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/*******************************************************************************
* Copyright (c) 2005, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Anton Leherbauer (anton.leherbauer@windriver.com) - initial API and implementation
*******************************************************************************/
package org.eclipse.jface.text;
import org.eclipse.core.runtime.Assert;
/**
* Copy-on-write <code>ITextStore</code> wrapper.
* <p>
* This implementation uses an unmodifiable text store for the initial content.
* Upon first modification attempt, the unmodifiable store is replaced with
* a modifiable instance which must be supplied in the constructor.</p>
* <p>
* This class is not intended to be subclassed.
* </p>
*
* @since 3.2
* @noextend This class is not intended to be subclassed by clients.
*/
public class CopyOnWriteTextStore implements ITextStore {
/**
* An unmodifiable String based text store. It is not possible to modify the content
* other than using {@link #set}. Trying to {@link #replace} a text range will
* throw an <code>UnsupportedOperationException</code>.
*/
private static class StringTextStore implements ITextStore {
/** Represents the content of this text store. */
private String fText= ""; //$NON-NLS-1$
/**
* Create an empty text store.
*/
private StringTextStore() {
super();
}
/**
* Create a text store with initial content.
* @param text the initial content
*/
private StringTextStore(String text) {
super();
set(text);
}
/*
* @see org.eclipse.jface.text.ITextStore#get(int)
*/
public char get(int offset) {
return fText.charAt(offset);
}
/*
* @see org.eclipse.jface.text.ITextStore#get(int, int)
*/
public String get(int offset, int length) {
return fText.substring(offset, offset + length);
}
/*
* @see org.eclipse.jface.text.ITextStore#getLength()
*/
public int getLength() {
return fText.length();
}
/*
* @see org.eclipse.jface.text.ITextStore#replace(int, int, java.lang.String)
*/
public void replace(int offset, int length, String text) {
// modification not supported
throw new UnsupportedOperationException();
}
/*
* @see org.eclipse.jface.text.ITextStore#set(java.lang.String)
*/
public void set(String text) {
fText= text != null ? text : ""; //$NON-NLS-1$
}
}
/** The underlying "real" text store */
protected ITextStore fTextStore= new StringTextStore();
/** A modifiable <code>ITextStore</code> instance */
private final ITextStore fModifiableTextStore;
/**
* Creates an empty text store. The given text store will be used upon first
* modification attempt.
*
* @param modifiableTextStore
* a modifiable <code>ITextStore</code> instance, may not be
* <code>null</code>
*/
public CopyOnWriteTextStore(ITextStore modifiableTextStore) {
Assert.isNotNull(modifiableTextStore);
fTextStore= new StringTextStore();
fModifiableTextStore= modifiableTextStore;
}
/*
* @see org.eclipse.jface.text.ITextStore#get(int)
*/
public char get(int offset) {
return fTextStore.get(offset);
}
/*
* @see org.eclipse.jface.text.ITextStore#get(int, int)
*/
public String get(int offset, int length) {
return fTextStore.get(offset, length);
}
/*
* @see org.eclipse.jface.text.ITextStore#getLength()
*/
public int getLength() {
return fTextStore.getLength();
}
/*
* @see org.eclipse.jface.text.ITextStore#replace(int, int, java.lang.String)
*/
public void replace(int offset, int length, String text) {
if (fTextStore != fModifiableTextStore) {
String content= fTextStore.get(0, fTextStore.getLength());
fTextStore= fModifiableTextStore;
fTextStore.set(content);
}
fTextStore.replace(offset, length, text);
}
/*
* @see org.eclipse.jface.text.ITextStore#set(java.lang.String)
*/
public void set(String text) {
fTextStore= new StringTextStore(text);
fModifiableTextStore.set(""); //$NON-NLS-1$
}
}
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