private final Map<Character, String> replacementMap = new HashMap<>();
    private char safeMin = Character.MIN_VALUE;
    private char safeMax = Character.MAX_VALUE;
    @CheckForNull private String unsafeReplacement = null;

    // The constructor is exposed via the builder() method above.
    private Builder() {}

    /**
     * Sets the safe range of characters for the escaper. Characters in this range that have no

  }

  /**
   * Returns the escaped form of the given character, or {@code null} if this character does not
   * need to be escaped. If an empty array is returned, this effectively strips the input character
   * from the resulting text.
   *
   * <p>If the character does not need to be escaped, this method should return {@code null}, rather
   * than a one-character array containing the character itself. This enables the escaping algorithm

   * Returns the index of the first matching BMP character in a character sequence, or {@code -1} if
   * no matching character is present.
   *
   * <p>The default implementation iterates over the sequence in forward order calling {@link
   * #matches} for each character.
   *
   * @param sequence the character sequence to examine from the beginning
   * @return an index, or {@code -1} if no character matches
   */

 * @author David Beaumont
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class ArrayBasedUnicodeEscaperTest extends TestCase {
  private static final ImmutableMap<Character, String> NO_REPLACEMENTS = ImmutableMap.of();
  private static final ImmutableMap<Character, String> SIMPLE_REPLACEMENTS =
      ImmutableMap.of(
          '\n', "<newline>",
          '\t', "<tab>",
          '&', "<and>");

  private boolean sawReturn;

  /**
   * Process additional characters from the stream. When a line separator is found the contents of
   * the line and the line separator itself are passed to the abstract {@link #handleLine} method.
   *
   * @param cbuf the character buffer to process
   * @param off the offset into the buffer
   * @param len the number of characters to process
   * @throws IOException if an I/O error occurs

 *       doing something and finally closing the writer that was opened.
 * </ul>
 *
 * <p>Any {@link ByteSink} may be viewed as a {@code CharSink} with a specific {@linkplain Charset
 * character encoding} using {@link ByteSink#asCharSink(Charset)}. Characters written to the
 * resulting {@code CharSink} will written to the {@code ByteSink} as encoded bytes.
 *
 * @since 14.0
 * @author Colin Decker
 */
@J2ktIncompatible
@GwtIncompatible

    // which means they are treated as pairs of safe characters).
    builder.setSafeRange(Character.MIN_VALUE, '\uFFFD');
    // Unsafe characters are replaced with the Unicode replacement character.
    builder.setUnsafeReplacement("\uFFFD");

    /*
     * Except for \n, \t, and \r, all ASCII control characters are replaced with the Unicode
     * replacement character.
     *

  private boolean doneFlushing;

  /**
   * Creates a new input stream that will encode the characters from {@code reader} into bytes using
   * the given character set. Malformed input and unmappable characters will be replaced.
   *
   * @param reader input source
   * @param charset character set used for encoding chars to bytes
   * @param bufferSize size of internal input and output buffers

          buffer |= charToTwoUtf8Bytes(c) << shift;
          shift += 16;
          len += 2;
        } else if (c < Character.MIN_SURROGATE || c > Character.MAX_SURROGATE) {
          buffer |= charToThreeUtf8Bytes(c) << shift;
          shift += 24;
          len += 3;
        } else {
          int codePoint = Character.codePointAt(input, i);
          if (codePoint == c) {

    return (char)
        (Character.MIN_LOW_SURROGATE
            + random.nextInt(Character.MAX_LOW_SURROGATE - Character.MIN_LOW_SURROGATE + 1));
  }

  static char randomHighSurrogate(Random random) {
    return (char)
        (Character.MIN_HIGH_SURROGATE
            + random.nextInt(Character.MAX_HIGH_SURROGATE - Character.MIN_HIGH_SURROGATE + 1));
  }