88 lines · cpp
1// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s2// expected-no-diagnostics3 4// Example function implementation from the variadic templates proposal,5// ISO C++ committee document number N2080.6 7template<typename Signature> class function;8 9template<typename R, typename... Args> class invoker_base {10public: 11 virtual ~invoker_base() { } 12 virtual R invoke(Args...) = 0; 13 virtual invoker_base* clone() = 0;14};15 16template<typename F, typename R, typename... Args> 17class functor_invoker : public invoker_base<R, Args...> {18public: 19 explicit functor_invoker(const F& f) : f(f) { } 20 R invoke(Args... args) { return f(args...); } 21 functor_invoker* clone() { return new functor_invoker(f); }22 23private:24 F f;25};26 27template<typename R, typename... Args>28class function<R (Args...)> {29public: 30 typedef R result_type;31 function() : invoker (0) { }32 function(const function& other) : invoker(0) { 33 if (other.invoker)34 invoker = other.invoker->clone();35 }36 37 template<typename F> function(const F& f) : invoker(0) {38 invoker = new functor_invoker<F, R, Args...>(f);39 }40 41 ~function() { 42 if (invoker)43 delete invoker;44 }45 46 function& operator=(const function& other) { 47 function(other).swap(*this); 48 return *this;49 }50 51 template<typename F> 52 function& operator=(const F& f) {53 function(f).swap(*this); 54 return *this;55 }56 57 void swap(function& other) { 58 invoker_base<R, Args...>* tmp = invoker; 59 invoker = other.invoker; 60 other.invoker = tmp;61 }62 63 result_type operator()(Args... args) const { 64 return invoker->invoke(args...);65 }66 67private: 68 invoker_base<R, Args...>* invoker;69};70 71template<typename T>72struct add {73 T operator()(T x, T y) { return x + y; }74};75 76int add_ints(int x, int y) { return x + y; }77 78void test_function() {79 function<int(int, int)> f2a;80 function<int(int, int)> f2b = add<int>();81 function<int(int, int)> f2c = add<float>();82 function<int(int, int)> f2d(f2b);83 function<int(int, int)> f2e = &add_ints;84 f2c = f2d;85 f2d = &add_ints;86 f2c(1.0, 3);87}88