*       which operate only on the ASCII characters of a string.
 * </ul>
 *
 * @author Catherine Berry
 * @author Gregory Kick
 * @since 7.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Ascii {

  private Ascii() {}

  /* The ASCII control characters, per RFC 20. */
  /**

 *       which operate only on the ASCII characters of a string.
 * </ul>
 *
 * @author Catherine Berry
 * @author Gregory Kick
 * @since 7.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Ascii {

  private Ascii() {}

  /* The ASCII control characters, per RFC 20. */
  /**

Kurt Kluever <******@****.***> 1372373349 -0400

zhenghua <******@****.***> 1492724018 -0700

    assertEquals(LOWER, Ascii.toLowerCase(UPPER));
    assertSame(LOWER, Ascii.toLowerCase(LOWER));
    assertEquals(IGNORED, Ascii.toLowerCase(IGNORED));
    assertEquals("foobar", Ascii.toLowerCase("fOobaR"));
  }

  public void testToUpperCase() {
    assertEquals(UPPER, Ascii.toUpperCase(LOWER));
    assertSame(UPPER, Ascii.toUpperCase(UPPER));
    assertEquals(IGNORED, Ascii.toUpperCase(IGNORED));

    assertEquals(LOWER, Ascii.toLowerCase(UPPER));
    assertSame(LOWER, Ascii.toLowerCase(LOWER));
    assertEquals(IGNORED, Ascii.toLowerCase(IGNORED));
    assertEquals("foobar", Ascii.toLowerCase("fOobaR"));
  }

  public void testToUpperCase() {
    assertEquals(UPPER, Ascii.toUpperCase(LOWER));
    assertSame(UPPER, Ascii.toUpperCase(UPPER));
    assertEquals(IGNORED, Ascii.toUpperCase(IGNORED));

    @Override
    String normalizeWord(String word) {
      return Ascii.toUpperCase(word);
    }

    @Override
    String convert(CaseFormat format, String s) {
      if (format == LOWER_HYPHEN) {
        return Ascii.toLowerCase(s.replace('_', '-'));
      }
      if (format == LOWER_UNDERSCORE) {
        return Ascii.toLowerCase(s);
      }
      return super.convert(format, s);
    }
  };

  public void testWhyUsAsciiIsDangerous() {
    byte[] b1 = "朝日新聞".getBytes(Charsets.US_ASCII);
    byte[] b2 = "聞朝日新".getBytes(Charsets.US_ASCII);
    byte[] b3 = "????".getBytes(Charsets.US_ASCII);
    byte[] b4 = "ニュース".getBytes(Charsets.US_ASCII);
    byte[] b5 = "スューー".getBytes(Charsets.US_ASCII);
    // Assert they are all equal (using the transitive property)
    assertTrue(Arrays.equals(b1, b2));

  }

  /** Sample CharMatcher instances for benchmarking. */
  public enum SampleMatcherConfig {
    WHITESPACE(CharMatcher.whitespace(), WHITESPACE_CHARACTERS),
    HASH(CharMatcher.is('#'), "#"),
    ASCII(CharMatcher.ascii(), ASCII_CHARACTERS),
    WESTERN_DIGIT("0123456789"),
    ALL_DIGIT(CharMatcher.digit(), ALL_DIGITS),
    OPS_5("+-*/%"),
    HEX_16(CharMatcher.inRange('0', '9').or(CharMatcher.inRange('A', 'F')), "0123456789ABCDEF"),

  }

  public void testToString() throws IOException {
    File asciiFile = getTestFile("ascii.txt");
    File i18nFile = getTestFile("i18n.txt");
    assertEquals(ASCII, Files.toString(asciiFile, Charsets.US_ASCII));
    assertEquals(I18N, Files.toString(i18nFile, Charsets.UTF_8));
    assertThat(Files.toString(i18nFile, Charsets.US_ASCII)).isNotEqualTo(I18N);
  }

  public void testWriteString() throws IOException {