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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
module.metadata = {
"stability": "experimental"
};
const { Cu } = require("chrome");
function makeGetterFor(Type) {
let cache = new WeakMap();
return {
getFor(target) {
if (!cache.has(target))
cache.set(target, new Type());
return cache.get(target);
},
clearFor(target) {
return cache.delete(target)
}
}
}
var {getFor: getLookupFor, clearFor: clearLookupFor} = makeGetterFor(WeakMap);
var {getFor: getRefsFor, clearFor: clearRefsFor} = makeGetterFor(Set);
function add(target, value) {
if (has(target, value))
return;
getLookupFor(target).set(value, true);
getRefsFor(target).add(Cu.getWeakReference(value));
}
exports.add = add;
function remove(target, value) {
getLookupFor(target).delete(value);
}
exports.remove = remove;
function has(target, value) {
return getLookupFor(target).has(value);
}
exports.has = has;
function clear(target) {
clearLookupFor(target);
clearRefsFor(target);
}
exports.clear = clear;
function iterator(target) {
let refs = getRefsFor(target);
for (let ref of refs) {
let value = ref.get();
// If `value` is already gc'ed, it would be `null`.
// The `has` function is using a WeakMap as lookup table, so passing `null`
// would raise an exception because WeakMap accepts as value only non-null
// object.
// Plus, if `value` is already gc'ed, we do not have to take it in account
// during the iteration, and remove it from the references.
if (value !== null && has(target, value))
yield value;
else
refs.delete(ref);
}
}
exports.iterator = iterator;
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