From f7971f04a5e21dcaaa0d559abf5b4d67d854c00f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= <theo.delrieu@tanker.io>
Date: Thu, 6 Sep 2018 16:08:01 +0200
Subject: [PATCH] make to_json SFINAE-correct
---
include/nlohmann/adl_serializer.hpp | 6 ++-
.../nlohmann/detail/conversions/to_json.hpp | 34 ++++------------
single_include/nlohmann/json.hpp | 40 +++++--------------
3 files changed, 22 insertions(+), 58 deletions(-)
diff --git a/include/nlohmann/adl_serializer.hpp b/include/nlohmann/adl_serializer.hpp
index 53c9009f..58d26ea9 100644
--- a/include/nlohmann/adl_serializer.hpp
+++ b/include/nlohmann/adl_serializer.hpp
@@ -35,9 +35,11 @@ struct adl_serializer
@param[in,out] j JSON value to write to
@param[in] val value to read from
*/
- template<typename BasicJsonType, typename ValueType>
- static void to_json(BasicJsonType& j, ValueType&& val) noexcept(
+ template <typename BasicJsonType, typename ValueType>
+ static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
+ -> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)),
+ void())
{
::nlohmann::to_json(j, std::forward<ValueType>(val));
}
diff --git a/include/nlohmann/detail/conversions/to_json.hpp b/include/nlohmann/detail/conversions/to_json.hpp
index 5e631a38..8f2bd266 100644
--- a/include/nlohmann/detail/conversions/to_json.hpp
+++ b/include/nlohmann/detail/conversions/to_json.hpp
@@ -286,9 +286,12 @@ void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
external_constructor<value_t::object>::construct(j, std::move(obj));
}
-template<typename BasicJsonType, typename T, std::size_t N,
- enable_if_t<not std::is_constructible<typename BasicJsonType::string_t, T (&)[N]>::value, int> = 0>
-void to_json(BasicJsonType& j, T (&arr)[N])
+template <
+ typename BasicJsonType, typename T, std::size_t N,
+ enable_if_t<not std::is_constructible<typename BasicJsonType::string_t,
+ const T (&)[N]>::value,
+ int> = 0 >
+void to_json(BasicJsonType& j, const T (&arr)[N])
{
external_constructor<value_t::array>::construct(j, arr);
}
@@ -321,35 +324,12 @@ void to_json(BasicJsonType& j, const std::tuple<Args...>& t)
struct to_json_fn
{
- private:
template<typename BasicJsonType, typename T>
- auto call(BasicJsonType& j, T&& val, priority_tag<1> /*unused*/) const noexcept(noexcept(to_json(j, std::forward<T>(val))))
+ auto operator()(BasicJsonType& j, T&& val) const noexcept(noexcept(to_json(j, std::forward<T>(val))))
-> decltype(to_json(j, std::forward<T>(val)), void())
{
return to_json(j, std::forward<T>(val));
}
-
- template<typename BasicJsonType, typename T>
- void call(BasicJsonType& /*unused*/, T&& /*unused*/, priority_tag<0> /*unused*/) const noexcept
- {
- static_assert(sizeof(BasicJsonType) == 0,
- "could not find to_json() method in T's namespace");
-
-#ifdef _MSC_VER
- // MSVC does not show a stacktrace for the above assert
- using decayed = uncvref_t<T>;
- static_assert(sizeof(typename decayed::force_msvc_stacktrace) == 0,
- "forcing MSVC stacktrace to show which T we're talking about.");
-#endif
- }
-
- public:
- template<typename BasicJsonType, typename T>
- void operator()(BasicJsonType& j, T&& val) const
- noexcept(noexcept(std::declval<to_json_fn>().call(j, std::forward<T>(val), priority_tag<1> {})))
- {
- return call(j, std::forward<T>(val), priority_tag<1> {});
- }
};
}
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index a90b52ae..16106c2f 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -1807,9 +1807,12 @@ void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
external_constructor<value_t::object>::construct(j, std::move(obj));
}
-template<typename BasicJsonType, typename T, std::size_t N,
- enable_if_t<not std::is_constructible<typename BasicJsonType::string_t, T (&)[N]>::value, int> = 0>
-void to_json(BasicJsonType& j, T (&arr)[N])
+template <
+ typename BasicJsonType, typename T, std::size_t N,
+ enable_if_t<not std::is_constructible<typename BasicJsonType::string_t,
+ const T (&)[N]>::value,
+ int> = 0 >
+void to_json(BasicJsonType& j, const T (&arr)[N])
{
external_constructor<value_t::array>::construct(j, arr);
}
@@ -1842,35 +1845,12 @@ void to_json(BasicJsonType& j, const std::tuple<Args...>& t)
struct to_json_fn
{
- private:
template<typename BasicJsonType, typename T>
- auto call(BasicJsonType& j, T&& val, priority_tag<1> /*unused*/) const noexcept(noexcept(to_json(j, std::forward<T>(val))))
+ auto operator()(BasicJsonType& j, T&& val) const noexcept(noexcept(to_json(j, std::forward<T>(val))))
-> decltype(to_json(j, std::forward<T>(val)), void())
{
return to_json(j, std::forward<T>(val));
}
-
- template<typename BasicJsonType, typename T>
- void call(BasicJsonType& /*unused*/, T&& /*unused*/, priority_tag<0> /*unused*/) const noexcept
- {
- static_assert(sizeof(BasicJsonType) == 0,
- "could not find to_json() method in T's namespace");
-
-#ifdef _MSC_VER
- // MSVC does not show a stacktrace for the above assert
- using decayed = uncvref_t<T>;
- static_assert(sizeof(typename decayed::force_msvc_stacktrace) == 0,
- "forcing MSVC stacktrace to show which T we're talking about.");
-#endif
- }
-
- public:
- template<typename BasicJsonType, typename T>
- void operator()(BasicJsonType& j, T&& val) const
- noexcept(noexcept(std::declval<to_json_fn>().call(j, std::forward<T>(val), priority_tag<1> {})))
- {
- return call(j, std::forward<T>(val), priority_tag<1> {});
- }
};
}
@@ -11147,9 +11127,11 @@ struct adl_serializer
@param[in,out] j JSON value to write to
@param[in] val value to read from
*/
- template<typename BasicJsonType, typename ValueType>
- static void to_json(BasicJsonType& j, ValueType&& val) noexcept(
+ template <typename BasicJsonType, typename ValueType>
+ static auto to_json(BasicJsonType& j, ValueType&& val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<ValueType>(val))))
+ -> decltype(::nlohmann::to_json(j, std::forward<ValueType>(val)),
+ void())
{
::nlohmann::to_json(j, std::forward<ValueType>(val));
}