| /* |
| * 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 com.google.common.base.Preconditions; |
| import com.google.errorprone.annotations.Immutable; |
| import java.io.ByteArrayOutputStream; |
| import java.nio.ByteBuffer; |
| import java.nio.ByteOrder; |
| import java.nio.charset.Charset; |
| import java.util.Arrays; |
| |
| /** |
| * Skeleton implementation of {@link HashFunction}, appropriate for non-streaming algorithms. All |
| * the hash computation done using {@linkplain #newHasher()} are delegated to the {@linkplain |
| * #hashBytes(byte[], int, int)} method. |
| * |
| * @author Dimitris Andreou |
| */ |
| @Immutable |
| abstract class AbstractNonStreamingHashFunction extends AbstractHashFunction { |
| @Override |
| public Hasher newHasher() { |
| return newHasher(32); |
| } |
| |
| @Override |
| public Hasher newHasher(int expectedInputSize) { |
| Preconditions.checkArgument(expectedInputSize >= 0); |
| return new BufferingHasher(expectedInputSize); |
| } |
| |
| @Override |
| public HashCode hashInt(int input) { |
| return hashBytes(ByteBuffer.allocate(4).order(ByteOrder.LITTLE_ENDIAN).putInt(input).array()); |
| } |
| |
| @Override |
| public HashCode hashLong(long input) { |
| return hashBytes(ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(input).array()); |
| } |
| |
| @Override |
| public HashCode hashUnencodedChars(CharSequence input) { |
| int len = input.length(); |
| ByteBuffer buffer = ByteBuffer.allocate(len * 2).order(ByteOrder.LITTLE_ENDIAN); |
| for (int i = 0; i < len; i++) { |
| buffer.putChar(input.charAt(i)); |
| } |
| return hashBytes(buffer.array()); |
| } |
| |
| @Override |
| public HashCode hashString(CharSequence input, Charset charset) { |
| return hashBytes(input.toString().getBytes(charset)); |
| } |
| |
| @Override |
| public abstract HashCode hashBytes(byte[] input, int off, int len); |
| |
| @Override |
| public HashCode hashBytes(ByteBuffer input) { |
| return newHasher(input.remaining()).putBytes(input).hash(); |
| } |
| |
| /** In-memory stream-based implementation of Hasher. */ |
| private final class BufferingHasher extends AbstractHasher { |
| final ExposedByteArrayOutputStream stream; |
| |
| BufferingHasher(int expectedInputSize) { |
| this.stream = new ExposedByteArrayOutputStream(expectedInputSize); |
| } |
| |
| @Override |
| public Hasher putByte(byte b) { |
| stream.write(b); |
| return this; |
| } |
| |
| @Override |
| public Hasher putBytes(byte[] bytes, int off, int len) { |
| stream.write(bytes, off, len); |
| return this; |
| } |
| |
| @Override |
| public Hasher putBytes(ByteBuffer bytes) { |
| stream.write(bytes); |
| return this; |
| } |
| |
| @Override |
| public HashCode hash() { |
| return hashBytes(stream.byteArray(), 0, stream.length()); |
| } |
| } |
| |
| // Just to access the byte[] without introducing an unnecessary copy |
| private static final class ExposedByteArrayOutputStream extends ByteArrayOutputStream { |
| ExposedByteArrayOutputStream(int expectedInputSize) { |
| super(expectedInputSize); |
| } |
| |
| void write(ByteBuffer input) { |
| int remaining = input.remaining(); |
| if (count + remaining > buf.length) { |
| buf = Arrays.copyOf(buf, count + remaining); |
| } |
| input.get(buf, count, remaining); |
| count += remaining; |
| } |
| |
| byte[] byteArray() { |
| return buf; |
| } |
| |
| int length() { |
| return count; |
| } |
| } |
| } |