logical.hpp

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#if !defined (LOGICAL_70B10597_2771_496C_9203_4CD3986547F1_H)
#  define LOGICAL_70B10597_2771_496C_9203_4CD3986547F1_H

#  include <type_traits>


namespace pgs {


template<class F, class Acc, class... Ts>
struct fold_left : Acc {
};


template <class F, class Acc, class T, class... Ts>
struct fold_left<F, Acc, T, Ts...> : 
  fold_left <F, typename F::template apply<Acc, T>::type, Ts...> {
};


namespace detail {
  struct or_helper {
    template <class Acc, class T>
    struct apply : std::integral_constant<bool, Acc::value || T::value> {
    };
  };

  struct and_helper {
    template <class Acc, class T>
    struct apply : std::integral_constant<bool, Acc::value && T::value> {
    };
};

}//namespace detail



template <class... Ts>
struct or_ : fold_left <detail::or_helper, std::false_type, Ts...> {
};


template <class... Ts>
struct and_ : fold_left <detail::and_helper, std::true_type, Ts...> {
};

}//namespace pgs

#endif