type_traits.hpp

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/*
   This file is part of PLYwoot, a header-only PLY parser.
 
   Copyright (C) 2023-2025, Ton van den Heuvel
 
   PLYwoot is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifndef PLYWOOT_TYPE_TRAITS_HPP
#define PLYWOOT_TYPE_TRAITS_HPP
 
 
#include "reflect.hpp"
#include "std.hpp"
#include "types.hpp"
 
#include <algorithm>
#include <type_traits>
 
namespace plywoot::detail {
 
template<typename T>
struct IsList
{
  static constexpr bool value = false;
};
 
template<typename T, std::size_t N>
struct IsList<reflect::Array<T, N>>
{
  static constexpr bool value = true;
};
 
template<typename T>
struct IsList<std::vector<T>>
{
  static constexpr bool value = true;
};
 
template<typename T>
struct IsList<reflect::Type<T>>
{
  static constexpr bool value = IsList<T>::value;
};
 
template<typename T>
constexpr bool isList()
{
  return IsList<T>::value;
}
 
template<typename... Ts>
struct NumProperties
{
  static constexpr std::size_t size = 0;
};
 
template<typename T, typename... Ts>
struct NumProperties<T, Ts...>
{
  static constexpr std::size_t size = NumProperties<T>::size + NumProperties<Ts...>::size;
};
 
template<typename T, std::size_t N>
struct NumProperties<reflect::Array<T, N>>
{
  static constexpr std::size_t size = 1;
};
 
template<typename T, std::size_t N>
struct NumProperties<reflect::Pack<T, N>>
{
  static constexpr std::size_t size = N;
};
 
template<typename T>
struct NumProperties<reflect::Stride<T>>
{
  static constexpr std::size_t size = 0;
};
 
template<typename T>
struct NumProperties<T>
{
  static constexpr std::size_t size = 1;
};
 
template<typename... Ts>
constexpr std::size_t numProperties()
{
  return NumProperties<Ts...>::size;
}
 
template<typename T>
constexpr bool isSame(PlyDataType type)
{
  switch (type)
  {
    case PlyDataType::Char:
      return std::is_same<T, char>::value;
    case PlyDataType::UChar:
      return std::is_same<T, unsigned char>::value;
    case PlyDataType::Short:
      return std::is_same<T, short>::value;
    case PlyDataType::UShort:
      return std::is_same<T, unsigned short>::value;
    case PlyDataType::Int:
      return std::is_same<T, int>::value;
    case PlyDataType::UInt:
      return std::is_same<T, unsigned int>::value;
    case PlyDataType::Float:
      return std::is_same<T, float>::value;
    case PlyDataType::Double:
      return std::is_same<T, double>::value;
  }
 
  return false;
}
 
template<typename T>
struct IsPack
{
  static constexpr bool value = false;
};
 
template<typename T, std::size_t N>
struct IsPack<reflect::Pack<T, N>>
{
  static constexpr bool value = true;
};
 
template<typename T, typename... Ts>
struct SizeOf
{
  static constexpr auto size = SizeOf<T>::size + SizeOf<Ts...>::size;
};
 
template<typename T>
struct SizeOf<T>
{
  static constexpr auto size = sizeof(T);
};
 
template<typename T, std::size_t N>
struct SizeOf<reflect::Array<T, N>>
{
  static constexpr auto size = N * SizeOf<T>::size;
};
 
template<typename T, std::size_t N>
struct SizeOf<reflect::Pack<T, N>>
{
  static constexpr auto size = N * SizeOf<T>::size;
};
 
template<typename... Ts>
constexpr std::size_t sizeOf()
{
  return SizeOf<Ts...>::size;
}
 
constexpr std::size_t sizeOf(PlyDataType type)
{
  switch (type)
  {
    case PlyDataType::Char:
    case PlyDataType::UChar:
      return 1;
    case PlyDataType::Short:
    case PlyDataType::UShort:
      return 2;
    case PlyDataType::Int:
    case PlyDataType::UInt:
    case PlyDataType::Float:
      return 4;
    case PlyDataType::Double:
      return 8;
  }
 
  return 0;
}
 
template<typename Ptr>
constexpr Ptr align(Ptr ptr, PlyDataType type)
{
  switch (type)
  {
    case PlyDataType::Char:
      return detail::align(ptr, alignof(char));
    case PlyDataType::UChar:
      return detail::align(ptr, alignof(unsigned char));
    case PlyDataType::Short:
      return detail::align(ptr, alignof(short));
    case PlyDataType::UShort:
      return detail::align(ptr, alignof(unsigned short));
    case PlyDataType::Int:
      return detail::align(ptr, alignof(int));
    case PlyDataType::UInt:
      return detail::align(ptr, alignof(unsigned int));
    case PlyDataType::Float:
      return detail::align(ptr, alignof(float));
    case PlyDataType::Double:
      return detail::align(ptr, alignof(double));
  }
 
  return ptr;
}
 
template<typename T>
constexpr bool isPacked(uintptr_t offset = 0)
{
  return (offset % alignof(T)) == 0;
}
 
template<typename T, typename U, typename... Ts>
constexpr bool isPacked(uintptr_t offset = 0)
{
  return (offset % alignof(T)) == 0 && isPacked<U, Ts...>(offset + sizeOf<T>());
}
 
template<typename... Ts>
constexpr bool isTriviallyCopyable()
{
  return (std::is_trivially_copyable_v<Ts> && ...);
}
 
template<typename T>
struct IsMemcpyable
{
  bool operator()(const PlyPropertyConstIterator first, const PlyPropertyConstIterator last) const
  {
    return first < last && isSame<T>(first->type());
  }
};
 
template<typename T, std::size_t N>
struct IsMemcpyable<reflect::Array<T, N>>
{
  bool operator()(const PlyPropertyConstIterator, const PlyPropertyConstIterator) const { return false; }
};
 
template<typename T, std::size_t N>
struct IsMemcpyable<reflect::Pack<T, N>>
{
  bool operator()(const PlyPropertyConstIterator first, const PlyPropertyConstIterator last) const
  {
    return first + N <= last &&
           std::all_of(first, first + N, [](const PlyProperty &p) { return isSame<T>(p.type()); });
  }
};
 
template<typename T>
bool isMemcpyable(const PlyPropertyConstIterator first, const PlyPropertyConstIterator last)
{
  return first + detail::numProperties<T>() == last && IsMemcpyable<T>{}(first, last);
}
 
template<typename T, typename U, typename... Ts>
bool isMemcpyable(const PlyPropertyConstIterator first, const PlyPropertyConstIterator last)
{
  return IsMemcpyable<T>{}(first, last) && isMemcpyable<U, Ts...>(first + detail::numProperties<T>(), last);
}
 
}
 
#endif