net.jpountz.lz4.LZ4SafeDecompressor Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of lz4 Show documentation
Java ports and bindings of the LZ4 compression algorithm and the xxHash hashing algorithm
There is a newer version: 1.3.0
package net.jpountz.lz4;

/*
 * 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.
 */

import java.util.Arrays;

/**
 * LZ4 decompressor that requires the size of the compressed data to be known.
 * 
 * Implementations of this class are usually a little slower than those of
 * {@link LZ4FastDecompressor} but do not require the size of the original data to
 * be known.
 */
public abstract class LZ4SafeDecompressor implements LZ4UnknownSizeDecompressor {

  /**
   * Uncompress src[srcOff:srcLen] into
   * dest[destOff:destOff+maxDestLen] and returns the number of
   * decompressed bytes written into dest.
   *
   * @param srcLen the exact size of the compressed stream
   * @return the original input size
   * @throws LZ4Exception if maxDestLen is too small
   */
  public abstract int decompress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff, int maxDestLen);

  /**
   * Convenience method, equivalent to calling
   * {@link #decompress(byte[], int, int, byte[], int, int) decompress(src, srcOff, srcLen, dest, destOff, dest.length - destOff)}.
   */
  public final int decompress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff) {
    return decompress(src, srcOff, srcLen, dest, destOff, dest.length - destOff);
  }

  /**
   * Convenience method, equivalent to calling
   * {@link #decompress(byte[], int, int, byte[], int) decompress(src, 0, src.length, dest, 0)}
   */
  public final int decompress(byte[] src, byte[] dest) {
    return decompress(src, 0, src.length, dest, 0);
  }

  /**
   * Convenience method which returns src[srcOff:srcOff+srcLen]
   * decompressed.
   * 
Warning: this method has an
   * important overhead due to the fact that it needs to allocate a buffer to
   * decompress into, and then needs to resize this buffer to the actual
   * decompressed length.
   * Here is how this method is implemented:
   *    * byte[] decompressed = new byte[maxDestLen];
   * final int decompressedLength = decompress(src, srcOff, srcLen, decompressed, 0, maxDestLen);
   * if (decompressedLength != decompressed.length) {
   *   decompressed = Arrays.copyOf(decompressed, decompressedLength);
   * }
   * return decompressed;
   * 
   */
  public final byte[] decompress(byte[] src, int srcOff, int srcLen, int maxDestLen) {
    byte[] decompressed = new byte[maxDestLen];
    final int decompressedLength = decompress(src, srcOff, srcLen, decompressed, 0, maxDestLen);
    if (decompressedLength != decompressed.length) {
      decompressed = Arrays.copyOf(decompressed, decompressedLength);
    }
    return decompressed;
  }

  /**
   * Convenience method, equivalent to calling
   * {@link #decompress(byte[], int, int, int) decompress(src, 0, src.length, maxDestLen)}.
   */
  public final byte[] decompress(byte[] src, int maxDestLen) {
    return decompress(src, 0, src.length, maxDestLen);
  }

  @Override
  public String toString() {
    return getClass().getSimpleName();
  }

}