/*
 * $Revision: 2523 $
 *
 * last checkin:
 *   $Author: gutwenger $
 *   $Date: 2012-07-02 20:59:27 +0200 (Mon, 02 Jul 2012) $
 ***************************************************************/

/** \file
 * \brief Declaration of class StaticSkeleton.
 *
 * \author Carsten Gutwenger
 *
 * \par License:
 * This file is part of the Open Graph Drawing Framework (OGDF).
 *
 * \par
 * Copyright (C)<br>
 * See README.txt in the root directory of the OGDF installation for details.
 *
 * \par
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * Version 2 or 3 as published by the Free Software Foundation;
 * see the file LICENSE.txt included in the packaging of this file
 * for details.
 *
 * \par
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * \par
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 * \see  http://www.gnu.org/copyleft/gpl.html
 ***************************************************************/


#ifdef _MSC_VER
#pragma once
#endif


#ifndef OGDF_STATIC_SKELETON_H
#define OGDF_STATIC_SKELETON_H


#include <ogdf/decomposition/Skeleton.h>


namespace ogdf {

	class OGDF_EXPORT StaticSPQRTree;


//! %Skeleton graphs of nodes in a static SPQR-tree.
/**
 * The class StaticSkeleton maintains the skeleton \a S of a node \a vT in a static SPQR-tree
 * \a T. We call \a T the owner tree of \a S and \a vT the corresponding tree node. Let
 * \a G be the original graph of \a T.
 *
 * \a S consists of an undirected multi-graph \a M. If the owner tree of \a S is
 * a PlanarSPQRTree, then \a M represents a combinatorial embedding.
 * The vertices in \a M correspond to vertices in \a G. The edges in \a M are of
 * two types: Real edges correspond to edges in \a G and virtual edges correspond
 * to tree-edges in \a T having \a vT as an endpoint.
 *
 * Let \a e in \a M be a virtual edge and \a eT be the corresponding tree-edge.
 * Then there exists exactly one edge \a e' in another skeleton \a S' of \a T that
 * corresponds to \a eT as well. We call \a e' the twin edge of \a e.
 */
class OGDF_EXPORT StaticSkeleton : public Skeleton
{
	friend class OGDF_EXPORT StaticSPQRTree;

public:

	// constructor

	//! Creates a skeleton \a S with owner tree \a T and corresponding node \a vT.
	/**
	 * \pre \a vT is a node in \a T
	 *
	 * \remarks Skeletons are created by the constructor of SPQRTree
	 *          and can be accessed with the skeleton() function of SPQRTree.
	 */
	StaticSkeleton(const StaticSPQRTree *T, node vT);


	// destructor
	~StaticSkeleton() { }


	//! Returns the owner tree \a T.
	const SPQRTree &owner() const;

	//! Returns the vertex in the original graph \a G that corresponds to \a v.
	/**
	 * \pre \a v is a node in \a M.
	 */
	node original (node v) const {
		return m_orig[v];
	}

	//! Returns true iff \a e is a virtual edge.
	/**
	 * \pre \a e is an edge in \a M
	 */
	bool isVirtual (edge e) const {
		return (m_real[e] == 0);
	}

	//! Returns the real edge that corresponds to skeleton edge \a e
	/**
	 * If \a e is virtual edge, then 0 is returned.
	 * \pre \a e is an edge in \a M
	 */
	edge realEdge (edge e) const {
		return m_real[e];
	}

	//! Returns the twin edge of skeleton edge \a e.
	/**
	 * If \a e is not a virtual edge, then 0 is returned.
	 * \pre \a e is an edge in \a M
	 */
	edge twinEdge (edge e) const;

	//! Returns the tree node in T containing the twin edge of skeleton edge \a e.
	/**
	 * If \a e is not a virtual edge, then 0 is returned.
	 * \pre \a e is an edge in \a M
	 */
	node twinTreeNode (edge e) const;

	//! Returns the tree edge which is associated with skeleton edge \a e.
	/**
	 * If \a e is not a virtual edge, then 0 is retuned.
	 * \pre \a e is an edge in \a M
	 */
	edge treeEdge (edge e) const {
		return m_treeEdge[e];
	}

	OGDF_MALLOC_NEW_DELETE

protected:
	const StaticSPQRTree *m_owner;     //!< owner tree
	NodeArray<node>       m_orig;      //!< corresp. original node
	EdgeArray<edge>       m_real;      //!< corresp. original edge (0 if virtual)
	EdgeArray<edge>       m_treeEdge;  //!< corresp. tree edge (0 if real)
};


} // end namespace ogdf


#endif
