280 lines
9.0 KiB
C++
280 lines
9.0 KiB
C++
// Copyright 2010-2025 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <atomic>
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#include <cstdint>
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#include <optional>
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#include <string>
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#include <utility>
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#include <vector>
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#include "absl/base/attributes.h"
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#include "absl/status/status.h"
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#include "absl/status/statusor.h"
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#include "ortools/base/logging.h"
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#include "ortools/linear_solver/linear_solver.h"
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#include "ortools/linear_solver/linear_solver.pb.h"
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#include "ortools/linear_solver/proto_solver/proto_utils.h"
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#include "ortools/linear_solver/proto_solver/sat_proto_solver.h"
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#include "ortools/port/proto_utils.h"
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#include "ortools/sat/cp_model.pb.h"
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#include "ortools/sat/cp_model_solver.h"
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#include "ortools/util/lazy_mutable_copy.h"
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namespace operations_research {
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class SatInterface : public MPSolverInterface {
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public:
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explicit SatInterface(MPSolver* solver);
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~SatInterface() override;
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// ----- Solve -----
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MPSolver::ResultStatus Solve(const MPSolverParameters& param) override;
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bool InterruptSolve() override;
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// ----- Directly solve proto is supported ---
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bool SupportsDirectlySolveProto(std::atomic<bool>* interrupt) const override {
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return true;
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}
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MPSolutionResponse DirectlySolveProto(LazyMutableCopy<MPModelRequest> request,
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std::atomic<bool>* interrupt) override {
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return SatSolveProto(std::move(request), interrupt);
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}
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// ----- Model modifications and extraction -----
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void Reset() override;
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void SetOptimizationDirection(bool maximize) override;
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void SetVariableBounds(int index, double lb, double ub) override;
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void SetVariableInteger(int index, bool integer) override;
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void SetConstraintBounds(int index, double lb, double ub) override;
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void AddRowConstraint(MPConstraint* ct) override;
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void AddVariable(MPVariable* var) override;
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void SetCoefficient(MPConstraint* constraint, const MPVariable* variable,
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double new_value, double old_value) override;
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void ClearConstraint(MPConstraint* constraint) override;
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void SetObjectiveCoefficient(const MPVariable* variable,
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double coefficient) override;
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void SetObjectiveOffset(double value) override;
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void ClearObjective() override;
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bool AddIndicatorConstraint(MPConstraint* const ct) override { return true; }
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// ------ Query statistics on the solution and the solve ------
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int64_t iterations() const override;
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int64_t nodes() const override;
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MPSolver::BasisStatus row_status(int constraint_index) const override;
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MPSolver::BasisStatus column_status(int variable_index) const override;
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// ----- Misc -----
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bool IsContinuous() const override;
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bool IsLP() const override;
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bool IsMIP() const override;
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std::string SolverVersion() const override;
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void* underlying_solver() override;
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void ExtractNewVariables() override;
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void ExtractNewConstraints() override;
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void ExtractObjective() override;
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void SetParameters(const MPSolverParameters& param) override;
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void SetRelativeMipGap(double value) override;
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void SetPrimalTolerance(double value) override;
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void SetDualTolerance(double value) override;
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void SetPresolveMode(int value) override;
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void SetScalingMode(int value) override;
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void SetLpAlgorithm(int value) override;
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bool SetSolverSpecificParametersAsString(
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const std::string& parameters) override;
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absl::Status SetNumThreads(int num_threads) override;
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private:
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void NonIncrementalChange();
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std::atomic<bool> interrupt_solve_;
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sat::SatParameters parameters_;
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int num_threads_ = 0;
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};
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SatInterface::SatInterface(MPSolver* const solver)
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: MPSolverInterface(solver), interrupt_solve_(false) {}
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SatInterface::~SatInterface() {}
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MPSolver::ResultStatus SatInterface::Solve(const MPSolverParameters& param) {
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interrupt_solve_ = false;
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// Reset extraction as this interface is not incremental yet.
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Reset();
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ExtractModel();
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SetParameters(param);
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solver_->SetSolverSpecificParametersAsString(
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solver_->solver_specific_parameter_string_);
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// Time limit.
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if (solver_->time_limit()) {
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VLOG(1) << "Setting time limit = " << solver_->time_limit() << " ms.";
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parameters_.set_max_time_in_seconds(
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static_cast<double>(solver_->time_limit()) / 1000.0);
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}
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// Mark variables and constraints as extracted.
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for (int i = 0; i < solver_->variables_.size(); ++i) {
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set_variable_as_extracted(i, true);
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}
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for (int i = 0; i < solver_->constraints_.size(); ++i) {
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set_constraint_as_extracted(i, true);
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}
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MPModelRequest request;
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solver_->ExportModelToProto(request.mutable_model());
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request.set_solver_specific_parameters(EncodeParametersAsString(parameters_));
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request.set_enable_internal_solver_output(!quiet_);
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const MPSolutionResponse response =
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SatSolveProto(std::move(request), &interrupt_solve_);
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// The solution must be marked as synchronized even when no solution exists.
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sync_status_ = SOLUTION_SYNCHRONIZED;
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result_status_ = static_cast<MPSolver::ResultStatus>(response.status());
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if (response.status() == MPSOLVER_FEASIBLE ||
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response.status() == MPSOLVER_OPTIMAL) {
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const absl::Status result = solver_->LoadSolutionFromProto(response);
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if (!result.ok()) {
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LOG(ERROR) << "LoadSolutionFromProto failed: " << result;
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}
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}
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return result_status_;
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}
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bool SatInterface::InterruptSolve() {
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interrupt_solve_ = true;
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return true;
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}
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void SatInterface::Reset() { ResetExtractionInformation(); }
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void SatInterface::SetOptimizationDirection(bool maximize) {
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NonIncrementalChange();
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}
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void SatInterface::SetVariableBounds(int index, double lb, double ub) {
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NonIncrementalChange();
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}
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void SatInterface::SetVariableInteger(int index, bool integer) {
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NonIncrementalChange();
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}
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void SatInterface::SetConstraintBounds(int index, double lb, double ub) {
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NonIncrementalChange();
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}
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void SatInterface::AddRowConstraint(MPConstraint* const ct) {
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NonIncrementalChange();
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}
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void SatInterface::AddVariable(MPVariable* const var) {
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NonIncrementalChange();
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}
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void SatInterface::SetCoefficient(MPConstraint* const constraint,
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const MPVariable* const variable,
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double new_value, double old_value) {
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NonIncrementalChange();
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}
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void SatInterface::ClearConstraint(MPConstraint* const constraint) {
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NonIncrementalChange();
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}
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void SatInterface::SetObjectiveCoefficient(const MPVariable* const variable,
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double coefficient) {
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NonIncrementalChange();
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}
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void SatInterface::SetObjectiveOffset(double value) { NonIncrementalChange(); }
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void SatInterface::ClearObjective() { NonIncrementalChange(); }
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int64_t SatInterface::iterations() const {
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return 0; // FIXME
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}
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int64_t SatInterface::nodes() const { return 0; }
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MPSolver::BasisStatus SatInterface::row_status(int constraint_index) const {
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return MPSolver::BasisStatus::FREE; // FIXME
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}
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MPSolver::BasisStatus SatInterface::column_status(int variable_index) const {
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return MPSolver::BasisStatus::FREE; // FIXME
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}
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bool SatInterface::IsContinuous() const { return false; }
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bool SatInterface::IsLP() const { return false; }
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bool SatInterface::IsMIP() const { return true; }
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std::string SatInterface::SolverVersion() const {
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return sat::CpSatSolverVersion();
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}
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void* SatInterface::underlying_solver() { return nullptr; }
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void SatInterface::ExtractNewVariables() { NonIncrementalChange(); }
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void SatInterface::ExtractNewConstraints() { NonIncrementalChange(); }
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void SatInterface::ExtractObjective() { NonIncrementalChange(); }
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void SatInterface::SetParameters(const MPSolverParameters& param) {
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parameters_.Clear();
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parameters_.set_num_workers(num_threads_);
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SetCommonParameters(param);
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}
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absl::Status SatInterface::SetNumThreads(int num_threads) {
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num_threads_ = num_threads;
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return absl::OkStatus();
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}
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// All these have no effect.
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void SatInterface::SetPrimalTolerance(double value) {}
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void SatInterface::SetDualTolerance(double value) {}
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void SatInterface::SetScalingMode(int value) {}
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void SatInterface::SetLpAlgorithm(int value) {}
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void SatInterface::SetRelativeMipGap(double value) {}
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// TODO(user): Implement me.
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void SatInterface::SetPresolveMode(int value) {}
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bool SatInterface::SetSolverSpecificParametersAsString(
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const std::string& parameters) {
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return ProtobufTextFormatMergeFromString(parameters, ¶meters_);
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}
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void SatInterface::NonIncrementalChange() {
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// The current implementation is not incremental.
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sync_status_ = MUST_RELOAD;
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}
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// Register Sat in the global linear solver factory.
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MPSolverInterface* BuildSatInterface(MPSolver* const solver) {
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return new SatInterface(solver);
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}
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} // namespace operations_research
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