*
   * <p>Anything after a {@code %} in an IPv6 address is ignored (assumed to be a Scope ID).
   *
   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
   * want to accept ASCII digits only, you can use something like {@code
   * CharMatcher.ascii().matchesAllOf(ipString)}.
   *

    assertUnescaped(e, 'a');
    assertUnescaped(e, 'z');
    assertUnescaped(e, 'A');
    assertUnescaped(e, 'Z');
    assertUnescaped(e, '0');
    assertUnescaped(e, '9');

    // Unreserved characters used in java.net.URLEncoder
    assertUnescaped(e, '-');
    assertUnescaped(e, '_');
    assertUnescaped(e, '.');
    assertUnescaped(e, '*');

    assertEscaping(e, "%00", '\u0000'); // nul

public abstract class ByteSource {

  /** Constructor for use by subclasses. */
  protected ByteSource() {}

  /**
   * Returns a {@link CharSource} view of this byte source that decodes bytes read from this source
   * as characters using the given {@link Charset}.
   *
   * <p>If {@link CharSource#asByteSource} is called on the returned source with the same charset,

          TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS * TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS
          +
          // Permutations of one and two byte characters
          3
              * TWO_BYTE_ROUNDTRIPPABLE_CHARACTERS
              * ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS
              * ONE_BYTE_ROUNDTRIPPABLE_CHARACTERS
          +
          // Four byte characters
          FOUR_BYTE_ROUNDTRIPPABLE_CHARACTERS;

    return total;
  }

  /**
   * Discards {@code n} characters of data from the reader. This method will block until the full
   * amount has been skipped. Does not close the reader.
   *
   * @param reader the reader to read from
   * @param n the number of characters to skip
   * @throws EOFException if this stream reaches the end before skipping all the characters
   * @throws IOException if an I/O error occurs
   */

 * href="http://www.unicode.org/glossary/#BMP_character">BMP characters</a>. It does not understand
 * <a href="http://www.unicode.org/glossary/#supplementary_code_point">supplementary Unicode code
 * points</a> in the range {@code 0x10000} to {@code 0x10FFFF} which includes the majority of
 * assigned characters, including important CJK characters and emoji.
 *
 * <p>Supplementary characters are <a

   * <p>Note however that if your escaper does not escape characters in the supplementary range, you
   * should either continue to validate the correctness of any surrogate characters encountered or
   * provide a clear warning to users that your escaper does not validate its input.
   *
   * <p>See {@link com.google.common.net.PercentEscaper} for an example.
   *
   * @param csq a sequence of characters

     * for this entry is one, this is simply the string representation of the corresponding element.
     * Otherwise, it is the string representation of the element, followed by the three characters
     * {@code " x "} (space, letter x, space), followed by the count.
     */
    @Override
    String toString();
  }

  // Comparison and hashing

  /**

    assertEquals("&lt;tab&gt;", xmlEscaper.escape("<tab>"));

    // Test all non-escaped ASCII characters.
    String s =
        "!@#$%^*()_+=-/?\\|]}[{,.;:"
            + "abcdefghijklmnopqrstuvwxyz"
            + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            + "1234567890";
    assertEquals(s, xmlEscaper.escape(s));

    // Test ASCII control characters.
    for (char ch = 0; ch < 0x20; ch++) {
      if (ch == '\t' || ch == '\n' || ch == '\r') {

   *
   * @param escaper the non-null escaper to test
   */
  public static void assertBasic(Escaper escaper) throws IOException {
    // Escapers operate on characters: no characters, no escaping.
    Assert.assertEquals("", escaper.escape(""));
    // Assert that escapers throw null pointer exceptions.
    try {
      escaper.escape((String) null);