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#ifndef optional_hh_INCLUDED
#define optional_hh_INCLUDED
namespace Kakoune
{
template<typename T>
struct Optional
{
public:
constexpr Optional() : m_valid(false) {}
Optional(const T& other) : m_valid(true) { new (&m_value) T(other); }
Optional(T&& other) : m_valid(true) { new (&m_value) T(std::move(other)); }
Optional(const Optional& other)
: m_valid(other.m_valid)
{
if (m_valid)
new (&m_value) T(other.m_value);
}
Optional(Optional&& other)
noexcept(noexcept(new ((void*)0) T(std::move(other.m_value))))
: m_valid(other.m_valid)
{
if (m_valid)
new (&m_value) T(std::move(other.m_value));
}
Optional& operator=(const Optional& other)
{
if (m_valid)
m_value.~T();
if ((m_valid = other.m_valid))
new (&m_value) T(other.m_value);
return *this;
}
Optional& operator=(Optional&& other)
{
if (m_valid)
m_value.~T();
if ((m_valid = other.m_valid))
new (&m_value) T(std::move(other.m_value));
return *this;
}
~Optional()
{
if (m_valid)
m_value.~T();
}
constexpr explicit operator bool() const noexcept { return m_valid; }
bool operator==(const Optional& other) const
{
if (m_valid == other.m_valid)
{
if (m_valid)
return m_value == other.m_value;
return true;
}
return false;
}
T& operator*()
{
kak_assert(m_valid);
return m_value;
}
const T& operator*() const { return *const_cast<Optional&>(*this); }
T* operator->()
{
kak_assert(m_valid);
return &m_value;
}
const T* operator->() const { return const_cast<Optional&>(*this).operator->(); }
private:
bool m_valid;
union { T m_value; };
};
}
#endif // optional_hh_INCLUDED
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