/*
* Copyright (c) 2011, the Dart project authors.
*
* Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.eclipse.org/legal/epl-v10.html
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.dart.tools.ui.internal.text.functions;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import java.text.CharacterIterator;
/**
* An <code>IDocument</code> based implementation of <code>CharacterIterator</code> and
* <code>CharSequence</code>. Note that the supplied document is not copied; if the document is
* modified during the lifetime of a <code>DocumentCharacterIterator</code>, the methods returning
* document content may not always return the same values. Also, if accessing the document fails
* with a {@link BadLocationException}, any of <code>CharacterIterator</code> methods as well as
* <code>charAt</code>may return {@link CharacterIterator#DONE}.
*/
public class DocumentCharacterIterator implements CharacterIterator, CharSequence {
private int fIndex = -1;
private final IDocument fDocument;
private final int fFirst;
private final int fLast;
/**
* Creates an iterator for the entire document.
*
* @param document the document backing this iterator
*/
public DocumentCharacterIterator(IDocument document) {
this(document, 0);
}
/**
* Creates an iterator, starting at offset <code>first</code>.
*
* @param document the document backing this iterator
* @param first the first character to consider
* @throws IllegalArgumentException if the indices are out of bounds
*/
public DocumentCharacterIterator(IDocument document, int first) throws IllegalArgumentException {
this(document, first, document.getLength());
}
/**
* Creates an iterator for the document contents from <code>first</code> (inclusive) to
* <code>last</code> (exclusive).
*
* @param document the document backing this iterator
* @param first the first character to consider
* @param last the last character index to consider
* @throws IllegalArgumentException if the indices are out of bounds
*/
public DocumentCharacterIterator(IDocument document, int first, int last)
throws IllegalArgumentException {
if (document == null) {
throw new NullPointerException();
}
if (first < 0 || first > last) {
throw new IllegalArgumentException();
}
if (last > document.getLength()) {
throw new IllegalArgumentException();
}
fDocument = document;
fFirst = first;
fLast = last;
fIndex = first;
invariant();
}
/**
* {@inheritDoc}
* <p>
* Note that, if the document is modified concurrently, this method may return
* {@link CharacterIterator#DONE} if a {@link BadLocationException} was thrown when accessing the
* backing document.
* </p>
*
* @param index {@inheritDoc}
* @return {@inheritDoc}
*/
@Override
public char charAt(int index) {
if (index >= 0 && index < length()) {
try {
return fDocument.getChar(getBeginIndex() + index);
} catch (BadLocationException e) {
// ignore and return DONE
return DONE;
}
} else {
throw new IndexOutOfBoundsException();
}
}
/*
* @see java.text.CharacterIterator#clone()
*/
@Override
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
/*
* @see java.text.CharacterIterator#current()
*/
@Override
public char current() {
if (fIndex >= fFirst && fIndex < fLast) {
try {
return fDocument.getChar(fIndex);
} catch (BadLocationException e) {
// ignore
}
}
return DONE;
}
/*
* @see java.text.CharacterIterator#first()
*/
@Override
public char first() {
return setIndex(getBeginIndex());
}
/*
* @see java.text.CharacterIterator#getBeginIndex()
*/
@Override
public int getBeginIndex() {
return fFirst;
}
/*
* @see java.text.CharacterIterator#getEndIndex()
*/
@Override
public int getEndIndex() {
return fLast;
}
/*
* @see java.text.CharacterIterator#getIndex()
*/
@Override
public int getIndex() {
return fIndex;
}
/*
* @see java.text.CharacterIterator#last()
*/
@Override
public char last() {
if (fFirst == fLast) {
return setIndex(getEndIndex());
} else {
return setIndex(getEndIndex() - 1);
}
}
/*
* @see java.lang.CharSequence#length()
*/
@Override
public int length() {
return getEndIndex() - getBeginIndex();
}
/*
* @see java.text.CharacterIterator#next()
*/
@Override
public char next() {
return setIndex(Math.min(fIndex + 1, getEndIndex()));
}
/*
* @see java.text.CharacterIterator#previous()
*/
@Override
public char previous() {
if (fIndex > getBeginIndex()) {
return setIndex(fIndex - 1);
} else {
return DONE;
}
}
/*
* @see java.text.CharacterIterator#setIndex(int)
*/
@Override
public char setIndex(int position) {
if (position >= getBeginIndex() && position <= getEndIndex()) {
fIndex = position;
} else {
throw new IllegalArgumentException();
}
invariant();
return current();
}
/*
* @see java.lang.CharSequence#subSequence(int, int)
*/
@Override
public CharSequence subSequence(int start, int end) {
if (start < 0) {
throw new IndexOutOfBoundsException();
}
if (end < start) {
throw new IndexOutOfBoundsException();
}
if (end > length()) {
throw new IndexOutOfBoundsException();
}
return new DocumentCharacterIterator(fDocument, getBeginIndex() + start, getBeginIndex() + end);
}
private void invariant() {
Assert.isTrue(fIndex >= fFirst);
Assert.isTrue(fIndex <= fLast);
}
}