objpricer.h

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*                                                                           */
/*                  This file is part of the program and library             */
/*         SCIP --- Solving Constraint Integer Programs                      */
/*                                                                           */
/*    Copyright (C) 2002-2022 Konrad-Zuse-Zentrum                            */
/*                            fuer Informationstechnik Berlin                */
/*                                                                           */
/*  SCIP is distributed under the terms of the ZIB Academic License.         */
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/*  You should have received a copy of the ZIB Academic License.             */
/*  along with SCIP; see the file COPYING. If not visit scipopt.org.         */
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/**@file   objpricer.h
 * @brief  C++ wrapper for variable pricers
 * @author Tobias Achterberg
 */

/*---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+----0----+----1----+----2*/

#ifndef __SCIP_OBJPRICER_H__
#define __SCIP_OBJPRICER_H__

#include <cstring>

#include "scip/scip.h"
#include "objscip/objprobcloneable.h"

namespace scip
{

/** @brief C++ wrapper for variable pricer
 *
 *  This class defines the interface for variable pricer implemented in C++. Note that there is a pure virtual
 *  function (this function has to be implemented). This function is: scip_redcost().
 *
 *  - \ref PRICER "Instructions for implementing a variable pricer"
 *  - \ref type_pricer.h "Corresponding C interface"
 */
class ObjPricer : public ObjProbCloneable
{
public:
   /*lint --e{1540}*/

   /** SCIP data structure */
   SCIP* scip_;

   /** name of the variable pricer */
   char* scip_name_;

   /** description of the variable pricer */
   char* scip_desc_;

   /** default priority of the variable pricer */
   const int scip_priority_;

   /** should the pricer be delayed until no other pricers or already existing problem variables with negative reduced
    *  costs are found?
    */
   const SCIP_Bool scip_delay_;

   /** default constructor */
   ObjPricer(
      SCIP*              scip,               /**< SCIP data structure */
      const char*        name,               /**< name of variable pricer */
      const char*        desc,               /**< description of variable pricer */
      int                priority,           /**< priority of the variable pricer */
      SCIP_Bool          delay               /**< should the pricer be delayed until no other pricers or already existing
                                              *   problem variables with negative reduced costs are found?
                                              *   if this is set to FALSE it may happen that the pricer produces columns
                                              *   that already exist in the problem (which are also priced in by the
                                              *   default problem variable pricing in the same round)
                                              */
      )
      : scip_(scip),
        scip_name_(0),
        scip_desc_(0),
        scip_priority_(priority),
        scip_delay_(delay)
   {
      /* the macro SCIPduplicateMemoryArray does not need the first argument: */
      SCIP_CALL_ABORT( SCIPduplicateMemoryArray(scip_, &scip_name_, name, std::strlen(name)+1) );
      SCIP_CALL_ABORT( SCIPduplicateMemoryArray(scip_, &scip_desc_, desc, std::strlen(desc)+1) );
   }

   /** destructor */
   virtual ~ObjPricer()
   {
      /* the macro SCIPfreeMemoryArray does not need the first argument: */
      /*lint --e{64}*/
      SCIPfreeMemoryArray(scip_, &scip_name_);
      SCIPfreeMemoryArray(scip_, &scip_desc_);
   }

   /** destructor of variable pricer to free user data (called when SCIP is exiting)
    *
    *  @see SCIP_DECL_PRICERFREE(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICERFREE(scip_free)
   {  /*lint --e{715}*/
      return SCIP_OKAY;
   }

   /** initialization method of variable pricer (called after problem was transformed)
    *
    *  @see SCIP_DECL_PRICERINIT(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICERINIT(scip_init)
   {  /*lint --e{715}*/
      return SCIP_OKAY;
   }

   /** deinitialization method of variable pricer (called before transformed problem is freed)
    *
    *  @see SCIP_DECL_PRICEREXIT(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICEREXIT(scip_exit)
   {  /*lint --e{715}*/
      return SCIP_OKAY;
   }

   /** solving process initialization method of variable pricer (called when branch and bound process is about to begin)
    *
    *  @see SCIP_DECL_PRICERINITSOL(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICERINITSOL(scip_initsol)
   {  /*lint --e{715}*/
      return SCIP_OKAY;
   }

   /** solving process deinitialization method of variable pricer (called before branch and bound process data is freed)
    *
    *  @see SCIP_DECL_PRICEREXITSOL(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICEREXITSOL(scip_exitsol)
   {  /*lint --e{715}*/
      return SCIP_OKAY;
   }

   /** reduced cost pricing method of variable pricer for feasible LPs
    *
    *  @see SCIP_DECL_PRICERREDCOST(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICERREDCOST(scip_redcost) = 0;

   /** farkas pricing method of variable pricer for infeasible LPs
    *
    *  @see SCIP_DECL_PRICERFARKAS(x) in @ref type_pricer.h
    */
   virtual SCIP_DECL_PRICERFARKAS(scip_farkas)
   {  /*lint --e{715}*/
      return SCIP_OKAY;
   }
};

} /* namespace scip */



/** creates the variable pricer for the given variable pricer object and includes it in SCIP
 *
 *  The method should be called in one of the following ways:
 *
 *   1. The user is resposible of deleting the object:
 *       SCIP_CALL( SCIPcreate(&scip) );
 *       ...
 *       MyPricer* mypricer = new MyPricer(...);
 *       SCIP_CALL( SCIPincludeObjPricer(scip, &mypricer, FALSE) );
 *       ...
 *       SCIP_CALL( SCIPfree(&scip) );
 *       delete mypricer;    // delete pricer AFTER SCIPfree() !
 *
 *   2. The object pointer is passed to SCIP and deleted by SCIP in the SCIPfree() call:
 *       SCIP_CALL( SCIPcreate(&scip) );
 *       ...
 *       SCIP_CALL( SCIPincludeObjPricer(scip, new MyPricer(...), TRUE) );
 *       ...
 *       SCIP_CALL( SCIPfree(&scip) );  // destructor of MyPricer is called here
 */
SCIP_EXPORT
SCIP_RETCODE SCIPincludeObjPricer(
   SCIP*                 scip,               /**< SCIP data structure */
   scip::ObjPricer*      objpricer,          /**< variable pricer object */
   SCIP_Bool             deleteobject        /**< should the pricer object be deleted when pricer is freed? */
   );

/** returns the variable pricer object of the given name, or 0 if not existing */
SCIP_EXPORT
scip::ObjPricer* SCIPfindObjPricer(
   SCIP*                 scip,               /**< SCIP data structure */
   const char*           name                /**< name of variable pricer */
   );

/** returns the variable pricer object for the given pricer */
SCIP_EXPORT
scip::ObjPricer* SCIPgetObjPricer(
   SCIP*                 scip,               /**< SCIP data structure */
   SCIP_PRICER*          pricer              /**< pricer */
   );

#endif