bind_front.hpp

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#ifndef VCCC_FUNCTIONAL_BIND_FRONT_HPP_
#define VCCC_FUNCTIONAL_BIND_FRONT_HPP_
 
#include <type_traits>
#include <utility>
 
#include "vccc/__functional/invoke.hpp"
#include "vccc/__functional/detail/bind_base.hpp"
#include "vccc/__type_traits/conjunction.hpp"
#include "vccc/__type_traits/is_invocable.hpp"
 
namespace vccc {
namespace detail {
 
template<typename F, typename... Args>
class bind_front_object : public bind_object_base<bind_front_object<F, Args...>, F, Args...> {
  using base = bind_object_base<bind_front_object<F, Args...>, F, Args...>;
  friend base;
 
  template<typename Self, typename... U>
  struct bind_invoke_result
      : invoke_result<copy_cvref_t<Self&&, F>, copy_cvref_t<Self&&, Args>..., U&&...> {};
 
  template<typename Self, typename... U>
  struct bind_nothrow_invocable
      : is_nothrow_invocable<copy_cvref_t<Self&&, F>, copy_cvref_t<Self&&, Args>..., U&&...> {};
 
  template<std::size_t...I, typename Self, typename... U>
  static constexpr typename bind_invoke_result<Self&&, U&&...>::type
  call(Self&& self, std::index_sequence<I...>, U&&... args) noexcept(bind_nothrow_invocable<Self&&, U&&...>::value) {
    return vccc::invoke(
        std::forward<Self>(self).func_,
        std::get<I>(std::forward<Self>(self).args_)...,
        std::forward<U>(args)...
    );
  }
 
 public:
  using base::base;
  using base::operator();
};
 
} // namespace detail
 
 
template<typename F, typename... Args, std::enable_if_t<conjunction<
    std::is_constructible<std::decay_t<F>, F>,
    std::is_move_constructible<std::decay_t<F>>,
    std::is_constructible<std::decay_t<Args>, Args>...,
    std::is_move_constructible<std::decay_t<Args>>...
>::value, int> = 0>
constexpr auto bind_front(F&& f, Args&&... args) {
  return detail::bind_front_object<std::decay_t<F>, std::decay_t<Args>...>{
    detail::bind_object_ctor_tag{},
    std::forward<F>(f),
    std::forward<Args>(args)...
  };
}
 
 
} // namespace vccc
 
#endif // VCCC_FUNCTIONAL_BIND_FRONT_HPP_