Method scanTextFile

packages/kaos/src/local.ts:495–531

(path: string)

  }

  async scanTextFile(path: string): Promise<TextFileScan> {
    const resolved = this._resolvePath(path);
    const fh = await open(resolved, 'r');
    try {
      const buf = Buffer.alloc(READ_CHUNK_SIZE);
      const flags: LineEndingFlags = { hasCrLf: false, hasLf: false, hasLoneCr: false };
      const validator = createUtf8Validator();
      let totalLines = 0;
      let totalBytes = 0;
      let endsWithNewline = false;
      let hasNul = false;
      let prevWasCr = false;

      while (true) {
        const { bytesRead } = await fh.read(buf, 0, buf.length, null);
        if (bytesRead === 0) break;
        const chunk = buf.subarray(0, bytesRead);
        validator.write(chunk);
        for (let i = 0; i < chunk.length; i += 1) {
          const byte = chunk[i];
          if (byte === undefined) continue;
          if (byte === 0) hasNul = true;
          if (byte === 0x0a) totalLines += 1;
        }
        prevWasCr = updateLineEndingFlagsFromBytes(flags, chunk, prevWasCr);
        totalBytes += bytesRead;
        endsWithNewline = chunk[bytesRead - 1] === 0x0a;
      }

      if (prevWasCr) flags.hasLoneCr = true;
      validator.end();
      if (totalBytes > 0 && !endsWithNewline) totalLines += 1;
      return { totalLines, endsWithNewline, hasNul, lineEndingFlags: flags };
    } finally {
      await fh.close();
    }
  }

  async *readLineRange(
    path: string,