| /* |
| * 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 java.io.ByteArrayOutputStream; |
| import java.io.IOException; |
| import java.io.UnsupportedEncodingException; |
| import java.nio.charset.Charset; |
| |
| /** |
| * 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 |
| */ |
| abstract class AbstractNonStreamingHashFunction implements HashFunction { |
| @Override |
| public Hasher newHasher() { |
| return new BufferingHasher(32); |
| } |
| |
| @Override |
| public Hasher newHasher(int expectedInputSize) { |
| Preconditions.checkArgument(expectedInputSize >= 0); |
| return new BufferingHasher(expectedInputSize); |
| } |
| |
| @Override public <T> HashCode hashObject(T instance, Funnel<? super T> funnel) { |
| return newHasher().putObject(instance, funnel).hash(); |
| } |
| |
| @Override public HashCode hashUnencodedChars(CharSequence input) { |
| int len = input.length(); |
| Hasher hasher = newHasher(len * 2); |
| for (int i = 0; i < len; i++) { |
| hasher.putChar(input.charAt(i)); |
| } |
| return hasher.hash(); |
| } |
| |
| @Override public HashCode hashString(CharSequence input, Charset charset) { |
| try { |
| return hashBytes(input.toString().getBytes(charset.name())); |
| } catch (UnsupportedEncodingException e) { |
| throw new AssertionError(e); |
| } |
| } |
| |
| @Override public HashCode hashInt(int input) { |
| return newHasher(4).putInt(input).hash(); |
| } |
| |
| @Override public HashCode hashLong(long input) { |
| return newHasher(8).putLong(input).hash(); |
| } |
| |
| @Override public HashCode hashBytes(byte[] input) { |
| return hashBytes(input, 0, input.length); |
| } |
| |
| /** |
| * In-memory stream-based implementation of Hasher. |
| */ |
| private final class BufferingHasher extends AbstractHasher { |
| final ExposedByteArrayOutputStream stream; |
| static final int BOTTOM_BYTE = 0xFF; |
| |
| 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) { |
| try { |
| stream.write(bytes); |
| } catch (IOException e) { |
| throw new RuntimeException(e); |
| } |
| return this; |
| } |
| |
| @Override |
| public Hasher putBytes(byte[] bytes, int off, int len) { |
| stream.write(bytes, off, len); |
| return this; |
| } |
| |
| @Override |
| public Hasher putShort(short s) { |
| stream.write(s & BOTTOM_BYTE); |
| stream.write((s >>> 8) & BOTTOM_BYTE); |
| return this; |
| } |
| |
| @Override |
| public Hasher putInt(int i) { |
| stream.write(i & BOTTOM_BYTE); |
| stream.write((i >>> 8) & BOTTOM_BYTE); |
| stream.write((i >>> 16) & BOTTOM_BYTE); |
| stream.write((i >>> 24) & BOTTOM_BYTE); |
| return this; |
| } |
| |
| @Override |
| public Hasher putLong(long l) { |
| for (int i = 0; i < 64; i += 8) { |
| stream.write((byte) ((l >>> i) & BOTTOM_BYTE)); |
| } |
| return this; |
| } |
| |
| @Override |
| public Hasher putChar(char c) { |
| stream.write(c & BOTTOM_BYTE); |
| stream.write((c >>> 8) & BOTTOM_BYTE); |
| return this; |
| } |
| |
| @Override |
| public <T> Hasher putObject(T instance, Funnel<? super T> funnel) { |
| funnel.funnel(instance, this); |
| 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); |
| } |
| byte[] byteArray() { |
| return buf; |
| } |
| int length() { |
| return count; |
| } |
| } |
| } |