feat: Rebase feature/optional to develop

include/nlohmann/detail/conversions/from_json.hpp

@@ -13,13 +13,17 @@
 #include <forward_list> // forward_list
 #include <iterator> // inserter, front_inserter, end
 #include <map> // map
+#ifdef JSON_HAS_CPP_17
+    #include <optional> // optional
+#endif
 #include <string> // string
 #include <tuple> // tuple, make_tuple
 #include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
 #include <unordered_map> // unordered_map
 #include <utility> // pair, declval
 #include <valarray> // valarray
 
+
 #include <nlohmann/detail/exceptions.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/cpp_future.hpp>
@@ -43,6 +47,24 @@ inline void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
     n = nullptr;
 }
 
+#ifdef JSON_HAS_CPP_17
+#ifndef JSON_USE_IMPLICIT_CONVERSIONS
+template<typename BasicJsonType, typename T>
+void from_json(const BasicJsonType& j, std::optional<T>& opt)
+{
+    if (j.is_null())
+    {
+        opt = std::nullopt;
+    }
+    else
+    {
+        opt.emplace(j.template get<T>());
+    }
+}
+
+#endif // JSON_USE_IMPLICIT_CONVERSIONS
+#endif // JSON_HAS_CPP_17
+
 // overloads for basic_json template parameters
 template < typename BasicJsonType, typename ArithmeticType,
            enable_if_t < std::is_arithmetic<ArithmeticType>::value&&

include/nlohmann/detail/conversions/to_json.hpp

@@ -10,6 +10,9 @@
 
 #include <algorithm> // copy
 #include <iterator> // begin, end
+#ifdef JSON_HAS_CPP_17
+    #include <optional> // optional
+#endif
 #include <string> // string
 #include <tuple> // tuple, get
 #include <type_traits> // is_same, is_constructible, is_floating_point, is_enum, underlying_type
@@ -260,6 +263,22 @@ struct external_constructor<value_t::object>
 // to_json //
 /////////////
 
+#ifdef JSON_HAS_CPP_17
+template<typename BasicJsonType, typename T,
+         enable_if_t<std::is_constructible<BasicJsonType, T>::value, int> = 0>
+void to_json(BasicJsonType& j, const std::optional<T>& opt)
+{
+    if (opt.has_value())
+    {
+        j = *opt;
+    }
+    else
+    {
+        j = nullptr;
+    }
+}
+#endif
+
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_same<T, typename BasicJsonType::boolean_t>::value, int> = 0>
 inline void to_json(BasicJsonType& j, T b) noexcept

single_include/nlohmann/json.hpp

@@ -162,13 +162,17 @@
 #include <forward_list> // forward_list
 #include <iterator> // inserter, front_inserter, end
 #include <map> // map
+#ifdef JSON_HAS_CPP_17
+    #include <optional> // optional
+#endif
 #include <string> // string
 #include <tuple> // tuple, make_tuple
 #include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
 #include <unordered_map> // unordered_map
 #include <utility> // pair, declval
 #include <valarray> // valarray
 
+
 // #include <nlohmann/detail/exceptions.hpp>
 //     __ _____ _____ _____
 //  __|  |   __|     |   | |  JSON for Modern C++
@@ -4696,6 +4700,24 @@ inline void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
     n = nullptr;
 }
 
+#ifdef JSON_HAS_CPP_17
+#ifndef JSON_USE_IMPLICIT_CONVERSIONS
+template<typename BasicJsonType, typename T>
+void from_json(const BasicJsonType& j, std::optional<T>& opt)
+{
+    if (j.is_null())
+    {
+        opt = std::nullopt;
+    }
+    else
+    {
+        opt.emplace(j.template get<T>());
+    }
+}
+
+#endif // JSON_USE_IMPLICIT_CONVERSIONS
+#endif // JSON_HAS_CPP_17
+
 // overloads for basic_json template parameters
 template < typename BasicJsonType, typename ArithmeticType,
            enable_if_t < std::is_arithmetic<ArithmeticType>::value&&
@@ -5162,6 +5184,9 @@ NLOHMANN_JSON_NAMESPACE_END
 
 #include <algorithm> // copy
 #include <iterator> // begin, end
+#ifdef JSON_HAS_CPP_17
+    #include <optional> // optional
+#endif
 #include <string> // string
 #include <tuple> // tuple, get
 #include <type_traits> // is_same, is_constructible, is_floating_point, is_enum, underlying_type
@@ -5663,6 +5688,22 @@ struct external_constructor<value_t::object>
 // to_json //
 /////////////
 
+#ifdef JSON_HAS_CPP_17
+template<typename BasicJsonType, typename T,
+         enable_if_t<std::is_constructible<BasicJsonType, T>::value, int> = 0>
+void to_json(BasicJsonType& j, const std::optional<T>& opt)
+{
+    if (opt.has_value())
+    {
+        j = *opt;
+    }
+    else
+    {
+        j = nullptr;
+    }
+}
+#endif
+
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_same<T, typename BasicJsonType::boolean_t>::value, int> = 0>
 inline void to_json(BasicJsonType& j, T b) noexcept

tests/src/unit-conversions.cpp

@@ -28,10 +28,30 @@ using nlohmann::json;
 #include <unordered_set>
 #include <valarray>
 
+
 // NLOHMANN_JSON_SERIALIZE_ENUM uses a static std::pair
 DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
 DOCTEST_CLANG_SUPPRESS_WARNING("-Wexit-time-destructors")
 
+#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
+    #define JSON_HAS_CPP_17
+    #define JSON_HAS_CPP_14
+#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
+    #define JSON_HAS_CPP_14
+#endif
+
+#ifdef JSON_HAS_CPP_17
+    #if __has_include(<optional>)
+        #include <optional>
+    #elif __has_include(<experimental/optional>)
+        #include <experimental/optional>
+    #endif
+#endif
+
+#if defined(JSON_HAS_CPP_17)
+    #include <string_view>
+#endif
+
 TEST_CASE("value conversion")
 {
     SECTION("get an object (explicit)")
@@ -153,6 +173,7 @@ TEST_CASE("value conversion")
     }
 
 #if JSON_USE_IMPLICIT_CONVERSIONS
+
     SECTION("get an object (implicit)")
     {
         const json::object_t o_reference = {{"object", json::object()},
@@ -1569,4 +1590,73 @@ TEST_CASE("JSON to enum mapping")
     }
 }
 
+
+#ifdef JSON_HAS_CPP_17
+#ifndef JSON_USE_IMPLICIT_CONVERSIONS
+TEST_CASE("std::optional")
+{
+    SECTION("null")
+    {
+        json j_null;
+        std::optional<std::string> opt_null;
+
+        CHECK(json(opt_null) == j_null);
+        CHECK(j_null.get<std::optional<std::string>>() == std::nullopt);
+    }
+
+    SECTION("string")
+    {
+        json j_string = "string";
+        std::optional<std::string> opt_string = "string";
+
+        CHECK(json(opt_string) == j_string);
+        CHECK(std::optional<std::string>(j_string) == opt_string);
+    }
+
+    SECTION("bool")
+    {
+        json j_bool = true;
+        std::optional<bool> opt_bool = true;
+
+        CHECK(json(opt_bool) == j_bool);
+        CHECK(std::optional<bool>(j_bool) == opt_bool);
+    }
+
+    SECTION("number")
+    {
+        json j_number = 1;
+        std::optional<int> opt_int = 1;
+
+        CHECK(json(opt_int) == j_number);
+        CHECK(j_number.get<std::optional<int>>() == opt_int);
+    }
+
+    SECTION("array")
+    {
+        json j_array = {1, 2, nullptr};
+        std::vector<std::optional<int>> opt_array = {{1, 2, std::nullopt}};
+
+        CHECK(json(opt_array) == j_array);
+        CHECK(j_array.get<std::vector<std::optional<int>>>() == opt_array);
+    }
+
+    SECTION("object")
+    {
+        json j_object = {{"one", 1}, {"two", 2}, {"zero", nullptr}};
+        std::map<std::string, std::optional<int>> opt_object {{"one", 1}, {"two", 2}, {"zero", std::nullopt}};
+
+        CHECK(json(opt_object) == j_object);
+        CHECK(std::map<std::string, std::optional<int>>(j_object) == opt_object);
+    }
+}
+#endif
+#endif
+
+#ifdef JSON_HAS_CPP_17
+    #undef JSON_HAS_CPP_17
+#endif
+
+#ifdef JSON_HAS_CPP_14
+    #undef JSON_HAS_CPP_14
+#endif
 DOCTEST_CLANG_SUPPRESS_WARNING_POP

tests/src/unit-readme.cpp

@@ -171,7 +171,7 @@ TEST_CASE("README" * doctest::skip())
 
             // find an entry
             CHECK(o.find("foo") != o.end());
-            if (o.find("foo") != o.end())
+            if (o.find("foo") != o.end()) // NOLINT(readability-container-contains)
             {
                 // there is an entry with key "foo"
             }