2d_distances_propagator.h

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// Copyright 2010-2025 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef OR_TOOLS_SAT_2D_DISTANCES_PROPAGATOR_H_
#define OR_TOOLS_SAT_2D_DISTANCES_PROPAGATOR_H_
 
#include <cstdint>
#include <utility>
#include <vector>
 
#include "ortools/sat/integer.h"
#include "ortools/sat/model.h"
#include "ortools/sat/no_overlap_2d_helper.h"
#include "ortools/sat/precedences.h"
#include "ortools/sat/synchronization.h"
 
namespace operations_research {
namespace sat {
 
// This class implements a propagator for non_overlap_2d constraints that uses
// the BinaryRelationsMaps to detect precedences between pairs of boxes and
// detect a conflict if the precedences implies an overlap between the two
// boxes. For doing this efficiently, it keep track of pairs of boxes that have
// non-fixed precedences in the BinaryRelationsMaps and only check those in the
// propagation.
class Precedences2DPropagator : public PropagatorInterface {
 public:
  Precedences2DPropagator(NoOverlap2DConstraintHelper* helper, Model* model);
 
  ~Precedences2DPropagator() override;
 
  bool Propagate() final;
  int RegisterWith(GenericLiteralWatcher* watcher);
 
 private:
  void CollectPairsOfBoxesWithNonTrivialDistance();
 
  std::vector<std::pair<int, int>> non_trivial_pairs_;
 
  NoOverlap2DConstraintHelper& helper_;
  BinaryRelationsMaps* binary_relations_maps_;
  SharedStatistics* shared_stats_;
 
  int last_helper_inprocessing_count_ = -1;
  int last_num_expressions_ = -1;
 
  int64_t num_conflicts_ = 0;
  int64_t num_calls_ = 0;
 
  Precedences2DPropagator(const Precedences2DPropagator&) = delete;
  Precedences2DPropagator& operator=(const Precedences2DPropagator&) = delete;
};
 
}  // namespace sat
}  // namespace operations_research
 
#endif  // OR_TOOLS_SAT_2D_DISTANCES_PROPAGATOR_H_