88 lines
2.8 KiB
TypeScript
88 lines
2.8 KiB
TypeScript
/*
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* Vencord, a modification for Discord's desktop app
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* Copyright (c) 2022 Vendicated and contributors
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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export function makeLazy<T>(factory: () => T): () => T {
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let cache: T;
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return () => cache ?? (cache = factory());
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}
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// Proxies demand that these properties be unmodified, so proxyLazy
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// will always return the function default for them.
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const unconfigurable = ["arguments", "caller", "prototype"];
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const handler: ProxyHandler<any> = {};
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const GET_KEY = Symbol.for("vencord.lazy.get");
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const CACHED_KEY = Symbol.for("vencord.lazy.cached");
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for (const method of [
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"apply",
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"construct",
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"defineProperty",
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"deleteProperty",
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"get",
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"getOwnPropertyDescriptor",
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"getPrototypeOf",
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"has",
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"isExtensible",
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"ownKeys",
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"preventExtensions",
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"set",
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"setPrototypeOf"
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]) {
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handler[method] =
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(target: any, ...args: any[]) => Reflect[method](target[GET_KEY](), ...args);
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}
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handler.ownKeys = target => {
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const v = target[GET_KEY]();
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const keys = Reflect.ownKeys(v);
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for (const key of unconfigurable) {
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if (!keys.includes(key)) keys.push(key);
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}
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return keys;
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};
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handler.getOwnPropertyDescriptor = (target, p) => {
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if (typeof p === "string" && unconfigurable.includes(p))
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return Reflect.getOwnPropertyDescriptor(target, p);
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const descriptor = Reflect.getOwnPropertyDescriptor(target[GET_KEY](), p);
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if (descriptor) Object.defineProperty(target, p, descriptor);
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return descriptor;
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};
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/**
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* Wraps the result of {@see makeLazy} in a Proxy you can consume as if it wasn't lazy.
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* On first property access, the lazy is evaluated
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* @param factory lazy factory
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* @returns Proxy
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*
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* Note that the example below exists already as an api, see {@link findByPropsLazy}
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* @example const mod = proxyLazy(() => findByProps("blah")); console.log(mod.blah);
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*/
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export function proxyLazy<T>(factory: () => T): T {
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const proxyDummy: { (): void;[CACHED_KEY]?: T;[GET_KEY](): T; } = Object.assign(function () { }, {
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[CACHED_KEY]: void 0,
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[GET_KEY]: () => proxyDummy[CACHED_KEY] ??= factory(),
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});
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return new Proxy(proxyDummy, handler) as any;
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}
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