Update #0 - First Release

sources/main/java/com/google/common/hash/AbstractByteHasher.java

@@ -0,0 +1,124 @@
+/*
+ * 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 java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+import com.google.common.primitives.Chars;
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import com.google.common.primitives.Shorts;
+
+/**
+ * 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 <T> Hasher putObject(T instance, Funnel<? super T> funnel) {
+		funnel.funnel(instance, this);
+		return this;
+	}
+}