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Merge pull request #545 from theodelrieu/feature/enum_class_support

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add enum class default conversions
This commit is contained in:
Niels Lohmann 2017-04-03 22:13:59 +02:00 committed by GitHub
commit 4f6b63e492
3 changed files with 29 additions and 30 deletions
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25
src/json.hpp
View file

@ -454,12 +454,6 @@ using enable_if_t = typename std::enable_if<B, T>::type;
template<typename T> template<typename T>
using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type; using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
// taken from http://stackoverflow.com/a/26936864/266378
template<typename T>
using is_unscoped_enum =
std::integral_constant<bool, std::is_convertible<T, int>::value and
std::is_enum<T>::value>;
/* /*
Implementation of two C++17 constructs: conjunction, negation. This is needed Implementation of two C++17 constructs: conjunction, negation. This is needed
to avoid evaluating all the traits in a condition to avoid evaluating all the traits in a condition
@ -818,11 +812,12 @@ void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val)); external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));
} }
template<typename BasicJsonType, typename UnscopedEnumType, template<typename BasicJsonType, typename EnumType,
enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0> enable_if_t<std::is_enum<EnumType>::value, int> = 0>
void to_json(BasicJsonType& j, UnscopedEnumType e) noexcept void to_json(BasicJsonType& j, EnumType e) noexcept
{ {
external_constructor<value_t::number_integer>::construct(j, e); using underlying_type = typename std::underlying_type<EnumType>::type;
external_constructor<value_t::number_integer>::construct(j, static_cast<underlying_type>(e));
} }
template<typename BasicJsonType> template<typename BasicJsonType>
@ -937,13 +932,13 @@ void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t&
get_arithmetic_value(j, val); get_arithmetic_value(j, val);
} }
template<typename BasicJsonType, typename UnscopedEnumType, template<typename BasicJsonType, typename EnumType,
enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0> enable_if_t<std::is_enum<EnumType>::value, int> = 0>
void from_json(const BasicJsonType& j, UnscopedEnumType& e) void from_json(const BasicJsonType& j, EnumType& e)
{ {
typename std::underlying_type<UnscopedEnumType>::type val; typename std::underlying_type<EnumType>::type val;
get_arithmetic_value(j, val); get_arithmetic_value(j, val);
e = static_cast<UnscopedEnumType>(val); e = static_cast<EnumType>(val);
} }
template<typename BasicJsonType> template<typename BasicJsonType>

25
src/json.hpp.re2c
View file

@ -454,12 +454,6 @@ using enable_if_t = typename std::enable_if<B, T>::type;
template<typename T> template<typename T>
using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type; using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
// taken from http://stackoverflow.com/a/26936864/266378
template<typename T>
using is_unscoped_enum =
std::integral_constant<bool, std::is_convertible<T, int>::value and
std::is_enum<T>::value>;
/* /*
Implementation of two C++17 constructs: conjunction, negation. This is needed Implementation of two C++17 constructs: conjunction, negation. This is needed
to avoid evaluating all the traits in a condition to avoid evaluating all the traits in a condition
@ -818,11 +812,12 @@ void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val)); external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));
} }
template<typename BasicJsonType, typename UnscopedEnumType, template<typename BasicJsonType, typename EnumType,
enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0> enable_if_t<std::is_enum<EnumType>::value, int> = 0>
void to_json(BasicJsonType& j, UnscopedEnumType e) noexcept void to_json(BasicJsonType& j, EnumType e) noexcept
{ {
external_constructor<value_t::number_integer>::construct(j, e); using underlying_type = typename std::underlying_type<EnumType>::type;
external_constructor<value_t::number_integer>::construct(j, static_cast<underlying_type>(e));
} }
template<typename BasicJsonType> template<typename BasicJsonType>
@ -937,13 +932,13 @@ void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t&
get_arithmetic_value(j, val); get_arithmetic_value(j, val);
} }
template<typename BasicJsonType, typename UnscopedEnumType, template<typename BasicJsonType, typename EnumType,
enable_if_t<is_unscoped_enum<UnscopedEnumType>::value, int> = 0> enable_if_t<std::is_enum<EnumType>::value, int> = 0>
void from_json(const BasicJsonType& j, UnscopedEnumType& e) void from_json(const BasicJsonType& j, EnumType& e)
{ {
typename std::underlying_type<UnscopedEnumType>::type val; typename std::underlying_type<EnumType>::type val;
get_arithmetic_value(j, val); get_arithmetic_value(j, val);
e = static_cast<UnscopedEnumType>(val); e = static_cast<EnumType>(val);
} }
template<typename BasicJsonType> template<typename BasicJsonType>

9
test/src/unit-conversions.cpp
View file

@ -917,6 +917,15 @@ TEST_CASE("value conversion")
} }
} }
SECTION("get an enum")
{
enum c_enum { value_1, value_2 };
enum class cpp_enum { value_1, value_2 };
CHECK(json(value_1).get<c_enum>() == value_1);
CHECK(json(cpp_enum::value_1).get<cpp_enum>() == cpp_enum::value_1);
}
SECTION("more involved conversions") SECTION("more involved conversions")
{ {
SECTION("object-like STL containers") SECTION("object-like STL containers")