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feat: Rebase feature/optional to develop (#4036)
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* 🚧 conversions for std::optional

* 🏁 fix <optional> inclusion

* 💚 overwork tests

* Use JSON_HAS_CPP_17 only after it has been defined

* ✅ update tests

* 🏁 include right <optional> header

* ♻️ do not include experimental headers

* Add missing #endif after rebase

* Fix failing test

* Only define conversion to std::optional when JSON_USE_IMPLICIT_CONVERSION is disabled.

* missing endif

* Remove Wfloat-equal suppress

* amalgamate

* Move include of optional out of macro_scope; probably does not make sense to be there

* Make clang-tidy happy

* Suppress lint instead of changing to 'contains'

---------

Co-authored-by: Niels Lohmann <[email protected]>
Co-authored-by: Markus Palonen <[email protected]>
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@fsandhei @nlohmann @remedi
3 people authored Nov 16, 2024
1 parent fd20975 commit 0604140
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22 changes: 22 additions & 0 deletions include/nlohmann/detail/conversions/from_json.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand All @@ -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&&
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19 changes: 19 additions & 0 deletions include/nlohmann/detail/conversions/to_json.hpp
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Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down
41 changes: 41 additions & 0 deletions single_include/nlohmann/json.hpp
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Expand Up @@ -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++
Expand Down Expand Up @@ -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&&
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down
90 changes: 90 additions & 0 deletions tests/src/unit-conversions.cpp
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Expand Up @@ -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)")
Expand Down Expand Up @@ -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()},
Expand Down Expand Up @@ -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

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