}

  static CharMatcher from(BitSet chars, String description) {
    // Compute the filter.
    long filter = 0;
    int size = chars.cardinality();
    boolean containsZero = chars.get(0);
    // Compute the hash table.
    char[] table = new char[chooseTableSize(size)];
    int mask = table.length - 1;
    for (int c = chars.nextSetBit(0); c != -1; c = chars.nextSetBit(c + 1)) {

          private final char[] unknown = new char[] {'?'};

          @Override
          protected char[] escapeUnsafe(char c) {
            return unknown;
          }
        };
    EscaperAsserts.assertBasic(replacingEscaper);

    // Replacements are applied first regardless of whether the character is in
    // the safe range or not ('&' is a safe char while '\t' and '\n' are not).

    public Escaper build() {
      return new ArrayBasedCharEscaper(replacementMap, safeMin, safeMax) {
        private final char @Nullable [] replacementChars =
            unsafeReplacement != null ? unsafeReplacement.toCharArray() : null;

        @Override
        protected char @Nullable [] escapeUnsafe(char c) {
          return replacementChars;
        }
      };
    }
  }

  /**

  private static final class AnyOf extends CharMatcher {

    private final char[] chars;

    AnyOf(CharSequence chars) {
      this.chars = chars.toString().toCharArray();
      Arrays.sort(this.chars);
    }

    @Override
    public boolean matches(char c) {
      return Arrays.binarySearch(chars, c) >= 0;
    }

    @Override

// Sets the attrs in the `ForwardOperation`.
absl::Status SetAttrString(AbstractOperation*, const char* attr_name,
                           const char* data, size_t length, ForwardOperation*);
absl::Status SetAttrInt(AbstractOperation*, const char* attr_name,
                        int64_t value, ForwardOperation*);
absl::Status SetAttrFloat(AbstractOperation*, const char* attr_name,
                          float value, ForwardOperation*);

            int i = 0;
            do {
                if (i >= buf.length) {
                    final char[] nb = new char[buf.length * 2];
                    System.arraycopy(buf, 0, nb, 0, buf.length);
                    buf = nb;
                }
                buf[i++] = (char) peekc;
                peekc = read();
                peekct = peekc < 0 ? CT_WHITESPACE : peekc < 256 ? ctype[peekc] : CT_ALPHA;

            char charA = (i < a.length) ? a[i] : '\0';
            char charB = (i < b.length) ? b[i] : '\0';
            result &= (charA == charB) ? 1 : 0;
        }

        return result == 1;
    }

    /** The authentication type */
    private AuthenticationType type;
    /** The authentication domain */
    private String domain;
    /** The username for authentication */

        assertNotNull(constantTimeMethod, "constantTimeEquals method should exist");
        constantTimeMethod.setAccessible(true);

        // Test the method directly
        char[] password1 = "testpassword".toCharArray();
        char[] password2 = "testpassword".toCharArray();
        char[] password3 = "testpassworX".toCharArray();

  static CharEscaper createSimpleCharEscaper(ImmutableMap<Character, char[]> replacementMap) {
    return new CharEscaper() {
      @Override
      protected char @Nullable [] escape(char c) {
        return replacementMap.get(c);
      }
    };
  }

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

    }
  }

  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);
      }
    }