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/*******************************************************************************
* Copyright (c) 2000, 2003 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jface.text;
/**
* Standard implementation of <code>ITextSelection</code>.
* Makes advantage of the weak contract of correctness of its
* interface. If generated from a selection provider, it only
* remembers its offset and length and computes the remaining
* information on request.
*/
public class TextSelection implements ITextSelection {
/** Internal empty text selection */
private final static ITextSelection NULL= new TextSelection();
/**
* Returns a shared instance of an empty text selection.
*
* @return a shared instance of an empty text selection
*/
public static ITextSelection emptySelection() {
return NULL;
}
/** Document which delivers the data of the selection */
private IDocument fDocument;
/** Offset of the selection */
private int fOffset;
/** Length of the selection */
private int fLength;
/**
* Creates an empty text selection.
*/
private TextSelection() {
this(null, -1, -1);
}
/**
* Creates a text selection for the given range. This
* selection object describes generically a text range and
* is intended to be an argument for the <code>setSelection</code>
* method of selection providers.
*
* @param offset the offset of the range
* @param length the length of the range
*/
public TextSelection(int offset, int length) {
this(null, offset, length);
}
/**
* Creates a text selection for the given range of the given document.
* This selection object is created by selection providers in responds
* <code>getSelection</code>.
*
* @param document the document whose text range is selected in a viewer
* @param offset the offset of the selected range
* @param length the length of the selected range
*/
public TextSelection(IDocument document, int offset, int length) {
fDocument= document;
fOffset= offset;
fLength= length;
}
/**
* Returns true if the offset and length are smaller than 0.
* A selection of length 0, is a valid text selection as it
* describes, e.g., the cursor position in a viewer.
*/
/*
* @see ISelection#isEmpty()
*/
public boolean isEmpty() {
return fOffset < 0 || fLength < 0;
}
/*
* @see ITextSelection#getOffset()
*/
public int getOffset() {
return fOffset;
}
/*
* @see ITextSelection#getLength()
*/
public int getLength() {
return fLength;
}
/*
* @see ITextSelection#getStartLine()
*/
public int getStartLine() {
try {
if (fDocument != null)
return fDocument.getLineOfOffset(fOffset);
} catch (BadLocationException x) {
}
return -1;
}
/*
* @see ITextSelection#getEndLine()
*/
public int getEndLine() {
try {
if (fDocument != null) {
int endOffset= fOffset + fLength;
if (fLength != 0)
endOffset--;
return fDocument.getLineOfOffset(endOffset);
}
} catch (BadLocationException x) {
}
return -1;
}
/*
* @see ITextSelection#getText()
*/
public String getText() {
try {
if (fDocument != null)
return fDocument.get(fOffset, fLength);
} catch (BadLocationException x) {
}
return null;
}
/*
* @see java.lang.Object#equals(Object)
*/
public boolean equals(Object obj) {
if (obj == this)
return true;
if (obj == null || getClass() != obj.getClass())
return false;
TextSelection s= (TextSelection) obj;
boolean sameRange= (s.fOffset == fOffset && s.fLength == fLength);
if (sameRange) {
if (s.fDocument == null && fDocument == null)
return true;
if (s.fDocument == null || fDocument == null)
return false;
try {
String sContent= s.fDocument.get(fOffset, fLength);
String content= fDocument.get(fOffset, fLength);
return sContent.equals(content);
} catch (BadLocationException x) {
}
}
return false;
}
/*
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
int low= fDocument != null ? fDocument.hashCode() : 0;
return (fOffset << 24) | (fLength << 16) | low;
}
}
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