isMonotonous.h

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#ifndef NPSTAT_ISMONOTONOUS_HH_
#define NPSTAT_ISMONOTONOUS_HH_

namespace npstat {
  template <class Iter>
  inline bool isStrictlyIncreasing(Iter begin, Iter const end) {
    if (begin == end)
      return false;
    Iter first(begin);
    bool status = ++begin != end;
    for (; begin != end && status; ++begin, ++first)
      if (!(*first < *begin))
        status = false;
    return status;
  }

  template <class Iter>
  inline bool isStrictlyDecreasing(Iter begin, Iter const end) {
    if (begin == end)
      return false;
    Iter first(begin);
    bool status = ++begin != end;
    for (; begin != end && status; ++begin, ++first)
      if (!(*begin < *first))
        status = false;
    return status;
  }

  template <class Iter>
  inline bool isStrictlyMonotonous(Iter const begin, Iter const end) {
    return isStrictlyIncreasing(begin, end) || isStrictlyDecreasing(begin, end);
  }

  template <class Iter>
  inline bool isNonDecreasing(Iter begin, Iter const end) {
    if (begin == end)
      return false;
    Iter first(begin);
    bool status = ++begin != end;
    for (; begin != end && status; ++begin, ++first)
      if (*begin < *first)
        status = false;
    return status;
  }

  template <class Iter>
  inline bool isNonIncreasing(Iter begin, Iter const end) {
    if (begin == end)
      return false;
    Iter first(begin);
    bool status = ++begin != end;
    for (; begin != end && status; ++begin, ++first)
      if (*begin > *first)
        status = false;
    return status;
  }

  template <class Iter>
  inline bool isMonotonous(Iter const begin, Iter const end) {
    return isNonDecreasing(begin, end) || isNonIncreasing(begin, end);
  }
}  // namespace npstat

#endif  // NPSTAT_ISMONOTONOUS_HH_