renderd7/internal/parameter.hpp
2021-07-23 13:58:16 +00:00

113 lines
3.3 KiB
C++

#pragma once
#include <tuple>
namespace RenderD7{
class Parameter
{
private:
using id = size_t;
template<typename T>
struct type { static void id() { } };
template<typename T>
static id type_id() { return reinterpret_cast<id>(&type<T>::id); }
template<typename T>
using decay = typename std::decay<T>::type;
template<typename T>
using none = typename std::enable_if<!std::is_same<Parameter, T>::value>::type;
struct base
{
virtual ~base() { }
virtual bool is(id) const = 0;
virtual base *copy() const = 0;
} *p = nullptr;
template<typename T>
struct data : base, std::tuple<T>
{
using std::tuple<T>::tuple;
T &get() & { return std::get<0>(*this); }
T const &get() const& { return std::get<0>(*this); }
bool is(id i) const override { return i == type_id<T>(); }
base *copy() const override { return new data{get()}; }
};
template<typename T>
T &stat() { return static_cast<data<T>&>(*p).get(); }
template<typename T>
T const &stat() const { return static_cast<data<T> const&>(*p).get(); }
template<typename T>
T &dyn() { return dynamic_cast<data<T>&>(*p).get(); }
template<typename T>
T const &dyn() const { return dynamic_cast<data<T> const&>(*p).get(); }
public:
/**
* @brief Default constructor
*/
Parameter() { }
/**
* @brief Destructs the Parameter
*/
~Parameter() { delete p; }
/**
* @brief Copy constructor
* @param s The Parameter to copy
*/
Parameter(Parameter &&s) : p{s.p} { s.p = nullptr; }
/**
* @brief Const copy constructor
* @param s The Parameter to copy
*/
Parameter(Parameter const &s) : p{s.p->copy()} { }
/**
* @brief Initializes the Parameter with the given value
* @param x The value to initialize the Parameter with
*/
template<typename T, typename U = decay<T>, typename = none<U>>
Parameter(T &&x) : p{new data<U>{std::forward<T>(x)}} { }
/**
* @brief Overloads the assignment operator
* @param s The value to set the Parameter to
*/
Parameter &operator=(Parameter s) { swap(*this, s); return *this; }
friend void swap(Parameter &s, Parameter &r) { std::swap(s.p, r.p); }
/**
* @brief Clears the Parameter
*/
void clear() { delete p; p = nullptr; }
/**
* @brief Checks whether the Parameter is the given type
* @tparam T The type to check
* @return Whether the Parameter has the given type or not
*/
template<typename T>
bool is() const { return p ? p->is(type_id<T>()) : false; }
/**
* @brief Returns the value of the Parameter
* @tparam T The type of the Parameter
* @return The value of the Parameter
* @warning If the type of the Parameter doesn't match the type of it's stored value, it will result in undefined behaviour.
*/
template<typename T> T &get() & { return stat<T>(); }
};
}