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145 lines
2.4 KiB
145 lines
2.4 KiB
#pragma once
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#include "gp/exception.hpp"
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namespace gp{
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template <typename>
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class function;
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template <typename ret, typename ...args>
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class function<ret(args...)>{
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struct virtual_callable
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{
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virtual ~virtual_callable() = default;
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virtual ret operator() (args...) = 0;
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};
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template<typename fn>
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class callable : public virtual_callable{
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fn internal_representation;
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public:
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callable(const fn& func)
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: internal_representation{func}
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{}
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virtual ~callable() override = default;
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ret operator() (args... arg_list) override
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{
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return internal_representation(arg_list...);
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}
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};
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// tweak a way to store a size in there for trivial copy
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enum state_t : uint8_t{
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INACTIVE = 0,
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ACTIVE = 1,
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NO_SOO = 0,
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SOO = 2
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};
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state_t state{};
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union{
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virtual_callable* functor = nullptr;
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char inplace[12];
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} self;
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public:
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template <typename T>
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function& operator=(T& t)
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{
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if(state & ACTIVE)
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{
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if(state & SOO)
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{
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((virtual_callable*)self.inplace)->~virtual_callable();
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}
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else
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{
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delete self.functor;
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}
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}
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if constexpr (sizeof(callable<T>) <= sizeof(self))
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{
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new((void*)self.inplace) callable(t);
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state = (state_t)(ACTIVE | SOO);
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}
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else
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{
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self.functor = new callable<T>(t);
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state = (state_t)(ACTIVE | NO_SOO);
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}
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}
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function()
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{
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state = INACTIVE;
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}
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template <typename T>
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function(T t)
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{
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if constexpr (sizeof(callable<T>) <= sizeof(self))
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{
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new((void*)self.inplace) callable<T>(t);
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state = (state_t)(ACTIVE | SOO);
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}
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else
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{
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self.functor = new callable<T>(t);
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state = (state_t)(ACTIVE | NO_SOO);
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}
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}
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template <typename T>
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function(T& t)
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{
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if constexpr (sizeof(callable<T>) <= sizeof(self))
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{
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new((void*)&self) callable<T>(t);
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state = (state_t)(ACTIVE | SOO);
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}
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else
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{
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self.functor = new callable<T>(t);
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state = (state_t)(ACTIVE | NO_SOO);
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}
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}
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ret operator()(args... arg_list) const {
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if constexpr (gp_config::has_exceptions)
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{
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if(!(state & ACTIVE))
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{
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throw bad_functor{};
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}
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}
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if(state & SOO)
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{
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return (*(virtual_callable*)&self)(arg_list...);
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}
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else
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{
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return (*self.functor)(arg_list...);
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}
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}
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~function()
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{
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if(state & ACTIVE)
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{
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if(state & SOO)
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{
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((virtual_callable*)&self)->~virtual_callable();
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}
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else
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{
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delete self.functor;
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}
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}
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}
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};
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}
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