case-study/jdt-after/ui/org/eclipse/jdt/internal/ui/text/SequenceCharacterIterator.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2011 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Eclipse Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/epl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package org.eclipse.jdt.internal.ui.text;
  12
  13 import java.text.CharacterIterator;
  14
  15 import org.eclipse.core.runtime.Assert;
  16
  17
  18
  19 /**
  20  * A <code>CharSequence</code> based implementation of <code>CharacterIterator</code>.
  21  *
  22  * @since 3.0
  23  */
  24 public class SequenceCharacterIterator implements CharacterIterator {
  25
  26         private int fIndex= -1;
  27         private final CharSequence fSequence;
  28         private final int fFirst;
  29         private final int fLast;
  30
  31         private void invariant() {
  32                 Assert.isTrue(fIndex >= fFirst);
  33                 Assert.isTrue(fIndex <= fLast);
  34         }
  35
  36         /**
  37          * Creates an iterator for the entire sequence.
  38          *
  39          * @param sequence the sequence backing this iterator
  40          */
  41         public SequenceCharacterIterator(CharSequence sequence) {
  42                 this(sequence, 0);
  43         }
  44
  45         /**
  46          * Creates an iterator.
  47          *
  48          * @param sequence the sequence backing this iterator
  49          * @param first the first character to consider
  50          * @throws IllegalArgumentException if the indices are out of bounds
  51          */
  52         public SequenceCharacterIterator(CharSequence sequence, int first) throws IllegalArgumentException {
  53                 this(sequence, first, sequence.length());
  54         }
  55
  56         /**
  57          * Creates an iterator.
  58          *
  59          * @param sequence the sequence backing this iterator
  60          * @param first the first character to consider
  61          * @param last the last character index to consider
  62          * @throws IllegalArgumentException if the indices are out of bounds
  63          */
  64         public SequenceCharacterIterator(CharSequence sequence, int first, int last) throws IllegalArgumentException {
  65                 if (sequence == null)
  66                         throw new NullPointerException();
  67                 if (first < 0 || first > last)
  68                         throw new IllegalArgumentException();
  69                 if (last > sequence.length())
  70                         throw new IllegalArgumentException();
  71                 fSequence= sequence;
  72                 fFirst= first;
  73                 fLast= last;
  74                 fIndex= first;
  75                 invariant();
  76         }
  77
  78         /*
  79          * @see java.text.CharacterIterator#first()
  80          */
  81         public char first() {
  82                 return setIndex(getBeginIndex());
  83         }
  84
  85         /*
  86          * @see java.text.CharacterIterator#last()
  87          */
  88         public char last() {
  89                 if (fFirst == fLast)
  90                         return setIndex(getEndIndex());
  91                 else
  92                         return setIndex(getEndIndex() - 1);
  93         }
  94
  95         /*
  96          * @see java.text.CharacterIterator#current()
  97          */
  98         public char current() {
  99                 if (fIndex >= fFirst && fIndex < fLast)
 100                         return fSequence.charAt(fIndex);
 101                 else
 102                         return DONE;
 103         }
 104
 105         /*
 106          * @see java.text.CharacterIterator#next()
 107          */
 108         public char next() {
 109                 return setIndex(Math.min(fIndex + 1, getEndIndex()));
 110         }
 111
 112         /*
 113          * @see java.text.CharacterIterator#previous()
 114          */
 115         public char previous() {
 116                 if (fIndex > getBeginIndex()) {
 117                         return setIndex(fIndex - 1);
 118                 } else {
 119                         return DONE;
 120                 }
 121         }
 122
 123         /*
 124          * @see java.text.CharacterIterator#setIndex(int)
 125          */
 126         public char setIndex(int position) {
 127                 if (position >= getBeginIndex() && position <= getEndIndex())
 128                         fIndex= position;
 129                 else
 130                         throw new IllegalArgumentException();
 131
 132                 invariant();
 133                 return current();
 134         }
 135
 136         /*
 137          * @see java.text.CharacterIterator#getBeginIndex()
 138          */
 139         public int getBeginIndex() {
 140                 return fFirst;
 141         }
 142
 143         /*
 144          * @see java.text.CharacterIterator#getEndIndex()
 145          */
 146         public int getEndIndex() {
 147                 return fLast;
 148         }
 149
 150         /*
 151          * @see java.text.CharacterIterator#getIndex()
 152          */
 153         public int getIndex() {
 154                 return fIndex;
 155         }
 156
 157         /*
 158          * @see java.text.CharacterIterator#clone()
 159          */
 160         @Override
 161         public Object clone() {
 162                 try {
 163                         return super.clone();
 164                 } catch (CloneNotSupportedException e) {
 165                         throw new InternalError();
 166                 }
 167         }
 168 }