From b6e2c6e235b18fcf581ff376363b273e789050f4 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Fri, 14 May 2021 15:46:00 +0900
Subject: [PATCH] feat: add detail::has_specialization_from/into

---
 toml/traits.hpp | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/toml/traits.hpp b/toml/traits.hpp
index eafa6af..209856d 100644
--- a/toml/traits.hpp
+++ b/toml/traits.hpp
@@ -2,6 +2,10 @@
 // Distributed under the MIT License.
 #ifndef TOML11_TRAITS_HPP
 #define TOML11_TRAITS_HPP
+
+#include "from.hpp"
+#include "into.hpp"
+
 #include <chrono>
 #include <forward_list>
 #include <string>
@@ -84,6 +88,22 @@ struct has_into_toml_method_impl
     static std::false_type check(...);
 };
 
+struct has_specialized_from_impl
+{
+    template<typename T>
+    static std::false_type check(...);
+    template<typename T>
+    static std::true_type check(std::nullptr_t, std::size_t S = sizeof(::toml::from<T>));
+};
+struct has_specialized_into_impl
+{
+    template<typename T>
+    static std::false_type check(...);
+    template<typename T>
+    static std::true_type check(std::nullptr_t, std::size_t S = sizeof(::toml::into<T>));
+};
+
+
 /// Intel C++ compiler can not use decltype in parent class declaration, here
 /// is a hack to work around it. https://stackoverflow.com/a/23953090/4692076
 #ifdef __INTEL_COMPILER
@@ -114,6 +134,11 @@ template<typename T>
 struct has_into_toml_method
 : decltype(has_into_toml_method_impl::check<T>(nullptr)){};
 
+template<typename T>
+struct has_specialized_from : decltype(has_specialized_from_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_specialized_into : decltype(has_specialized_into_impl::check<T>(nullptr)){};
+
 #ifdef __INTEL_COMPILER
 #undef decltype
 #endif