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denoland-deno/js/files.ts
2018-10-19 15:25:29 -04:00

111 lines
3.4 KiB
TypeScript

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