chi_math_range.h

Go to the documentation of this file.

#ifndef CHITECH_CHI_MATH_RANGE_H
#define CHITECH_CHI_MATH_RANGE_H
 
#include <type_traits>
#include <vector>
 
namespace chi_math
{
//###################################################################
/**Returns a range of number according to the logic of the parameters.
 *
 * \param start First number in the sequence.
 * \param end   Termination criteria. If the delta is positive then
 *              the sequence will terminate if i>=end, otherwise if the
 *              delta is negative the sequence will terminate if i<=end
 * \param delta Cannot be 0. Default 1. Can be negative.*/
template<typename T, typename D = int>
std::vector<T> Range(T start, T end, D delta=1)
{
  static_assert(std::is_signed<D>::value,
                "chi_math::Range delta parameter must be signed");
  const bool forward = (delta > 0);
 
  std::vector<T> sequence = {};
 
  if (    forward and start >= end) return sequence;
  if (not forward and start <= end) return sequence;
 
  T i = start;
  bool terminate = false;
  while (not terminate)
  {
    sequence.push_back(i);
    i += delta;
 
    if (    forward and i >= end) terminate = true;
    if (not forward and i <= end) terminate = true;
 
    if (not forward and i > start) terminate = true; //Wrap-around check
  }
 
  return sequence;
}
 
}//namespace chi_math
 
#endif //CHITECH_CHI_MATH_RANGE_H