ByteSequence xref

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    1   /*
    2    * Copyright  2000-2004 The Apache Software Foundation
    3    *
    4    *  Licensed under the Apache License, Version 2.0 (the "License");
    5    *  you may not use this file except in compliance with the License.
    6    *  You may obtain a copy of the License at
    7    *
    8    *      http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   *  Unless required by applicable law or agreed to in writing, software
    11   *  distributed under the License is distributed on an "AS IS" BASIS,
    12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   *  See the License for the specific language governing permissions and
    14   *  limitations under the License.
    15   *
    16   */
    17  package org.apache.bcel.util;
    18
    19  import java.io.ByteArrayInputStream;
    20  import java.io.DataInputStream;
    21
    22  /***
    23   * Utility class that implements a sequence of bytes which can be read
    24   * via the `readByte()' method. This is used to implement a wrapper for the
    25   * Java byte code stream to gain some more readability.
    26   *
    27   * @version $Id: ByteSequence.java 386056 2006-03-15 11:31:56Z tcurdt $
    28   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
    29   */
    30  public final class ByteSequence extends DataInputStream {
    31
    32      private ByteArrayStream byte_stream;
    33
    34
    35      public ByteSequence(byte[] bytes) {
    36          super(new ByteArrayStream(bytes));
    37          byte_stream = (ByteArrayStream) in;
    38      }
    39
    40
    41      public final int getIndex() {
    42          return byte_stream.getPosition();
    43      }
    44
    45
    46      final void unreadByte() {
    47          byte_stream.unreadByte();
    48      }
    49
    50      private static final class ByteArrayStream extends ByteArrayInputStream {
    51
    52          ByteArrayStream(byte[] bytes) {
    53              super(bytes);
    54          }
    55
    56
    57          final int getPosition() {
    58              return pos;
    59          } // is protected in ByteArrayInputStream
    60
    61
    62          final void unreadByte() {
    63              if (pos > 0) {
    64                  pos--;
    65              }
    66          }
    67      }
    68  }