55 lines
1.7 KiB
C++
55 lines
1.7 KiB
C++
#ifndef LIBSRK31CXX_UTIL_HPP_
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#define LIBSRK31CXX_UTIL_HPP_
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/* This is a hack. "using" is a better C++11 feature to use, but g++ doesn't support it yet. */
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#define forward_constructors(base_typename, this_typename) \
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template <typename... Args> \
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this_typename(Args&&... args) \
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: base_typename(std::forward<Args>(args)...) {}
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/* This is something that really should be in C++1x.
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* Thanks to T.C.:
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* https://stackoverflow.com/questions/27879815/c11-get-type-of-first-second-etc-argument-similar-to-result-of#27885283 */
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// primary template.
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template<class T>
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struct function_traits : function_traits<decltype(&T::operator())> {
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};
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// partial specialization for function type
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template<class R, class... Args>
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struct function_traits<R(Args...)> {
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using result_type = R;
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using argument_types = std::tuple<Args...>;
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};
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// partial specialization for function pointer
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template<class R, class... Args>
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struct function_traits<R (*)(Args...)> {
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using result_type = R;
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using argument_types = std::tuple<Args...>;
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};
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// partial specialization for std::function
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template<class R, class... Args>
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struct function_traits<std::function<R(Args...)>> {
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using result_type = R;
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using argument_types = std::tuple<Args...>;
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};
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// partial specialization for pointer-to-member-function (i.e., operator()'s)
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template<class T, class R, class... Args>
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struct function_traits<R (T::*)(Args...)> {
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using result_type = R;
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using argument_types = std::tuple<Args...>;
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};
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template<class T, class R, class... Args>
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struct function_traits<R (T::*)(Args...) const> {
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using result_type = R;
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using argument_types = std::tuple<Args...>;
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};
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template<class T>
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using first_argument_type = typename std::tuple_element<0, typename function_traits<T>::argument_types>::type;
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#endif
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