bsnes/nall/function.hpp

71 lines
2.8 KiB
C++

#pragma once
#include <nall/traits.hpp>
namespace nall {
template<typename T> struct function;
template<typename R, typename... P> struct function<auto (P...) -> R> {
//value = true if auto L::operator()(P...) -> R exists
template<typename L> struct is_compatible {
template<typename T> static auto exists(T*) -> const typename is_same<R, decltype(declval<T>().operator()(declval<P>()...))>::type;
template<typename T> static auto exists(...) -> const false_type;
static constexpr bool value = decltype(exists<L>(0))::value;
};
function() = default;
function(const function& source) { operator=(source); }
function(void* function) { if(function) callback = new global((auto (*)(P...) -> R)function); }
function(auto (*function)(P...) -> R) { callback = new global(function); }
template<typename C> function(auto (C::*function)(P...) -> R, C* object) { callback = new member<C>(function, object); }
template<typename C> function(auto (C::*function)(P...) const -> R, C* object) { callback = new member<C>((auto (C::*)(P...) -> R)function, object); }
template<typename L, typename = enable_if<is_compatible<L>>> function(const L& object) { callback = new lambda<L>(object); }
~function() { if(callback) delete callback; }
explicit operator bool() const { return callback; }
auto operator()(P... p) const -> R { return (*callback)(forward<P>(p)...); }
auto reset() -> void { if(callback) { delete callback; callback = nullptr; } }
auto operator=(const function& source) -> function& {
if(this != &source) {
if(callback) { delete callback; callback = nullptr; }
if(source.callback) callback = source.callback->copy();
}
return *this;
}
private:
struct container {
virtual auto operator()(P... p) const -> R = 0;
virtual auto copy() const -> container* = 0;
virtual ~container() = default;
};
container* callback = nullptr;
struct global : container {
auto (*function)(P...) -> R;
auto operator()(P... p) const -> R { return function(forward<P>(p)...); }
auto copy() const -> container* { return new global(function); }
global(auto (*function)(P...) -> R) : function(function) {}
};
template<typename C> struct member : container {
auto (C::*function)(P...) -> R;
C* object;
auto operator()(P... p) const -> R { return (object->*function)(forward<P>(p)...); }
auto copy() const -> container* { return new member(function, object); }
member(auto (C::*function)(P...) -> R, C* object) : function(function), object(object) {}
};
template<typename L> struct lambda : container {
mutable L object;
auto operator()(P... p) const -> R { return object(forward<P>(p)...); }
auto copy() const -> container* { return new lambda(object); }
lambda(const L& object) : object(object) {}
};
};
}