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

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2005 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 net.sourceforge.phpdt.internal.ui.text;
  12
  13 import java.text.CharacterIterator;
  14
  15 import org.eclipse.jface.text.Assert;
  16 import org.eclipse.jface.text.BadLocationException;
  17 import org.eclipse.jface.text.IDocument;
  18
  19
  20 /**
  21  * An <code>IDocument</code> based implementation of
  22  * <code>CharacterIterator</code> and <code>CharSequence</code>. Note that
  23  * the supplied document is not copied; if the document is modified during the
  24  * lifetime of a <code>DocumentCharacterIterator</code>, the methods
  25  * returning document content may not always return the same values. Also, if
  26  * accessing the document fails with a {@link BadLocationException}, any of
  27  * <code>CharacterIterator</code> methods as well as <code>charAt</code>may
  28  * return {@link CharacterIterator#DONE}.
  29  *
  30  * @since 3.0
  31  */
  32 public class DocumentCharacterIterator implements CharacterIterator, CharSequence {
  33
  34         private int fIndex= -1;
  35         private final IDocument fDocument;
  36         private final int fFirst;
  37         private final int fLast;
  38
  39         private void invariant() {
  40                 Assert.isTrue(fIndex >= fFirst);
  41                 Assert.isTrue(fIndex <= fLast);
  42         }
  43
  44         /**
  45          * Creates an iterator for the entire document.
  46          *
  47          * @param document the document backing this iterator
  48          */
  49         public DocumentCharacterIterator(IDocument document) {
  50                 this(document, 0);
  51         }
  52
  53         /**
  54          * Creates an iterator, starting at offset <code>first</code>.
  55          *
  56          * @param document the document backing this iterator
  57          * @param first the first character to consider
  58          * @throws IllegalArgumentException if the indices are out of bounds
  59          */
  60         public DocumentCharacterIterator(IDocument document, int first) throws IllegalArgumentException {
  61                 this(document, first, document.getLength());
  62         }
  63
  64         /**
  65          * Creates an iterator for the document contents from <code>first</code>
  66          * (inclusive) to <code>last</code> (exclusive).
  67          *
  68          * @param document the document backing this iterator
  69          * @param first the first character to consider
  70          * @param last the last character index to consider
  71          * @throws IllegalArgumentException if the indices are out of bounds
  72          */
  73         public DocumentCharacterIterator(IDocument document, int first, int last) throws IllegalArgumentException {
  74                 if (document == null)
  75                         throw new NullPointerException();
  76                 if (first < 0 || first > last)
  77                         throw new IllegalArgumentException();
  78                 if (last > document.getLength())
  79                         throw new IllegalArgumentException();
  80                 fDocument= document;
  81                 fFirst= first;
  82                 fLast= last;
  83                 fIndex= first;
  84                 invariant();
  85         }
  86
  87         /*
  88          * @see java.text.CharacterIterator#first()
  89          */
  90         public char first() {
  91                 return setIndex(getBeginIndex());
  92         }
  93
  94         /*
  95          * @see java.text.CharacterIterator#last()
  96          */
  97         public char last() {
  98                 if (fFirst == fLast)
  99                         return setIndex(getEndIndex());
 100                 else
 101                         return setIndex(getEndIndex() - 1);
 102         }
 103
 104         /*
 105          * @see java.text.CharacterIterator#current()
 106          */
 107         public char current() {
 108                 if (fIndex >= fFirst && fIndex < fLast)
 109                         try {
 110                                 return fDocument.getChar(fIndex);
 111                         } catch (BadLocationException e) {
 112                                 // ignore
 113                         }
 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
 180         /*
 181          * @see java.lang.CharSequence#length()
 182          */
 183         public int length() {
 184                 return getEndIndex() - getBeginIndex();
 185         }
 186
 187         /**
 188          * {@inheritDoc}
 189          * <p>
 190          * Note that, if the document is modified concurrently, this method may
 191          * return {@link CharacterIterator#DONE} if a {@link BadLocationException}
 192          * was thrown when accessing the backing document.
 193          * </p>
 194          *
 195          * @param index {@inheritDoc}
 196          * @return {@inheritDoc}
 197          */
 198         public char charAt(int index) {
 199                 if (index >= 0 && index < length())
 200                         try {
 201                                 return fDocument.getChar(getBeginIndex() + index);
 202                         } catch (BadLocationException e) {
 203                                 // ignore and return DONE
 204                                 return DONE;
 205                         }
 206                 else
 207                         throw new IndexOutOfBoundsException();
 208         }
 209
 210         /*
 211          * @see java.lang.CharSequence#subSequence(int, int)
 212          */
 213         public CharSequence subSequence(int start, int end) {
 214                 if (start < 0)
 215                         throw new IndexOutOfBoundsException();
 216                 if (end < start)
 217                         throw new IndexOutOfBoundsException();
 218                 if (end > length())
 219                         throw new IndexOutOfBoundsException();
 220                 return new DocumentCharacterIterator(fDocument, getBeginIndex() + start, getBeginIndex() + end);
 221         }
 222 }