61 lines
1.2 KiB
C++
61 lines
1.2 KiB
C++
#pragma once
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#include <memory>
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template <typename Fun>
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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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{
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private:
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class callable_base
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{
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public:
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virtual Ret call(Args...) const = 0;
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virtual ~callable_base() = default;
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};
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template <typename Fun>
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class callable : public callable_base
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{
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private:
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Fun _fun;
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public:
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callable(Fun fun):_fun(fun) {}
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virtual Ret call(Args... args) const override
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{ return _fun(std::forward<Args>(args)...); }
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virtual ~callable() override {}
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};
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std::unique_ptr<callable_base> _fun;
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bool _is_null = false;
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public:
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Function() {}
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template <typename Fun>
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Function& operator=(Fun fun)
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{
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_fun = std::make_unique<callable<Fun>>(fun);
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_is_null = false;
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return *this;
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}
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Function& operator=(std::nullptr_t)
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{ _is_null = true; return *this; }
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Ret operator()(Args... args) const
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{
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if (_is_null)
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throw std::bad_function_call();
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return _fun->call(std::forward<Args>(args)...);
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}
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operator bool() const
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{ return static_cast<bool>(_fun); }
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};
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