feat: std/node (denoland#3319)

std/node/README.md

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+# Deno Node compatibility
+
+This module is meant to have a compatibility layer for the
+[nodeJS standard library](https://nodejs.org/docs/latest-v12.x/api/).
+
+**Warning** : Any function of this module should not be referred anywhere in the
+deno standard library as it's a compatiblity module.

std/node/_utils.ts

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+export function notImplemented(msg?: string): never {
+  const message = msg ? `Not implemented: ${msg}` : "Not implemented";
+  throw new Error(message);
+}
+
+// API helpers
+
+export type MaybeNull<T> = T | null;
+export type MaybeDefined<T> = T | undefined;
+export type MaybeEmpty<T> = T | null | undefined;
+
+export function intoCallbackAPI<T>(
+  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+  func: (...args: any[]) => Promise<T>,
+  cb: MaybeEmpty<(err: MaybeNull<Error>, value: MaybeEmpty<T>) => void>,
+  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+  ...args: any[]
+): void {
+  func(...args)
+    .then(value => cb && cb(null, value))
+    .catch(err => cb && cb(err, null));
+}
+
+export function intoCallbackAPIWithIntercept<T1, T2>(
+  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+  func: (...args: any[]) => Promise<T1>,
+  interceptor: (v: T1) => T2,
+  cb: MaybeEmpty<(err: MaybeNull<Error>, value: MaybeEmpty<T2>) => void>,
+  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+  ...args: any[]
+): void {
+  func(...args)
+    .then(value => cb && cb(null, interceptor(value)))
+    .catch(err => cb && cb(err, null));
+}

std/node/fs.ts

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+import { notImplemented, intoCallbackAPIWithIntercept } from "./_utils.ts";
+const { readFile: denoReadFile, readFileSync: denoReadFileSync } = Deno;
+
+type ReadFileCallback = (err: Error | null, data: string | Uint8Array) => void;
+
+interface ReadFileOptions {
+  encoding?: string | null;
+  flag?: string;
+}
+
+function getEncoding(
+  optOrCallback?: ReadFileOptions | ReadFileCallback
+): string | null {
+  if (!optOrCallback || typeof optOrCallback === "function") {
+    return null;
+  } else {
+    if (optOrCallback.encoding) {
+      if (
+        optOrCallback.encoding === "utf8" ||
+        optOrCallback.encoding === "utf-8"
+      ) {
+        return "utf8";
+      } else {
+        notImplemented();
+      }
+    }
+    return null;
+  }
+}
+
+function maybeDecode(
+  data: Uint8Array,
+  encoding: string | null
+): string | Uint8Array {
+  if (encoding === "utf8") {
+    return new TextDecoder().decode(data);
+  }
+  return data;
+}
+
+export function readFile(
+  path: string,
+  optOrCallback: ReadFileCallback | ReadFileOptions,
+  callback?: ReadFileCallback
+): void {
+  let cb: ReadFileCallback | undefined;
+  if (typeof optOrCallback === "function") {
+    cb = optOrCallback;
+  } else {
+    cb = callback;
+  }
+
+  const encoding = getEncoding(optOrCallback);
+
+  intoCallbackAPIWithIntercept<Uint8Array, string | Uint8Array>(
+    denoReadFile,
+    (data: Uint8Array): string | Uint8Array => maybeDecode(data, encoding),
+    cb,
+    path
+  );
+}
+
+export function readFileSync(
+  path: string,
+  opt?: ReadFileOptions
+): string | Uint8Array {
+  return maybeDecode(denoReadFileSync(path), getEncoding(opt));
+}

std/node/fs_test.ts

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+import { readFile, readFileSync } from "./fs.ts";
+import { test } from "../testing/mod.ts";
+import * as path from "../path/mod.ts";
+import { assertEquals, assert } from "../testing/asserts.ts";
+
+const testData = path.resolve(path.join("node", "testdata", "hello.txt"));
+
+// Need to convert to promises, otherwise test() won't report error correctly.
+test(async function readFileSuccess() {
+  const data = await new Promise((res, rej) => {
+    readFile(testData, (err, data) => {
+      if (err) {
+        rej(err);
+      }
+      res(data);
+    });
+  });
+
+  assert(data instanceof Uint8Array);
+  assertEquals(new TextDecoder().decode(data as Uint8Array), "hello world");
+});
+
+test(async function readFileEncodeUtf8Success() {
+  const data = await new Promise((res, rej) => {
+    readFile(testData, { encoding: "utf8" }, (err, data) => {
+      if (err) {
+        rej(err);
+      }
+      res(data);
+    });
+  });
+
+  assertEquals(typeof data, "string");
+  assertEquals(data as string, "hello world");
+});
+
+test(function readFileSyncSuccess() {
+  const data = readFileSync(testData);
+  assert(data instanceof Uint8Array);
+  assertEquals(new TextDecoder().decode(data as Uint8Array), "hello world");
+});
+
+test(function readFileEncodeUtf8Success() {
+  const data = readFileSync(testData, { encoding: "utf8" });
+  assertEquals(typeof data, "string");
+  assertEquals(data as string, "hello world");
+});

std/node/testdata/hello.txt

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+hello world

std/node/util.ts

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+export function isArray(value: unknown): boolean {
+  return Array.isArray(value);
+}
+
+export function isBoolean(value: unknown): boolean {
+  return typeof value === "boolean" || value instanceof Boolean;
+}
+
+export function isNull(value: unknown): boolean {
+  return value === null;
+}
+
+export function isNullOrUndefined(value: unknown): boolean {
+  return value === null || value === undefined;
+}
+
+export function isNumber(value: unknown): boolean {
+  return typeof value === "number" || value instanceof Number;
+}
+
+export function isString(value: unknown): boolean {
+  return typeof value === "string" || value instanceof String;
+}
+
+export function isSymbol(value: unknown): boolean {
+  return typeof value === "symbol";
+}
+
+export function isUndefined(value: unknown): boolean {
+  return value === undefined;
+}
+
+export function isObject(value: unknown): boolean {
+  return value !== null && typeof value === "object";
+}
+
+export function isError(e: unknown): boolean {
+  return e instanceof Error;
+}
+
+export function isFunction(value: unknown): boolean {
+  return typeof value === "function";
+}
+
+export function isRegExp(value: unknown): boolean {
+  return value instanceof RegExp;
+}

std/node/util_test.ts

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+import { test } from "../testing/mod.ts";
+import { assert } from "../testing/asserts.ts";
+import * as util from "./util.ts";
+
+test({
+  name: "[util] isBoolean",
+  fn() {
+    assert(util.isBoolean(true));
+    assert(util.isBoolean(new Boolean()));
+    assert(util.isBoolean(new Boolean(true)));
+    assert(util.isBoolean(false));
+    assert(!util.isBoolean("deno"));
+    assert(!util.isBoolean("true"));
+  }
+});
+
+test({
+  name: "[util] isNull",
+  fn() {
+    let n;
+    assert(util.isNull(null));
+    assert(!util.isNull(n));
+    assert(!util.isNull(0));
+    assert(!util.isNull({}));
+  }
+});
+
+test({
+  name: "[util] isNullOrUndefined",
+  fn() {
+    let n;
+    assert(util.isNullOrUndefined(null));
+    assert(util.isNullOrUndefined(n));
+    assert(!util.isNullOrUndefined({}));
+    assert(!util.isNullOrUndefined("undefined"));
+  }
+});
+
+test({
+  name: "[util] isNumber",
+  fn() {
+    assert(util.isNumber(666));
+    assert(util.isNumber(new Number(666)));
+    assert(!util.isNumber("999"));
+    assert(!util.isNumber(null));
+  }
+});
+
+test({
+  name: "[util] isString",
+  fn() {
+    assert(util.isString("deno"));
+    assert(util.isString(new String("DIO")));
+    assert(!util.isString(1337));
+  }
+});
+
+test({
+  name: "[util] isSymbol",
+  fn() {}
+});
+
+test({
+  name: "[util] isUndefined",
+  fn() {
+    let t;
+    assert(util.isUndefined(t));
+    assert(!util.isUndefined("undefined"));
+    assert(!util.isUndefined({}));
+  }
+});
+
+test({
+  name: "[util] isObject",
+  fn() {
+    const dio = { stand: "Za Warudo" };
+    assert(util.isObject(dio));
+    assert(util.isObject(new RegExp(/Toki Wo Tomare/)));
+    assert(!util.isObject("Jotaro"));
+  }
+});
+
+test({
+  name: "[util] isError",
+  fn() {
+    const java = new Error();
+    const nodejs = new TypeError();
+    const deno = "Future";
+    assert(util.isError(java));
+    assert(util.isError(nodejs));
+    assert(!util.isError(deno));
+  }
+});
+
+test({
+  name: "[util] isFunction",
+  fn() {
+    const f = function(): void {};
+    assert(util.isFunction(f));
+    assert(!util.isFunction({}));
+    assert(!util.isFunction(new RegExp(/f/)));
+  }
+});
+
+test({
+  name: "[util] isRegExp",
+  fn() {
+    assert(util.isRegExp(new RegExp(/f/)));
+    assert(util.isRegExp(/fuManchu/));
+    assert(!util.isRegExp({ evil: "eye" }));
+    assert(!util.isRegExp(null));
+  }
+});
+
+test({
+  name: "[util] isArray",
+  fn() {
+    assert(util.isArray([]));
+    assert(!util.isArray({ yaNo: "array" }));
+    assert(!util.isArray(null));
+  }
+});