sorted_interval_list.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_UTIL_SORTED_INTERVAL_LIST_H_
#define OR_TOOLS_UTIL_SORTED_INTERVAL_LIST_H_
 
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <ostream>
#include <set>
#include <string>
#include <utility>
#include <vector>
 
#include "absl/container/inlined_vector.h"
#include "absl/types/span.h"
#include "ortools/base/logging.h"
 
namespace operations_research {

struct ClosedInterval {
#if !defined(SWIG)
  class Iterator;
#endif  // !defined(SWIG)
 
  ClosedInterval() {}
  explicit ClosedInterval(int64_t v) : start(v), end(v) {}
  ClosedInterval(int64_t s, int64_t e) : start(s), end(e) {
    DLOG_IF(DFATAL, s > e) << "Invalid ClosedInterval(" << s << ", " << e
                           << ")";
  }
 
  std::string DebugString() const;
  constexpr bool operator==(const ClosedInterval& other) const {
    return start == other.start && end == other.end;
  }
 
  // Because we mainly manipulate vector of disjoint intervals, we only need to
  // sort by the start. We do not care about the order in which interval with
  // the same start appear since they will always be merged into one interval.
  constexpr bool operator<(const ClosedInterval& other) const {
    return start < other.start;
  }
 
  template <typename H>
  friend H AbslHashValue(H h, const ClosedInterval& interval) {
    return H::combine(std::move(h), interval.start, interval.end);
  }
 
  int64_t start = 0;  // Inclusive.
  int64_t end = 0;    // Inclusive.
};
 
#if !defined(SWIG)
inline ClosedInterval::Iterator begin(ClosedInterval interval);
inline ClosedInterval::Iterator end(ClosedInterval interval);
#endif  // !defined(SWIG)
 
std::ostream& operator<<(std::ostream& out, const ClosedInterval& interval);
std::ostream& operator<<(std::ostream& out,
                         const std::vector<ClosedInterval>& intervals);

bool IntervalsAreSortedAndNonAdjacent(
    absl::Span<const ClosedInterval> intervals);

class Domain {
 public:
  Domain() {}
 
#if !defined(SWIG)
  Domain(const Domain& other) : intervals_(other.intervals_) {}

  Domain& operator=(const Domain& other) {
    intervals_ = other.intervals_;
    return *this;
  }

  Domain(Domain&& other) noexcept : intervals_(std::move(other.intervals_)) {}

  Domain& operator=(Domain&& other) noexcept {
    intervals_ = std::move(other.intervals_);
    return *this;
  }
#endif  // !defined(SWIG)

  explicit Domain(int64_t value);

  Domain(int64_t left, int64_t right);

  static Domain AllValues();

  static Domain FromValues(std::vector<int64_t> values);

  static Domain FromIntervals(absl::Span<const ClosedInterval> intervals);

  static Domain FromFlatSpanOfIntervals(
      absl::Span<const int64_t> flat_intervals);

  static Domain FromVectorIntervals(
      const std::vector<std::vector<int64_t> >& intervals);

  static Domain FromFlatIntervals(const std::vector<int64_t>& flat_intervals);

  std::vector<int64_t> FlattenedIntervals() const;
 
#if !defined(SWIG)
  class DomainIterator {
   public:
    explicit DomainIterator(
        const absl::InlinedVector<ClosedInterval, 1>& intervals)
        : value_(intervals.empty() ? int64_t{0} : intervals.front().start),
          it_(intervals.begin()),
          end_(intervals.end()) {}
 
    int64_t operator*() const { return value_; }
 
    void operator++() {
      if (value_ == it_->end) {
        ++it_;
        if (it_ != end_) value_ = it_->start;
      } else {
        ++value_;
      }
    }
 
    bool operator!=(
        absl::InlinedVector<ClosedInterval, 1>::const_iterator end) const {
      return it_ != end;
    }
 
   private:
    int64_t value_;
    absl::InlinedVector<ClosedInterval, 1>::const_iterator it_;
    absl::InlinedVector<ClosedInterval, 1>::const_iterator end_;
  };
  struct DomainIteratorBeginEnd {
    DomainIterator begin() const { return DomainIterator(intervals); }
    absl::InlinedVector<ClosedInterval, 1>::const_iterator end() const {
      return intervals.end();
    }
    const absl::InlinedVector<ClosedInterval, 1>& intervals;
  };
  struct DomainIteratorBeginEndWithOwnership {
    DomainIterator begin() const { return DomainIterator(intervals); }
    absl::InlinedVector<ClosedInterval, 1>::const_iterator end() const {
      return intervals.end();
    }
    absl::InlinedVector<ClosedInterval, 1> intervals;
  };
  DomainIteratorBeginEnd Values() const& { return {this->intervals_}; }
  DomainIteratorBeginEndWithOwnership Values() const&& {
    return {std::move(this->intervals_)};
  }
#endif  // !defined(SWIG)

  bool IsEmpty() const;

  int64_t Size() const;

  bool HasTwoValues() const {
    if (intervals_.size() == 1) {
      return intervals_[0].end == intervals_[0].start + 1;
    } else if (intervals_.size() == 2) {
      return intervals_[0].end == intervals_[0].start &&
             intervals_[1].end == intervals_[1].start;
    }
    return false;
  }

  int64_t Min() const;

  int64_t Max() const;

  int64_t SmallestValue() const;

  int64_t ClosestValue(int64_t wanted) const;

  int64_t ValueAtOrBefore(int64_t input) const;
  int64_t ValueAtOrAfter(int64_t input) const;

  Domain PartAroundZero() const;

  bool IsFixed() const;

  int64_t FixedValue() const;

  bool Contains(int64_t value) const;

  int64_t Distance(int64_t value) const;

  bool IsIncludedIn(const Domain& domain) const;

  Domain Complement() const;

  Domain Negation() const;

  Domain IntersectionWith(const Domain& domain) const;

  Domain UnionWith(const Domain& domain) const;

  Domain AdditionWith(const Domain& domain) const;

  Domain MultiplicationBy(int64_t coeff, bool* exact = nullptr) const;

  Domain RelaxIfTooComplex() const;

  Domain ContinuousMultiplicationBy(int64_t coeff) const;

  Domain ContinuousMultiplicationBy(const Domain& domain) const;

  Domain DivisionBy(int64_t coeff) const;

  Domain InverseMultiplicationBy(int64_t coeff) const;

  Domain PositiveModuloBySuperset(const Domain& modulo) const;

  Domain PositiveDivisionBySuperset(const Domain& divisor) const;

  Domain SquareSuperset() const;

  Domain QuadraticSuperset(int64_t a, int64_t b, int64_t c, int64_t d) const;

  Domain SimplifyUsingImpliedDomain(const Domain& implied_domain) const;

  std::string ToString() const;

  bool operator<(const Domain& other) const;
 
  bool operator==(const Domain& other) const {
    return intervals_ == other.intervals_;
  }
 
  bool operator!=(const Domain& other) const {
    return intervals_ != other.intervals_;
  }
 
  template <typename H>
  friend H AbslHashValue(H h, const Domain& domain) {
    return H::combine(std::move(h), domain.intervals_);
  }

  int NumIntervals() const { return intervals_.size(); }
  ClosedInterval front() const { return intervals_.front(); }
  ClosedInterval back() const { return intervals_.back(); }
  ClosedInterval operator[](int i) const { return intervals_[i]; }
  absl::InlinedVector<ClosedInterval, 1>::const_iterator begin() const {
    return intervals_.begin();
  }
  absl::InlinedVector<ClosedInterval, 1>::const_iterator end() const {
    return intervals_.end();
  }
 
 private:
  // Same as Negation() but modify the current domain.
  void NegateInPlace();
 
  // Some functions relax the domain when its "complexity" (i.e NumIntervals())
  // become too large.
  static constexpr int kDomainComplexityLimit = 100;
 
  // Invariant: will always satisfy IntervalsAreSortedAndNonAdjacent().
  //
  // Note that we use InlinedVector for the common case of single internal
  // interval. This provide a good performance boost when working with a
  // std::vector<Domain>.
  absl::InlinedVector<ClosedInterval, 1> intervals_;
};
 
std::ostream& operator<<(std::ostream& out, const Domain& domain);
 
// Returns the sum of smallest k values in the domain.
int64_t SumOfKMinValueInDomain(const Domain& domain, int k);
 
// Returns the sum of largest k values in the domain.
int64_t SumOfKMaxValueInDomain(const Domain& domain, int k);

// TODO(user): Templatize the class on the type of the bounds.
class SortedDisjointIntervalList {
 public:
  struct IntervalComparator {
    bool operator()(const ClosedInterval& a, const ClosedInterval& b) const {
      return a.start != b.start ? a.start < b.start : a.end < b.end;
    }
  };
  typedef std::set<ClosedInterval, IntervalComparator> IntervalSet;
  typedef IntervalSet::iterator Iterator;
  typedef IntervalSet::const_iterator ConstIterator;
 
  SortedDisjointIntervalList();
  explicit SortedDisjointIntervalList(
      const std::vector<ClosedInterval>& intervals);

  // TODO(user): Explain why we favored this API to the more natural
  // input std::vector<ClosedInterval> or std::vector<std::pair<int, int>>.
  SortedDisjointIntervalList(const std::vector<int64_t>& starts,
                             const std::vector<int64_t>& ends);
  SortedDisjointIntervalList(const std::vector<int>& starts,
                             const std::vector<int>& ends);

  SortedDisjointIntervalList BuildComplementOnInterval(int64_t start,
                                                       int64_t end);

  Iterator InsertInterval(int64_t start, int64_t end);

  Iterator GrowRightByOne(int64_t value, int64_t* newly_covered);

  void InsertIntervals(const std::vector<int64_t>& starts,
                       const std::vector<int64_t>& ends);
  void InsertIntervals(const std::vector<int>& starts,
                       const std::vector<int>& ends);

  int NumIntervals() const { return intervals_.size(); }

  Iterator FirstIntervalGreaterOrEqual(int64_t value) const;
  Iterator LastIntervalLessOrEqual(int64_t value) const;
 
  std::string DebugString() const;

  ConstIterator begin() const { return intervals_.begin(); }
  ConstIterator end() const { return intervals_.end(); }

  const ClosedInterval& last() const { return *intervals_.rbegin(); }
 
  void clear() { intervals_.clear(); }
  void swap(SortedDisjointIntervalList& other) {
    intervals_.swap(other.intervals_);
  }
 
 private:
  template <class T>
  void InsertAll(const std::vector<T>& starts, const std::vector<T>& ends);
 
  IntervalSet intervals_;
};
 
// Implementation details.
 
#if !defined(SWIG)
class ClosedInterval::Iterator {
 public:
  using value_type = int64_t;
  using difference_type = std::ptrdiff_t;
 
  Iterator(const Iterator&) = default;
 
  int64_t operator*() const { return static_cast<int64_t>(current_); }
 
  Iterator& operator++() {
    ++current_;
    return *this;
  }
  void operator++(int) { ++current_; }
 
  bool operator==(Iterator other) const { return current_ == other.current_; }
  bool operator!=(Iterator other) const { return current_ != other.current_; }
 
  Iterator& operator=(const Iterator&) = default;
 
  static Iterator Begin(ClosedInterval interval) {
    AssertNotFullInt64Range(interval);
    return Iterator(static_cast<uint64_t>(interval.start));
  }
  static Iterator End(ClosedInterval interval) {
    AssertNotFullInt64Range(interval);
    return Iterator(static_cast<uint64_t>(interval.end) + 1);
  }
 
 private:
  explicit Iterator(uint64_t current) : current_(current) {}
 
  // Triggers a DCHECK-failure when `interval` represents the full int64_t
  // range.
  static void AssertNotFullInt64Range(ClosedInterval interval) {
    DCHECK_NE(static_cast<uint64_t>(interval.start),
              static_cast<uint64_t>(interval.end) + 1)
        << "Iteration over the full int64_t range is not supported.";
  }
 
  // Implementation note: In C++, integer overflow is well-defined only for
  // unsigned integers. To avoid any compilation issues or UBSan failures, the
  // iterator uses uint64_t internally and relies on the fact that since C++20
  // unsigned->signed conversion is well-defined for all values using modulo
  // arithmetic.
  uint64_t current_;
};
#if __cplusplus >= 202002L
static_assert(std::input_iterator<ClosedInterval::Iterator>);
#endif
// begin()/end() are required for iteration over ClosedInterval in a range for
// loop.
inline ClosedInterval::Iterator begin(ClosedInterval interval) {
  return ClosedInterval::Iterator::Begin(interval);
}
inline ClosedInterval::Iterator end(ClosedInterval interval) {
  return ClosedInterval::Iterator::End(interval);
}
#endif  // !defined(SWIG)
 
}  // namespace operations_research
 
#endif  // OR_TOOLS_UTIL_SORTED_INTERVAL_LIST_H_