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Because many Reader/Writer implementations (e.g. bufio) assume their able to use subarray() with byte indexes and often ask for byte values, it makes sense to simply restrict all implementations to Uint8Array.
108 lines
3.4 KiB
TypeScript
108 lines
3.4 KiB
TypeScript
// Copyright 2018 the Deno authors. All rights reserved. MIT license.
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import { Reader, Writer, Closer, ReadResult } from "./io";
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import * as dispatch from "./dispatch";
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import * as msg from "gen/msg_generated";
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import { assert } from "./util";
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import * as flatbuffers from "./flatbuffers";
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/** The Deno abstraction for reading and writing files. */
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export class File implements Reader, Writer, Closer {
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constructor(readonly rid: number) {}
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write(p: Uint8Array): Promise<number> {
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return write(this.rid, p);
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}
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read(p: Uint8Array): Promise<ReadResult> {
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return read(this.rid, p);
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}
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close(): void {
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close(this.rid);
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}
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}
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/** An instance of `File` for stdin. */
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export const stdin = new File(0);
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/** An instance of `File` for stdout. */
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export const stdout = new File(1);
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/** An instance of `File` for stderr. */
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export const stderr = new File(2);
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// TODO This is just a placeholder - not final API.
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export type OpenMode = "r" | "w" | "w+" | "x";
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/** A factory function for creating instances of `File` associated with the
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* supplied file name.
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*/
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export function create(filename: string): Promise<File> {
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return open(filename, "x");
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}
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/** Open a file and return an instance of the `File` object.
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*
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* import * as deno from "deno";
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* (async () => {
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* const file = await deno.open("/foo/bar.txt");
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* })();
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*/
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export async function open(
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filename: string,
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mode: OpenMode = "r"
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): Promise<File> {
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const builder = flatbuffers.createBuilder();
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const filename_ = builder.createString(filename);
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msg.Open.startOpen(builder);
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msg.Open.addFilename(builder, filename_);
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const inner = msg.Open.endOpen(builder);
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const baseRes = await dispatch.sendAsync(builder, msg.Any.Open, inner);
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assert(baseRes != null);
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assert(msg.Any.OpenRes === baseRes!.innerType());
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const res = new msg.OpenRes();
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assert(baseRes!.inner(res) != null);
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const rid = res.rid();
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return new File(rid);
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}
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/** Read from a file ID into an array buffer.
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*
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* Resolves with the `ReadResult` for the operation.
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*/
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export async function read(rid: number, p: Uint8Array): Promise<ReadResult> {
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const builder = flatbuffers.createBuilder();
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msg.Read.startRead(builder);
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msg.Read.addRid(builder, rid);
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const inner = msg.Read.endRead(builder);
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const baseRes = await dispatch.sendAsync(builder, msg.Any.Read, inner, p);
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assert(baseRes != null);
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assert(msg.Any.ReadRes === baseRes!.innerType());
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const res = new msg.ReadRes();
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assert(baseRes!.inner(res) != null);
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return { nread: res.nread(), eof: res.eof() };
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}
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/** Write to the file ID the contents of the array buffer.
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*
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* Resolves with the number of bytes written.
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*/
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export async function write(rid: number, p: Uint8Array): Promise<number> {
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const builder = flatbuffers.createBuilder();
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msg.Write.startWrite(builder);
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msg.Write.addRid(builder, rid);
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const inner = msg.Write.endWrite(builder);
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const baseRes = await dispatch.sendAsync(builder, msg.Any.Write, inner, p);
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assert(baseRes != null);
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assert(msg.Any.WriteRes === baseRes!.innerType());
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const res = new msg.WriteRes();
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assert(baseRes!.inner(res) != null);
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return res.nbyte();
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}
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/** Close the file ID. */
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export function close(rid: number): void {
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const builder = flatbuffers.createBuilder();
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msg.Close.startClose(builder);
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msg.Close.addRid(builder, rid);
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const inner = msg.Close.endClose(builder);
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dispatch.sendSync(builder, msg.Any.Close, inner);
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}
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