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

   1 /*
   2  * Copyright (C) 2008, Google Inc.
   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 /** A more efficient List<Integer> using a primitive integer array. */
  41 public class IntList {
  42         private int[] entries;
  43
  44         private int count;
  45
  46         /** Create an empty list with a default capacity. */
  47         public IntList() {
  48                 this(10);
  49         }
  50
  51         /**
  52          * Create an empty list with the specified capacity.
  53          *
  54          * @param capacity
  55          *            number of entries the list can initially hold.
  56          */
  57         public IntList(final int capacity) {
  58                 entries = new int[capacity];
  59         }
  60
  61         /** @return number of entries in this list */
  62         public int size() {
  63                 return count;
  64         }
  65
  66         /**
  67          * @param i
  68          *            index to read, must be in the range [0, {@link #size()}).
  69          * @return the number at the specified index
  70          * @throws ArrayIndexOutOfBoundsException
  71          *             the index outside the valid range
  72          */
  73         public int get(final int i) {
  74                 if (count <= i)
  75                         throw new ArrayIndexOutOfBoundsException(i);
  76                 return entries[i];
  77         }
  78
  79         /** Empty this list */
  80         public void clear() {
  81                 count = 0;
  82         }
  83
  84         /**
  85          * Add an entry to the end of the list.
  86          *
  87          * @param n
  88          *            the number to add.
  89          */
  90         public void add(final int n) {
  91                 if (count == entries.length)
  92                         grow();
  93                 entries[count++] = n;
  94         }
  95
  96         /**
  97          * Pad the list with entries.
  98          *
  99          * @param toIndex
 100          *            index position to stop filling at. 0 inserts no filler. 1
 101          *            ensures the list has a size of 1, adding <code>val</code> if
 102          *            the list is currently empty.
 103          * @param val
 104          *            value to insert into padded positions.
 105          */
 106         public void fillTo(int toIndex, final int val) {
 107                 while (count < toIndex)
 108                         add(val);
 109         }
 110
 111         private void grow() {
 112                 final int[] n = new int[(entries.length + 16) * 3 / 2];
 113                 System.arraycopy(entries, 0, n, 0, count);
 114                 entries = n;
 115         }
 116
 117         public String toString() {
 118                 final StringBuilder r = new StringBuilder();
 119                 r.append('[');
 120                 for (int i = 0; i < count; i++) {
 121                         if (i > 0)
 122                                 r.append(", ");
 123                         r.append(entries[i]);
 124                 }
 125                 r.append(']');
 126                 return r.toString();
 127         }
 128 }