From f83a8b450e68441a4f76ef3e71071a0bc80050b1 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Sun, 2 Dec 2018 23:05:15 +0900
Subject: [PATCH] add concat_to_string to utility for error messges

---
 toml/utility.hpp | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/toml/utility.hpp b/toml/utility.hpp
index 0df0d07..2e7b0f0 100644
--- a/toml/utility.hpp
+++ b/toml/utility.hpp
@@ -3,6 +3,7 @@
 #include "traits.hpp"
 #include <utility>
 #include <memory>
+#include <sstream>
 
 namespace toml
 {
@@ -30,7 +31,7 @@ inline void resize_impl(T& container, std::size_t N, std::false_type)
     else throw std::invalid_argument("not resizable type");
 }
 
-}
+} // detail
 
 template<typename T>
 inline void resize(T& container, std::size_t N)
@@ -39,5 +40,27 @@ inline void resize(T& container, std::size_t N)
     else return detail::resize_impl(container, N, detail::has_resize_method<T>());
 }
 
+namespace detail
+{
+inline std::string concat_to_string_impl(std::ostringstream& oss)
+{
+    return oss.str();
+}
+template<typename T, typename ... Ts>
+std::string concat_to_string_impl(std::ostringstream& oss, T&& head, Ts&& ... tail)
+{
+    oss << std::forward<T>(head);
+    return concat_to_string_impl(oss, std::forward<Ts>(tail) ... );
+}
+} // detail
+
+template<typename ... Ts>
+std::string concat_to_string(Ts&& ... args)
+{
+    std::ostringstream oss;
+    oss << std::boolalpha << std::fixed;
+    return detail::concat_to_string_impl(oss, std::forward<Ts>(args) ...);
+}
+
 }// toml
 #endif // TOML11_UTILITY