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/*
* Copyright (C) 2012 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 static com.google.common.base.Preconditions.checkPositionIndexes;
import com.google.common.primitives.Chars;
import com.google.common.primitives.Ints;
import com.google.common.primitives.Longs;
import com.google.common.primitives.Shorts;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* Abstract {@link Hasher} that handles converting primitives to bytes using a scratch {@code
* ByteBuffer} and streams all bytes to a sink to compute the hash.
*
* @author Colin Decker
*/
abstract class AbstractByteHasher extends AbstractHasher {
private final ByteBuffer scratch = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN);
/**
* Updates this hasher with the given byte.
*/
protected abstract void update(byte b);
/**
* Updates this hasher with the given bytes.
*/
protected void update(byte[] b) {
update(b, 0, b.length);
}
/**
* Updates this hasher with {@code len} bytes starting at {@code off} in the given buffer.
*/
protected void update(byte[] b, int off, int len) {
for (int i = off; i < off + len; i++) {
update(b[i]);
}
}
@Override
public Hasher putByte(byte b) {
update(b);
return this;
}
@Override
public Hasher putBytes(byte[] bytes) {
checkNotNull(bytes);
update(bytes);
return this;
}
@Override
public Hasher putBytes(byte[] bytes, int off, int len) {
checkPositionIndexes(off, off + len, bytes.length);
update(bytes, off, len);
return this;
}
/**
* Updates the sink with the given number of bytes from the buffer.
*/
private Hasher update(int bytes) {
try {
update(scratch.array(), 0, bytes);
} finally {
scratch.clear();
}
return this;
}
@Override
public Hasher putShort(short s) {
scratch.putShort(s);
return update(Shorts.BYTES);
}
@Override
public Hasher putInt(int i) {
scratch.putInt(i);
return update(Ints.BYTES);
}
@Override
public Hasher putLong(long l) {
scratch.putLong(l);
return update(Longs.BYTES);
}
@Override
public Hasher putChar(char c) {
scratch.putChar(c);
return update(Chars.BYTES);
}
@Override
public Hasher putObject(T instance, Funnel super T> funnel) {
funnel.funnel(instance, this);
return this;
}
}