Add functions to get the values of weak collections

common/modules/common.js

@@ -3,3 +3,4 @@ export { default as Filters } from './filters';
 export { default as Logger, ClientLogger } from './logger';
 export { default as ClientIPC } from './bdipc';
 export { default as AsyncEventEmitter } from './async-eventemitter';
+export * from './iterable-weak-collections';

common/modules/iterable-weak-collections.js

@@ -0,0 +1,117 @@
+/**
+ * BetterDiscord Iterable Weak Collections
+ * Copyright (c) 2015-present Jiiks/JsSucks - https://github.com/Jiiks / https://github.com/JsSucks
+ * All rights reserved.
+ * https://betterdiscord.net
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+*/
+
+import process from 'process';
+
+export class IterableWeakMap extends WeakMap {
+    [Symbol.iterator]() {
+        return this.entries();
+    }
+
+    entries() {
+        return IterableWeakCollections.getWeakMapEntries(this).values();
+    }
+
+    keys() {
+        return IterableWeakCollections.getWeakMapEntries(this).map(e => e[0]).values();
+    }
+
+    values() {
+        return IterableWeakCollections.getWeakMapEntries(this).map(e => e[1]).values();
+    }
+}
+
+export class IterableWeakSet extends WeakSet {
+    [Symbol.iterator]() {
+        return this.values();
+    }
+
+    values() {
+        return IterableWeakCollections.getWeakSetValues(this).values();
+    }
+}
+
+export class IterableWeakCollections {
+
+    /**
+     * Returns a WeakMap's entries.
+     * @param {WeakMap} weakmap
+     * @return {Array}
+     */
+    static getWeakMapEntries(wm) {
+        const keysAndValues = this._getWeakMapEntries(wm);
+        const entries = [];
+
+        while (keysAndValues.length) {
+            const key = keysAndValues.shift();
+            const value = keysAndValues.shift();
+
+            entries.push([key, value]);
+        }
+
+        return entries;
+    }
+
+    static mapFromWeakMap(wm) {
+        return new Map(this.getWeakMapEntries(wm));
+    }
+
+    /**
+     * Returns a WeakSet's values.
+     * @param {WeakSet} weakset
+     * @return {Array}
+     */
+    static getWeakSetValues(ws) {
+        return this._getWeakSetValues(ws);
+    }
+
+    static setFromWeakSet(ws) {
+        return new Set(this.getWeakSetValues(ws));
+    }
+
+    static _setup() {
+        const v8 = process.binding('v8');
+
+        // Enable natives syntax
+        v8.setFlagsFromString('--allow_natives_syntax');
+
+        // Use eval otherwise webpack will throw a syntax error
+        // eslint-disable-next-line no-eval
+        this._getWeakMapEntries = eval(`(function (wm, max) {
+            // Retrieve all WeakMap instance key / value pairs up to \`max\`. \`max\` limits the
+            // number of key / value pairs returned. Make sure it is a positive number,
+            // otherwise V8 aborts. Passing through \`0\` returns all elements.
+            if (!(wm instanceof WeakMap)) throw new Error('weakmap must be an instance of WeakMap');
+            return %GetWeakMapEntries(wm, typeof max === 'number' && max > 0 ? max : 0);
+        })`);
+
+        // eslint-disable-next-line no-eval
+        this._getWeakSetValues = eval(`(function (ws, max) {
+            // Retrieve all WeakSet instance values up to \`max\`. \`max\` limits the
+            // number of values returned. Make sure it is a positive number,
+            // otherwise V8 aborts. Passing through \`0\` returns all elements.
+            if (!(ws instanceof WeakSet)) throw new Error('weakset must be an instance of WeakSet');
+            return %GetWeakSetValues(ws, typeof max === 'number' && max > 0 ? max : 0);
+        })`);
+
+        // Warm up the map and set iterator preview functions. V8 compiles
+        // functions lazily (unless --nolazy is set) so we need to do this
+        // before we turn off --allow_natives_syntax again.
+        this._getWeakMapEntries(new WeakMap(), 1);
+        this._getWeakSetValues(new WeakSet(), 1);
+
+        // Disable --allow_natives_syntax again unless it was explicitly
+        // specified on the command line
+        if (!process.execArgv.some(s => /^--allow[-_]natives[-_]syntax$/.test(s))) v8.setFlagsFromString('--noallow_natives_syntax');
+    }
+
+}
+
+IterableWeakCollections._setup();