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element.cc
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element.cc
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// Copyright 2010-2018 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.
#include <algorithm>
#include <memory>
#include <numeric>
#include <string>
#include <utility>
#include <vector>
#include "absl/strings/str_format.h"
#include "absl/strings/str_join.h"
#include "ortools/base/integral_types.h"
#include "ortools/base/logging.h"
#include "ortools/constraint_solver/constraint_solver.h"
#include "ortools/constraint_solver/constraint_solveri.h"
#include "ortools/util/range_minimum_query.h"
#include "ortools/util/string_array.h"
DEFINE_bool(cp_disable_element_cache, true,
"If true, caching for IntElement is disabled.");
namespace operations_research {
// ----- IntExprElement -----
void LinkVarExpr(Solver* const s, IntExpr* const expr, IntVar* const var);
namespace {
template <class T>
class VectorLess {
public:
explicit VectorLess(const std::vector<T>* values) : values_(values) {}
bool operator()(const T& x, const T& y) const {
return (*values_)[x] < (*values_)[y];
}
private:
const std::vector<T>* values_;
};
template <class T>
class VectorGreater {
public:
explicit VectorGreater(const std::vector<T>* values) : values_(values) {}
bool operator()(const T& x, const T& y) const {
return (*values_)[x] > (*values_)[y];
}
private:
const std::vector<T>* values_;
};
// ----- BaseIntExprElement -----
class BaseIntExprElement : public BaseIntExpr {
public:
BaseIntExprElement(Solver* const s, IntVar* const e);
~BaseIntExprElement() override {}
int64 Min() const override;
int64 Max() const override;
void Range(int64* mi, int64* ma) override;
void SetMin(int64 m) override;
void SetMax(int64 m) override;
void SetRange(int64 mi, int64 ma) override;
bool Bound() const override { return (expr_->Bound()); }
// TODO(user) : improve me, the previous test is not always true
void WhenRange(Demon* d) override { expr_->WhenRange(d); }
protected:
virtual int64 ElementValue(int index) const = 0;
virtual int64 ExprMin() const = 0;
virtual int64 ExprMax() const = 0;
IntVar* const expr_;
private:
void UpdateSupports() const;
mutable int64 min_;
mutable int min_support_;
mutable int64 max_;
mutable int max_support_;
mutable bool initial_update_;
IntVarIterator* const expr_iterator_;
};
BaseIntExprElement::BaseIntExprElement(Solver* const s, IntVar* const e)
: BaseIntExpr(s),
expr_(e),
min_(0),
min_support_(-1),
max_(0),
max_support_(-1),
initial_update_(true),
expr_iterator_(expr_->MakeDomainIterator(true)) {
CHECK(s != nullptr);
CHECK(e != nullptr);
}
int64 BaseIntExprElement::Min() const {
UpdateSupports();
return min_;
}
int64 BaseIntExprElement::Max() const {
UpdateSupports();
return max_;
}
void BaseIntExprElement::Range(int64* mi, int64* ma) {
UpdateSupports();
*mi = min_;
*ma = max_;
}
#define UPDATE_BASE_ELEMENT_INDEX_BOUNDS(test) \
const int64 emin = ExprMin(); \
const int64 emax = ExprMax(); \
int64 nmin = emin; \
int64 value = ElementValue(nmin); \
while (nmin < emax && test) { \
nmin++; \
value = ElementValue(nmin); \
} \
if (nmin == emax && test) { \
solver()->Fail(); \
} \
int64 nmax = emax; \
value = ElementValue(nmax); \
while (nmax >= nmin && test) { \
nmax--; \
value = ElementValue(nmax); \
} \
expr_->SetRange(nmin, nmax);
void BaseIntExprElement::SetMin(int64 m) {
UPDATE_BASE_ELEMENT_INDEX_BOUNDS(value < m);
}
void BaseIntExprElement::SetMax(int64 m) {
UPDATE_BASE_ELEMENT_INDEX_BOUNDS(value > m);
}
void BaseIntExprElement::SetRange(int64 mi, int64 ma) {
if (mi > ma) {
solver()->Fail();
}
UPDATE_BASE_ELEMENT_INDEX_BOUNDS((value < mi || value > ma));
}
#undef UPDATE_BASE_ELEMENT_INDEX_BOUNDS
void BaseIntExprElement::UpdateSupports() const {
if (initial_update_ || !expr_->Contains(min_support_) ||
!expr_->Contains(max_support_)) {
const int64 emin = ExprMin();
const int64 emax = ExprMax();
int64 min_value = ElementValue(emax);
int64 max_value = min_value;
int min_support = emax;
int max_support = emax;
const uint64 expr_size = expr_->Size();
if (expr_size > 1) {
if (expr_size == emax - emin + 1) {
// Value(emax) already stored in min_value, max_value.
for (int64 index = emin; index < emax; ++index) {
const int64 value = ElementValue(index);
if (value > max_value) {
max_value = value;
max_support = index;
} else if (value < min_value) {
min_value = value;
min_support = index;
}
}
} else {
for (const int64 index : InitAndGetValues(expr_iterator_)) {
if (index >= emin && index <= emax) {
const int64 value = ElementValue(index);
if (value > max_value) {
max_value = value;
max_support = index;
} else if (value < min_value) {
min_value = value;
min_support = index;
}
}
}
}
}
Solver* s = solver();
s->SaveAndSetValue(&min_, min_value);
s->SaveAndSetValue(&min_support_, min_support);
s->SaveAndSetValue(&max_, max_value);
s->SaveAndSetValue(&max_support_, max_support);
s->SaveAndSetValue(&initial_update_, false);
}
}
// ----- IntElementConstraint -----
// This constraint implements 'elem' == 'values'['index'].
// It scans the bounds of 'elem' to propagate on the domain of 'index'.
// It scans the domain of 'index' to compute the new bounds of 'elem'.
class IntElementConstraint : public CastConstraint {
public:
IntElementConstraint(Solver* const s, const std::vector<int64>& values,
IntVar* const index, IntVar* const elem)
: CastConstraint(s, elem),
values_(values),
index_(index),
index_iterator_(index_->MakeDomainIterator(true)) {
CHECK(index != nullptr);
}
void Post() override {
Demon* const d =
solver()->MakeDelayedConstraintInitialPropagateCallback(this);
index_->WhenDomain(d);
target_var_->WhenRange(d);
}
void InitialPropagate() override {
index_->SetRange(0, values_.size() - 1);
const int64 target_var_min = target_var_->Min();
const int64 target_var_max = target_var_->Max();
int64 new_min = target_var_max;
int64 new_max = target_var_min;
to_remove_.clear();
for (const int64 index : InitAndGetValues(index_iterator_)) {
const int64 value = values_[index];
if (value < target_var_min || value > target_var_max) {
to_remove_.push_back(index);
} else {
if (value < new_min) {
new_min = value;
}
if (value > new_max) {
new_max = value;
}
}
}
target_var_->SetRange(new_min, new_max);
if (!to_remove_.empty()) {
index_->RemoveValues(to_remove_);
}
}
std::string DebugString() const override {
return absl::StrFormat("IntElementConstraint(%s, %s, %s)",
absl::StrJoin(values_, ", "), index_->DebugString(),
target_var_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitConstraint(ModelVisitor::kElementEqual, this);
visitor->VisitIntegerArrayArgument(ModelVisitor::kValuesArgument, values_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
index_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kTargetArgument,
target_var_);
visitor->EndVisitConstraint(ModelVisitor::kElementEqual, this);
}
private:
const std::vector<int64> values_;
IntVar* const index_;
IntVarIterator* const index_iterator_;
std::vector<int64> to_remove_;
};
// ----- IntExprElement
IntVar* BuildDomainIntVar(Solver* const solver, std::vector<int64>* values);
class IntExprElement : public BaseIntExprElement {
public:
IntExprElement(Solver* const s, const std::vector<int64>& vals,
IntVar* const expr)
: BaseIntExprElement(s, expr), values_(vals) {}
~IntExprElement() override {}
std::string name() const override {
const int size = values_.size();
if (size > 10) {
return absl::StrFormat("IntElement(array of size %d, %s)", size,
expr_->name());
} else {
return absl::StrFormat("IntElement(%s, %s)", absl::StrJoin(values_, ", "),
expr_->name());
}
}
std::string DebugString() const override {
const int size = values_.size();
if (size > 10) {
return absl::StrFormat("IntElement(array of size %d, %s)", size,
expr_->DebugString());
} else {
return absl::StrFormat("IntElement(%s, %s)", absl::StrJoin(values_, ", "),
expr_->DebugString());
}
}
IntVar* CastToVar() override {
Solver* const s = solver();
IntVar* const var = s->MakeIntVar(values_);
s->AddCastConstraint(
s->RevAlloc(new IntElementConstraint(s, values_, expr_, var)), var,
this);
return var;
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitIntegerExpression(ModelVisitor::kElement, this);
visitor->VisitIntegerArrayArgument(ModelVisitor::kValuesArgument, values_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
expr_);
visitor->EndVisitIntegerExpression(ModelVisitor::kElement, this);
}
protected:
int64 ElementValue(int index) const override {
DCHECK_LT(index, values_.size());
return values_[index];
}
int64 ExprMin() const override { return std::max<int64>(0, expr_->Min()); }
int64 ExprMax() const override {
return values_.empty() ? 0
: std::min<int64>(values_.size() - 1, expr_->Max());
}
private:
const std::vector<int64> values_;
};
// ----- Range Minimum Query-based Element -----
class RangeMinimumQueryExprElement : public BaseIntExpr {
public:
RangeMinimumQueryExprElement(Solver* solver, const std::vector<int64>& values,
IntVar* index);
~RangeMinimumQueryExprElement() override {}
int64 Min() const override;
int64 Max() const override;
void Range(int64* mi, int64* ma) override;
void SetMin(int64 m) override;
void SetMax(int64 m) override;
void SetRange(int64 mi, int64 ma) override;
bool Bound() const override { return (index_->Bound()); }
// TODO(user) : improve me, the previous test is not always true
void WhenRange(Demon* d) override { index_->WhenRange(d); }
IntVar* CastToVar() override {
// TODO(user): Should we try to make holes in the domain of index_, as we
// do here, or should we only propagate bounds as we do in
// IncreasingIntExprElement ?
IntVar* const var = solver()->MakeIntVar(min_rmq_.array());
solver()->AddCastConstraint(solver()->RevAlloc(new IntElementConstraint(
solver(), min_rmq_.array(), index_, var)),
var, this);
return var;
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitIntegerExpression(ModelVisitor::kElement, this);
visitor->VisitIntegerArrayArgument(ModelVisitor::kValuesArgument,
min_rmq_.array());
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
index_);
visitor->EndVisitIntegerExpression(ModelVisitor::kElement, this);
}
private:
int64 IndexMin() const { return std::max<int64>(0, index_->Min()); }
int64 IndexMax() const {
return std::min<int64>(min_rmq_.array().size() - 1, index_->Max());
}
IntVar* const index_;
const RangeMinimumQuery<int64, std::less<int64>> min_rmq_;
const RangeMinimumQuery<int64, std::greater<int64>> max_rmq_;
};
RangeMinimumQueryExprElement::RangeMinimumQueryExprElement(
Solver* solver, const std::vector<int64>& values, IntVar* index)
: BaseIntExpr(solver), index_(index), min_rmq_(values), max_rmq_(values) {
CHECK(solver != nullptr);
CHECK(index != nullptr);
}
int64 RangeMinimumQueryExprElement::Min() const {
return min_rmq_.GetMinimumFromRange(IndexMin(), IndexMax() + 1);
}
int64 RangeMinimumQueryExprElement::Max() const {
return max_rmq_.GetMinimumFromRange(IndexMin(), IndexMax() + 1);
}
void RangeMinimumQueryExprElement::Range(int64* mi, int64* ma) {
const int64 range_min = IndexMin();
const int64 range_max = IndexMax() + 1;
*mi = min_rmq_.GetMinimumFromRange(range_min, range_max);
*ma = max_rmq_.GetMinimumFromRange(range_min, range_max);
}
#define UPDATE_RMQ_BASE_ELEMENT_INDEX_BOUNDS(test) \
const std::vector<int64>& values = min_rmq_.array(); \
int64 index_min = IndexMin(); \
int64 index_max = IndexMax(); \
int64 value = values[index_min]; \
while (index_min < index_max && (test)) { \
index_min++; \
value = values[index_min]; \
} \
if (index_min == index_max && (test)) { \
solver()->Fail(); \
} \
value = values[index_max]; \
while (index_max >= index_min && (test)) { \
index_max--; \
value = values[index_max]; \
} \
index_->SetRange(index_min, index_max);
void RangeMinimumQueryExprElement::SetMin(int64 m) {
UPDATE_RMQ_BASE_ELEMENT_INDEX_BOUNDS(value < m);
}
void RangeMinimumQueryExprElement::SetMax(int64 m) {
UPDATE_RMQ_BASE_ELEMENT_INDEX_BOUNDS(value > m);
}
void RangeMinimumQueryExprElement::SetRange(int64 mi, int64 ma) {
if (mi > ma) {
solver()->Fail();
}
UPDATE_RMQ_BASE_ELEMENT_INDEX_BOUNDS(value < mi || value > ma);
}
#undef UPDATE_RMQ_BASE_ELEMENT_INDEX_BOUNDS
// ----- Increasing Element -----
class IncreasingIntExprElement : public BaseIntExpr {
public:
IncreasingIntExprElement(Solver* const s, const std::vector<int64>& values,
IntVar* const index);
~IncreasingIntExprElement() override {}
int64 Min() const override;
void SetMin(int64 m) override;
int64 Max() const override;
void SetMax(int64 m) override;
void SetRange(int64 mi, int64 ma) override;
bool Bound() const override { return (index_->Bound()); }
// TODO(user) : improve me, the previous test is not always true
std::string name() const override {
return absl::StrFormat("IntElement(%s, %s)", absl::StrJoin(values_, ", "),
index_->name());
}
std::string DebugString() const override {
return absl::StrFormat("IntElement(%s, %s)", absl::StrJoin(values_, ", "),
index_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitIntegerExpression(ModelVisitor::kElement, this);
visitor->VisitIntegerArrayArgument(ModelVisitor::kValuesArgument, values_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
index_);
visitor->EndVisitIntegerExpression(ModelVisitor::kElement, this);
}
void WhenRange(Demon* d) override { index_->WhenRange(d); }
IntVar* CastToVar() override {
Solver* const s = solver();
IntVar* const var = s->MakeIntVar(values_);
LinkVarExpr(s, this, var);
return var;
}
private:
const std::vector<int64> values_;
IntVar* const index_;
};
IncreasingIntExprElement::IncreasingIntExprElement(
Solver* const s, const std::vector<int64>& values, IntVar* const index)
: BaseIntExpr(s), values_(values), index_(index) {
DCHECK(index);
DCHECK(s);
}
int64 IncreasingIntExprElement::Min() const {
const int64 expression_min = std::max<int64>(0, index_->Min());
return (expression_min < values_.size() ? values_[expression_min]
: kint64max);
}
void IncreasingIntExprElement::SetMin(int64 m) {
const int64 index_min = std::max<int64>(0, index_->Min());
const int64 index_max = std::min<int64>(values_.size() - 1, index_->Max());
if (index_min > index_max || m > values_[index_max]) {
solver()->Fail();
}
const std::vector<int64>::const_iterator first =
std::lower_bound(values_.begin(), values_.end(), m);
const int64 new_index_min = first - values_.begin();
index_->SetMin(new_index_min);
}
int64 IncreasingIntExprElement::Max() const {
const int64 expression_max =
std::min<int64>(values_.size() - 1, index_->Max());
return (expression_max >= 0 ? values_[expression_max] : kint64max);
}
void IncreasingIntExprElement::SetMax(int64 m) {
int64 index_min = std::max<int64>(0, index_->Min());
if (m < values_[index_min]) {
solver()->Fail();
}
const std::vector<int64>::const_iterator last_after =
std::upper_bound(values_.begin(), values_.end(), m);
const int64 new_index_max = (last_after - values_.begin()) - 1;
index_->SetRange(0, new_index_max);
}
void IncreasingIntExprElement::SetRange(int64 mi, int64 ma) {
if (mi > ma) {
solver()->Fail();
}
const int64 index_min = std::max<int64>(0, index_->Min());
const int64 index_max = std::min<int64>(values_.size() - 1, index_->Max());
if (mi > ma || ma < values_[index_min] || mi > values_[index_max]) {
solver()->Fail();
}
const std::vector<int64>::const_iterator first =
std::lower_bound(values_.begin(), values_.end(), mi);
const int64 new_index_min = first - values_.begin();
const std::vector<int64>::const_iterator last_after =
std::upper_bound(first, values_.end(), ma);
const int64 new_index_max = (last_after - values_.begin()) - 1;
// Assign.
index_->SetRange(new_index_min, new_index_max);
}
// ----- Solver::MakeElement(int array, int var) -----
IntExpr* BuildElement(Solver* const solver, const std::vector<int64>& values,
IntVar* const index) {
// Various checks.
// Is array constant?
if (IsArrayConstant(values, values[0])) {
solver->AddConstraint(solver->MakeBetweenCt(index, 0, values.size() - 1));
return solver->MakeIntConst(values[0]);
}
// Is array built with booleans only?
// TODO(user): We could maintain the index of the first one.
if (IsArrayBoolean(values)) {
std::vector<int64> ones;
int first_zero = -1;
for (int i = 0; i < values.size(); ++i) {
if (values[i] == 1) {
ones.push_back(i);
} else {
first_zero = i;
}
}
if (ones.size() == 1) {
DCHECK_EQ(GG_LONGLONG(1), values[ones.back()]);
solver->AddConstraint(solver->MakeBetweenCt(index, 0, values.size() - 1));
return solver->MakeIsEqualCstVar(index, ones.back());
} else if (ones.size() == values.size() - 1) {
solver->AddConstraint(solver->MakeBetweenCt(index, 0, values.size() - 1));
return solver->MakeIsDifferentCstVar(index, first_zero);
} else if (ones.size() == ones.back() - ones.front() + 1) { // contiguous.
solver->AddConstraint(solver->MakeBetweenCt(index, 0, values.size() - 1));
IntVar* const b = solver->MakeBoolVar("ContiguousBooleanElementVar");
solver->AddConstraint(
solver->MakeIsBetweenCt(index, ones.front(), ones.back(), b));
return b;
} else {
IntVar* const b = solver->MakeBoolVar("NonContiguousBooleanElementVar");
solver->AddConstraint(solver->MakeBetweenCt(index, 0, values.size() - 1));
solver->AddConstraint(solver->MakeIsMemberCt(index, ones, b));
return b;
}
}
IntExpr* cache = nullptr;
if (!FLAGS_cp_disable_element_cache) {
cache = solver->Cache()->FindVarConstantArrayExpression(
index, values, ModelCache::VAR_CONSTANT_ARRAY_ELEMENT);
}
if (cache != nullptr) {
return cache;
} else {
IntExpr* result = nullptr;
if (values.size() >= 2 && index->Min() == 0 && index->Max() == 1) {
result = solver->MakeSum(solver->MakeProd(index, values[1] - values[0]),
values[0]);
} else if (values.size() == 2 && index->Contains(0) && index->Contains(1)) {
solver->AddConstraint(solver->MakeBetweenCt(index, 0, 1));
result = solver->MakeSum(solver->MakeProd(index, values[1] - values[0]),
values[0]);
} else if (IsIncreasingContiguous(values)) {
result = solver->MakeSum(index, values[0]);
} else if (IsIncreasing(values)) {
result = solver->RegisterIntExpr(solver->RevAlloc(
new IncreasingIntExprElement(solver, values, index)));
} else {
if (solver->parameters().use_element_rmq()) {
result = solver->RegisterIntExpr(solver->RevAlloc(
new RangeMinimumQueryExprElement(solver, values, index)));
} else {
result = solver->RegisterIntExpr(
solver->RevAlloc(new IntExprElement(solver, values, index)));
}
}
if (!FLAGS_cp_disable_element_cache) {
solver->Cache()->InsertVarConstantArrayExpression(
result, index, values, ModelCache::VAR_CONSTANT_ARRAY_ELEMENT);
}
return result;
}
}
} // namespace
IntExpr* Solver::MakeElement(const std::vector<int64>& values,
IntVar* const index) {
DCHECK(index);
DCHECK_EQ(this, index->solver());
if (index->Bound()) {
return MakeIntConst(values[index->Min()]);
}
return BuildElement(this, values, index);
}
IntExpr* Solver::MakeElement(const std::vector<int>& values,
IntVar* const index) {
DCHECK(index);
DCHECK_EQ(this, index->solver());
if (index->Bound()) {
return MakeIntConst(values[index->Min()]);
}
return BuildElement(this, ToInt64Vector(values), index);
}
// ----- IntExprFunctionElement -----
namespace {
class IntExprFunctionElement : public BaseIntExprElement {
public:
IntExprFunctionElement(Solver* const s, Solver::IndexEvaluator1 values,
IntVar* const e);
~IntExprFunctionElement() override;
std::string name() const override {
return absl::StrFormat("IntFunctionElement(%s)", expr_->name());
}
std::string DebugString() const override {
return absl::StrFormat("IntFunctionElement(%s)", expr_->DebugString());
}
void Accept(ModelVisitor* const visitor) const override {
// Warning: This will expand all values into a vector.
visitor->BeginVisitIntegerExpression(ModelVisitor::kElement, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
expr_);
visitor->VisitInt64ToInt64Extension(values_, expr_->Min(), expr_->Max());
visitor->EndVisitIntegerExpression(ModelVisitor::kElement, this);
}
protected:
int64 ElementValue(int index) const override { return values_(index); }
int64 ExprMin() const override { return expr_->Min(); }
int64 ExprMax() const override { return expr_->Max(); }
private:
Solver::IndexEvaluator1 values_;
};
IntExprFunctionElement::IntExprFunctionElement(Solver* const s,
Solver::IndexEvaluator1 values,
IntVar* const e)
: BaseIntExprElement(s, e), values_(std::move(values)) {
CHECK(values_ != nullptr);
}
IntExprFunctionElement::~IntExprFunctionElement() {}
// ----- Increasing Element -----
class IncreasingIntExprFunctionElement : public BaseIntExpr {
public:
IncreasingIntExprFunctionElement(Solver* const s,
Solver::IndexEvaluator1 values,
IntVar* const index)
: BaseIntExpr(s), values_(std::move(values)), index_(index) {
DCHECK(values_ != nullptr);
DCHECK(index);
DCHECK(s);
}
~IncreasingIntExprFunctionElement() override {}
int64 Min() const override { return values_(index_->Min()); }
void SetMin(int64 m) override {
const int64 index_min = index_->Min();
const int64 index_max = index_->Max();
if (m > values_(index_max)) {
solver()->Fail();
}
const int64 new_index_min = FindNewIndexMin(index_min, index_max, m);
index_->SetMin(new_index_min);
}
int64 Max() const override { return values_(index_->Max()); }
void SetMax(int64 m) override {
int64 index_min = index_->Min();
int64 index_max = index_->Max();
if (m < values_(index_min)) {
solver()->Fail();
}
const int64 new_index_max = FindNewIndexMax(index_min, index_max, m);
index_->SetMax(new_index_max);
}
void SetRange(int64 mi, int64 ma) override {
const int64 index_min = index_->Min();
const int64 index_max = index_->Max();
const int64 value_min = values_(index_min);
const int64 value_max = values_(index_max);
if (mi > ma || ma < value_min || mi > value_max) {
solver()->Fail();
}
if (mi <= value_min && ma >= value_max) {
// Nothing to do.
return;
}
const int64 new_index_min = FindNewIndexMin(index_min, index_max, mi);
const int64 new_index_max = FindNewIndexMax(new_index_min, index_max, ma);
// Assign.
index_->SetRange(new_index_min, new_index_max);
}
std::string name() const override {
return absl::StrFormat("IncreasingIntExprFunctionElement(values, %s)",
index_->name());
}
std::string DebugString() const override {
return absl::StrFormat("IncreasingIntExprFunctionElement(values, %s)",
index_->DebugString());
}
void WhenRange(Demon* d) override { index_->WhenRange(d); }
void Accept(ModelVisitor* const visitor) const override {
// Warning: This will expand all values into a vector.
visitor->BeginVisitIntegerExpression(ModelVisitor::kElement, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
index_);
if (index_->Min() == 0) {
visitor->VisitInt64ToInt64AsArray(values_, ModelVisitor::kValuesArgument,
index_->Max());
} else {
visitor->VisitInt64ToInt64Extension(values_, index_->Min(),
index_->Max());
}
visitor->EndVisitIntegerExpression(ModelVisitor::kElement, this);
}
private:
int64 FindNewIndexMin(int64 index_min, int64 index_max, int64 m) {
if (m <= values_(index_min)) {
return index_min;
}
DCHECK_LT(values_(index_min), m);
DCHECK_GE(values_(index_max), m);
int64 index_lower_bound = index_min;
int64 index_upper_bound = index_max;
while (index_upper_bound - index_lower_bound > 1) {
DCHECK_LT(values_(index_lower_bound), m);
DCHECK_GE(values_(index_upper_bound), m);
const int64 pivot = (index_lower_bound + index_upper_bound) / 2;
const int64 pivot_value = values_(pivot);
if (pivot_value < m) {
index_lower_bound = pivot;
} else {
index_upper_bound = pivot;
}
}
DCHECK(values_(index_upper_bound) >= m);
return index_upper_bound;
}
int64 FindNewIndexMax(int64 index_min, int64 index_max, int64 m) {
if (m >= values_(index_max)) {
return index_max;
}
DCHECK_LE(values_(index_min), m);
DCHECK_GT(values_(index_max), m);
int64 index_lower_bound = index_min;
int64 index_upper_bound = index_max;
while (index_upper_bound - index_lower_bound > 1) {
DCHECK_LE(values_(index_lower_bound), m);
DCHECK_GT(values_(index_upper_bound), m);
const int64 pivot = (index_lower_bound + index_upper_bound) / 2;
const int64 pivot_value = values_(pivot);
if (pivot_value > m) {
index_upper_bound = pivot;
} else {
index_lower_bound = pivot;
}
}
DCHECK(values_(index_lower_bound) <= m);
return index_lower_bound;
}
Solver::IndexEvaluator1 values_;
IntVar* const index_;
};
} // namespace
IntExpr* Solver::MakeElement(Solver::IndexEvaluator1 values,
IntVar* const index) {
CHECK_EQ(this, index->solver());
return RegisterIntExpr(
RevAlloc(new IntExprFunctionElement(this, std::move(values), index)));
}
IntExpr* Solver::MakeMonotonicElement(Solver::IndexEvaluator1 values,
bool increasing, IntVar* const index) {
CHECK_EQ(this, index->solver());
if (increasing) {
return RegisterIntExpr(
RevAlloc(new IncreasingIntExprFunctionElement(this, values, index)));
} else {
// You need to pass by copy such that opposite_value does not include a
// dandling reference when leaving this scope.
Solver::IndexEvaluator1 opposite_values = [values](int64 i) {
return -values(i);
};
return RegisterIntExpr(MakeOpposite(RevAlloc(
new IncreasingIntExprFunctionElement(this, opposite_values, index))));
}
}
// ----- IntIntExprFunctionElement -----
namespace {
class IntIntExprFunctionElement : public BaseIntExpr {
public:
IntIntExprFunctionElement(Solver* const s, Solver::IndexEvaluator2 values,
IntVar* const expr1, IntVar* const expr2);
~IntIntExprFunctionElement() override;
std::string DebugString() const override {
return absl::StrFormat("IntIntFunctionElement(%s,%s)",
expr1_->DebugString(), expr2_->DebugString());
}
int64 Min() const override;
int64 Max() const override;
void Range(int64* lower_bound, int64* upper_bound) override;
void SetMin(int64 lower_bound) override;
void SetMax(int64 upper_bound) override;
void SetRange(int64 lower_bound, int64 upper_bound) override;
bool Bound() const override { return expr1_->Bound() && expr2_->Bound(); }
// TODO(user) : improve me, the previous test is not always true
void WhenRange(Demon* d) override {
expr1_->WhenRange(d);
expr2_->WhenRange(d);
}
void Accept(ModelVisitor* const visitor) const override {
visitor->BeginVisitIntegerExpression(ModelVisitor::kElement, this);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndexArgument,
expr1_);
visitor->VisitIntegerExpressionArgument(ModelVisitor::kIndex2Argument,
expr2_);
// Warning: This will expand all values into a vector.
const int64 expr1_min = expr1_->Min();
const int64 expr1_max = expr1_->Max();
visitor->VisitIntegerArgument(ModelVisitor::kMinArgument, expr1_min);
visitor->VisitIntegerArgument(ModelVisitor::kMaxArgument, expr1_max);
for (int i = expr1_min; i <= expr1_max; ++i) {
visitor->VisitInt64ToInt64Extension(
[this, i](int64 j) { return values_(i, j); }, expr2_->Min(),
expr2_->Max());
}
visitor->EndVisitIntegerExpression(ModelVisitor::kElement, this);
}
private:
int64 ElementValue(int index1, int index2) const {
return values_(index1, index2);
}
void UpdateSupports() const;
IntVar* const expr1_;
IntVar* const expr2_;
mutable int64 min_;
mutable int min_support1_;
mutable int min_support2_;
mutable int64 max_;
mutable int max_support1_;
mutable int max_support2_;
mutable bool initial_update_;
Solver::IndexEvaluator2 values_;
IntVarIterator* const expr1_iterator_;
IntVarIterator* const expr2_iterator_;
};
IntIntExprFunctionElement::IntIntExprFunctionElement(
Solver* const s, Solver::IndexEvaluator2 values, IntVar* const expr1,
IntVar* const expr2)
: BaseIntExpr(s),
expr1_(expr1),
expr2_(expr2),
min_(0),
min_support1_(-1),
min_support2_(-1),
max_(0),
max_support1_(-1),
max_support2_(-1),
initial_update_(true),
values_(std::move(values)),
expr1_iterator_(expr1_->MakeDomainIterator(true)),
expr2_iterator_(expr2_->MakeDomainIterator(true)) {
CHECK(values_ != nullptr);
}
IntIntExprFunctionElement::~IntIntExprFunctionElement() {}
int64 IntIntExprFunctionElement::Min() const {
UpdateSupports();
return min_;
}
int64 IntIntExprFunctionElement::Max() const {
UpdateSupports();
return max_;
}
void IntIntExprFunctionElement::Range(int64* lower_bound, int64* upper_bound) {
UpdateSupports();
*lower_bound = min_;
*upper_bound = max_;
}
#define UPDATE_ELEMENT_INDEX_BOUNDS(test) \
const int64 emin1 = expr1_->Min(); \
const int64 emax1 = expr1_->Max(); \
const int64 emin2 = expr2_->Min(); \
const int64 emax2 = expr2_->Max(); \
int64 nmin1 = emin1; \
bool found = false; \
while (nmin1 <= emax1 && !found) { \
for (int i = emin2; i <= emax2; ++i) { \
int64 value = ElementValue(nmin1, i); \
if (test) { \
found = true; \
break; \
} \
} \
if (!found) { \
nmin1++; \
} \
} \
if (nmin1 > emax1) { \
solver()->Fail(); \
} \
int64 nmin2 = emin2; \
found = false; \