include/openvic-dataloader/detail/Concepts.hpp


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#pragma once

#include <concepts>
#include <cstdint>
#include <functional>
#include <utility>

namespace ovdl {
   struct File;
   namespace detail {
      enum class buffer_error : std::uint8_t;
   }
}

namespace ovdl::detail {
   template<typename T, typename... Ts>
   concept any_of = std::disjunction_v<std::is_same<T, Ts>...>;

   template<typename T>
   concept HasCstr =
      requires(T t) {
         { t.c_str() } -> std::same_as<const char*>;
      };

   template<typename T>
   concept HasPath = requires(T& t) {
      { t.path() } -> std::same_as<const char*>;
   };

   template<typename T, typename Self, typename... Args>
   concept LoadCallback =
      requires(T&& t, Self&& self, Args&&... args) {
         { std::invoke(std::forward<T>(t), std::forward<Self>(self), std::forward<Args>(args)...) } -> std::same_as<ovdl::detail::buffer_error>;
      };

   template<typename T>
   concept IsEncoding = requires(T t) {
      typename T::char_type;
      typename T::int_type;
      { T::template is_secondary_char_type<typename T::char_type>() } -> std::same_as<bool>;
      { T::eof() } -> std::same_as<typename T::int_type>;
      { T::to_int_type(typename T::char_type {}) } -> std::same_as<typename T::int_type>;
   };

   template<typename T, typename R, typename... Args>
   concept Invocable_R = std::invocable<T, Args...> && requires(Args&&... args) {
      { invoke(forward<Args>(args)...) } -> std::convertible_to<R>;
   };
}