Flags.h

/*
 * Gamedev Framework (gf)
 * Copyright (C) 2016-2018 Julien Bernard
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */
#ifndef GF_FLAGS_H
#define GF_FLAGS_H

#include <type_traits>

#include "Types.h"

namespace gf {
#ifndef DOXYGEN_SHOULD_SKIP_THIS
inline namespace v1 {
#endif

  template<typename E>
  class Flags {
  public:
    Flags() = default;

    constexpr Flags(NoneType)
    : m_data(0)
    {

    }

    constexpr Flags(AllType)
    : m_data(static_cast<Type>(~0))
    {

    }

    constexpr Flags(E e)
    : m_data(static_cast<Type>(e))
    {

    }

    constexpr Flags<E> operator~() const {
      return Flags(~m_data);
    }

    constexpr Flags operator|(Flags flags) const {
      return Flags(m_data | flags.m_data);
    }

    Flags<E>& operator|=(Flags<E> flags) {
      m_data |= flags.m_data;
      return *this;
    }

    constexpr Flags operator&(Flags flags) const {
      return Flags(m_data & flags.m_data);
    }

    Flags<E>& operator&=(Flags<E> flags) {
      m_data &= flags.m_data;
      return *this;
    }

    constexpr operator bool() const {
      return m_data != 0;
    }

    constexpr bool test(E flag) const {
      return (m_data & static_cast<Type>(flag)) != 0;
    }

    void set(E flag) {
      m_data |= static_cast<Type>(flag);
    }

    void reset(E flag) {
      m_data &= ~static_cast<Type>(flag);
    }

    using Type = typename std::underlying_type<E>::type;

    Type getValue() const {
      return m_data;
    }

  private:
    constexpr Flags(Type data)
    : m_data(data)
    {

    }

    Type m_data;
  };

  template<typename E>
  constexpr
  Flags<E> operator|(Flags<E> lhs, E rhs) {
    return lhs | Flags<E>(rhs);
  }

  template<typename E>
  constexpr
  Flags<E> operator|(E lhs, Flags<E> rhs) {
    return Flags<E>(lhs) | rhs;
  }

  template<typename E>
  constexpr
  Flags<E> operator&(Flags<E> lhs, E rhs) {
    return lhs & Flags<E>(rhs);
  }

  template<typename E>
  constexpr
  Flags<E> operator&(E lhs, Flags<E> rhs) {
    return Flags<E>(lhs) & rhs;
  }


  template<typename E>
  constexpr Flags<E> combineFlags(E flag) {
    return Flags<E>(flag);
  }

  template<typename E, typename ... F>
  constexpr Flags<E> combineFlags(E flag, F ... others) {
    return Flags<E>(flag) | combineFlags(others ...);
  }

#ifndef DOXYGEN_SHOULD_SKIP_THIS
}


// this traits is not versioned

template<typename E>
struct EnableBitmaskOperators {
  static constexpr bool value = false;
};

// these overloads are only available to gf enum types and gf flags
// unless you add: "using gf::operator|;"

template<typename E>
constexpr
typename std::enable_if<EnableBitmaskOperators<E>::value, gf::Flags<E>>::type
operator|(E lhs, E rhs) {
  return gf::Flags<E>(lhs) | gf::Flags<E>(rhs);
}

template<typename E>
constexpr
typename std::enable_if<EnableBitmaskOperators<E>::value, gf::Flags<E>>::type
operator&(E lhs, E rhs) {
  return gf::Flags<E>(lhs) & gf::Flags<E>(rhs);
}

template<typename E>
constexpr
typename std::enable_if<EnableBitmaskOperators<E>::value, gf::Flags<E>>::type
operator~(E val) {
  return ~gf::Flags<E>(val);
}

#endif
}

#endif // GF_FLAGS_H