/* $Id$
 *
 * Name:    CouenneThreeWayBranchObj.hpp
 * Authors: Pierre Bonami, IBM Corp.
 *          Pietro Belotti, Carnegie Mellon University
 * Purpose: Three way branching object for auxiliary variables
 *
 * (C) Carnegie-Mellon University, 2006-10.
 * This file is licensed under the Eclipse Public License (EPL)
 */

#ifndef COUENNETHREEWAYBRANCHOBJ_HPP
#define COUENNETHREEWAYBRANCHOBJ_HPP

#include "OsiBranchingObject.hpp"

#include "CouenneExprAux.hpp"
#include "CouenneObject.hpp"

namespace Couenne {

/// \brief Spatial, three-way branching object. 
///
/// Branching is performed on continuous variables but a better
/// convexification is sought around the current point by dividing the
/// interval in three parts

class COUENNELIB_EXPORT CouenneThreeWayBranchObj: public OsiBranchingObject {

public:

  /// Constructor
  CouenneThreeWayBranchObj (JnlstPtr jnlst,
			    expression *, 
			    CouNumber,
			    CouNumber, 
			    int  = THREE_CENTER
			    //bool = false
			    );

  /// Copy constructor
  CouenneThreeWayBranchObj (const CouenneThreeWayBranchObj &src):
    OsiBranchingObject (src),
    brVar_ (src.brVar_),
    lcrop_ (src.lcrop_),
    rcrop_ (src.rcrop_),
    firstBranch_ (src.firstBranch_),
    jnlst_ (src.jnlst_){}

  /// Cloning method
  virtual OsiBranchingObject * clone () const
  {return new CouenneThreeWayBranchObj (*this);}

  /** \brief Execute the actions required to branch, as specified by the
	     current state of the branching object, and advance the object's
	     state. 
	     Returns change in guessed objective on next (what does
	     "next" mean here?) branch
  */
  virtual double branch (OsiSolverInterface * solver = NULL);

protected:

  /// The variable this branching object refers to. If the
  /// corresponding CouenneObject was created on w=f(x,y), it is
  /// either x or y.
  expression *brVar_;

  CouNumber lcrop_;  ///< left divider
  CouNumber rcrop_;  ///< right divider

  /// First branch to be performed: 0 is left, 1 is central, 2 is right
  int firstBranch_;

  /// True if the associated variable is integer
  //  bool integer_;

  /// SmartPointer to the Journalist
  JnlstPtr jnlst_;
};

}

#endif