#ifndef SASS_PATHS_H

#define SASS_PATHS_H

#include <string>

#include <vector>

#include <sstream>

template<typename T>

std::string vector_to_string(std::vector<T> v)

{

  std::stringstream buffer;

  buffer << "[";

  if (!v.empty())

  {  buffer << v[0]; }

  else

  { buffer << "]"; }

  if (v.size() == 1)

  { buffer << "]"; }

  else

  {

    for (size_t i = 1, S = v.size(); i < S; ++i) buffer << ", " << v[i];

    buffer << "]";

  }

  return buffer.str();

}

namespace Sass {

  template<typename T>

  std::vector<std::vector<T> > paths(std::vector<std::vector<T> > strata, size_t from_end = 0)

  {

    if (strata.empty()) {

      return std::vector<std::vector<T> >();

    }

    size_t end = strata.size() - from_end;

    if (end <= 1) {

      std::vector<std::vector<T> > starting_points;

      starting_points.reserve(strata[0].size());

      for (size_t i = 0, S = strata[0].size(); i < S; ++i) {

        std::vector<T> starting_point;

        starting_point.push_back(strata[0][i]);

        starting_points.push_back(starting_point);

      }

      return starting_points;

    }

    std::vector<std::vector<T> > up_to_here = paths(strata, from_end + 1);

    std::vector<T>          here       = strata[end-1];

    std::vector<std::vector<T> > branches;

    branches.reserve(up_to_here.size() * here.size());

    for (size_t i = 0, S1 = up_to_here.size(); i < S1; ++i) {

      for (size_t j = 0, S2 = here.size(); j < S2; ++j) {

        std::vector<T> branch = up_to_here[i];

        branch.push_back(here[j]);

        branches.push_back(branch);

      }

    }

    return branches;

  }

}

#endif