import { createLPS } from "./_common.ts";
export class TextDelimiterStream extends TransformStream<string, string> { #buf = ""; #delimiter: string; #inspectIndex = 0; #matchIndex = 0; #delimLPS: Uint8Array;
constructor(delimiter: string) { super({ transform: (chunk, controller) => { this.#handle(chunk, controller); }, flush: (controller) => { controller.enqueue(this.#buf); }, });
this.#delimiter = delimiter; this.#delimLPS = createLPS(new TextEncoder().encode(delimiter)); }
#handle( chunk: string, controller: TransformStreamDefaultController<string>, ) { this.#buf += chunk; let localIndex = 0; while (this.#inspectIndex < this.#buf.length) { if (chunk[localIndex] === this.#delimiter[this.#matchIndex]) { this.#inspectIndex++; localIndex++; this.#matchIndex++; if (this.#matchIndex === this.#delimiter.length) { const matchEnd = this.#inspectIndex - this.#delimiter.length; const readyString = this.#buf.slice(0, matchEnd); controller.enqueue(readyString); this.#buf = this.#buf.slice(this.#inspectIndex); this.#inspectIndex = 0; this.#matchIndex = 0; } } else { if (this.#matchIndex === 0) { this.#inspectIndex++; localIndex++; } else { this.#matchIndex = this.#delimLPS[this.#matchIndex - 1]; } } } }}