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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// Based on https://github.com/golang/go/blob/0452f9460f50f0f0aba18df43dc2b31906fb66cc/src/io/io.go// Copyright 2009 The Go Authors. All rights reserved.// Use of this source code is governed by a BSD-style// license that can be found in the LICENSE file.
import { Buffer } from "./buffer.ts";
/** * Reader utility for strings. * * @example * ```ts * import { StringReader } from "https://deno.land/std@$STD_VERSION/io/mod.ts"; * * const data = new Uint8Array(6); * const r = new StringReader("abcdef"); * const res0 = await r.read(data); * const res1 = await r.read(new Uint8Array(6)); * * // Number of bytes read * console.log(res0); // 6 * console.log(res1); // null, no byte left to read. EOL * * // text * * console.log(new TextDecoder().decode(data)); // abcdef * ``` * * **Output:** * * ```text * 6 * null * abcdef * ``` */export class StringReader extends Buffer {  constructor(s: string) {    super(new TextEncoder().encode(s).buffer);  }}
/** Reader utility for combining multiple readers */export class MultiReader implements Deno.Reader {  readonly #readers: Deno.Reader[];  #currentIndex = 0;
  constructor(readers: Deno.Reader[]) {    this.#readers = [...readers];  }
  async read(p: Uint8Array): Promise<number | null> {    const r = this.#readers[this.#currentIndex];    if (!r) return null;    const result = await r.read(p);    if (result === null) {      this.#currentIndex++;      return 0;    }    return result;  }}
/** * A `LimitedReader` reads from `reader` but limits the amount of data returned to just `limit` bytes. * Each call to `read` updates `limit` to reflect the new amount remaining. * `read` returns `null` when `limit` <= `0` or * when the underlying `reader` returns `null`. */export class LimitedReader implements Deno.Reader {  constructor(public reader: Deno.Reader, public limit: number) {}
  async read(p: Uint8Array): Promise<number | null> {    if (this.limit <= 0) {      return null;    }
    if (p.length > this.limit) {      p = p.subarray(0, this.limit);    }    const n = await this.reader.read(p);    if (n == null) {      return null;    }
    this.limit -= n;    return n;  }}