mirror of
https://github.com/denoland/std.git
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566 lines
15 KiB
TypeScript
566 lines
15 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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import {
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assert,
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assertAlmostEquals,
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assertEquals,
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assertRejects,
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} from "@std/assert";
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import { memoize } from "./memoize.ts";
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import { LruCache } from "./lru_cache.ts";
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import { FakeTime } from "@std/testing/time";
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Deno.test(
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"memoize() memoizes nullary function (lazy/singleton)",
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async (t) => {
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await t.step("async function", async () => {
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let numTimesCalled = 0;
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const db = {
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connect() {
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++numTimesCalled;
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return Promise.resolve({});
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},
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};
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const getConn = memoize(async () => await db.connect());
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const conn = await getConn();
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assertEquals(numTimesCalled, 1);
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const conn2 = await getConn();
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// equal by reference
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assert(conn2 === conn);
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assertEquals(numTimesCalled, 1);
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});
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await t.step("sync function", async () => {
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using time = new FakeTime();
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const firstHitDate = memoize(() => new Date());
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const date = firstHitDate();
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await time.tickAsync(10);
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const date2 = firstHitDate();
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assertEquals(date, date2);
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});
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},
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);
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Deno.test("memoize() allows simple memoization with primitive arg", () => {
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let numTimesCalled = 0;
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const fn = memoize((n: number) => {
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++numTimesCalled;
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return 0 - n;
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});
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assertEquals(fn(42), -42);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(42), -42);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(888), -888);
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assertEquals(numTimesCalled, 2);
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});
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Deno.test("memoize() is performant for expensive fibonacci function", () => {
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// Typically should take a maximum of a couple of milliseconds, but this
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// test is really just a smoke test to make sure the memoization is working
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// correctly, so we don't set a deadline to make sure it isn't flaky
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// dependent on hardware, test runner, etc.
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const fib = memoize((n: bigint): bigint => {
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return n <= 2n ? 1n : fib(n - 1n) + fib(n - 2n);
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});
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assertEquals(fib(100n), 354224848179261915075n);
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});
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Deno.test("memoize() allows multiple primitive args", () => {
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let numTimesCalled = 0;
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const fn = memoize((a: number, b: number) => {
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++numTimesCalled;
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return a + b;
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});
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assertEquals(fn(7, 8), 15);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(7, 8), 15);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(7, 9), 16);
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assertEquals(numTimesCalled, 2);
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assertEquals(fn(8, 7), 15);
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assertEquals(numTimesCalled, 3);
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});
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Deno.test("memoize() allows ...spread primitive args", () => {
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let numTimesCalled = 0;
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const fn = memoize((...ns: number[]) => {
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++numTimesCalled;
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return ns.reduce((total, val) => total + val, 0);
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});
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assertEquals(fn(), 0);
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assertEquals(fn(), 0);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(7), 7);
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assertEquals(fn(7), 7);
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assertEquals(numTimesCalled, 2);
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assertEquals(fn(7, 8), 15);
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assertEquals(fn(7, 8), 15);
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assertEquals(numTimesCalled, 3);
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assertEquals(fn(7, 8, 9), 24);
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assertEquals(fn(7, 8, 9), 24);
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assertEquals(numTimesCalled, 4);
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});
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Deno.test(
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"memoize() caches unary function by all passed args by default (implicit extra args as array callback)",
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() => {
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let numTimesCalled = 0;
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const fn = memoize((n: number) => {
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++numTimesCalled;
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return 0 - n;
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});
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assertEquals([1, 1, 2, 2].map(fn), [-1, -1, -2, -2]);
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assertEquals(numTimesCalled, 4);
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},
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);
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Deno.test("memoize() preserves `this` binding`", () => {
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class X {
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readonly key = "CONSTANT";
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timesCalled = 0;
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#method() {
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return 1;
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}
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method() {
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++this.timesCalled;
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return this.#method();
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}
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}
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const x = new X();
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const method = x.method.bind(x);
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const fn = memoize(method);
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assertEquals(fn(), 1);
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const fn2 = memoize(x.method).bind(x);
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assertEquals(fn2(), 1);
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});
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// based on https://github.com/lodash/lodash/blob/4.17.15/test/test.js#L14704-L14716
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Deno.test("memoize() uses `this` binding of function for `getKey`", () => {
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type Obj = { b: number; c: number; memoized: (a: number) => number };
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let numTimesCalled = 0;
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const fn = function (this: Obj, a: number) {
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++numTimesCalled;
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return a + this.b + this.c;
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};
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const getKey = function (this: Obj, a: number) {
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return JSON.stringify([a, this.b, this.c]);
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};
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const memoized = memoize(fn, { getKey });
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const obj: Obj = { memoized, "b": 2, "c": 3 };
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assertEquals(obj.memoized(1), 6);
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assertEquals(numTimesCalled, 1);
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assertEquals(obj.memoized(1), 6);
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assertEquals(numTimesCalled, 1);
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obj.b = 3;
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obj.c = 5;
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assertEquals(obj.memoized(1), 9);
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assertEquals(numTimesCalled, 2);
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});
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Deno.test("memoize() allows reference arg with default caching", () => {
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let numTimesCalled = 0;
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const fn = memoize((sym: symbol) => {
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++numTimesCalled;
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return sym;
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});
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const sym1 = Symbol();
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const sym2 = Symbol();
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fn(sym1);
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assertEquals(numTimesCalled, 1);
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fn(sym1);
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assertEquals(numTimesCalled, 1);
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fn(sym2);
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assertEquals(numTimesCalled, 2);
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});
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Deno.test("memoize() allows multiple reference args with default caching", () => {
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let numTimesCalled = 0;
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const fn = memoize((obj1: unknown, obj2: unknown) => {
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++numTimesCalled;
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return { obj1, obj2 };
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});
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const obj1 = {};
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const obj2 = {};
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fn(obj1, obj1);
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assertEquals(numTimesCalled, 1);
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fn(obj1, obj1);
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assertEquals(numTimesCalled, 1);
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fn(obj1, obj2);
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assertEquals(numTimesCalled, 2);
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fn(obj2, obj2);
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assertEquals(numTimesCalled, 3);
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fn(obj2, obj1);
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assertEquals(numTimesCalled, 4);
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});
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Deno.test("memoize() allows non-primitive arg with `getKey`", () => {
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let numTimesCalled = 0;
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const fn = memoize((d: Date) => {
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++numTimesCalled;
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return new Date(0 - d.valueOf());
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}, { getKey: (n) => n.valueOf() });
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const date1 = new Date(42);
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const date2 = new Date(888);
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assertEquals(fn(date1), new Date(-42));
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(date1), new Date(-42));
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(date2), new Date(-888));
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assertEquals(numTimesCalled, 2);
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});
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Deno.test("memoize() allows non-primitive arg with `getKey`", () => {
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const fn = memoize(({ value }: { cacheKey: number; value: number }) => {
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return value;
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}, { getKey: ({ cacheKey }) => cacheKey });
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assertEquals(fn({ cacheKey: 1, value: 2 }), 2);
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assertEquals(fn({ cacheKey: 1, value: 99 }), 2);
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assertEquals(fn({ cacheKey: 2, value: 99 }), 99);
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});
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Deno.test(
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"memoize() allows multiple non-primitive args with `getKey` returning primitive",
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() => {
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let numTimesCalled = 0;
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const fn = memoize((...args: { val: number }[]) => {
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++numTimesCalled;
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return args.reduce((total, { val }) => total + val, 0);
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}, { getKey: (...args) => JSON.stringify(args) });
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assertEquals(fn({ val: 1 }, { val: 2 }), 3);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn({ val: 1 }, { val: 2 }), 3);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn({ val: 2 }, { val: 1 }), 3);
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assertEquals(numTimesCalled, 2);
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},
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);
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Deno.test(
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"memoize() allows multiple non-primitive args with `getKey` returning stringified array of primitives",
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() => {
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let numTimesCalled = 0;
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const fn = memoize((...args: { val: number }[]) => {
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++numTimesCalled;
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return args.reduce((total, { val }) => total + val, 0);
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}, { getKey: (...args) => JSON.stringify(args.map((arg) => arg.val)) });
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assertEquals(fn({ val: 1 }, { val: 2 }), 3);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn({ val: 1 }, { val: 2 }), 3);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn({ val: 2 }, { val: 1 }), 3);
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assertEquals(numTimesCalled, 2);
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},
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);
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Deno.test(
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"memoize() allows multiple non-primitive args of different types, `getKey` returning custom string from props",
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() => {
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let numTimesCalled = 0;
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const fn = memoize((one: { one: number }, two: { two: number }) => {
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++numTimesCalled;
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return one.one + two.two;
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}, { getKey: (one, two) => `${one.one},${two.two}` });
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assertEquals(fn({ one: 1 }, { two: 2 }), 3);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn({ one: 1 }, { two: 2 }), 3);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn({ one: 2 }, { two: 1 }), 3);
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assertEquals(numTimesCalled, 2);
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},
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);
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Deno.test("memoize() allows primitive arg with `getKey`", () => {
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let numTimesCalled = 0;
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const fn = memoize((arg: string | number | boolean) => {
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++numTimesCalled;
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try {
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return JSON.parse(String(arg)) as string | number | boolean;
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} catch {
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return arg;
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}
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}, { getKey: (arg) => String(arg) });
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assertEquals(fn("true"), true);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(true), true);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn("42"), 42);
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assertEquals(numTimesCalled, 2);
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assertEquals(fn(42), 42);
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assertEquals(numTimesCalled, 2);
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});
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Deno.test("memoize() works with async functions", async () => {
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using time = new FakeTime();
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// wait time per call of the original (un-memoized) function
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const DELAY_MS = 100;
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const startTime = Date.now();
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const fn = memoize(async (n: number) => {
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await time.tickAsync(DELAY_MS);
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return 0 - n;
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});
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const nums = [42, 888, 42, 42, 42, 42, 888, 888, 888, 888];
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const expected = [-42, -888, -42, -42, -42, -42, -888, -888, -888, -888];
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const results: number[] = [];
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// call in serial to test time elapsed
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for (const num of nums) {
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results.push(await fn(num));
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}
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assertEquals(results, expected);
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const numUnique = new Set(nums).size;
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assertAlmostEquals(
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Date.now() - startTime,
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numUnique * DELAY_MS,
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nums.length,
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);
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});
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Deno.test(
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"memoize() doesn’t cache rejected promises for future function calls",
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async () => {
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let rejectNext = true;
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const fn = memoize(async (n: number) => {
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await Promise.resolve();
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const thisCallWillReject = rejectNext;
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rejectNext = !rejectNext;
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if (thisCallWillReject) {
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throw new Error();
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}
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return 0 - n;
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});
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// first call rejects
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await assertRejects(() => fn(42));
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// second call succeeds (rejected response is discarded)
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assertEquals(await fn(42), -42);
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// subsequent calls also succeed (successful response from cache is used)
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assertEquals(await fn(42), -42);
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},
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);
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Deno.test(
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"memoize() causes async functions called in parallel to return the same promise (even if rejected)",
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async () => {
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let rejectNext = true;
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const fn = memoize(async (n: number) => {
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await Promise.resolve();
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if (rejectNext) {
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rejectNext = false;
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throw new Error(`Rejected ${n}`);
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}
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return 0 - n;
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});
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const promises = [42, 42, 888, 888].map((x) => fn(x));
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const results = await Promise.allSettled(promises);
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assert(promises[1] === promises[0]);
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assert(results[1]!.status === "rejected");
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assert(results[1]!.reason.message === "Rejected 42");
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assert(promises[3] === promises[2]);
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assert(results[3]!.status === "fulfilled");
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assert(results[3]!.value === -888);
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},
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);
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Deno.test("memoize() allows passing a `Map` as a cache", () => {
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let numTimesCalled = 0;
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const cache = new Map();
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const fn = memoize((n: number) => {
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++numTimesCalled;
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return 0 - n;
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}, { cache });
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assertEquals(fn(42), -42);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(42), -42);
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assertEquals(numTimesCalled, 1);
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});
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Deno.test("memoize() allows passing a custom cache object", () => {
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let numTimesCalled = 0;
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const uselessCache = {
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has: () => false,
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get: () => {
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throw new Error("`has` is always false, so `get` is never called");
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},
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set: () => {},
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delete: () => {},
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keys: () => [],
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};
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const fn = memoize((n: number) => {
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++numTimesCalled;
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return 0 - n;
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}, { cache: uselessCache });
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assertEquals(fn(42), -42);
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assertEquals(numTimesCalled, 1);
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assertEquals(fn(42), -42);
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assertEquals(numTimesCalled, 2);
|
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});
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Deno.test("memoize() deletes stale entries of passed `LruCache`", () => {
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let numTimesCalled = 0;
|
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const MAX_SIZE = 5;
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const fn = memoize((n: number) => {
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++numTimesCalled;
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return 0 - n;
|
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}, { cache: new LruCache<string, number>(MAX_SIZE) });
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|
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assertEquals(fn(0), 0);
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assertEquals(fn(0), 0);
|
||
assertEquals(numTimesCalled, 1);
|
||
|
||
for (let i = 1; i < MAX_SIZE; ++i) {
|
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assertEquals(fn(i), 0 - i);
|
||
assertEquals(fn(i), 0 - i);
|
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assertEquals(numTimesCalled, i + 1);
|
||
}
|
||
|
||
assertEquals(fn(MAX_SIZE), 0 - MAX_SIZE);
|
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assertEquals(fn(MAX_SIZE), 0 - MAX_SIZE);
|
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assertEquals(numTimesCalled, MAX_SIZE + 1);
|
||
|
||
assertEquals(fn(0), 0);
|
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assertEquals(fn(0), 0);
|
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assertEquals(numTimesCalled, MAX_SIZE + 2);
|
||
});
|
||
|
||
Deno.test("memoize() only caches single latest result with a `LruCache` of maxSize=1", () => {
|
||
let numTimesCalled = 0;
|
||
|
||
const fn = memoize((n: number) => {
|
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++numTimesCalled;
|
||
return 0 - n;
|
||
}, { cache: new LruCache<string, number>(1) });
|
||
|
||
assertEquals(fn(0), 0);
|
||
assertEquals(fn(0), 0);
|
||
assertEquals(numTimesCalled, 1);
|
||
|
||
assertEquals(fn(1), -1);
|
||
assertEquals(numTimesCalled, 2);
|
||
});
|
||
|
||
Deno.test("memoize() preserves function length", () => {
|
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assertEquals(memoize.length, 2);
|
||
|
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assertEquals(memoize(() => {}).length, 0);
|
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assertEquals(memoize((_arg) => {}).length, 1);
|
||
assertEquals(memoize((_1, _2) => {}).length, 2);
|
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assertEquals(memoize((..._args) => {}).length, 0);
|
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assertEquals(memoize((_1, ..._args) => {}).length, 1);
|
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});
|
||
|
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Deno.test("memoize() preserves function name", () => {
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||
assertEquals(memoize.name, "memoize");
|
||
|
||
const fn1 = () => {};
|
||
function fn2() {}
|
||
const obj = { ["!"]: () => {} };
|
||
|
||
assertEquals(memoize(() => {}).name, "");
|
||
assertEquals(memoize(fn1).name, "fn1");
|
||
assertEquals(memoize(fn1.bind({})).name, "bound fn1");
|
||
assertEquals(memoize(fn2).name, "fn2");
|
||
assertEquals(memoize(function fn3() {}).name, "fn3");
|
||
assertEquals(memoize(obj["!"]).name, "!");
|
||
});
|
||
|
||
Deno.test("memoize() has correct TS types", async (t) => {
|
||
await t.step("simple types", () => {
|
||
// no need to run, only for type checking
|
||
void (() => {
|
||
const fn: (this: number, x: number) => number = (_) => 1;
|
||
const memoized = memoize(fn);
|
||
|
||
const _fn2: typeof fn = memoized;
|
||
const _fn3: Omit<typeof memoized, "cache" | "getKey"> = fn;
|
||
|
||
const _t1: ThisParameterType<typeof fn> = 1;
|
||
// @ts-expect-error Type 'string' is not assignable to type 'number'.
|
||
const _t2: ThisParameterType<typeof fn> = "1";
|
||
|
||
const _a1: Parameters<typeof fn>[0] = 1;
|
||
// @ts-expect-error Type 'string' is not assignable to type 'number'.
|
||
const _a2: Parameters<typeof fn>[0] = "1";
|
||
// @ts-expect-error Tuple type '[x: number]' of length '1' has no element at index '1'.
|
||
const _a3: Parameters<typeof fn>[1] = {} as never;
|
||
|
||
const _r1: ReturnType<typeof fn> = 1;
|
||
// @ts-expect-error Type 'string' is not assignable to type 'number'.
|
||
const _r2: ReturnType<typeof fn> = "1";
|
||
});
|
||
});
|
||
|
||
await t.step("memoize() correctly preserves generic types", () => {
|
||
// no need to run, only for type checking
|
||
void (() => {
|
||
const fn = <T>(x: T): T => x;
|
||
const memoized = memoize(fn);
|
||
|
||
const _fn2: typeof fn = memoized;
|
||
const _fn3: Omit<typeof memoized, "cache" | "getKey"> = fn;
|
||
|
||
const _r1: number = fn(1);
|
||
const _r2: string = fn("1");
|
||
// @ts-expect-error Type 'string' is not assignable to type 'number'.
|
||
const _r3: number = fn("1");
|
||
|
||
const _fn4: typeof fn<number> = (n: number) => n;
|
||
// @ts-expect-error Type 'string' is not assignable to type 'number'.
|
||
const _fn5: typeof fn<string> = (n: number) => n;
|
||
});
|
||
});
|
||
});
|