rea/src/process/DecodedNdjsonLineBuffer.ts

/** Incrementally splits decoded newline-delimited JSON socket data into lines. */
export class DecodedNdjsonLineBuffer {
  #buffer = "";
  #fragments: string[] = [];

  /**
   * Consume a chunk and yield each complete, trimmed, nonblank line.
   * Unconsumed complete lines remain buffered if iteration stops early.
   */
  *push(chunk: string): Generator<string> {
    this.#fragments.push(chunk);
    if (!chunk.includes("\n")) return;
    this.#buffer += this.#fragments.join("");
    this.#fragments = [];

    let newline = this.#buffer.indexOf("\n");
    while (newline >= 0) {
      const encodedLine = this.#buffer.slice(0, newline);
      this.#buffer = this.#buffer.slice(newline + 1);
      const line = encodedLine.trim();
      if (line.length > 0) yield line;
      newline = this.#buffer.indexOf("\n");
    }
  }

  /** Drop incomplete and unconsumed lines when a session closes. */
  reset(): void {
    this.#buffer = "";
    this.#fragments = [];
  }
}