com.azure.cosmos.implementation.guava25.hash.AbstractByteHasher Maven / Gradle / Ivy

/*
 * Copyright (C) 2008 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.
 */

/*
 * Portions Copyright (c) Microsoft Corporation
 */

package com.azure.cosmos.implementation.guava25.hash;

import com.azure.cosmos.implementation.guava25.errorprone.annotations.CanIgnoreReturnValue;
import com.azure.cosmos.implementation.guava25.primitives.Chars;
import com.azure.cosmos.implementation.guava25.primitives.Ints;
import com.azure.cosmos.implementation.guava25.primitives.Longs;
import com.azure.cosmos.implementation.guava25.primitives.Shorts;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import static com.azure.cosmos.implementation.guava25.base.Preconditions.checkNotNull;
import static com.azure.cosmos.implementation.guava25.base.Preconditions.checkPositionIndexes;

/**
 * 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
 */
@CanIgnoreReturnValue
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]);
        }
    }

    /** Updates this hasher with bytes from the given buffer. */
    protected void update(ByteBuffer b) {
        if (b.hasArray()) {
            update(b.array(), b.arrayOffset() + b.position(), b.remaining());
            b.position(b.limit());
        } else {
            for (int remaining = b.remaining(); remaining > 0; remaining--) {
                update(b.get());
            }
        }
    }

    /** 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 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;
    }

    @Override
    public Hasher putBytes(ByteBuffer bytes) {
        update(bytes);
        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);
    }
}