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AK: Make Optional<T> explicitly constructible from Optional<U>

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As long as T is constructible from U. This allows us to avoid patterns
like `abc.has_value() ? Optional<U>(abc.value()) : Optional<U>()`.
This commit is contained in:
Idan Horowitz
2022-01-23 13:03:29 +02:00
parent fb06d494f0
commit a3a4d0aea2
1 changed files with 21 additions and 4 deletions
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25
AK/Optional.h
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@@ -24,6 +24,9 @@ namespace AK {
template<typename T> template<typename T>
class [[nodiscard]] Optional { class [[nodiscard]] Optional {
template<typename U>
friend class Optional;
public: public:
using ValueType = T; using ValueType = T;
@@ -50,17 +53,31 @@ public:
#endif #endif
: m_has_value(other.m_has_value) : m_has_value(other.m_has_value)
{ {
if (other.has_value()) { if (other.has_value())
new (&m_storage) T(other.value()); new (&m_storage) T(other.value());
}
} }
ALWAYS_INLINE Optional(Optional&& other) ALWAYS_INLINE Optional(Optional&& other)
: m_has_value(other.m_has_value) : m_has_value(other.m_has_value)
{ {
if (other.has_value()) { if (other.has_value())
new (&m_storage) T(other.release_value());
}
template<typename U>
requires(IsConstructible<T, U const&> && !IsSpecializationOf<T, Optional> && !IsSpecializationOf<U, Optional>) ALWAYS_INLINE explicit Optional(Optional<U> const& other)
: m_has_value(other.m_has_value)
{
if (other.has_value())
new (&m_storage) T(other.value());
}
template<typename U>
requires(IsConstructible<T, U&&> && !IsSpecializationOf<T, Optional> && !IsSpecializationOf<U, Optional>) ALWAYS_INLINE explicit Optional(Optional<U>&& other)
: m_has_value(other.m_has_value)
{
if (other.has_value())
new (&m_storage) T(other.release_value()); new (&m_storage) T(other.release_value());
}
} }
template<typename U = T> template<typename U = T>