lobe-chat

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import brotliPromise from 'brotli-wasm';
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/**
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 * @title 字符串压缩器
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 */
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export class StrCompressor {
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  /**
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   * @ignore
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   */
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  private instance!: {
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    compress(buf: Uint8Array, options?: any): Uint8Array;
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    decompress(buf: Uint8Array): Uint8Array;
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  };
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  async init(): Promise<void> {
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    this.instance = await brotliPromise; // Import is async in browsers due to wasm requirements!
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  }
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  /**
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   * @title 压缩字符串
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   * @param str - 要压缩的字符串
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   * @returns 压缩后的字符串
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   */
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  compress(str: string): string {
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    const input = new TextEncoder().encode(str);
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    const compressedData = this.instance.compress(input);
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    return this.urlSafeBase64Encode(compressedData);
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  }
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  /**
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   * @title 解压缩字符串
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   * @param str - 要解压缩的字符串
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   * @returns 解压缩后的字符串
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   */
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  decompress(str: string): string {
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    const compressedData = this.urlSafeBase64Decode(str);
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    const decompressedData = this.instance.decompress(compressedData);
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    return new TextDecoder().decode(decompressedData);
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  }
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  /**
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   * @title 异步压缩字符串
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   * @param str - 要压缩的字符串
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   * @returns Promise
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   */
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  async compressAsync(str: string) {
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    const brotli = await brotliPromise;
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    const input = new TextEncoder().encode(str);
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    const compressedData = brotli.compress(input);
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    return this.urlSafeBase64Encode(compressedData);
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  }
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  /**
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   * @title 异步解压缩字符串
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   * @param str - 要解压缩的字符串
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   * @returns Promise
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   */
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  async decompressAsync(str: string) {
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    const brotli = await brotliPromise;
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    const compressedData = this.urlSafeBase64Decode(str);
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    const decompressedData = brotli.decompress(compressedData);
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    return new TextDecoder().decode(decompressedData);
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  }
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  private urlSafeBase64Encode = (data: Uint8Array): string => {
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    const base64Str = btoa(String.fromCharCode(...data));
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    return base64Str.replaceAll('+', '_0_').replaceAll('/', '_').replace(/=+$/, '');
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  };
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  private urlSafeBase64Decode = (data: string): Uint8Array => {
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    let after = data.replaceAll('_0_', '+').replaceAll('_', '/');
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    while (after.length % 4) {
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      after += '=';
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    }
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    return new Uint8Array([...atob(after)].map((c) => c.charCodeAt(0)));
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  };
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}
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export const Compressor = new StrCompressor();
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