains nested
// * quantifiers. That has been known to have extremely bad performance
// problems on some browsers for very long strings. A PATH is expected to be
// reasonably short. A PATH is allowed to belong to a very restricted subset of
// Goessner's JSONPath.
// So,
// var s = '[{"$ref":"$"}]';
// return JSON.retrocycle(JSON.parse(s));
// produces an array containing a single element which is the array itself.
var px =
/^\$(?:\[(?:\d+|\"(?:[^\\\"\u0000-\u001f]|\\([\\\"\/bfnrt]|u[0-9a-zA-Z]{4}))*\")\])*$/;
(function rez(value) {
// The rez function walks recursively through the object looking for $ref
// properties. When it finds one that has a value that is a path, then it
// replaces the $ref object with a reference to the value that is found by
// the path.
var i, item, name, path;
if (value && typeof value === 'object') {
if (Object.prototype.toString.apply(value) === '[object Array]') {
for (i = 0; i < value.length; i += 1) {
item = value[i];
if (item && typeof item === 'object') {
path = item.$ref;
if (typeof path === 'string' && px.test(path)) {
value[i] = eval(path);
} else {
rez(item);
}
}
}
} else {
for (name in value) {
if (typeof value[name] === 'object') {
item = value[name];
if (item) {
path = item.$ref;
if (typeof path === 'string' && px.test(path)) {
value[name] = eval(path);
} else {
rez(item);
}
}
}
}
}
}
}($));
return $;
};
}
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