react-native-fast-io/lib/module/w3c/blob.js

Modern IO for React Native, built on top of Nitro and Web standards

"use strict";

import { ReadableStream } from "./streams.js";
import { TextDecoder } from "./text.js";
export class Blob {
  get size() {
    return this._size;
  }
  constructor(parts = [], options = {}) {
    this.parts = parts;
    this.type = options?.type?.toLowerCase() || '';
    this._size = calculateSize(parts);
  }
  slice() {
    throw new Error('Not implemented');
  }
  stream() {
    const streams = this.parts.map(part => {
      if (part instanceof Blob) {
        return part.stream();
      }
      return new ReadableStream({
        start(controller) {
          // tbd: handle all types and convert to Uint8Array
          // @ts-ignore
          controller.enqueue(part);
          controller.close();
        }
      });
    });
    return new ReadableStream({
      async start(controller) {
        try {
          for (const stream of streams) {
            for await (const chunk of stream) {
              controller.enqueue(chunk);
            }
          }
          controller.close();
        } catch (error) {
          controller.error(error);
        }
      }
    });
  }
  async arrayBuffer() {
    const view = await this.bytes();
    return view.buffer;
  }
  async bytes() {
    const result = new ArrayBuffer(this.size);
    const view = new Uint8Array(result);
    let offset = 0;
    for await (const chunk of this.stream()) {
      view.set(chunk, offset);
      offset += chunk.length;
    }
    return view;
  }
  async text() {
    const buffer = await this.bytes();
    return new TextDecoder().decode(buffer);
  }
  get [Symbol.toStringTag]() {
    return 'Blob';
  }
}

// tbd: verify this
function calculateSize(parts) {
  return parts.reduce((acc, part) => {
    if (part instanceof ArrayBuffer || ArrayBuffer.isView(part)) {
      return acc + part.byteLength;
    }
    if (part instanceof Blob) {
      return acc + part.size;
    }
    if (typeof part === 'string') {
      return acc + new TextEncoder().encode(part).length;
    }
    return acc;
  }, 0);
}
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