139 lines
4.8 KiB
C++
139 lines
4.8 KiB
C++
// 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 ORTOOLS_SAT_ENFORCEMENT_H_
|
|
#define ORTOOLS_SAT_ENFORCEMENT_H_
|
|
|
|
#include <cstdint>
|
|
#include <functional>
|
|
#include <ostream>
|
|
#include <utility>
|
|
#include <vector>
|
|
|
|
#include "absl/container/inlined_vector.h"
|
|
#include "absl/types/span.h"
|
|
#include "ortools/base/strong_vector.h"
|
|
#include "ortools/sat/model.h"
|
|
#include "ortools/sat/sat_base.h"
|
|
#include "ortools/util/rev.h"
|
|
#include "ortools/util/strong_integers.h"
|
|
|
|
namespace operations_research {
|
|
namespace sat {
|
|
|
|
DEFINE_STRONG_INDEX_TYPE(EnforcementId);
|
|
|
|
// An enforced constraint can be in one of these 4 states.
|
|
// Note that we rely on the integer encoding to take 2 bits for optimization.
|
|
enum class EnforcementStatus {
|
|
// One enforcement literal is false.
|
|
IS_FALSE = 0,
|
|
// More than two literals are unassigned.
|
|
CANNOT_PROPAGATE = 1,
|
|
// All enforcement literals are true but one.
|
|
CAN_PROPAGATE_ENFORCEMENT = 2,
|
|
// All enforcement literals are true.
|
|
IS_ENFORCED = 3,
|
|
};
|
|
|
|
std::ostream& operator<<(std::ostream& os, const EnforcementStatus& e);
|
|
|
|
// This is meant as an helper to deal with enforcement for any constraint.
|
|
class EnforcementPropagator : public SatPropagator {
|
|
public:
|
|
explicit EnforcementPropagator(Model* model);
|
|
|
|
// SatPropagator interface.
|
|
bool Propagate(Trail* trail) final;
|
|
void Untrail(const Trail& trail, int trail_index) final;
|
|
|
|
// Adds a new constraint to the class and register a callback that will
|
|
// be called on status change. Note that we also call the callback with the
|
|
// initial status if different from CANNOT_PROPAGATE when added.
|
|
//
|
|
// It is better to not call this for empty enforcement list, but you can. A
|
|
// negative id means the level zero status will never change, and only the
|
|
// first call to callback() should be necessary, we don't save it.
|
|
EnforcementId Register(
|
|
absl::Span<const Literal> enforcement,
|
|
std::function<void(EnforcementId, EnforcementStatus)> callback = nullptr);
|
|
|
|
// Add the enforcement reason to the given vector.
|
|
void AddEnforcementReason(EnforcementId id,
|
|
std::vector<Literal>* reason) const;
|
|
|
|
EnforcementStatus Status(EnforcementId id) const {
|
|
if (id < 0) return EnforcementStatus::IS_ENFORCED;
|
|
return statuses_[id];
|
|
}
|
|
|
|
// This recomputes the current status by scanning the given list.
|
|
// It thus has a linear complexity and should not be used in hot loops.
|
|
EnforcementStatus Status(absl::Span<const Literal> enforcement) const;
|
|
|
|
// Recompute the status from the current assignment.
|
|
// This should only used in DCHECK().
|
|
EnforcementStatus DebugStatus(EnforcementId id);
|
|
|
|
// Returns the enforcement literals of the given id.
|
|
absl::Span<const Literal> GetEnforcementLiterals(EnforcementId id) const {
|
|
if (id < 0) return {};
|
|
return GetSpan(id);
|
|
}
|
|
|
|
private:
|
|
absl::Span<Literal> GetSpan(EnforcementId id);
|
|
absl::Span<const Literal> GetSpan(EnforcementId id) const;
|
|
void ChangeStatus(EnforcementId id, EnforcementStatus new_status);
|
|
|
|
// Returns kNoLiteralIndex if nothing need to change or a new literal to
|
|
// watch. This also calls the registered callback.
|
|
LiteralIndex ProcessIdOnTrue(Literal watched, EnforcementId id);
|
|
|
|
// External classes.
|
|
const Trail& trail_;
|
|
const VariablesAssignment& assignment_;
|
|
RevRepository<int> rev_int_repository_;
|
|
|
|
// All enforcement will be copied there, and we will create Span out of this.
|
|
// Note that we don't store the span so that we are not invalidated on buffer_
|
|
// resizing.
|
|
util_intops::StrongVector<EnforcementId, int> starts_;
|
|
std::vector<Literal> buffer_;
|
|
|
|
util_intops::StrongVector<EnforcementId, EnforcementStatus> statuses_;
|
|
util_intops::StrongVector<
|
|
EnforcementId, std::function<void(EnforcementId, EnforcementStatus)>>
|
|
callbacks_;
|
|
|
|
// Used to restore status and call callback on untrail.
|
|
std::vector<std::pair<EnforcementId, EnforcementStatus>> untrail_stack_;
|
|
int rev_stack_size_ = 0;
|
|
int64_t rev_stamp_ = 0;
|
|
|
|
// We use a two watcher scheme.
|
|
util_intops::StrongVector<LiteralIndex, absl::InlinedVector<EnforcementId, 6>>
|
|
watcher_;
|
|
|
|
std::vector<Literal> temp_literals_;
|
|
|
|
std::vector<EnforcementId> ids_to_fix_until_next_root_level_;
|
|
|
|
friend class EnforcementHelper;
|
|
};
|
|
|
|
} // namespace sat
|
|
} // namespace operations_research
|
|
|
|
#endif // ORTOOLS_SAT_ENFORCEMENT_H_
|