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denoland-deno/js/util.ts
2018-09-05 08:45:55 -04:00

85 lines
2.2 KiB
TypeScript

// Copyright 2018 the Deno authors. All rights reserved. MIT license.
import { TypedArray } from "./types";
let logDebug = false;
// @internal
export function setLogDebug(debug: boolean): void {
logDebug = debug;
}
/**
* Debug logging for deno. Enable with the `--DEBUG` command line flag.
* @internal
*/
// tslint:disable-next-line:no-any
export function log(...args: any[]): void {
if (logDebug) {
console.log("DEBUG JS -", ...args);
}
}
// @internal
export function assert(cond: boolean, msg = "assert") {
if (!cond) {
throw Error(msg);
}
}
// @internal
export function typedArrayToArrayBuffer(ta: TypedArray): ArrayBuffer {
const ab = ta.buffer.slice(ta.byteOffset, ta.byteOffset + ta.byteLength);
return ab as ArrayBuffer;
}
// @internal
export function arrayToStr(ui8: Uint8Array): string {
return String.fromCharCode(...ui8);
}
/**
* A `Resolvable` is a Promise with the `reject` and `resolve` functions
* placed as methods on the promise object itself. It allows you to do:
*
* const p = createResolvable<number>();
* ...
* p.resolve(42);
*
* It'd be prettier to make Resolvable a class that inherits from Promise,
* rather than an interface. This is possible in ES2016, however typescript
* produces broken code when targeting ES5 code.
* See https://github.com/Microsoft/TypeScript/issues/15202
* At the time of writing, the github issue is closed but the problem remains.
*
* @internal
*/
export interface ResolvableMethods<T> {
resolve: (value?: T | PromiseLike<T>) => void;
// tslint:disable-next-line:no-any
reject: (reason?: any) => void;
}
// @internal
export type Resolvable<T> = Promise<T> & ResolvableMethods<T>;
// @internal
export function createResolvable<T>(): Resolvable<T> {
let methods: ResolvableMethods<T>;
const promise = new Promise<T>((resolve, reject) => {
methods = { resolve, reject };
});
// TypeScript doesn't know that the Promise callback occurs synchronously
// therefore use of not null assertion (`!`)
return Object.assign(promise, methods!) as Resolvable<T>;
}
// @internal
export function notImplemented(): never {
throw new Error("Not implemented");
}
// @internal
export function unreachable(): never {
throw new Error("Code not reachable");
}