Class Key

api/src/main/java/io/grpc/Metadata.java:670–857

Key for metadata entries. Allows for parsing and serialization of metadata. Valid characters in key names Only the following ASCII characters are allowed in the names of keys: digits: 0-9 uppercase letters: A-Z (normalized to lower) lowercase letters:

   * @see <a href="https://tools.ietf.org/html/rfc5234#appendix-B.1">RFC5234</a>
   */
  @Immutable
  public abstract static class Key<T> {

    /** Valid characters for field names as defined in RFC7230 and RFC5234. */
    private static final BitSet VALID_T_CHARS = generateValidTChars();

    /**
     * Creates a key for a binary header.
     *
     * @param name Must contain only the valid key characters as defined in the class comment. Must
     *     end with {@link #BINARY_HEADER_SUFFIX}.
     */
    public static <T> Key<T> of(String name, BinaryMarshaller<T> marshaller) {
      return new BinaryKey<>(name, marshaller);
    }

    /**
     * Creates a key for a binary header, serializing to input streams.
     *
     * @param name Must contain only the valid key characters as defined in the class comment. Must
     *     end with {@link #BINARY_HEADER_SUFFIX}.
     */
    @ExperimentalApi("https://github.com/grpc/grpc-java/issues/6575")
    public static <T> Key<T> of(String name, BinaryStreamMarshaller<T> marshaller) {
      return new LazyStreamBinaryKey<>(name, marshaller);
    }

    /**
     * Creates a key for an ASCII header.
     *
     * @param name Must contain only the valid key characters as defined in the class comment. Must
     *     <b>not</b> end with {@link #BINARY_HEADER_SUFFIX}
     */
    public static <T> Key<T> of(String name, AsciiMarshaller<T> marshaller) {
      return of(name, false, marshaller);
    }

    static <T> Key<T> of(String name, boolean pseudo, AsciiMarshaller<T> marshaller) {
      return new AsciiKey<>(name, pseudo, marshaller);
    }

    static <T> Key<T> of(String name, boolean pseudo, TrustedAsciiMarshaller<T> marshaller) {
      return new TrustedAsciiKey<>(name, pseudo, marshaller);
    }

    private final String originalName;

    private final String name;
    private final byte[] nameBytes;
    private final Object marshaller;

    private static BitSet generateValidTChars() {
      BitSet valid = new BitSet(0x7f);
      valid.set('-');
      valid.set('_');
      valid.set('.');
      for (char c = '0'; c <= '9'; c++) {
        valid.set(c);