banan-os/BAN/include/BAN/Function.h

148 lines
3.1 KiB
C++

#pragma once
#include <BAN/Errors.h>
#include <BAN/Move.h>
#include <BAN/New.h>
namespace BAN
{
template<typename>
class Function;
template<typename Ret, typename... Args>
class Function<Ret(Args...)>
{
public:
Function() = default;
Function(Ret(*function)(Args...))
{
static_assert(sizeof(CallablePointer) <= m_size);
new (m_storage) CallablePointer(function);
}
template<typename Own>
Function(Ret(Own::*function)(Args...), Own* owner)
{
static_assert(sizeof(CallableMember<Own>) <= m_size);
new (m_storage) CallableMember<Own>(function, owner);
}
template<typename Own>
Function(Ret(Own::*function)(Args...) const, const Own* owner)
{
static_assert(sizeof(CallableMemberConst<Own>) <= m_size);
new (m_storage) CallableMemberConst<Own>(function, owner);
}
template<typename Lambda>
Function(Lambda lambda)
{
static_assert(sizeof(CallableLambda<Lambda>) <= m_size);
new (m_storage) CallableLambda<Lambda>(lambda);
}
~Function()
{
clear();
}
Ret operator()(Args... args) const
{
ASSERT(*this);
return reinterpret_cast<const CallableBase*>(m_storage)->call(forward<Args>(args)...);
}
operator bool() const
{
for (size_t i = 0; i < m_size; i++)
if (m_storage[i])
return true;
return false;
}
void clear()
{
if (*this)
reinterpret_cast<CallableBase*>(m_storage)->~CallableBase();
memset(m_storage, 0, m_size);
}
static constexpr size_t size() { return m_size; }
private:
struct CallableBase
{
virtual ~CallableBase() {}
virtual Ret call(Args...) const = 0;
};
struct CallablePointer : public CallableBase
{
CallablePointer(Ret(*function)(Args...))
: m_function(function)
{ }
virtual Ret call(Args... args) const override
{
return m_function(forward<Args>(args)...);
}
private:
Ret(*m_function)(Args...) = nullptr;
};
template<typename Own>
struct CallableMember : public CallableBase
{
CallableMember(Ret(Own::*function)(Args...), Own* owner)
: m_owner(owner)
, m_function(function)
{ }
virtual Ret call(Args... args) const override
{
return (m_owner->*m_function)(forward<Args>(args)...);
}
private:
Own* m_owner = nullptr;
Ret(Own::*m_function)(Args...) = nullptr;
};
template<typename Own>
struct CallableMemberConst : public CallableBase
{
CallableMemberConst(Ret(Own::*function)(Args...) const, const Own* owner)
: m_owner(owner)
, m_function(function)
{ }
virtual Ret call(Args... args) const override
{
return (m_owner->*m_function)(forward<Args>(args)...);
}
private:
const Own* m_owner = nullptr;
Ret(Own::*m_function)(Args...) const = nullptr;
};
template<typename Lambda>
struct CallableLambda : public CallableBase
{
CallableLambda(Lambda lambda)
: m_lambda(lambda)
{ }
virtual Ret call(Args... args) const override
{
return m_lambda(forward<Args>(args)...);
}
private:
Lambda m_lambda;
};
private:
static constexpr size_t m_size = sizeof(void*) * 5;
alignas(CallableBase) uint8_t m_storage[m_size] { 0 };
};
}