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  * A <code>CharSequence</code> based implementation of
  19  * <code>CharacterIterator</code>.
  20  *
  21  * @since 3.0
  22  */
  23 public class SequenceCharacterIterator implements CharacterIterator {
  24
  25         private int fIndex = -1;
  26
  27         private final CharSequence fSequence;
  28
  29         private final int fFirst;
  30
  31         private final int fLast;
  32
  33         private void invariant() {
  34                 Assert.isTrue(fIndex >= fFirst);
  35                 Assert.isTrue(fIndex <= fLast);
  36         }
  37
  38         /**
  39          * Creates an iterator for the entire sequence.
  40          *
  41          * @param sequence
  42          *            the sequence backing this iterator
  43          */
  44         public SequenceCharacterIterator(CharSequence sequence) {
  45                 this(sequence, 0);
  46         }
  47
  48         /**
  49          * Creates an iterator.
  50          *
  51          * @param sequence
  52          *            the sequence backing this iterator
  53          * @param first
  54          *            the first character to consider
  55          * @throws IllegalArgumentException
  56          *             if the indices are out of bounds
  57          */
  58         public SequenceCharacterIterator(CharSequence sequence, int first)
  59                         throws IllegalArgumentException {
  60                 this(sequence, first, sequence.length());
  61         }
  62
  63         /**
  64          * Creates an iterator.
  65          *
  66          * @param sequence
  67          *            the sequence backing this iterator
  68          * @param first
  69          *            the first character to consider
  70          * @param last
  71          *            the last character index to consider
  72          * @throws IllegalArgumentException
  73          *             if the indices are out of bounds
  74          */
  75         public SequenceCharacterIterator(CharSequence sequence, int first, int last)
  76                         throws IllegalArgumentException {
  77                 if (sequence == null)
  78                         throw new NullPointerException();
  79                 if (first < 0 || first > last)
  80                         throw new IllegalArgumentException();
  81                 if (last > sequence.length())
  82                         throw new IllegalArgumentException();
  83                 fSequence = sequence;
  84                 fFirst = first;
  85                 fLast = last;
  86                 fIndex = first;
  87                 invariant();
  88         }
  89
  90         /*
  91          * @see java.text.CharacterIterator#first()
  92          */
  93         public char first() {
  94                 return setIndex(getBeginIndex());
  95         }
  96
  97         /*
  98          * @see java.text.CharacterIterator#last()
  99          */
 100         public char last() {
 101                 if (fFirst == fLast)
 102                         return setIndex(getEndIndex());
 103                 else
 104                         return setIndex(getEndIndex() - 1);
 105         }
 106
 107         /*
 108          * @see java.text.CharacterIterator#current()
 109          */
 110         public char current() {
 111                 if (fIndex >= fFirst && fIndex < fLast)
 112                         return fSequence.charAt(fIndex);
 113                 else
 114                         return DONE;
 115         }
 116
 117         /*
 118          * @see java.text.CharacterIterator#next()
 119          */
 120         public char next() {
 121                 return setIndex(Math.min(fIndex + 1, getEndIndex()));
 122         }
 123
 124         /*
 125          * @see java.text.CharacterIterator#previous()
 126          */
 127         public char previous() {
 128                 if (fIndex > getBeginIndex()) {
 129                         return setIndex(fIndex - 1);
 130                 } else {
 131                         return DONE;
 132                 }
 133         }
 134
 135         /*
 136          * @see java.text.CharacterIterator#setIndex(int)
 137          */
 138         public char setIndex(int position) {
 139                 if (position >= getBeginIndex() && position <= getEndIndex())
 140                         fIndex = position;
 141                 else
 142                         throw new IllegalArgumentException();
 143
 144                 invariant();
 145                 return current();
 146         }
 147
 148         /*
 149          * @see java.text.CharacterIterator#getBeginIndex()
 150          */
 151         public int getBeginIndex() {
 152                 return fFirst;
 153         }
 154
 155         /*
 156          * @see java.text.CharacterIterator#getEndIndex()
 157          */
 158         public int getEndIndex() {
 159                 return fLast;
 160         }
 161
 162         /*
 163          * @see java.text.CharacterIterator#getIndex()
 164          */
 165         public int getIndex() {
 166                 return fIndex;
 167         }
 168
 169         /*
 170          * @see java.text.CharacterIterator#clone()
 171          */
 172         public Object clone() {
 173                 try {
 174                         return super.clone();
 175                 } catch (CloneNotSupportedException e) {
 176                         throw new InternalError();
 177                 }
 178         }
 179 }