github/JSON-js
2
0
Fork 0
mirror of https://github.com/donl/JSON-js.git synced 2026-05-25 22:06:23 -06:00
Code Issues Projects Packages Wiki Activity Actions

WeakMap

Browse source
This commit is contained in:
Douglas Crockford 2017-02-08 10:28:50 -08:00
parent 031b1d9e69
commit e25ba46913
1 changed files with 14 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

29
cycle.js
View file

@ -1,6 +1,6 @@
/*
cycle.js
2016-05-01
2017-02-07
Public Domain.
@ -13,11 +13,13 @@
NOT CONTROL.
*/
/*jslint eval, for */
// The file uses the WeakMap feature of ES6.
/*jslint es6, eval */
/*property
$ref, decycle, forEach, indexOf, isArray, keys, length, push, retrocycle,
stringify, test
$ref, decycle, forEach, get, indexOf, isArray, keys, length, push,
retrocycle, set, stringify, test
*/
if (typeof JSON.decycle !== "function") {
@ -48,14 +50,13 @@ if (typeof JSON.decycle !== "function") {
// the object or array. [NUMBER] or [STRING] indicates a child element or
// property.
var objects = []; // Keep a reference to each unique object or array
var paths = []; // Keep the path to each unique object or array
var objects = new WeakMap(); // object to path mappings
return (function derez(value, path) {
// The derez function recurses through the object, producing the deep copy.
var i; // The loop counter
var old_path; // The path of an earlier occurance of value
var nu; // The new object or array
// If a replacer function was provided, then call it to get a replacement value.
@ -77,19 +78,17 @@ if (typeof JSON.decycle !== "function") {
) {
// If the value is an object or array, look to see if we have already
// encountered it. If so, return a {"$ref":PATH} object. This is a hard
// linear search that will get slower as the number of unique objects grows.
// Someday, this should be replaced with an ES6 WeakMap.
// encountered it. If so, return a {"$ref":PATH} object. This uses an
// ES6 WeakMap.
i = objects.indexOf(value);
if (i >= 0) {
return {$ref: paths[i]};
old_path = objects.get(value);
if (old_path !== undefined) {
return {$ref: old_path};
}
// Otherwise, accumulate the unique value and its path.
objects.push(value);
paths.push(path);
objects.set(value, path);
// If it is an array, replicate the array.