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denoland-deno/cli/js/io.ts

106 lines
2.8 KiB
TypeScript

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
// Interfaces 100% copied from Go.
// Documentation liberally lifted from them too.
// Thank you! We love Go!
export const EOF: unique symbol = Symbol("EOF");
export type EOF = typeof EOF;
// Seek whence values.
// https://golang.org/pkg/io/#pkg-constants
export enum SeekMode {
SEEK_START = 0,
SEEK_CURRENT = 1,
SEEK_END = 2,
}
// Reader is the interface that wraps the basic read() method.
// https://golang.org/pkg/io/#Reader
export interface Reader {
read(p: Uint8Array): Promise<number | EOF>;
}
export interface SyncReader {
readSync(p: Uint8Array): number | EOF;
}
// Writer is the interface that wraps the basic write() method.
// https://golang.org/pkg/io/#Writer
export interface Writer {
write(p: Uint8Array): Promise<number>;
}
export interface SyncWriter {
writeSync(p: Uint8Array): number;
}
// https://golang.org/pkg/io/#Closer
export interface Closer {
// The behavior of Close after the first call is undefined. Specific
// implementations may document their own behavior.
close(): void;
}
// https://golang.org/pkg/io/#Seeker
export interface Seeker {
seek(offset: number, whence: SeekMode): Promise<number>;
}
export interface SyncSeeker {
seekSync(offset: number, whence: SeekMode): number;
}
// https://golang.org/pkg/io/#ReadCloser
export interface ReadCloser extends Reader, Closer {}
// https://golang.org/pkg/io/#WriteCloser
export interface WriteCloser extends Writer, Closer {}
// https://golang.org/pkg/io/#ReadSeeker
export interface ReadSeeker extends Reader, Seeker {}
// https://golang.org/pkg/io/#WriteSeeker
export interface WriteSeeker extends Writer, Seeker {}
// https://golang.org/pkg/io/#ReadWriteCloser
export interface ReadWriteCloser extends Reader, Writer, Closer {}
// https://golang.org/pkg/io/#ReadWriteSeeker
export interface ReadWriteSeeker extends Reader, Writer, Seeker {}
// https://golang.org/pkg/io/#Copy
export async function copy(dst: Writer, src: Reader): Promise<number> {
let n = 0;
const b = new Uint8Array(32 * 1024);
let gotEOF = false;
while (gotEOF === false) {
const result = await src.read(b);
if (result === EOF) {
gotEOF = true;
} else {
n += await dst.write(b.subarray(0, result));
}
}
return n;
}
export function toAsyncIterator(r: Reader): AsyncIterableIterator<Uint8Array> {
const b = new Uint8Array(1024);
return {
[Symbol.asyncIterator](): AsyncIterableIterator<Uint8Array> {
return this;
},
async next(): Promise<IteratorResult<Uint8Array>> {
const result = await r.read(b);
if (result === EOF) {
return { value: new Uint8Array(), done: true };
}
return {
value: b.subarray(0, result),
done: false,
};
},
};
}