Merge pull request #1228 from theodelrieu/remove_static_asserts

Remove static asserts

include/nlohmann/adl_serializer.hpp

@@ -20,8 +20,10 @@ struct adl_serializer
     @param[in,out] val  value to write to
     */
     template<typename BasicJsonType, typename ValueType>
-    static void from_json(BasicJsonType&& j, ValueType& val) noexcept(
-        noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val)))
+    static auto from_json(BasicJsonType&& j, ValueType& val) noexcept(
+        noexcept(::nlohmann::from_json(std::forward<BasicJsonType>(j), val))) -> decltype(
+            ::nlohmann::from_json(std::forward<BasicJsonType>(j), val), void()
+        )
     {
         ::nlohmann::from_json(std::forward<BasicJsonType>(j), val);
     }
@@ -35,9 +37,11 @@ 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));
     }

include/nlohmann/detail/conversions/from_json.hpp

@@ -127,16 +127,6 @@ void from_json(const BasicJsonType& j, EnumType& e)
     e = static_cast<EnumType>(val);
 }
 
-template<typename BasicJsonType>
-void from_json(const BasicJsonType& j, typename BasicJsonType::array_t& arr)
-{
-    if (JSON_UNLIKELY(not j.is_array()))
-    {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
-    }
-    arr = *j.template get_ptr<const typename BasicJsonType::array_t*>();
-}
-
 // forward_list doesn't have an insert method
 template<typename BasicJsonType, typename T, typename Allocator,
          enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
@@ -166,24 +156,28 @@ void from_json(const BasicJsonType& j, std::valarray<T>& l)
     std::copy(j.m_value.array->begin(), j.m_value.array->end(), std::begin(l));
 }
 
-template<typename BasicJsonType, typename CompatibleArrayType>
-void from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<0> /*unused*/)
+template<typename BasicJsonType>
+void from_json_array_impl(const BasicJsonType& j, typename BasicJsonType::array_t& arr, priority_tag<3> /*unused*/)
 {
-    using std::end;
+    arr = *j.template get_ptr<const typename BasicJsonType::array_t*>();
+}
 
-    std::transform(j.begin(), j.end(),
-                   std::inserter(arr, end(arr)), [](const BasicJsonType & i)
+template <typename BasicJsonType, typename T, std::size_t N>
+auto from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr,
+                          priority_tag<2> /*unused*/)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i = 0; i < N; ++i)
     {
-        // get<BasicJsonType>() returns *this, this won't call a from_json
-        // method when value_type is BasicJsonType
-        return i.template get<typename CompatibleArrayType::value_type>();
-    });
+        arr[i] = j.at(i).template get<T>();
+    }
 }
 
 template<typename BasicJsonType, typename CompatibleArrayType>
 auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<1> /*unused*/)
 -> decltype(
     arr.reserve(std::declval<typename CompatibleArrayType::size_type>()),
+    j.template get<typename CompatibleArrayType::value_type>(),
     void())
 {
     using std::end;
@@ -198,25 +192,34 @@ auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, prio
     });
 }
 
-template<typename BasicJsonType, typename T, std::size_t N>
-void from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr, priority_tag<2> /*unused*/)
+template <typename BasicJsonType, typename CompatibleArrayType>
+void from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr,
+                          priority_tag<0> /*unused*/)
 {
-    for (std::size_t i = 0; i < N; ++i)
+    using std::end;
+
+    std::transform(
+        j.begin(), j.end(), std::inserter(arr, end(arr)),
+        [](const BasicJsonType & i)
     {
-        arr[i] = j.at(i).template get<T>();
-    }
+        // get<BasicJsonType>() returns *this, this won't call a from_json
+        // method when value_type is BasicJsonType
+        return i.template get<typename CompatibleArrayType::value_type>();
+    });
 }
 
-template <
-    typename BasicJsonType, typename CompatibleArrayType,
-    enable_if_t <
-        is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
-        not std::is_same<typename BasicJsonType::array_t,
-                         CompatibleArrayType>::value and
-        std::is_constructible <
-            BasicJsonType, typename CompatibleArrayType::value_type >::value,
-        int > = 0 >
-void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
+template <typename BasicJsonType, typename CompatibleArrayType,
+          enable_if_t <
+              is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
+              not is_compatible_object_type<BasicJsonType, CompatibleArrayType>::value and
+              not is_compatible_string_type<BasicJsonType, CompatibleArrayType>::value and
+              not is_basic_json<CompatibleArrayType>::value,
+              int > = 0 >
+
+auto from_json(const BasicJsonType& j, CompatibleArrayType& arr)
+-> decltype(from_json_array_impl(j, arr, priority_tag<3> {}),
+            j.template get<typename CompatibleArrayType::value_type>(),
+            void())
 {
     if (JSON_UNLIKELY(not j.is_array()))
     {
@@ -224,7 +227,7 @@ void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
                                       std::string(j.type_name())));
     }
 
-    from_json_array_impl(j, arr, priority_tag<2> {});
+    from_json_array_impl(j, arr, priority_tag<3> {});
 }
 
 template<typename BasicJsonType, typename CompatibleObjectType,
@@ -347,35 +350,13 @@ void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Hash, KeyE
 
 struct from_json_fn
 {
-  private:
     template<typename BasicJsonType, typename T>
-    auto call(const BasicJsonType& j, T& val, priority_tag<1> /*unused*/) const
+    auto operator()(const BasicJsonType& j, T& val) const
     noexcept(noexcept(from_json(j, val)))
     -> decltype(from_json(j, val), void())
     {
         return from_json(j, val);
     }
-
-    template<typename BasicJsonType, typename T>
-    void call(const BasicJsonType& /*unused*/, T& /*unused*/, priority_tag<0> /*unused*/) const noexcept
-    {
-        static_assert(sizeof(BasicJsonType) == 0,
-                      "could not find from_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()(const BasicJsonType& j, T& val) const
-    noexcept(noexcept(std::declval<from_json_fn>().call(j, val, priority_tag<1> {})))
-    {
-        return call(j, val, priority_tag<1> {});
-    }
 };
 }
 

include/nlohmann/detail/conversions/to_json.hpp

@@ -248,10 +248,14 @@ void to_json(BasicJsonType& j, const std::vector<bool>& e)
     external_constructor<value_t::array>::construct(j, e);
 }
 
-template<typename BasicJsonType, typename CompatibleArrayType,
-         enable_if_t<is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value or
-                     std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value,
-                     int> = 0>
+template <typename BasicJsonType, typename CompatibleArrayType,
+          enable_if_t<is_compatible_array_type<BasicJsonType,
+                      CompatibleArrayType>::value and
+                      not is_compatible_object_type<
+                          BasicJsonType, CompatibleArrayType>::value and
+                      not is_compatible_string_type<BasicJsonType, CompatibleArrayType>::value and
+                      not is_basic_json<CompatibleArrayType>::value,
+                      int> = 0>
 void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
 {
     external_constructor<value_t::array>::construct(j, arr);
@@ -271,7 +275,7 @@ void to_json(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
 }
 
 template<typename BasicJsonType, typename CompatibleObjectType,
-         enable_if_t<is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value, int> = 0>
+         enable_if_t<is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value and not is_basic_json<CompatibleObjectType>::value, int> = 0>
 void to_json(BasicJsonType& j, const CompatibleObjectType& obj)
 {
     external_constructor<value_t::object>::construct(j, obj);
@@ -283,9 +287,12 @@ 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);
 }
@@ -318,35 +325,12 @@ 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> {});
-    }
 };
 }
 

include/nlohmann/detail/macro_scope.hpp

@@ -102,22 +102,3 @@
     basic_json<ObjectType, ArrayType, StringType, BooleanType,             \
     NumberIntegerType, NumberUnsignedType, NumberFloatType,                \
     AllocatorType, JSONSerializer>
-
-/*!
-@brief Helper to determine whether there's a key_type for T.
-
-This helper is used to tell associative containers apart from other containers
-such as sequence containers. For instance, `std::map` passes the test as it
-contains a `mapped_type`, whereas `std::vector` fails the test.
-
-@sa http://stackoverflow.com/a/7728728/266378
-@since version 1.0.0, overworked in version 2.0.6
-*/
-#define NLOHMANN_JSON_HAS_HELPER(type)                                        \
-    template<typename T> struct has_##type {                                  \
-        template<typename U, typename = typename U::type>                     \
-        static int detect(U &&);                                              \
-        static void detect(...);                                              \
-        static constexpr bool value =                                         \
-                std::is_integral<decltype(detect(std::declval<T>()))>::value; \
-    }

include/nlohmann/detail/macro_unscope.hpp

@@ -20,4 +20,3 @@
 #undef JSON_HAS_CPP_17
 #undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
 #undef NLOHMANN_BASIC_JSON_TPL
-#undef NLOHMANN_JSON_HAS_HELPER

include/nlohmann/detail/meta/cpp_future.hpp

@@ -46,26 +46,6 @@ template<> struct make_index_sequence<1> : index_sequence<0> {};
 template<typename... Ts>
 using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
 
-/*
-Implementation of two C++17 constructs: conjunction, negation. This is needed
-to avoid evaluating all the traits in a condition
-
-For example: not std::is_same<void, T>::value and has_value_type<T>::value
-will not compile when T = void (on MSVC at least). Whereas
-conjunction<negation<std::is_same<void, T>>, has_value_type<T>>::value will
-stop evaluating if negation<...>::value == false
-
-Please note that those constructs must be used with caution, since symbols can
-become very long quickly (which can slow down compilation and cause MSVC
-internal compiler errors). Only use it when you have to (see example ahead).
-*/
-template<class...> struct conjunction : std::true_type {};
-template<class B1> struct conjunction<B1> : B1 {};
-template<class B1, class... Bn>
-struct conjunction<B1, Bn...> : std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
-
-template<class B> struct negation : std::integral_constant<bool, not B::value> {};
-
 // dispatch utility (taken from ranges-v3)
 template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
 template<> struct priority_tag<0> {};

include/nlohmann/detail/meta/void_t.hpp

@@ -4,7 +4,10 @@ namespace nlohmann
 {
 namespace detail
 {
-template <typename...>
-using void_t = void;
+template <typename ...Ts> struct make_void
+{
+    using type = void;
+};
+template <typename ...Ts> using void_t = typename make_void<Ts...>::type;
 }
 }

include/nlohmann/json.hpp

@@ -1243,7 +1243,7 @@ class basic_json
     template <typename CompatibleType,
               typename U = detail::uncvref_t<CompatibleType>,
               detail::enable_if_t<
-                  detail::is_compatible_type<basic_json_t, U>::value, int> = 0>
+                  not detail::is_basic_json<U>::value and detail::is_compatible_type<basic_json_t, U>::value, int> = 0>
     basic_json(CompatibleType && val) noexcept(noexcept(
                 JSONSerializer<U>::to_json(std::declval<basic_json_t&>(),
                                            std::forward<CompatibleType>(val))))

test/src/unit-inspection.cpp

@@ -317,8 +317,8 @@ TEST_CASE("object inspection")
     SECTION("round trips")
     {
         for (const auto& s :
-                {"3.141592653589793", "1000000000000000010E5"
-                })
+    {"3.141592653589793", "1000000000000000010E5"
+    })
         {
             json j1 = json::parse(s);
             std::string s1 = j1.dump();