// original character value.
  @VisibleForTesting
  static char[][] createReplacementArray(Map<Character, String> map) {
    checkNotNull(map); // GWT specific check (do not optimize)
    if (map.isEmpty()) {
      return EMPTY_REPLACEMENT_ARRAY;
    }
    char max = Collections.max(map.keySet());
    char[][] replacements = new char[max + 1][];
    for (Character c : map.keySet()) {

    // read char by char
    CharSequenceReader reader = new CharSequenceReader(charSequence);
    for (int i = 0; i < expected.length(); i++) {
      assertEquals(expected.charAt(i), reader.read());
    }
    assertFullyRead(reader);

    // read all to one array
    reader = new CharSequenceReader(charSequence);
    char[] buf = new char[expected.length()];

final class Platform {

  private static final char[] CHAR_BUFFER = new char[1024];

  static char[] charBufferFromThreadLocal() {
    // ThreadLocal is not available to GWT, so we always reuse the same
    // instance.  It is always safe to return the same instance because
    // javascript is single-threaded, and only used by blocks that doesn't
    // involve async callbacks.
    return CHAR_BUFFER;
  }

  private Platform() {}

    }
  }

  public void testUtf8() {
    char[] charsA = new char[128];
    char[] charsB = new char[128];

    for (int i = 0; i < charsA.length; i++) {
      if (i < 100) {
        charsA[i] = 'a';
        charsB[i] = 'a';
      } else {
        // Both two-byte characters, but must be different
        charsA[i] = (char) (0x0180 + i);
        charsB[i] = (char) (0x0280 + i);
      }
    }

        new UnicodeEscaper() {
          // Canonical escaper method that only escapes lower case ASCII letters.
          @Override
          protected char @Nullable [] escape(int cp) {
            return ('a' <= cp && cp <= 'z') ? new char[] {Character.toUpperCase((char) cp)} : null;
          }
          // Inefficient implementation that defines all letters as escapable.
          @Override

    return new CharEscaper() {
      @Override
      protected char[] escape(char c) {
        return replacementMap.get(c);
      }
    };
  }

  // A trivial non-optimized escaper for testing.
  static UnicodeEscaper createSimpleUnicodeEscaper(
      final ImmutableMap<Integer, char[]> replacementMap) {
    return new UnicodeEscaper() {

      assertThat(expected).hasMessageThat().isEqualTo(msg);
    }
  }

  public void testBadArguments_plusforspace() {
    // space can be a safe char if plusForSpace is false
    PercentEscaper unused = new PercentEscaper(" ", false);

    // space cannot be a safe char is plusForSpace is true
    String msg = "plusForSpace cannot be specified when space is a 'safe' character";
    try {
      new PercentEscaper(" ", true);

    @Override
    MessageBuilder append(char c);

    /**
     * Append content to the message buffer.
     *
     * @param value the content to append
     * @param offset the index of the first {@code char} to append
     * @param len the number of {@code char}s to append
     * @return the current builder
     */
    @Nonnull
    default MessageBuilder a(char[] value, int offset, int len) {

    this.source = factory.createSource(data);
  }

  public void testOpenStream() throws IOException {
    Reader reader = source.openStream();

    StringWriter writer = new StringWriter();
    char[] buf = new char[64];
    int read;
    while ((read = reader.read(buf)) != -1) {
      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    assertExpectedString(writer.toString());
  }

   */
  AppendableWriter(Appendable target) {
    this.target = checkNotNull(target);
  }

  /*
   * Abstract methods from Writer
   */

  @Override
  public void write(char[] cbuf, int off, int len) throws IOException {
    checkNotClosed();
    // It turns out that creating a new String is usually as fast, or faster
    // than wrapping cbuf in a light-weight CharSequence.