text: /**
   * @license
   * Copyright 2016 Google Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  goog.provide('shaka.util.StringUtils');
  
  goog.require('goog.asserts');
  goog.require('shaka.log');
  goog.require('shaka.util.BufferUtils');
  goog.require('shaka.util.Error');
  goog.require('shaka.util.Iterables');
  goog.require('shaka.util.Lazy');
  
  
  /**
   * @namespace shaka.util.StringUtils
   * @summary A set of string utility functions.
   * @export
   */
  shaka.util.StringUtils = class {
    /**
     * Creates a string from the given buffer as UTF-8 encoding.
     *
     * @param {?BufferSource} data
     * @return {string}
     * @export
     */
    static fromUTF8(data) {
      if (!data) {
        return '';
      }
  
      let uint8 = shaka.util.BufferUtils.toUint8(data);
      // If present, strip off the UTF-8 BOM.
      if (uint8[0] == 0xef && uint8[1] == 0xbb && uint8[2] == 0xbf) {
        uint8 = uint8.subarray(3);
      }
  
      // http://stackoverflow.com/a/13691499
      const utf8 = shaka.util.StringUtils.fromCharCode(uint8);
      // This converts each character in the string to an escape sequence.  If the
      // character is in the ASCII range, it is not converted; otherwise it is
      // converted to a URI escape sequence.
      // Example: '\x67\x35\xe3\x82\xac' -> 'g#%E3%82%AC'
      const escaped = escape(utf8);
      // Decode the escaped sequence.  This will interpret UTF-8 sequences into
      // the correct character.
      // Example: 'g#%E3%82%AC' -> 'g#€'
      try {
        return decodeURIComponent(escaped);
      } catch (e) {
        throw new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL, shaka.util.Error.Category.TEXT,
            shaka.util.Error.Code.BAD_ENCODING);
      }
    }
  
  
    /**
     * Creates a string from the given buffer as UTF-16 encoding.
     *
     * @param {?BufferSource} data
     * @param {boolean} littleEndian
           true to read little endian, false to read big.
     * @param {boolean=} noThrow true to avoid throwing in cases where we may
     *     expect invalid input.  If noThrow is true and the data has an odd
     *     length,it will be truncated.
     * @return {string}
     * @export
     */
    static fromUTF16(data, littleEndian, noThrow) {
      if (!data) {
        return '';
      }
  
      if (!noThrow && data.byteLength % 2 != 0) {
        shaka.log.error('Data has an incorrect length, must be even.');
        throw new shaka.util.Error(
            shaka.util.Error.Severity.CRITICAL, shaka.util.Error.Category.TEXT,
            shaka.util.Error.Code.BAD_ENCODING);
      }
  
      // Use a DataView to ensure correct endianness.
      const length = Math.floor(data.byteLength / 2);
      const arr = new Uint16Array(length);
      const dataView = shaka.util.BufferUtils.toDataView(data);
      for (const i of shaka.util.Iterables.range(length)) {
        arr[i] = dataView.getUint16(i * 2, littleEndian);
      }
      return shaka.util.StringUtils.fromCharCode(arr);
    }
  
  
    /**
     * Creates a string from the given buffer, auto-detecting the encoding that is
     * being used.  If it cannot detect the encoding, it will throw an exception.
     *
     * @param {?BufferSource} data
     * @return {string}
     * @export
     */
    static fromBytesAutoDetect(data) {
      const StringUtils = shaka.util.StringUtils;
      if (!data) {
        return '';
      }
  
      const uint8 = shaka.util.BufferUtils.toUint8(data);
      if (uint8[0] == 0xef && uint8[1] == 0xbb && uint8[2] == 0xbf) {
        return StringUtils.fromUTF8(uint8);
      } else if (uint8[0] == 0xfe && uint8[1] == 0xff) {
        return StringUtils.fromUTF16(uint8.subarray(2), false /* littleEndian */);
      } else if (uint8[0] == 0xff && uint8[1] == 0xfe) {
        return StringUtils.fromUTF16(uint8.subarray(2), true /* littleEndian */);
      }
  
      const isAscii = (i) => {
        // arr[i] >= ' ' && arr[i] <= '~';
        return uint8.byteLength <= i || (uint8[i] >= 0x20 && uint8[i] <= 0x7e);
      };
  
      shaka.log.debug(
          'Unable to find byte-order-mark, making an educated guess.');
      if (uint8[0] == 0 && uint8[2] == 0) {
        return StringUtils.fromUTF16(data, false /* littleEndian */);
      } else if (uint8[1] == 0 && uint8[3] == 0) {
        return StringUtils.fromUTF16(data, true /* littleEndian */);
      } else if (isAscii(0) && isAscii(1) && isAscii(2) && isAscii(3)) {
        return StringUtils.fromUTF8(data);
      }
  
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.TEXT,
          shaka.util.Error.Code.UNABLE_TO_DETECT_ENCODING);
    }
  
  
    /**
     * Creates a ArrayBuffer from the given string, converting to UTF-8 encoding.
     *
     * @param {string} str
     * @return {!ArrayBuffer}
     * @export
     */
    static toUTF8(str) {
      // http://stackoverflow.com/a/13691499
      // Converts the given string to a URI encoded string.  If a character falls
      // in the ASCII range, it is not converted; otherwise it will be converted
      // to a series of URI escape sequences according to UTF-8.
      // Example: 'g#€' -> 'g#%E3%82%AC'
      const encoded = encodeURIComponent(str);
      // Convert each escape sequence individually into a character.  Each escape
      // sequence is interpreted as a code-point, so if an escape sequence happens
      // to be part of a multi-byte sequence, each byte will be converted to a
      // single character.
      // Example: 'g#%E3%82%AC' -> '\x67\x35\xe3\x82\xac'
      const utf8 = unescape(encoded);
  
      const result = new Uint8Array(utf8.length);
      const enumerate = (it) => shaka.util.Iterables.enumerate(it);
      for (const {i, item} of enumerate(utf8)) {
        result[i] = item.charCodeAt(0);
      }
      return shaka.util.BufferUtils.toArrayBuffer(result);
    }
  
  
    /**
     * Creates a ArrayBuffer from the given string, converting to UTF-16 encoding.
     *
     * @param {string} str
     * @param {boolean} littleEndian
     * @return {!ArrayBuffer}
     * @export
     */
    static toUTF16(str, littleEndian) {
      const result = new ArrayBuffer(str.length * 2);
      const view = new DataView(result);
      const enumerate = (it) => shaka.util.Iterables.enumerate(it);
      for (const {i, item} of enumerate(str)) {
        const value = item.charCodeAt(0);
        view.setUint16(/* position= */ i * 2, value, littleEndian);
      }
      return result;
    }
  
  
    /**
     * Creates a new string from the given array of char codes.
     *
     * Using String.fromCharCode.apply is risky because you can trigger stack
     * errors on very large arrays.  This breaks up the array into several pieces
     * to avoid this.
     *
     * @param {!TypedArray} array
     * @return {string}
     */
    static fromCharCode(array) {
      return shaka.util.StringUtils.fromCharCodeImpl_.value()(array);
    }
  };
  
  
  /** @private {!shaka.util.Lazy.<function(!TypedArray):string>} */
  shaka.util.StringUtils.fromCharCodeImpl_ = new shaka.util.Lazy(() => {
    /** @param {number} size @return {boolean} */
    const supportsChunkSize = (size) => {
      try {
        const buffer = new Uint8Array(size);
        // The compiler will complain about suspicious value if this isn't
        // stored in a variable and used.
        const foo = String.fromCharCode(...buffer);
        goog.asserts.assert(foo, 'Should get value');
        return true;
      } catch (error) {
        return false;
      }
    };
  
    // Different browsers support different chunk sizes; find out the largest
    // this browser supports so we can use larger chunks on supported browsers
    // but still support lower-end devices that require small chunks.
    // 64k is supported on all major desktop browsers.
    for (let size = 64 * 1024; size > 0; size /= 2) {
      if (supportsChunkSize(size)) {
        return (buffer) => {
          let ret = '';
          for (let i = 0; i < buffer.length; i += size) {
            const subArray = buffer.subarray(i, i + size);
            ret += String.fromCharCode(...subArray);
          }
          return ret;
        };
      }
    }
    goog.asserts.assert(false, 'Unable to create a fromCharCode method');
    return null;
  });
  