native-file-system-adapter-ts/src/file-system-writable-file-stream.ts

Native File System API

import { FileSystemWriteChunkType, FileSystemWritableFileStream } from './types';

export class FileSystemWritableFileStreamImpl extends WritableStream implements FileSystemWritableFileStream {
  private _closed: boolean;

  constructor(
    underlyingSink?: UnderlyingSink<FileSystemWriteChunkType>,
    strategy?: QueuingStrategy<FileSystemWriteChunkType>,
  ) {
    super(underlyingSink, strategy);

    // Stupid Safari hack to extend native classes
    // https://bugs.webkit.org/show_bug.cgi?id=226201
    Object.setPrototypeOf(this, FileSystemWritableFileStreamImpl.prototype);

    this._closed = false;
  }

  close() {
    this._closed = true;
    const w = this.getWriter();
    const p = w.close();
    w.releaseLock();
    return p;
    // return super.close ? super.close() : this.getWriter().close()
  }

  seek(position: number) {
    return this.write({ type: 'seek', position });
  }

  truncate(size: number) {
    return this.write({ type: 'truncate', size });
  }

  write(data: FileSystemWriteChunkType) {
    if (this._closed) {
      return Promise.reject(new TypeError('Cannot write to a CLOSED writable stream'));
    }

    const writer = this.getWriter();
    const p = writer.write(data);
    writer.releaseLock();
    return p;
  }
}

Object.defineProperty(FileSystemWritableFileStreamImpl.prototype, Symbol.toStringTag, {
  value: 'FileSystemWritableFileStream',
  writable: false,
  enumerable: false,
  configurable: true,
});

Object.defineProperties(FileSystemWritableFileStreamImpl.prototype, {
  close: { enumerable: true },
  seek: { enumerable: true },
  truncate: { enumerable: true },
  write: { enumerable: true },
});