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April 5, 2020 23:30
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| #include <cstdio> | |
| #include <stdlib.h> | |
| //Stub environment | |
| struct Environment { | |
| int GetRegister(int i) const { | |
| printf("GetRegister(%d)\n", i); | |
| return i; | |
| } | |
| }; | |
| //Actual implementation | |
| template<auto F, typename = decltype(F)> | |
| struct Invoker; | |
| //Forward to Invoker<F, R (*)(Args...)> | |
| template<auto F, typename R, typename... Args> | |
| struct Invoker<F, R (*)(Args...) noexcept> { | |
| [[gnu::always_inline]] | |
| inline static R invoke(const Environment& env) { | |
| return Invoker<F, R (*)(Args...)>::invoke(env); | |
| } | |
| }; | |
| template<auto F, size_t N, typename...> | |
| struct InternalInvoker; | |
| template<auto F> | |
| struct InternalInvoker<F, 0> { | |
| template<typename R, typename... Values> | |
| [[gnu::always_inline]] | |
| inline static R internal_invoke(const Environment& env, Values... values) { | |
| return (*F)(values...); | |
| } | |
| }; | |
| template<auto F, size_t N, typename T, typename... TS> | |
| struct InternalInvoker<F, N, T, TS...> { | |
| template<typename R, typename... Values> | |
| [[gnu::always_inline]] | |
| inline static R internal_invoke(const Environment& env, Values... values) { | |
| return InternalInvoker<F, N - 1, TS...>::template internal_invoke<R, T, Values...>(env, static_cast<T>(env.GetRegister(N - 1)), values...); | |
| } | |
| }; | |
| template<auto F, typename R, typename... Args> | |
| struct Invoker<F, R (*)(Args...)> { | |
| static_assert(sizeof...(Args) < 8); | |
| //TODO add static_assert for Args to ensure that conversion from int to Arg is valid | |
| //static_assert((CX::IsCastable<Args, int>::value && ...)); | |
| [[gnu::always_inline]] | |
| inline static R invoke(const Environment& env) { | |
| return InternalInvoker<F, sizeof...(Args), Args...>::template internal_invoke<R>(env); | |
| } | |
| }; | |
| void test(int i1, float i2, short i3) { | |
| printf("test: %d %f %hi\n", i1, i2, i3); | |
| } | |
| double test2(double d, long l) noexcept { | |
| printf("test2: %f %ld\n", d, l); | |
| return d + l; | |
| } | |
| int main() { | |
| Environment env; | |
| Invoker<test>::invoke(env); | |
| auto ret = Invoker<test2>::invoke(env); | |
| printf("test2 returned %f\n", ret); | |
| auto ptr = Invoker<malloc>::invoke(env); | |
| if (ptr) { | |
| free(ptr); | |
| } | |
| return 0; | |
| } |
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