* Implementations for common types can be found in {@link Funnels}.
 *
 * <p>Note that serialization of {@linkplain BloomFilter bloom filters} requires the proper
 * serialization of funnels. When possible, it is recommended that funnels be implemented as a
 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item

    @SuppressWarnings({"unchecked", "DoNotMock"})
    Funnel<Object> elementFunnel = mock(Funnel.class);
    PrimitiveSink primitiveSink = mock(PrimitiveSink.class);
    Funnel<Iterable<?>> sequential = sequentialFunnel(elementFunnel);
    sequential.funnel(Arrays.asList("foo", "bar", "baz", "quux"), primitiveSink);
    InOrder inOrder = inOrder(elementFunnel);
    inOrder.verify(elementFunnel).funnel("foo", primitiveSink);

      implements Funnel<Iterable<? extends E>> {
    private final Funnel<E> elementFunnel;

    SequentialFunnel(Funnel<E> elementFunnel) {
      this.elementFunnel = Preconditions.checkNotNull(elementFunnel);
    }

    @Override
    public void funnel(Iterable<? extends E> from, PrimitiveSink into) {
      for (E e : from) {
        elementFunnel.funnel(e, into);
      }
    }

        }
        return this;
      }

      @Override
      public <T extends @Nullable Object> Hasher putObject(
          @ParametricNullness T instance, Funnel<? super T> funnel) {
        for (Hasher hasher : hashers) {
          hasher.putObject(instance, funnel);
        }
        return this;
      }

      @Override
      public HashCode hash() {
        return makeHash(hashers);
      }
    };

 */
@Immutable
abstract class AbstractHashFunction implements HashFunction {
  @Override
  public <T extends @Nullable Object> HashCode hashObject(
      @ParametricNullness T instance, Funnel<? super T> funnel) {
    return newHasher().putObject(instance, funnel).hash();
  }

  @Override
  public HashCode hashUnencodedChars(CharSequence input) {
    int len = input.length();
    return newHasher(len * 2).putUnencodedChars(input).hash();

    putByte((byte) (c >>> 8));
    return this;
  }

  @Override
  @CanIgnoreReturnValue
  public <T extends @Nullable Object> Hasher putObject(
      @ParametricNullness T instance, Funnel<? super T> funnel) {
    funnel.funnel(instance, this);
    return this;
  }

  @Override
  Hasher putString(CharSequence charSequence, Charset charset);

  /** A simple convenience for {@code funnel.funnel(object, this)}. */
  @CanIgnoreReturnValue
  <T extends @Nullable Object> Hasher putObject(
      @ParametricNullness T instance, Funnel<? super T> funnel);

  /**
   * Computes a hash code based on the data that have been provided to this hasher. The result is

    HashFn hf =
        new HashFn() {
          @Override
          public byte[] hash(byte[] input, int seed) {
            Hasher hasher = murmur3_128(seed).newHasher();
            byteArrayFunnel().funnel(input, hasher);
            return hasher.hash().asBytes();
          }
        };
    // Murmur3F, MurmurHash3 for x64, 128-bit (MurmurHash3_x64_128)
    // From http://code.google.com/p/smhasher/source/browse/trunk/main.cpp

    HashFn hf =
        new HashFn() {
          @Override
          public byte[] hash(byte[] input, int seed) {
            Hasher hasher = murmur3_32(seed).newHasher();
            byteArrayFunnel().funnel(input, hasher);
            return hasher.hash().asBytes();
          }
        };
    // Murmur3A, MurmurHash3 for x86, 32-bit (MurmurHash3_x86_32)
    // https://github.com/aappleby/smhasher/blob/master/src/main.cpp

    HashFn hf =
        new HashFn() {
          @Override
          public byte[] hash(byte[] input, int seed) {
            Hasher hasher = murmur3_32(seed).newHasher();
            byteArrayFunnel().funnel(input, hasher);
            return hasher.hash().asBytes();
          }
        };
    // Murmur3A, MurmurHash3 for x86, 32-bit (MurmurHash3_x86_32)
    // https://github.com/aappleby/smhasher/blob/master/src/main.cpp