local-search.hh

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// METS lib source file - local-search.hh                   -*- C++ -*-
//
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#ifndef LOCAL_SEARCH_HH_
#define LOCAL_SEARCH_HH_

namespace mets {

  template<typename move_manager_type>
  class local_search : public mets::abstract_search<move_manager_type>
  {
  public:
    local_search(evaluable_solution& starting_point,
                 solution_recorder& recorder,
                 move_manager_type& moveman,
                 gol_type epsilon = 1e-7,
                 bool short_circuit = false);

    local_search(const local_search&);
    local_search& operator=(const local_search&);
    
    virtual void
    search()
      throw(no_moves_error);

  protected:
    bool short_circuit_m;
    gol_type epsilon_m;
  };

  
}

template<typename move_manager_t>
mets::local_search<move_manager_t>::local_search(evaluable_solution& working,
                                                 solution_recorder& recorder,
                                                 move_manager_t& moveman,
                                                 gol_type epsilon,
                                                 bool short_circuit)
  : abstract_search<move_manager_t>(working, recorder, moveman),
    short_circuit_m(short_circuit), epsilon_m(epsilon)
{ 
  typedef abstract_search<move_manager_t> base_t;
  base_t::step_m = 0; 
}

template<typename move_manager_t>
void
mets::local_search<move_manager_t>::search()
  throw(no_moves_error)
{
  typedef abstract_search<move_manager_t> base_t;
  typename move_manager_t::iterator best_movit;

  base_t::solution_recorder_m.accept(base_t::working_solution_m);

  gol_type best_cost = 
    static_cast<mets::evaluable_solution&>(base_t::working_solution_m)
    .cost_function();

  do
    {
      base_t::moves_m.refresh(base_t::working_solution_m);
      best_movit = base_t::moves_m.end();
      for(typename move_manager_t::iterator movit = base_t::moves_m.begin();
          movit != base_t::moves_m.end(); ++movit)
        {
          // evaluate the cost after the move
          gol_type cost = (*movit)->evaluate(base_t::working_solution_m);
          if(cost < best_cost - epsilon_m)
            {
              best_cost = cost;
              best_movit = movit;
              if(short_circuit_m) break;
            }
        } // end for each move
      
      if(best_movit != base_t::moves_m.end()) 
        {
          (*best_movit)->apply(base_t::working_solution_m);
          base_t::solution_recorder_m.accept(base_t::working_solution_m);
          base_t::current_move_m = best_movit;
          this->notify();
        }
      
    } while(best_movit != base_t::moves_m.end());
}
#endif