/*
  (c) Copyright 2003, 2004, 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
  [See end of file]
  $Id: Delta.java,v 1.14 2008/01/02 12:10:19 andy_seaborne Exp $
*/

package com.hp.hpl.jena.graph.compose;

import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.util.iterator.*;

/**
    Graph operation for wrapping a base graph and leaving it unchanged while recording
    all the attempted updates for later access.
<p>    
    TODO review in the light of GraphWrapper
	@author hedgehog
*/

public class Delta extends Dyadic implements Graph 
	{
	private Graph base;
	
	public Delta( Graph base )
		{
		super( Factory.createGraphMem(), Factory.createGraphMem() );
		this.base = base;
		}
		
    /**
        Answer the graph of all triples added
    */
	public Graph getAdditions()
		{ return L; }
		
    /**
        Answer the graph of all triples removed
    */
	public Graph getDeletions()
		{ return R; }
		
    /**
        Add the triple to the graph, ie add it to the additions, remove it from the removals.
    */
	public void performAdd( Triple t )
		{
		L.add( t );
		R.delete( t );
		}

    /**
        Remove the triple, ie, remove it from the adds, add it to the removals.
    */
	public void performDelete( Triple t )
		{
		L.delete( t );
		R.add( t );
		}
		 
    /**
        Find all the base triples matching tm, exclude the ones that are deleted, add the ones
        that  have been added.
    */
	public ExtendedIterator graphBaseFind( TripleMatch tm ) 
		{
        return base.find( tm ) .filterDrop( ifIn( GraphUtil.findAll( R ) ) ) .andThen( L.find( tm ) );
		}

	public void close() 
		{
		super.close();
		base.close();
		}

	public int graphBaseSize()
		{ return base.size() + L.size() - R.size(); }
	}

/*
    (c) Copyright 2003, 2004, 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.

    3. The name of the author may not be used to endorse or promote products
       derived from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
