WarmStart.h

// 
//     Minotaur -- It's only 1/2 bull
// 
//     (C)opyright 2008 - 2025 The Minotaur Team.
// 
 
// /**
// \file WarmStart.h
// \brief Define the base class WarmStart for storing the warm starting
// information for different types of engines.
// \author Ashutosh Mahajan, Argonne National Laboratory
// */
 
 
#ifndef MINOTAURWARMSTART_H
#define MINOTAURWARMSTART_H
 
#include "Types.h"
 
namespace Minotaur {
 
  class WarmStart;
  typedef WarmStart* WarmStartPtr;
  typedef const WarmStart* ConstWarmStartPtr;
 
  // /** 
  // Warm starting information enables an engine to quickly resolve a problem
  // after that has been modified. 
  //
  // We save warm start information on all those
  // nodes of the branch-and-bound tree whose at least one child is saved for
  // later processing. If all the children of a node are pruned or if the node
  // has only one child and we decide to process it next, then we don't need
  // to save warm start information for that node.
  //
  // For now we save complete warm-start information on each active node. A more
  // memory efficient method is to save warm-start information for each node
  // by just storing the differences from the parent.
  // However, the benefits of saving the complete information are:
  //  -# Ease of coding.
  //  -# We can delete warm-start information of a node when it is processed.
  //  Thus, we have at most `A' nodes that have warm-start information saved
  //  on them, where `A' is the total number of active nodes in the tree.
  // */
  class WarmStart {
    public:
      WarmStart() {cnt_ = 0;} ;
 
      virtual ~WarmStart() {} ;
      
      virtual void decrUseCnt()
      {--cnt_;} ;
 
      virtual int getUseCnt()
      {return cnt_;} ;
      
      virtual bool hasInfo() = 0;
 
      virtual void incrUseCnt()
      {++cnt_;} ;
      
      virtual void write(std::ostream &out) const = 0;
 
    protected:
      int cnt_;
  };
}
#endif