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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
interface TextLineStreamOptions {  /** Allow splitting by solo \r */  allowCR: boolean;}
/** Transform a stream into a stream where each chunk is divided by a newline, * be it `\n` or `\r\n`. `\r` can be enabled via the `allowCR` option. * * ```ts * import { TextLineStream } from "https://deno.land/std@$STD_VERSION/streams/text_line_stream.ts"; * const res = await fetch("https://example.com"); * const lines = res.body! *   .pipeThrough(new TextDecoderStream()) *   .pipeThrough(new TextLineStream()); * ``` */export class TextLineStream extends TransformStream<string, string> {  readonly #allowCR: boolean;  #buf = "";
  constructor(options?: TextLineStreamOptions) {    super({      transform: (chunk, controller) => this.#handle(chunk, controller),      flush: (controller) => {        if (this.#buf.length > 0) {          if (            this.#allowCR &&            this.#buf[this.#buf.length - 1] === "\r"          ) controller.enqueue(this.#buf.slice(0, -1));          else controller.enqueue(this.#buf);        }      },    });    this.#allowCR = options?.allowCR ?? false;  }
  #handle(chunk: string, controller: TransformStreamDefaultController<string>) {    chunk = this.#buf + chunk;
    for (;;) {      const lfIndex = chunk.indexOf("\n");
      if (this.#allowCR) {        const crIndex = chunk.indexOf("\r");
        if (          crIndex !== -1 && crIndex !== (chunk.length - 1) &&          (lfIndex === -1 || (lfIndex - 1) > crIndex)        ) {          controller.enqueue(chunk.slice(0, crIndex));          chunk = chunk.slice(crIndex + 1);          continue;        }      }
      if (lfIndex !== -1) {        let crOrLfIndex = lfIndex;        if (chunk[lfIndex - 1] === "\r") {          crOrLfIndex--;        }        controller.enqueue(chunk.slice(0, crOrLfIndex));        chunk = chunk.slice(lfIndex + 1);        continue;      }
      break;    }
    this.#buf = chunk;  }}