HADOOP-1498. Add file missed in prior commit.

git-svn-id: https://svn.apache.org/repos/asf/lucene/hadoop/trunk@548794 13f79535-47bb-0310-9956-ffa450edef68

src/contrib/hbase/src/java/org/apache/hadoop/hbase/io/ImmutableBytesWritable.java

@@ -0,0 +1,200 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.hadoop.hbase.io;
+
+import java.io.IOException;
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.util.List;
+
+import org.apache.hadoop.io.BytesWritable;
+import org.apache.hadoop.io.WritableComparable;
+import org.apache.hadoop.io.WritableComparator;
+
+/** 
+ * A byte sequence that is usable as a key or value.  Based on
+ * {@link org.apache.hadoop.io.BytesWritable} only this class is NOT resizable
+ * and DOES NOT distinguish between the size of the seqeunce and the current
+ * capacity as {@link org.apache.hadoop.io.BytesWritable} does. Hence its
+ * comparatively 'immutable'.
+ */
+public class ImmutableBytesWritable implements WritableComparable {
+  private byte[] bytes;
+  
+  /**
+   * Create a zero-size sequence.
+   */
+  public ImmutableBytesWritable() {
+    super();
+  }
+  
+  /**
+   * Create a ImmutableBytesWritable using the byte array as the initial value.
+   * @param bytes This array becomes the backing storage for the object.
+   */
+  public ImmutableBytesWritable(byte[] bytes) {
+    this.bytes = bytes;
+  }
+  
+  /**
+   * Set the new ImmutableBytesWritable to a copy of the contents of the passed
+   * <code>ibw</code>.
+   * @param ibw the value to set this ImmutableBytesWritable to.
+   */
+  public ImmutableBytesWritable(final ImmutableBytesWritable ibw) {
+    this(ibw.get(), 0, ibw.getSize());
+  }
+  
+  /**
+   * Set the value to a copy of the given byte range
+   * @param newData the new values to copy in
+   * @param offset the offset in newData to start at
+   * @param length the number of bytes to copy
+   */
+  public ImmutableBytesWritable(final byte[] newData, final int offset,
+      final int length) {
+    this.bytes = new byte[length];
+    System.arraycopy(newData, offset, this.bytes, 0, length);
+  }
+  
+  /**
+   * Get the data from the BytesWritable.
+   * @return The data is only valid between 0 and getSize() - 1.
+   */
+  public byte[] get() {
+    if (this.bytes == null) {
+      throw new IllegalStateException("Uninitialiized. Null constructor " +
+        "called w/o accompaying readFields invocation");
+    }
+    return this.bytes;
+  }
+  
+  /**
+   * Get the current size of the buffer.
+   */
+  public int getSize() {
+    if (this.bytes == null) {
+      throw new IllegalStateException("Uninitialiized. Null constructor " +
+        "called w/o accompaying readFields invocation");
+    }
+    return this.bytes.length;
+  }
+
+
+  // inherit javadoc
+  public void readFields(final DataInput in) throws IOException {
+    this.bytes = new byte[in.readInt()];
+    in.readFully(this.bytes, 0, this.bytes.length);
+  }
+  
+  // inherit javadoc
+  public void write(final DataOutput out) throws IOException {
+    out.writeInt(this.bytes.length);
+    out.write(this.bytes, 0, this.bytes.length);
+  }
+  
+  // Below methods copied from BytesWritable
+  
+  public int hashCode() {
+    return WritableComparator.hashBytes(bytes, this.bytes.length);
+  }
+  
+  /**
+   * Define the sort order of the BytesWritable.
+   * @param right_obj The other bytes writable
+   * @return Positive if left is bigger than right, 0 if they are equal, and
+   *         negative if left is smaller than right.
+   */
+  public int compareTo(Object right_obj) {
+    return compareTo(((ImmutableBytesWritable)right_obj).get());
+  }
+  
+  public int compareTo(final byte [] that) {
+    int diff = this.bytes.length - that.length;
+    return (diff != 0)?
+      diff:
+      WritableComparator.compareBytes(this.bytes, 0, this.bytes.length, that,
+        0, that.length);
+  }
+  
+  /**
+   * Are the two byte sequences equal?
+   */
+  public boolean equals(Object right_obj) {
+    if (right_obj instanceof ImmutableBytesWritable) {
+      return compareTo(right_obj) == 0;
+    }
+    return false;
+  }
+  
+  /**
+   * Generate the stream of bytes as hex pairs separated by ' '.
+   */
+  public String toString() { 
+    StringBuffer sb = new StringBuffer(3*this.bytes.length);
+    for (int idx = 0; idx < this.bytes.length; idx++) {
+      // if not the first, put a blank separator in
+      if (idx != 0) {
+        sb.append(' ');
+      }
+      String num = Integer.toHexString(bytes[idx]);
+      // if it is only one digit, add a leading 0.
+      if (num.length() < 2) {
+        sb.append('0');
+      }
+      sb.append(num);
+    }
+    return sb.toString();
+  }
+
+  /** A Comparator optimized for ImmutableBytesWritable.
+   */ 
+  public static class Comparator extends WritableComparator {
+    private BytesWritable.Comparator comparator =
+      new BytesWritable.Comparator();
+    
+    public Comparator() {
+      super(ImmutableBytesWritable.class);
+    }
+    
+    /**
+     * Compare the buffers in serialized form.
+     */
+    public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
+      return comparator.compare(b1, s1, l1, b2, s2, l2);
+    }
+  }
+  
+  static { // register this comparator
+    WritableComparator.define(ImmutableBytesWritable.class, new Comparator());
+  }
+  
+  /**
+   * @param array List of byte [].
+   * @return Array of byte [].
+   */
+  public static byte [][] toArray(final List<byte []> array) {
+    // List#toArray doesn't work on lists of byte [].
+    byte[][] results = new byte[array.size()][];
+    for (int i = 0; i < array.size(); i++) {
+      results[i] = array.get(i);
+    }
+    return results;
+  }
+}