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GAPI: utils - variant::get_if

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adding one more missing function to local version of std::variant
This commit is contained in:
Anton Potapov 2020-04-13 11:17:08 +03:00 committed by Anton Potapov
parent f351653589
commit dd2c7c5140
2 changed files with 49 additions and 9 deletions
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42
modules/gapi/include/opencv2/gapi/util/variant.hpp
View File

@ -150,6 +150,9 @@ namespace util
protected: protected:
template<typename T, typename... Us> friend T& get(variant<Us...> &v); template<typename T, typename... Us> friend T& get(variant<Us...> &v);
template<typename T, typename... Us> friend const T& get(const variant<Us...> &v); template<typename T, typename... Us> friend const T& get(const variant<Us...> &v);
template<typename T, typename... Us> friend T* get_if(variant<Us...> *v) noexcept;
template<typename T, typename... Us> friend const T* get_if(const variant<Us...> *v) noexcept;
template<typename... Us> friend bool operator==(const variant<Us...> &lhs, template<typename... Us> friend bool operator==(const variant<Us...> &lhs,
const variant<Us...> &rhs); const variant<Us...> &rhs);
Memory memory; Memory memory;
@ -201,6 +204,11 @@ namespace util
}; };
// FIMXE: visit // FIMXE: visit
template<typename T, typename... Types>
T* get_if(util::variant<Types...>* v) noexcept;
template<typename T, typename... Types>
const T* get_if(const util::variant<Types...>* v) noexcept;
template<typename T, typename... Types> template<typename T, typename... Types>
T& get(util::variant<Types...> &v); T& get(util::variant<Types...> &v);
@ -335,14 +343,34 @@ namespace util
} }
template<typename T, typename... Types> template<typename T, typename... Types>
T& get(util::variant<Types...> &v) T* get_if(util::variant<Types...>* v) noexcept
{ {
const constexpr std::size_t t_index = const constexpr std::size_t t_index =
util::type_list_index<T, Types...>::value; util::type_list_index<T, Types...>::value;
if (v.index() == t_index) if (v && v->index() == t_index)
return *(T*)(&v.memory); // workaround for ICC 2019 return (T*)(&v->memory); // workaround for ICC 2019
// original code: return reinterpret_cast<T&>(v.memory); // original code: return reinterpret_cast<T&>(v.memory);
return nullptr;
}
template<typename T, typename... Types>
const T* get_if(const util::variant<Types...>* v) noexcept
{
const constexpr std::size_t t_index =
util::type_list_index<T, Types...>::value;
if (v && v->index() == t_index)
return (const T*)(&v->memory); // workaround for ICC 2019
// original code: return reinterpret_cast<const T&>(v.memory);
return nullptr;
}
template<typename T, typename... Types>
T& get(util::variant<Types...> &v)
{
if (auto* p = get_if<T>(&v))
return *p;
else else
throw_error(bad_variant_access()); throw_error(bad_variant_access());
} }
@ -350,12 +378,8 @@ namespace util
template<typename T, typename... Types> template<typename T, typename... Types>
const T& get(const util::variant<Types...> &v) const T& get(const util::variant<Types...> &v)
{ {
const constexpr std::size_t t_index = if (auto* p = get_if<T>(&v))
util::type_list_index<T, Types...>::value; return *p;
if (v.index() == t_index)
return *(const T*)(&v.memory); // workaround for ICC 2019
// original code: return reinterpret_cast<const T&>(v.memory);
else else
throw_error(bad_variant_access()); throw_error(bad_variant_access());
} }

16
modules/gapi/test/util/variant_tests.cpp
View File

@ -289,6 +289,22 @@ TEST(Variant, Swap_DiffIndex)
EXPECT_EQ(3.14f, util::get<float>(tv1)); EXPECT_EQ(3.14f, util::get<float>(tv1));
} }
TEST(Variant, GetIf)
{
const TestVar cv(42);
// Test const& get_if()
EXPECT_EQ(nullptr, util::get_if<std::string>(&cv));
ASSERT_NE(nullptr, util::get_if<int>(&cv));
EXPECT_EQ(42, *util::get_if<int>(&cv));
// Test &get_if
TestVar cv2(std::string("42"));
EXPECT_EQ(nullptr, util::get_if<int>(&cv2));
ASSERT_NE(nullptr, util::get_if<std::string>(&cv2));
EXPECT_EQ("42", *util::get_if<std::string>(&cv2));
}
TEST(Variant, Get) TEST(Variant, Get)
{ {
const TestVar cv(42); const TestVar cv(42);