content: /**
   * 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 com.aliyun.odps.io;
  
  import java.io.ByteArrayInputStream;
  import java.io.DataOutput;
  import java.io.FilterInputStream;
  import java.io.InputStream;
  
  /**
   * A reusable {@link InputStream} implementation that reads from an in-memory
   * buffer.
   *
   * <p>
   * This saves memory over creating a new InputStream and ByteArrayInputStream
   * each time data is read.
   *
   * <p>
   * Typical usage is something like the following:
   *
   * <pre>
   *
   * InputBuffer buffer = new InputBuffer();
   * while (... loop condition ...) {
   *   byte[] data = ... get data ...;
   *   int dataLength = ... get data length ...;
   *   buffer.reset(data, dataLength);
   *   ... read buffer using InputStream methods ...
   * }
   * </pre>
   *
   * @see DataInputBuffer
   * @see DataOutput
   */
  public class InputBuffer extends FilterInputStream {
  
    private static class Buffer extends ByteArrayInputStream {
  
      public Buffer() {
        super(new byte[]{});
      }
  
      public void reset(byte[] input, int start, int length) {
        this.buf = input;
        this.count = start + length;
        this.mark = start;
        this.pos = start;
      }
  
      public int getPosition() {
        return pos;
      }
  
      public int getLength() {
        return count;
      }
    }
  
    private Buffer buffer;
  
    /**
     * Constructs a new empty buffer.
     */
    public InputBuffer() {
      this(new Buffer());
    }
  
    private InputBuffer(Buffer buffer) {
      super(buffer);
      this.buffer = buffer;
    }
  
    /**
     * Resets the data that the buffer reads.
     */
    public void reset(byte[] input, int length) {
      buffer.reset(input, 0, length);
    }
  
    /**
     * Resets the data that the buffer reads.
     */
    public void reset(byte[] input, int start, int length) {
      buffer.reset(input, start, length);
    }
  
    /**
     * Returns the current position in the input.
     */
    public int getPosition() {
      return buffer.getPosition();
    }
  
    /**
     * Returns the length of the input.
     */
    public int getLength() {
      return buffer.getLength();
    }
  
  }
  