deno.land / std@0.224.0 / io / string_writer.ts
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.
import type { Writer, WriterSync } from "./types.ts";
const decoder = new TextDecoder();
/** * Writer utility for buffering string chunks. * * @example * ```ts * import { * copyN, * StringReader, * StringWriter, * } from "https://deno.land/std@$STD_VERSION/io/mod.ts"; * import { copy } from "https://deno.land/std@$STD_VERSION/io/copy.ts"; * * const w = new StringWriter("base"); * const r = new StringReader("0123456789"); * await copyN(r, w, 4); // copy 4 bytes * * // Number of bytes read * console.log(w.toString()); //base0123 * * await copy(r, w); // copy all * console.log(w.toString()); // base0123456789 * ``` * * **Output:** * * ```text * base0123 * base0123456789 * ``` * * @deprecated This will be removed in 1.0.0. Use the {@link https://developer.mozilla.org/en-US/docs/Web/API/Streams_API | Web Streams API} instead. */export class StringWriter implements Writer, WriterSync { #chunks: Uint8Array[] = []; #byteLength = 0; #cache: string | undefined;
constructor(private base: string = "") { const c = new TextEncoder().encode(base); this.#chunks.push(c); this.#byteLength += c.byteLength; }
write(p: Uint8Array): Promise<number> { return Promise.resolve(this.writeSync(p)); }
writeSync(p: Uint8Array): number { this.#chunks.push(new Uint8Array(p)); this.#byteLength += p.byteLength; this.#cache = undefined; return p.byteLength; }
toString(): string { if (this.#cache) { return this.#cache; } const buf = new Uint8Array(this.#byteLength); let offs = 0; for (const chunk of this.#chunks) { buf.set(chunk, offs); offs += chunk.byteLength; } this.#cache = decoder.decode(buf); return this.#cache; }}
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