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expr_cst.cc
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// Copyright 2010-2021 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.
//
// Expression constraints
#include <cstddef>
#include <cstdint>
#include <limits>
#include <set>
#include <string>
#include <vector>
#include "absl/strings/str_format.h"
#include "absl/strings/str_join.h"
#include "ortools/base/commandlineflags.h"
#include "ortools/base/integral_types.h"
#include "ortools/base/logging.h"
#include "ortools/base/stl_util.h"
#include "ortools/constraint_solver/constraint_solver.h"
#include "ortools/constraint_solver/constraint_solveri.h"
#include "ortools/util/saturated_arithmetic.h"
#include "ortools/util/sorted_interval_list.h"
ABSL_FLAG(int, cache_initial_size, 1024,
"Initial size of the array of the hash "
"table of caches for objects of type Var(x == 3)");
namespace operations_research {
//-----------------------------------------------------------------------------
// Equality
namespace {
class EqualityExprCst : public Constraint {
public:
EqualityExprCst(Solver* const s, IntExpr* const e, int64_t v);
~EqualityExprCst() override {}
void Post() override;
void InitialPropagate() override;
IntVar* Var() override {
return solver()->MakeIsEqualCstVar(expr_->Var(), value_);
}
std::string DebugString() const override;
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kEquality, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, value_);
visitor->EndVisitConstraint(ModelVisitor::kEquality, this);
}
private:
IntExpr* const expr_;
int64_t value_;
};
EqualityExprCst::EqualityExprCst(Solver* const s, IntExpr* const e, int64_t v)
: Constraint(s), expr_(e), value_(v) {}
void EqualityExprCst::Post() {
if (!expr_->IsVar()) {
Demon* d = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(d);
}
}
void EqualityExprCst::InitialPropagate() { expr_->SetValue(value_); }
std::string EqualityExprCst::DebugString() const {
return absl::StrFormat("(%s == %d)", expr_->DebugString(), value_);
}
} // namespace
Constraint* Solver::MakeEquality(IntExpr* const e, int64_t v) {
CHECK_EQ(this, e->solver());
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(e, &left, &right)) {
return MakeEquality(left, MakeSum(right, v));
} else if (e->IsVar() && !e->Var()->Contains(v)) {
return MakeFalseConstraint();
} else if (e->Min() == e->Max() && e->Min() == v) {
return MakeTrueConstraint();
} else {
return RevAlloc(new EqualityExprCst(this, e, v));
}
}
Constraint* Solver::MakeEquality(IntExpr* const e, int v) {
CHECK_EQ(this, e->solver());
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(e, &left, &right)) {
return MakeEquality(left, MakeSum(right, v));
} else if (e->IsVar() && !e->Var()->Contains(v)) {
return MakeFalseConstraint();
} else if (e->Min() == e->Max() && e->Min() == v) {
return MakeTrueConstraint();
} else {
return RevAlloc(new EqualityExprCst(this, e, v));
}
}
//-----------------------------------------------------------------------------
// Greater or equal constraint
namespace {
class GreaterEqExprCst : public Constraint {
public:
GreaterEqExprCst(Solver* const s, IntExpr* const e, int64_t v);
~GreaterEqExprCst() override {}
void Post() override;
void InitialPropagate() override;
std::string DebugString() const override;
IntVar* Var() override {
return solver()->MakeIsGreaterOrEqualCstVar(expr_->Var(), value_);
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kGreaterOrEqual, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, value_);
visitor->EndVisitConstraint(ModelVisitor::kGreaterOrEqual, this);
}
private:
IntExpr* const expr_;
int64_t value_;
Demon* demon_;
};
GreaterEqExprCst::GreaterEqExprCst(Solver* const s, IntExpr* const e, int64_t v)
: Constraint(s), expr_(e), value_(v), demon_(nullptr) {}
void GreaterEqExprCst::Post() {
if (!expr_->IsVar() && expr_->Min() < value_) {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
} else {
// Let's clean the demon in case the constraint is posted during search.
demon_ = nullptr;
}
}
void GreaterEqExprCst::InitialPropagate() {
expr_->SetMin(value_);
if (demon_ != nullptr && expr_->Min() >= value_) {
demon_->inhibit(solver());
}
}
std::string GreaterEqExprCst::DebugString() const {
return absl::StrFormat("(%s >= %d)", expr_->DebugString(), value_);
}
} // namespace
Constraint* Solver::MakeGreaterOrEqual(IntExpr* const e, int64_t v) {
CHECK_EQ(this, e->solver());
if (e->Min() >= v) {
return MakeTrueConstraint();
} else if (e->Max() < v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new GreaterEqExprCst(this, e, v));
}
}
Constraint* Solver::MakeGreaterOrEqual(IntExpr* const e, int v) {
CHECK_EQ(this, e->solver());
if (e->Min() >= v) {
return MakeTrueConstraint();
} else if (e->Max() < v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new GreaterEqExprCst(this, e, v));
}
}
Constraint* Solver::MakeGreater(IntExpr* const e, int64_t v) {
CHECK_EQ(this, e->solver());
if (e->Min() > v) {
return MakeTrueConstraint();
} else if (e->Max() <= v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new GreaterEqExprCst(this, e, v + 1));
}
}
Constraint* Solver::MakeGreater(IntExpr* const e, int v) {
CHECK_EQ(this, e->solver());
if (e->Min() > v) {
return MakeTrueConstraint();
} else if (e->Max() <= v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new GreaterEqExprCst(this, e, v + 1));
}
}
//-----------------------------------------------------------------------------
// Less or equal constraint
namespace {
class LessEqExprCst : public Constraint {
public:
LessEqExprCst(Solver* const s, IntExpr* const e, int64_t v);
~LessEqExprCst() override {}
void Post() override;
void InitialPropagate() override;
std::string DebugString() const override;
IntVar* Var() override {
return solver()->MakeIsLessOrEqualCstVar(expr_->Var(), value_);
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kLessOrEqual, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, value_);
visitor->EndVisitConstraint(ModelVisitor::kLessOrEqual, this);
}
private:
IntExpr* const expr_;
int64_t value_;
Demon* demon_;
};
LessEqExprCst::LessEqExprCst(Solver* const s, IntExpr* const e, int64_t v)
: Constraint(s), expr_(e), value_(v), demon_(nullptr) {}
void LessEqExprCst::Post() {
if (!expr_->IsVar() && expr_->Max() > value_) {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
} else {
// Let's clean the demon in case the constraint is posted during search.
demon_ = nullptr;
}
}
void LessEqExprCst::InitialPropagate() {
expr_->SetMax(value_);
if (demon_ != nullptr && expr_->Max() <= value_) {
demon_->inhibit(solver());
}
}
std::string LessEqExprCst::DebugString() const {
return absl::StrFormat("(%s <= %d)", expr_->DebugString(), value_);
}
} // namespace
Constraint* Solver::MakeLessOrEqual(IntExpr* const e, int64_t v) {
CHECK_EQ(this, e->solver());
if (e->Max() <= v) {
return MakeTrueConstraint();
} else if (e->Min() > v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new LessEqExprCst(this, e, v));
}
}
Constraint* Solver::MakeLessOrEqual(IntExpr* const e, int v) {
CHECK_EQ(this, e->solver());
if (e->Max() <= v) {
return MakeTrueConstraint();
} else if (e->Min() > v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new LessEqExprCst(this, e, v));
}
}
Constraint* Solver::MakeLess(IntExpr* const e, int64_t v) {
CHECK_EQ(this, e->solver());
if (e->Max() < v) {
return MakeTrueConstraint();
} else if (e->Min() >= v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new LessEqExprCst(this, e, v - 1));
}
}
Constraint* Solver::MakeLess(IntExpr* const e, int v) {
CHECK_EQ(this, e->solver());
if (e->Max() < v) {
return MakeTrueConstraint();
} else if (e->Min() >= v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new LessEqExprCst(this, e, v - 1));
}
}
//-----------------------------------------------------------------------------
// Different constraints
namespace {
class DiffCst : public Constraint {
public:
DiffCst(Solver* const s, IntVar* const var, int64_t value);
~DiffCst() override {}
void Post() override {}
void InitialPropagate() override;
void BoundPropagate();
std::string DebugString() const override;
IntVar* Var() override {
return solver()->MakeIsDifferentCstVar(var_, value_);
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kNonEqual, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
var_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, value_);
visitor->EndVisitConstraint(ModelVisitor::kNonEqual, this);
}
private:
bool HasLargeDomain(IntVar* var);
IntVar* const var_;
int64_t value_;
Demon* demon_;
};
DiffCst::DiffCst(Solver* const s, IntVar* const var, int64_t value)
: Constraint(s), var_(var), value_(value), demon_(nullptr) {}
void DiffCst::InitialPropagate() {
if (HasLargeDomain(var_)) {
demon_ = MakeConstraintDemon0(solver(), this, &DiffCst::BoundPropagate,
"BoundPropagate");
var_->WhenRange(demon_);
} else {
var_->RemoveValue(value_);
}
}
void DiffCst::BoundPropagate() {
const int64_t var_min = var_->Min();
const int64_t var_max = var_->Max();
if (var_min > value_ || var_max < value_) {
demon_->inhibit(solver());
} else if (var_min == value_) {
var_->SetMin(value_ + 1);
} else if (var_max == value_) {
var_->SetMax(value_ - 1);
} else if (!HasLargeDomain(var_)) {
demon_->inhibit(solver());
var_->RemoveValue(value_);
}
}
std::string DiffCst::DebugString() const {
return absl::StrFormat("(%s != %d)", var_->DebugString(), value_);
}
bool DiffCst::HasLargeDomain(IntVar* var) {
return CapSub(var->Max(), var->Min()) > 0xFFFFFF;
}
} // namespace
Constraint* Solver::MakeNonEquality(IntExpr* const e, int64_t v) {
CHECK_EQ(this, e->solver());
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(e, &left, &right)) {
return MakeNonEquality(left, MakeSum(right, v));
} else if (e->IsVar() && !e->Var()->Contains(v)) {
return MakeTrueConstraint();
} else if (e->Bound() && e->Min() == v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new DiffCst(this, e->Var(), v));
}
}
Constraint* Solver::MakeNonEquality(IntExpr* const e, int v) {
CHECK_EQ(this, e->solver());
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(e, &left, &right)) {
return MakeNonEquality(left, MakeSum(right, v));
} else if (e->IsVar() && !e->Var()->Contains(v)) {
return MakeTrueConstraint();
} else if (e->Bound() && e->Min() == v) {
return MakeFalseConstraint();
} else {
return RevAlloc(new DiffCst(this, e->Var(), v));
}
}
// ----- is_equal_cst Constraint -----
namespace {
class IsEqualCstCt : public CastConstraint {
public:
IsEqualCstCt(Solver* const s, IntVar* const v, int64_t c, IntVar* const b)
: CastConstraint(s, b), var_(v), cst_(c), demon_(nullptr) {}
void Post() override {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
var_->WhenDomain(demon_);
target_var_->WhenBound(demon_);
}
void InitialPropagate() override {
bool inhibit = var_->Bound();
int64_t u = var_->Contains(cst_);
int64_t l = inhibit ? u : 0;
target_var_->SetRange(l, u);
if (target_var_->Bound()) {
if (target_var_->Min() == 0) {
if (var_->Size() <= 0xFFFFFF) {
var_->RemoveValue(cst_);
inhibit = true;
}
} else {
var_->SetValue(cst_);
inhibit = true;
}
}
if (inhibit) {
demon_->inhibit(solver());
}
}
std::string DebugString() const override {
return absl::StrFormat("IsEqualCstCt(%s, %d, %s)", var_->DebugString(),
cst_, target_var_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kIsEqual, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
var_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, cst_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kTargetArgument,
target_var_);
visitor->EndVisitConstraint(ModelVisitor::kIsEqual, this);
}
private:
IntVar* const var_;
int64_t cst_;
Demon* demon_;
};
} // namespace
IntVar* Solver::MakeIsEqualCstVar(IntExpr* const var, int64_t value) {
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(var, &left, &right)) {
return MakeIsEqualVar(left, MakeSum(right, value));
}
if (CapSub(var->Max(), var->Min()) == 1) {
if (value == var->Min()) {
return MakeDifference(value + 1, var)->Var();
} else if (value == var->Max()) {
return MakeSum(var, -value + 1)->Var();
} else {
return MakeIntConst(0);
}
}
if (var->IsVar()) {
return var->Var()->IsEqual(value);
} else {
IntVar* const boolvar =
MakeBoolVar(absl::StrFormat("Is(%s == %d)", var->DebugString(), value));
AddConstraint(MakeIsEqualCstCt(var, value, boolvar));
return boolvar;
}
}
Constraint* Solver::MakeIsEqualCstCt(IntExpr* const var, int64_t value,
IntVar* const boolvar) {
CHECK_EQ(this, var->solver());
CHECK_EQ(this, boolvar->solver());
if (value == var->Min()) {
if (CapSub(var->Max(), var->Min()) == 1) {
return MakeEquality(MakeDifference(value + 1, var), boolvar);
}
return MakeIsLessOrEqualCstCt(var, value, boolvar);
}
if (value == var->Max()) {
if (CapSub(var->Max(), var->Min()) == 1) {
return MakeEquality(MakeSum(var, -value + 1), boolvar);
}
return MakeIsGreaterOrEqualCstCt(var, value, boolvar);
}
if (boolvar->Bound()) {
if (boolvar->Min() == 0) {
return MakeNonEquality(var, value);
} else {
return MakeEquality(var, value);
}
}
// TODO(user) : what happens if the constraint is not posted?
// The cache becomes tainted.
model_cache_->InsertExprConstantExpression(
boolvar, var, value, ModelCache::EXPR_CONSTANT_IS_EQUAL);
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(var, &left, &right)) {
return MakeIsEqualCt(left, MakeSum(right, value), boolvar);
} else {
return RevAlloc(new IsEqualCstCt(this, var->Var(), value, boolvar));
}
}
// ----- is_diff_cst Constraint -----
namespace {
class IsDiffCstCt : public CastConstraint {
public:
IsDiffCstCt(Solver* const s, IntVar* const v, int64_t c, IntVar* const b)
: CastConstraint(s, b), var_(v), cst_(c), demon_(nullptr) {}
void Post() override {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
var_->WhenDomain(demon_);
target_var_->WhenBound(demon_);
}
void InitialPropagate() override {
bool inhibit = var_->Bound();
int64_t l = 1 - var_->Contains(cst_);
int64_t u = inhibit ? l : 1;
target_var_->SetRange(l, u);
if (target_var_->Bound()) {
if (target_var_->Min() == 1) {
if (var_->Size() <= 0xFFFFFF) {
var_->RemoveValue(cst_);
inhibit = true;
}
} else {
var_->SetValue(cst_);
inhibit = true;
}
}
if (inhibit) {
demon_->inhibit(solver());
}
}
std::string DebugString() const override {
return absl::StrFormat("IsDiffCstCt(%s, %d, %s)", var_->DebugString(), cst_,
target_var_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kIsDifferent, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
var_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, cst_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kTargetArgument,
target_var_);
visitor->EndVisitConstraint(ModelVisitor::kIsDifferent, this);
}
private:
IntVar* const var_;
int64_t cst_;
Demon* demon_;
};
} // namespace
IntVar* Solver::MakeIsDifferentCstVar(IntExpr* const var, int64_t value) {
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(var, &left, &right)) {
return MakeIsDifferentVar(left, MakeSum(right, value));
}
return var->Var()->IsDifferent(value);
}
Constraint* Solver::MakeIsDifferentCstCt(IntExpr* const var, int64_t value,
IntVar* const boolvar) {
CHECK_EQ(this, var->solver());
CHECK_EQ(this, boolvar->solver());
if (value == var->Min()) {
return MakeIsGreaterOrEqualCstCt(var, value + 1, boolvar);
}
if (value == var->Max()) {
return MakeIsLessOrEqualCstCt(var, value - 1, boolvar);
}
if (var->IsVar() && !var->Var()->Contains(value)) {
return MakeEquality(boolvar, int64_t{1});
}
if (var->Bound() && var->Min() == value) {
return MakeEquality(boolvar, Zero());
}
if (boolvar->Bound()) {
if (boolvar->Min() == 0) {
return MakeEquality(var, value);
} else {
return MakeNonEquality(var, value);
}
}
model_cache_->InsertExprConstantExpression(
boolvar, var, value, ModelCache::EXPR_CONSTANT_IS_NOT_EQUAL);
IntExpr* left = nullptr;
IntExpr* right = nullptr;
if (IsADifference(var, &left, &right)) {
return MakeIsDifferentCt(left, MakeSum(right, value), boolvar);
} else {
return RevAlloc(new IsDiffCstCt(this, var->Var(), value, boolvar));
}
}
// ----- is_greater_equal_cst Constraint -----
namespace {
class IsGreaterEqualCstCt : public CastConstraint {
public:
IsGreaterEqualCstCt(Solver* const s, IntExpr* const v, int64_t c,
IntVar* const b)
: CastConstraint(s, b), expr_(v), cst_(c), demon_(nullptr) {}
void Post() override {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
target_var_->WhenBound(demon_);
}
void InitialPropagate() override {
bool inhibit = false;
int64_t u = expr_->Max() >= cst_;
int64_t l = expr_->Min() >= cst_;
target_var_->SetRange(l, u);
if (target_var_->Bound()) {
inhibit = true;
if (target_var_->Min() == 0) {
expr_->SetMax(cst_ - 1);
} else {
expr_->SetMin(cst_);
}
}
if (inhibit && ((target_var_->Max() == 0 && expr_->Max() < cst_) ||
(target_var_->Min() == 1 && expr_->Min() >= cst_))) {
// Can we safely inhibit? Sometimes an expression is not
// persistent, just monotonic.
demon_->inhibit(solver());
}
}
std::string DebugString() const override {
return absl::StrFormat("IsGreaterEqualCstCt(%s, %d, %s)",
expr_->DebugString(), cst_,
target_var_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kIsGreaterOrEqual, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, cst_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kTargetArgument,
target_var_);
visitor->EndVisitConstraint(ModelVisitor::kIsGreaterOrEqual, this);
}
private:
IntExpr* const expr_;
int64_t cst_;
Demon* demon_;
};
} // namespace
IntVar* Solver::MakeIsGreaterOrEqualCstVar(IntExpr* const var, int64_t value) {
if (var->Min() >= value) {
return MakeIntConst(int64_t{1});
}
if (var->Max() < value) {
return MakeIntConst(int64_t{0});
}
if (var->IsVar()) {
return var->Var()->IsGreaterOrEqual(value);
} else {
IntVar* const boolvar =
MakeBoolVar(absl::StrFormat("Is(%s >= %d)", var->DebugString(), value));
AddConstraint(MakeIsGreaterOrEqualCstCt(var, value, boolvar));
return boolvar;
}
}
IntVar* Solver::MakeIsGreaterCstVar(IntExpr* const var, int64_t value) {
return MakeIsGreaterOrEqualCstVar(var, value + 1);
}
Constraint* Solver::MakeIsGreaterOrEqualCstCt(IntExpr* const var, int64_t value,
IntVar* const boolvar) {
if (boolvar->Bound()) {
if (boolvar->Min() == 0) {
return MakeLess(var, value);
} else {
return MakeGreaterOrEqual(var, value);
}
}
CHECK_EQ(this, var->solver());
CHECK_EQ(this, boolvar->solver());
model_cache_->InsertExprConstantExpression(
boolvar, var, value, ModelCache::EXPR_CONSTANT_IS_GREATER_OR_EQUAL);
return RevAlloc(new IsGreaterEqualCstCt(this, var, value, boolvar));
}
Constraint* Solver::MakeIsGreaterCstCt(IntExpr* const v, int64_t c,
IntVar* const b) {
return MakeIsGreaterOrEqualCstCt(v, c + 1, b);
}
// ----- is_lesser_equal_cst Constraint -----
namespace {
class IsLessEqualCstCt : public CastConstraint {
public:
IsLessEqualCstCt(Solver* const s, IntExpr* const v, int64_t c,
IntVar* const b)
: CastConstraint(s, b), expr_(v), cst_(c), demon_(nullptr) {}
void Post() override {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
target_var_->WhenBound(demon_);
}
void InitialPropagate() override {
bool inhibit = false;
int64_t u = expr_->Min() <= cst_;
int64_t l = expr_->Max() <= cst_;
target_var_->SetRange(l, u);
if (target_var_->Bound()) {
inhibit = true;
if (target_var_->Min() == 0) {
expr_->SetMin(cst_ + 1);
} else {
expr_->SetMax(cst_);
}
}
if (inhibit && ((target_var_->Max() == 0 && expr_->Min() > cst_) ||
(target_var_->Min() == 1 && expr_->Max() <= cst_))) {
// Can we safely inhibit? Sometimes an expression is not
// persistent, just monotonic.
demon_->inhibit(solver());
}
}
std::string DebugString() const override {
return absl::StrFormat("IsLessEqualCstCt(%s, %d, %s)", expr_->DebugString(),
cst_, target_var_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kIsLessOrEqual, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kValueArgument, cst_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kTargetArgument,
target_var_);
visitor->EndVisitConstraint(ModelVisitor::kIsLessOrEqual, this);
}
private:
IntExpr* const expr_;
int64_t cst_;
Demon* demon_;
};
} // namespace
IntVar* Solver::MakeIsLessOrEqualCstVar(IntExpr* const var, int64_t value) {
if (var->Max() <= value) {
return MakeIntConst(int64_t{1});
}
if (var->Min() > value) {
return MakeIntConst(int64_t{0});
}
if (var->IsVar()) {
return var->Var()->IsLessOrEqual(value);
} else {
IntVar* const boolvar =
MakeBoolVar(absl::StrFormat("Is(%s <= %d)", var->DebugString(), value));
AddConstraint(MakeIsLessOrEqualCstCt(var, value, boolvar));
return boolvar;
}
}
IntVar* Solver::MakeIsLessCstVar(IntExpr* const var, int64_t value) {
return MakeIsLessOrEqualCstVar(var, value - 1);
}
Constraint* Solver::MakeIsLessOrEqualCstCt(IntExpr* const var, int64_t value,
IntVar* const boolvar) {
if (boolvar->Bound()) {
if (boolvar->Min() == 0) {
return MakeGreater(var, value);
} else {
return MakeLessOrEqual(var, value);
}
}
CHECK_EQ(this, var->solver());
CHECK_EQ(this, boolvar->solver());
model_cache_->InsertExprConstantExpression(
boolvar, var, value, ModelCache::EXPR_CONSTANT_IS_LESS_OR_EQUAL);
return RevAlloc(new IsLessEqualCstCt(this, var, value, boolvar));
}
Constraint* Solver::MakeIsLessCstCt(IntExpr* const v, int64_t c,
IntVar* const b) {
return MakeIsLessOrEqualCstCt(v, c - 1, b);
}
// ----- BetweenCt -----
namespace {
class BetweenCt : public Constraint {
public:
BetweenCt(Solver* const s, IntExpr* const v, int64_t l, int64_t u)
: Constraint(s), expr_(v), min_(l), max_(u), demon_(nullptr) {}
void Post() override {
if (!expr_->IsVar()) {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
}
}
void InitialPropagate() override {
expr_->SetRange(min_, max_);
int64_t emin = 0;
int64_t emax = 0;
expr_->Range(&emin, &emax);
if (demon_ != nullptr && emin >= min_ && emax <= max_) {
demon_->inhibit(solver());
}
}
std::string DebugString() const override {
return absl::StrFormat("BetweenCt(%s, %d, %d)", expr_->DebugString(), min_,
max_);
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kBetween, this);
visitor->VisitIntegerArgument(ModelVisitor::kMinArgument, min_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kMaxArgument, max_);
visitor->EndVisitConstraint(ModelVisitor::kBetween, this);
}
private:
IntExpr* const expr_;
int64_t min_;
int64_t max_;
Demon* demon_;
};
// ----- NonMember constraint -----
class NotBetweenCt : public Constraint {
public:
NotBetweenCt(Solver* const s, IntExpr* const v, int64_t l, int64_t u)
: Constraint(s), expr_(v), min_(l), max_(u), demon_(nullptr) {}
void Post() override {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
}
void InitialPropagate() override {
int64_t emin = 0;
int64_t emax = 0;
expr_->Range(&emin, &emax);
if (emin >= min_) {
expr_->SetMin(max_ + 1);
} else if (emax <= max_) {
expr_->SetMax(min_ - 1);
}
if (!expr_->IsVar() && (emax < min_ || emin > max_)) {
demon_->inhibit(solver());
}
}
std::string DebugString() const override {
return absl::StrFormat("NotBetweenCt(%s, %d, %d)", expr_->DebugString(),
min_, max_);
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kNotBetween, this);
visitor->VisitIntegerArgument(ModelVisitor::kMinArgument, min_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kExpressionArgument,
expr_);
visitor->VisitIntegerArgument(ModelVisitor::kMaxArgument, max_);
visitor->EndVisitConstraint(ModelVisitor::kBetween, this);
}
private:
IntExpr* const expr_;
int64_t min_;
int64_t max_;
Demon* demon_;
};
int64_t ExtractExprProductCoeff(IntExpr** expr) {
int64_t prod = 1;
int64_t coeff = 1;
while ((*expr)->solver()->IsProduct(*expr, expr, &coeff)) prod *= coeff;
return prod;
}
} // namespace
Constraint* Solver::MakeBetweenCt(IntExpr* expr, int64_t l, int64_t u) {
DCHECK_EQ(this, expr->solver());
// Catch empty and singleton intervals.
if (l >= u) {
if (l > u) return MakeFalseConstraint();
return MakeEquality(expr, l);
}
int64_t emin = 0;
int64_t emax = 0;
expr->Range(&emin, &emax);
// Catch the trivial cases first.
if (emax < l || emin > u) return MakeFalseConstraint();
if (emin >= l && emax <= u) return MakeTrueConstraint();
// Catch one-sided constraints.
if (emax <= u) return MakeGreaterOrEqual(expr, l);
if (emin >= l) return MakeLessOrEqual(expr, u);
// Simplify the common factor, if any.
int64_t coeff = ExtractExprProductCoeff(&expr);
if (coeff != 1) {
CHECK_NE(coeff, 0); // Would have been caught by the trivial cases already.
if (coeff < 0) {
std::swap(u, l);
u = -u;
l = -l;
coeff = -coeff;
}
return MakeBetweenCt(expr, PosIntDivUp(l, coeff), PosIntDivDown(u, coeff));
} else {
// No further reduction is possible.
return RevAlloc(new BetweenCt(this, expr, l, u));
}
}
Constraint* Solver::MakeNotBetweenCt(IntExpr* expr, int64_t l, int64_t u) {
DCHECK_EQ(this, expr->solver());
// Catch empty interval.
if (l > u) {
return MakeTrueConstraint();
}
int64_t emin = 0;
int64_t emax = 0;
expr->Range(&emin, &emax);
// Catch the trivial cases first.
if (emax < l || emin > u) return MakeTrueConstraint();
if (emin >= l && emax <= u) return MakeFalseConstraint();
// Catch one-sided constraints.
if (emin >= l) return MakeGreater(expr, u);
if (emax <= u) return MakeLess(expr, l);
// TODO(user): Add back simplification code if expr is constant *
// other_expr.
return RevAlloc(new NotBetweenCt(this, expr, l, u));
}
// ----- is_between_cst Constraint -----
namespace {
class IsBetweenCt : public Constraint {
public:
IsBetweenCt(Solver* const s, IntExpr* const e, int64_t l, int64_t u,
IntVar* const b)
: Constraint(s),
expr_(e),
min_(l),
max_(u),
boolvar_(b),
demon_(nullptr) {}
void Post() override {
demon_ = solver()->MakeConstraintInitialPropagateCallback(this);
expr_->WhenRange(demon_);
boolvar_->WhenBound(demon_);
}
void InitialPropagate() override {
bool inhibit = false;
int64_t emin = 0;
int64_t emax = 0;