org.spearce.jgit/src/org/spearce/jgit/util/RawCharSequence.java

   1 /*
   2  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
   3  *
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or
   7  * without modification, are permitted provided that the following
   8  * conditions are met:
   9  *
  10  * - Redistributions of source code must retain the above copyright
  11  *   notice, this list of conditions and the following disclaimer.
  12  *
  13  * - Redistributions in binary form must reproduce the above
  14  *   copyright notice, this list of conditions and the following
  15  *   disclaimer in the documentation and/or other materials provided
  16  *   with the distribution.
  17  *
  18  * - Neither the name of the Git Development Community nor the
  19  *   names of its contributors may be used to endorse or promote
  20  *   products derived from this software without specific prior
  21  *   written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  24  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  25  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  28  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  31  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  32  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  33  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  35  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 package org.spearce.jgit.util;
  39
  40 /**
  41  * A rough character sequence around a raw byte buffer.
  42  * <p>
  43  * Characters are assumed to be 8-bit US-ASCII.
  44  */
  45 public final class RawCharSequence implements CharSequence {
  46         /** A zero-length character sequence. */
  47         public static final RawCharSequence EMPTY = new RawCharSequence(null, 0, 0);
  48
  49         final byte[] buffer;
  50
  51         final int startPtr;
  52
  53         final int endPtr;
  54
  55         /**
  56          * Create a rough character sequence around the raw byte buffer.
  57          *
  58          * @param buf
  59          *            buffer to scan.
  60          * @param start
  61          *            starting position for the sequence.
  62          * @param end
  63          *            ending position for the sequence.
  64          */
  65         public RawCharSequence(final byte[] buf, final int start, final int end) {
  66                 buffer = buf;
  67                 startPtr = start;
  68                 endPtr = end;
  69         }
  70
  71         public char charAt(final int index) {
  72                 return (char) (buffer[startPtr + index] & 0xff);
  73         }
  74
  75         public int length() {
  76                 return endPtr - startPtr;
  77         }
  78
  79         public CharSequence subSequence(final int start, final int end) {
  80                 return new RawCharSequence(buffer, startPtr + start, startPtr + end);
  81         }
  82
  83         @Override
  84         public String toString() {
  85                 final int n = length();
  86                 final StringBuilder b = new StringBuilder(n);
  87                 for (int i = 0; i < n; i++)
  88                         b.append(charAt(i));
  89                 return b.toString();
  90         }
  91 }