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Use a universal reference to implement dereferenceMaybe()

This commit is contained in:
Martchus 2020-02-18 19:20:24 +01:00
parent 0733f0705d
commit c7c5352325
2 changed files with 5 additions and 16 deletions
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16
misc/traits.h
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@ -159,25 +159,13 @@ CPP_UTILITIES_TRAITS_DEFINE_TYPE_CHECK(IsIteratable,
void(*begin(std::declval<T &>()))); void(*begin(std::declval<T &>())));
/// \brief Dereferences the specified \a value if possible; otherwise just returns \a value itself. /// \brief Dereferences the specified \a value if possible; otherwise just returns \a value itself.
template <typename T, EnableIf<IsDereferencable<T>> * = nullptr> constexpr auto &dereferenceMaybe(T &value) template <typename T, EnableIf<IsDereferencable<T>> * = nullptr> constexpr auto &dereferenceMaybe(T &&value)
{ {
return *value; return *value;
} }
/// \brief Dereferences the specified \a value if possible; otherwise just returns \a value itself. /// \brief Dereferences the specified \a value if possible; otherwise just returns \a value itself.
template <typename T, DisableIf<IsDereferencable<T>> * = nullptr> constexpr auto &dereferenceMaybe(T &value) template <typename T, DisableIf<IsDereferencable<T>> * = nullptr> constexpr auto &dereferenceMaybe(T &&value)
{
return value;
}
/// \brief Dereferences the specified \a value if possible; otherwise just returns \a value itself.
template <typename T, EnableIf<IsDereferencable<T>> * = nullptr> constexpr const auto &dereferenceMaybe(const T &value)
{
return *value;
}
/// \brief Dereferences the specified \a value if possible; otherwise just returns \a value itself.
template <typename T, DisableIf<IsDereferencable<T>> * = nullptr> constexpr const auto &dereferenceMaybe(const T &value)
{ {
return value; return value;
} }

5
tests/traitstests.cpp
View File

@ -133,8 +133,9 @@ CPPUNIT_TEST_SUITE_REGISTRATION(TraitsTest);
*/ */
void TraitsTest::testDereferenceMaybe() void TraitsTest::testDereferenceMaybe()
{ {
const auto someString = "foo"s; auto someString = "foo"s;
const auto someSmartPointer = make_unique<string>("foo"); auto someSmartPointer = make_unique<string>("foo");
CPPUNIT_ASSERT_EQUAL("foo"s, dereferenceMaybe(someString)); CPPUNIT_ASSERT_EQUAL("foo"s, dereferenceMaybe(someString));
CPPUNIT_ASSERT_EQUAL("foo"s, dereferenceMaybe(someSmartPointer)); CPPUNIT_ASSERT_EQUAL("foo"s, dereferenceMaybe(someSmartPointer));
CPPUNIT_ASSERT_EQUAL("foo"s, dereferenceMaybe(make_unique<string>("foo")));
} }