replace constructor by from/to_json: number_unsigned_t

This commit forces a design change in custom JSONSerializer, which might
be temporary

src/json.hpp

@@ -248,6 +248,18 @@ struct external_constructor<value_t::number_float>
   }
 };
 
+template <>
+struct external_constructor<value_t::number_unsigned>
+{
+  template <typename Json>
+  static void construct(Json &j, typename Json::number_unsigned_t val) noexcept
+  {
+    j.m_type = value_t::number_unsigned;
+    j.m_value = val;
+    j.assert_invariant();
+  }
+};
+
 // very useful construct against boilerplate (more boilerplate needed than in
 // C++17: http://en.cppreference.com/w/cpp/types/void_t)
 template <typename...> struct make_void
@@ -411,9 +423,7 @@ struct is_compatible_basic_json_type
         std::is_same<T, BasicJson>::value or
         is_compatible_array_type<BasicJson, T>::value or
         is_compatible_object_type<typename BasicJson::object_t, T>::value or
-        is_compatible_integer_type<typename BasicJson::number_integer_t, T>::value or
+        is_compatible_integer_type<typename BasicJson::number_integer_t, T>::value;
-        is_compatible_integer_type<typename BasicJson::number_unsigned_t,
-        T>::value;
 };
 
 template <typename T, typename BasicJson, typename PrimitiveIterator>
@@ -526,6 +536,17 @@ void to_json(Json &j, CompatibleNumberFloatType val) noexcept
   external_constructor<value_t::number_float>::construct(j, val);
 }
 
+
+template <
+    typename Json, typename CompatibleNumberUnsignedType,
+   enable_if_t<is_compatible_integer_type<typename Json::number_unsigned_t,
+                                         CompatibleNumberUnsignedType>::value,
+                int> = 0>
+void to_json(Json &j, CompatibleNumberUnsignedType val) noexcept
+{
+  external_constructor<value_t::number_unsigned>::construct(j, val);
+}
+
 template <typename Json>
 void from_json(Json const& j, typename Json::boolean_t& b)
 {
@@ -548,6 +569,12 @@ void from_json(Json const& j, typename Json::number_float_t& val)
   get_arithmetic_value(j, val);
 }
 
+template <typename Json>
+void from_json(Json const& j, typename Json::number_unsigned_t& val)
+{
+  get_arithmetic_value(j, val);
+}
+
 // overload for arithmetic types, not chosen for basic_json template arguments (BooleanType, etc..)
 //
 // note: Is it really necessary to provide explicit overloads for boolean_t etc..
@@ -1897,64 +1924,6 @@ class basic_json
         assert_invariant();
     }
 
-    /*!
-    @brief create an unsigned integer number (explicit)
-
-    Create an unsigned integer number JSON value with a given content.
-
-    @tparam T  helper type to compare number_unsigned_t and unsigned int (not
-    visible in) the interface.
-
-    @param[in] val  an integer to create a JSON number from
-
-    @complexity Constant.
-
-    @sa @ref basic_json(const CompatibleNumberUnsignedType) -- create a number
-    value (unsigned integer) from a compatible number type
-
-    @since version 2.0.0
-    */
-    template<typename T, typename std::enable_if<
-                 not (std::is_same<T, int>::value) and
-                 std::is_same<T, number_unsigned_t>::value, int>::type = 0>
-    basic_json(const number_unsigned_t val) noexcept
-        : m_type(value_t::number_unsigned), m_value(val)
-    {
-        assert_invariant();
-    }
-
-    /*!
-    @brief create an unsigned number (implicit)
-
-    Create an unsigned number JSON value with a given content. This
-    constructor allows any type @a CompatibleNumberUnsignedType that can be
-    used to construct values of type @ref number_unsigned_t.
-
-    @tparam CompatibleNumberUnsignedType An integer type which is compatible
-    to @ref number_unsigned_t. Examples may include the types `unsigned int`,
-    `uint32_t`, or `unsigned short`.
-
-    @param[in] val  an unsigned integer to create a JSON number from
-
-    @complexity Constant.
-
-    @sa @ref basic_json(const number_unsigned_t) -- create a number value
-    (unsigned)
-
-    @since version 2.0.0
-    */
-    template <
-        typename CompatibleNumberUnsignedType,
-        enable_if_t<detail::is_compatible_integer_type<
-                        number_unsigned_t, CompatibleNumberUnsignedType>::value,
-                    int> = 0 >
-    basic_json(const CompatibleNumberUnsignedType val) noexcept
-        : m_type(value_t::number_unsigned),
-          m_value(static_cast<number_unsigned_t>(val))
-    {
-        assert_invariant();
-    }
-
     /*!
     @brief create a container (array or object) from an initializer list
 

src/json.hpp.re2c

@@ -248,6 +248,18 @@ struct external_constructor<value_t::number_float>
   }
 };
 
+template <>
+struct external_constructor<value_t::number_unsigned>
+{
+  template <typename Json>
+  static void construct(Json &j, typename Json::number_unsigned_t val) noexcept
+  {
+    j.m_type = value_t::number_unsigned;
+    j.m_value = val;
+    j.assert_invariant();
+  }
+};
+
 // very useful construct against boilerplate (more boilerplate needed than in
 // C++17: http://en.cppreference.com/w/cpp/types/void_t)
 template <typename...> struct make_void
@@ -411,9 +423,7 @@ struct is_compatible_basic_json_type
         std::is_same<T, BasicJson>::value or
         is_compatible_array_type<BasicJson, T>::value or
         is_compatible_object_type<typename BasicJson::object_t, T>::value or
-        is_compatible_integer_type<typename BasicJson::number_integer_t, T>::value or
+        is_compatible_integer_type<typename BasicJson::number_integer_t, T>::value;
-        is_compatible_integer_type<typename BasicJson::number_unsigned_t,
-        T>::value;
 };
 
 template <typename T, typename BasicJson, typename PrimitiveIterator>
@@ -526,6 +536,17 @@ void to_json(Json &j, CompatibleNumberFloatType val) noexcept
   external_constructor<value_t::number_float>::construct(j, val);
 }
 
+
+template <
+    typename Json, typename CompatibleNumberUnsignedType,
+   enable_if_t<is_compatible_integer_type<typename Json::number_unsigned_t,
+                                         CompatibleNumberUnsignedType>::value,
+                int> = 0>
+void to_json(Json &j, CompatibleNumberUnsignedType val) noexcept
+{
+  external_constructor<value_t::number_unsigned>::construct(j, val);
+}
+
 template <typename Json>
 void from_json(Json const& j, typename Json::boolean_t& b)
 {
@@ -548,6 +569,12 @@ void from_json(Json const& j, typename Json::number_float_t& val)
   get_arithmetic_value(j, val);
 }
 
+template <typename Json>
+void from_json(Json const& j, typename Json::number_unsigned_t& val)
+{
+  get_arithmetic_value(j, val);
+}
+
 // overload for arithmetic types, not chosen for basic_json template arguments (BooleanType, etc..)
 //
 // note: Is it really necessary to provide explicit overloads for boolean_t etc..
@@ -1898,64 +1925,6 @@ class basic_json
         assert_invariant();
     }
 
-    /*!
-    @brief create an unsigned integer number (explicit)
-
-    Create an unsigned integer number JSON value with a given content.
-
-    @tparam T  helper type to compare number_unsigned_t and unsigned int (not
-    visible in) the interface.
-
-    @param[in] val  an integer to create a JSON number from
-
-    @complexity Constant.
-
-    @sa @ref basic_json(const CompatibleNumberUnsignedType) -- create a number
-    value (unsigned integer) from a compatible number type
-
-    @since version 2.0.0
-    */
-    template<typename T, typename std::enable_if<
-                 not (std::is_same<T, int>::value) and
-                 std::is_same<T, number_unsigned_t>::value, int>::type = 0>
-    basic_json(const number_unsigned_t val) noexcept
-        : m_type(value_t::number_unsigned), m_value(val)
-    {
-        assert_invariant();
-    }
-
-    /*!
-    @brief create an unsigned number (implicit)
-
-    Create an unsigned number JSON value with a given content. This
-    constructor allows any type @a CompatibleNumberUnsignedType that can be
-    used to construct values of type @ref number_unsigned_t.
-
-    @tparam CompatibleNumberUnsignedType An integer type which is compatible
-    to @ref number_unsigned_t. Examples may include the types `unsigned int`,
-    `uint32_t`, or `unsigned short`.
-
-    @param[in] val  an unsigned integer to create a JSON number from
-
-    @complexity Constant.
-
-    @sa @ref basic_json(const number_unsigned_t) -- create a number value
-    (unsigned)
-
-    @since version 2.0.0
-    */
-    template <
-        typename CompatibleNumberUnsignedType,
-        enable_if_t<detail::is_compatible_integer_type<
-                        number_unsigned_t, CompatibleNumberUnsignedType>::value,
-                    int> = 0 >
-    basic_json(const CompatibleNumberUnsignedType val) noexcept
-        : m_type(value_t::number_unsigned),
-          m_value(static_cast<number_unsigned_t>(val))
-    {
-        assert_invariant();
-    }
-
     /*!
     @brief create a container (array or object) from an initializer list
 

test/src/unit-udt.cpp

@@ -483,11 +483,18 @@ TEST_CASE("Non-copyable types", "[udt]")
 template <typename T, typename = typename std::enable_if<std::is_pod<T>::value>::type>
 struct pod_serializer
 {
-    // I could forward-declare this struct, and add a basic_json alias
     template <typename Json>
     static void from_json(Json const& j , T& t)
     {
-        auto value = j.template get<std::uint64_t>();
+      std::uint64_t value;
+      // Why cannot we simply use: j.get<std::uint64_t>() ?
+      // Well, with the current experiment, the get method looks for a from_json function, which we are currently defining!
+      // This would end up in a stack overflow. Calling nlohmann::from_json is a workaround.
+      // I shall find a good way to avoid this once all constructors are converted to free methods
+      //
+      // In short, constructing a json by constructor calls to_json
+      // calling get calls from_json, for now, we cannot do this in custom serializers
+      nlohmann::from_json(j, value);
       auto bytes = static_cast<char *>(static_cast<void *>(&value));
       std::memcpy(&t, bytes, sizeof(value));
     }
@@ -501,8 +508,8 @@ struct pod_serializer
         {
             value |= bytes[i] << 8 * i;
         }
-
+        // same thing here
-        j = value;
+        nlohmann::to_json(j, value);
     }
 };