net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/ui/text/SequenceCharacterIterator.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2004 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpdt.internal.ui.text;
  12
  13 import java.text.CharacterIterator;
  14
  15 import org.eclipse.jface.text.Assert;
  16
  17
  18 /**
  19  * A <code>CharSequence</code> based implementation of <code>CharacterIterator</code>.
  20  *
  21  * @since 3.0
  22  */
  23 public class SequenceCharacterIterator implements CharacterIterator {
  24
  25         private int fIndex= -1;
  26         private final CharSequence fSequence;
  27         private final int fFirst;
  28         private final int fLast;
  29
  30         private void invariant() {
  31                 Assert.isTrue(fIndex >= fFirst);
  32                 Assert.isTrue(fIndex <= fLast);
  33         }
  34
  35         /**
  36          * Creates an iterator for the entire sequence.
  37          *
  38          * @param sequence the sequence backing this iterator
  39          */
  40         public SequenceCharacterIterator(CharSequence sequence) {
  41                 this(sequence, 0);
  42         }
  43
  44         /**
  45          * Creates an iterator.
  46          *
  47          * @param sequence the sequence backing this iterator
  48          * @param first the first character to consider
  49          * @throws IllegalArgumentException if the indices are out of bounds
  50          */
  51         public SequenceCharacterIterator(CharSequence sequence, int first) throws IllegalArgumentException {
  52                 this(sequence, first, sequence.length());
  53         }
  54
  55         /**
  56          * Creates an iterator.
  57          *
  58          * @param sequence the sequence backing this iterator
  59          * @param first the first character to consider
  60          * @param last the last character index to consider
  61          * @throws IllegalArgumentException if the indices are out of bounds
  62          */
  63         public SequenceCharacterIterator(CharSequence sequence, int first, int last) throws IllegalArgumentException {
  64                 if (sequence == null)
  65                         throw new NullPointerException();
  66                 if (first < 0 || first > last)
  67                         throw new IllegalArgumentException();
  68                 if (last > sequence.length())
  69                         throw new IllegalArgumentException();
  70                 fSequence= sequence;
  71                 fFirst= first;
  72                 fLast= last;
  73                 fIndex= first;
  74                 invariant();
  75         }
  76
  77         /*
  78          * @see java.text.CharacterIterator#first()
  79          */
  80         public char first() {
  81                 return setIndex(getBeginIndex());
  82         }
  83
  84         /*
  85          * @see java.text.CharacterIterator#last()
  86          */
  87         public char last() {
  88                 if (fFirst == fLast)
  89                         return setIndex(getEndIndex());
  90                 else
  91                         return setIndex(getEndIndex() - 1);
  92         }
  93
  94         /*
  95          * @see java.text.CharacterIterator#current()
  96          */
  97         public char current() {
  98                 if (fIndex >= fFirst && fIndex < fLast)
  99                         return fSequence.charAt(fIndex);
 100                 else
 101                         return DONE;
 102         }
 103
 104         /*
 105          * @see java.text.CharacterIterator#next()
 106          */
 107         public char next() {
 108                 return setIndex(Math.min(fIndex + 1, getEndIndex()));
 109         }
 110
 111         /*
 112          * @see java.text.CharacterIterator#previous()
 113          */
 114         public char previous() {
 115                 if (fIndex > getBeginIndex()) {
 116                         return setIndex(fIndex - 1);
 117                 } else {
 118                         return DONE;
 119                 }
 120         }
 121
 122         /*
 123          * @see java.text.CharacterIterator#setIndex(int)
 124          */
 125         public char setIndex(int position) {
 126                 if (position >= getBeginIndex() && position <= getEndIndex())
 127                         fIndex= position;
 128                 else
 129                         throw new IllegalArgumentException();
 130
 131                 invariant();
 132                 return current();
 133         }
 134
 135         /*
 136          * @see java.text.CharacterIterator#getBeginIndex()
 137          */
 138         public int getBeginIndex() {
 139                 return fFirst;
 140         }
 141
 142         /*
 143          * @see java.text.CharacterIterator#getEndIndex()
 144          */
 145         public int getEndIndex() {
 146                 return fLast;
 147         }
 148
 149         /*
 150          * @see java.text.CharacterIterator#getIndex()
 151          */
 152         public int getIndex() {
 153                 return fIndex;
 154         }
 155
 156         /*
 157          * @see java.text.CharacterIterator#clone()
 158          */
 159         public Object clone() {
 160                 try {
 161                         return super.clone();
 162                 } catch (CloneNotSupportedException e) {
 163                         throw new InternalError();
 164                 }
 165         }
 166 }