openmesh/src/OpenMesh/Core/Mesh/SmartRange.hh

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#pragma once

#include <utility>
#include <array>
#include <vector>

//== NAMESPACES ===============================================================

namespace OpenMesh {

//== FORWARD DECLARATION ======================================================

//== CLASS DEFINITION =========================================================

namespace  {

struct Identity
{
  template <typename T>
  T operator()(const T& _t) const { return _t; }
};

}

/// Base class for all smart range types
template <typename RangeT, typename HandleT>
struct SmartRangeT
{
  // TODO: Someone with better c++ knowledge may improve the code below.



  template <typename Functor>
  auto sum(Functor&& f) -> decltype (f(std::declval<HandleT>())+f(std::declval<HandleT>()))
  {
    auto range = static_cast<const RangeT*>(this);
    auto begin = range->begin();
    auto end   = range->end();
    assert(begin != end);
    decltype (f(*begin) + f(*begin)) sum = f(*begin);
    auto it = begin;
    ++it;
    for (; it != end; ++it)
      sum += f(*it);
    return sum;
  }

  template <typename Functor>
  auto avg(Functor&& f) -> decltype (1.0 * (f(std::declval<HandleT>())+f(std::declval<HandleT>())))
  {
    auto range = static_cast<const RangeT*>(this);
    auto begin = range->begin();
    auto end   = range->end();
    assert(begin != end);
    decltype (f(*begin) + f(*begin)) sum = f(*begin);
    auto it = begin;
    ++it;
    int n_elements = 1;
    for (; it != end; ++it)
    {
      sum += f(*it);
      ++n_elements;
    }
    return (1.0 / n_elements) * sum;
  }

  template <int n, typename Functor = Identity>
  auto to_array(Functor&& f = {}) -> std::array<typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type, n>
  {
    auto range = static_cast<const RangeT*>(this);
    std::array<typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type, n> res;
    auto it = range->begin();
    auto end = range->end();
    int i = 0;
    while (i < n && it != end)
      res[i++] = f(*(it++));
    return res;
  }

  template <typename Functor = Identity>
  auto to_vector(Functor&& f = {}) -> std::vector<typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type>
  {
    auto range = static_cast<const RangeT*>(this);
    std::vector<typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type> res;
    for (auto e : *range)
      res.push_back(f(e));
    return res;
  }


  template <int n, typename Functor>
  auto elem_wise_min(Functor&& f) -> typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type
  {
    auto range = static_cast<const RangeT*>(this);
    auto it    = range->begin();
    auto end   = range->end();
    assert(it != end);

    typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type min = f(*it);
    ++it;

    for (; it != end; ++it)
    {
      const auto& tmp = f(*it);
      for (int i = 0; i < n; ++i)
        min[i] = std::min(min[i], tmp[i]);
    }

    return min;
  }

  template <int n, typename Functor>
  auto elem_wise_max(Functor&& f) -> typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type
  {
    auto range = static_cast<const RangeT*>(this);
    auto it    = range->begin();
    auto end   = range->end();
    assert(it != end);

    typename std::remove_reference<decltype (f(std::declval<HandleT>()))>::type max = f(*it);
    ++it;

    for (; it != end; ++it)
    {
      const auto& tmp = f(*it);
      for (int i = 0; i < n; ++i)
        max[i] = std::max(max[i], tmp[i]);
    }

    return max;
  }





};



//=============================================================================
} // namespace OpenMesh
//=============================================================================

//=============================================================================