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/*
* Copyright (C) 2011 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.hash;
import static com.google.common.base.Preconditions.checkNotNull;
import java.nio.charset.Charset;
/**
* An abstract composition of multiple hash functions. {@linkplain #newHasher()} delegates to the
* {@code Hasher} objects of the delegate hash functions, and in the end, they are used by
* {@linkplain #makeHash(Hasher[])} that constructs the final {@code HashCode}.
*
* @author Dimitris Andreou
*/
abstract class AbstractCompositeHashFunction extends AbstractStreamingHashFunction {
final HashFunction[] functions;
AbstractCompositeHashFunction(HashFunction... functions) {
for (HashFunction function : functions) {
checkNotNull(function);
}
this.functions = functions;
}
/**
* Constructs a {@code HashCode} from the {@code Hasher} objects of the functions. Each of them
* has consumed the entire input and they are ready to output a {@code HashCode}. The order of
* the hashers are the same order as the functions given to the constructor.
*/
// this could be cleaner if it passed HashCode[], but that would create yet another array...
/* protected */ abstract HashCode makeHash(Hasher[] hashers);
@Override
public Hasher newHasher() {
final Hasher[] hashers = new Hasher[functions.length];
for (int i = 0; i < hashers.length; i++) {
hashers[i] = functions[i].newHasher();
}
return new Hasher() {
@Override public Hasher putByte(byte b) {
for (Hasher hasher : hashers) {
hasher.putByte(b);
}
return this;
}
@Override public Hasher putBytes(byte[] bytes) {
for (Hasher hasher : hashers) {
hasher.putBytes(bytes);
}
return this;
}
@Override public Hasher putBytes(byte[] bytes, int off, int len) {
for (Hasher hasher : hashers) {
hasher.putBytes(bytes, off, len);
}
return this;
}
@Override public Hasher putShort(short s) {
for (Hasher hasher : hashers) {
hasher.putShort(s);
}
return this;
}
@Override public Hasher putInt(int i) {
for (Hasher hasher : hashers) {
hasher.putInt(i);
}
return this;
}
@Override public Hasher putLong(long l) {
for (Hasher hasher : hashers) {
hasher.putLong(l);
}
return this;
}
@Override public Hasher putFloat(float f) {
for (Hasher hasher : hashers) {
hasher.putFloat(f);
}
return this;
}
@Override public Hasher putDouble(double d) {
for (Hasher hasher : hashers) {
hasher.putDouble(d);
}
return this;
}
@Override public Hasher putBoolean(boolean b) {
for (Hasher hasher : hashers) {
hasher.putBoolean(b);
}
return this;
}
@Override public Hasher putChar(char c) {
for (Hasher hasher : hashers) {
hasher.putChar(c);
}
return this;
}
@Override public Hasher putString(CharSequence chars) {
for (Hasher hasher : hashers) {
hasher.putString(chars);
}
return this;
}
@Override public Hasher putString(CharSequence chars, Charset charset) {
for (Hasher hasher : hashers) {
hasher.putString(chars, charset);
}
return this;
}
@Override public <T> Hasher putObject(T instance, Funnel<? super T> funnel) {
for (Hasher hasher : hashers) {
hasher.putObject(instance, funnel);
}
return this;
}
@Override public HashCode hash() {
return makeHash(hashers);
}
};
}
private static final long serialVersionUID = 0L;
}
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