/*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2003 The Apache Software Foundation.
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* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
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*
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package org.apache.commons.jrcs.diff;
import java.util.List;
/**
* Holds a "delta" difference between to revisions of a text.
*
* @version $Revision: 1.5 $ $Date: 2003/05/06 19:07:13 $
*
* @author <a href="mailto:juanco@suigeneris.org">Juanco Anez</a>
* @author <a href="mailto:bwm@hplb.hpl.hp.com">Brian McBride</a>
* @see Diff
* @see Chunk
* @see Revision
*
* modifications
*
* 27 Apr 2003 bwm
*
* Added getOriginal() and getRevised() accessor methods
* Added visitor pattern accept() method
*/
public abstract class Delta
extends org.apache.commons.jrcs.util.ToString
{
protected Chunk original;
protected Chunk revised;
static Class[][] DeltaClass;
static
{
DeltaClass = new Class[2][2];
try
{
DeltaClass[0][0] = org.apache.commons.jrcs.diff.ChangeDelta.class;
DeltaClass[0][1] = org.apache.commons.jrcs.diff.AddDelta.class;
DeltaClass[1][0] = org.apache.commons.jrcs.diff.DeleteDelta.class;
DeltaClass[1][1] = org.apache.commons.jrcs.diff.ChangeDelta.class;
}
catch (Throwable o)
{
}
}
/**
* Returns a Delta that corresponds to the given chunks in the
* original and revised text respectively.
* @param orig the chunk in the original text.
* @param rev the chunk in the revised text.
*/
public static Delta newDelta(Chunk orig, Chunk rev)
{
Class c = DeltaClass[orig.size() > 0 ? 1 : 0][rev.size() > 0 ? 1 : 0];
Delta result;
try
{
result = (Delta) c.newInstance();
}
catch (Throwable e)
{
return null;
}
result.init(orig, rev);
return result;
}
/**
* Creates an uninitialized delta.
*/
protected Delta()
{
}
/**
* Creates a delta object with the given chunks from the original
* and revised texts.
*/
protected Delta(Chunk orig, Chunk rev)
{
init(orig, rev);
}
/**
* Initializaes the delta with the given chunks from the original
* and revised texts.
*/
protected void init(Chunk orig, Chunk rev)
{
original = orig;
revised = rev;
}
/**
* Verifies that this delta can be used to patch the given text.
* @param target the text to patch.
* @throws PatchFailedException if the patch cannot be applied.
*/
public abstract void verify(List target)
throws PatchFailedException;
/**
* Applies this delta as a patch to the given text.
* @param target the text to patch.
* @throws PatchFailedException if the patch cannot be applied.
*/
public final void patch(List target)
throws PatchFailedException
{
verify(target);
try
{
applyTo(target);
}
catch (Exception e)
{
throw new PatchFailedException(e.getMessage());
}
}
/**
* Applies this delta as a patch to the given text.
* @param target the text to patch.
* @throws PatchFailedException if the patch cannot be applied.
*/
public abstract void applyTo(List target);
/**
* Converts this delta into its Unix diff style string representation.
* @param s a {@link StringBuffer StringBuffer} to which the string
* representation will be appended.
*/
public void toString(StringBuffer s)
{
original.rangeString(s);
s.append("x");
revised.rangeString(s);
s.append(Diff.NL);
original.toString(s, "> ", "\n");
s.append("---");
s.append(Diff.NL);
revised.toString(s, "< ", "\n");
}
/**
* Converts this delta into its RCS style string representation.
* @param s a {@link StringBuffer StringBuffer} to which the string
* representation will be appended.
* @param EOL the string to use as line separator.
*/
public abstract void toRCSString(StringBuffer s, String EOL);
/**
* Converts this delta into its RCS style string representation.
* @param EOL the string to use as line separator.
*/
public String toRCSString(String EOL)
{
StringBuffer s = new StringBuffer();
toRCSString(s, EOL);
return s.toString();
}
/**
* Accessor method to return the chunk representing the original
* sequence of items
*
* @return the original sequence
*/
public Chunk getOriginal()
{
return original;
}
/**
* Accessor method to return the chunk representing the updated
* sequence of items.
*
* @return the updated sequence
*/
public Chunk getRevised()
{
return revised;
}
/**
* Accepts a visitor.
* <p>
* See the Visitor pattern in "Design Patterns" by the GOF4.
* @param visitor The visitor.
*/
public abstract void accept(RevisionVisitor visitor);
}