threads in MinGW

mingw.invoke.h

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+/// \file mingw.invoke.h
+/// \brief Lightweight `invoke` implementation, for C++11 and C++14.
+///
+/// (c) 2018-2019 by Nathaniel J. McClatchey, San Jose, CA, United States
+/// \author Nathaniel J. McClatchey, PhD
+///
+/// \copyright Simplified (2-clause) BSD License.
+///
+/// \note This file may become part of the mingw-w64 runtime package. If/when
+/// this happens, the appropriate license will be added, i.e. this code will
+/// become dual-licensed, and the current BSD 2-clause license will stay.
+
+#ifndef MINGW_INVOKE_H_
+#define MINGW_INVOKE_H_
+
+#include <type_traits>  //  For std::result_of, etc.
+#include <utility>      //  For std::forward
+#include <functional>   //  For std::reference_wrapper
+
+namespace mingw_stdthread
+{
+namespace detail
+{
+//  For compatibility, implement std::invoke for C++11 and C++14
+#if __cplusplus < 201703L
+  template<bool PMemFunc, bool PMemData>
+  struct Invoker
+  {
+    template<class F, class... Args>
+    inline static typename std::result_of<F(Args...)>::type invoke (F&& f, Args&&... args)
+    {
+      return std::forward<F>(f)(std::forward<Args>(args)...);
+    }
+  };
+  template<bool>
+  struct InvokerHelper;
+
+  template<>
+  struct InvokerHelper<false>
+  {
+    template<class T1>
+    inline static auto get (T1&& t1) -> decltype(*std::forward<T1>(t1))
+    {
+      return *std::forward<T1>(t1);
+    }
+
+    template<class T1>
+    inline static auto get (const std::reference_wrapper<T1>& t1) -> decltype(t1.get())
+    {
+      return t1.get();
+    }
+  };
+
+  template<>
+  struct InvokerHelper<true>
+  {
+    template<class T1>
+    inline static auto get (T1&& t1) -> decltype(std::forward<T1>(t1))
+    {
+      return std::forward<T1>(t1);
+    }
+  };
+
+  template<>
+  struct Invoker<true, false>
+  {
+    template<class T, class F, class T1, class... Args>
+    inline static auto invoke (F T::* f, T1&& t1, Args&&... args) ->\
+      decltype((InvokerHelper<std::is_base_of<T,typename std::decay<T1>::type>::value>::get(std::forward<T1>(t1)).*f)(std::forward<Args>(args)...))
+    {
+      return (InvokerHelper<std::is_base_of<T,typename std::decay<T1>::type>::value>::get(std::forward<T1>(t1)).*f)(std::forward<Args>(args)...);
+    }
+  };
+
+  template<>
+  struct Invoker<false, true>
+  {
+    template<class T, class F, class T1, class... Args>
+    inline static auto invoke (F T::* f, T1&& t1, Args&&... args) ->\
+      decltype(InvokerHelper<std::is_base_of<T,typename std::decay<T1>::type>::value>::get(t1).*f)
+    {
+      return InvokerHelper<std::is_base_of<T,typename std::decay<T1>::type>::value>::get(t1).*f;
+    }
+  };
+
+  template<class F, class... Args>
+  struct InvokeResult
+  {
+    typedef Invoker<std::is_member_function_pointer<typename std::remove_reference<F>::type>::value,
+                    std::is_member_object_pointer<typename std::remove_reference<F>::type>::value &&
+                    (sizeof...(Args) == 1)> invoker;
+    inline static auto invoke (F&& f, Args&&... args) -> decltype(invoker::invoke(std::forward<F>(f), std::forward<Args>(args)...))
+    {
+      return invoker::invoke(std::forward<F>(f), std::forward<Args>(args)...);
+    }
+  };
+
+  template<class F, class...Args>
+  auto invoke (F&& f, Args&&... args) -> decltype(InvokeResult<F, Args...>::invoke(std::forward<F>(f), std::forward<Args>(args)...))
+  {
+    return InvokeResult<F, Args...>::invoke(std::forward<F>(f), std::forward<Args>(args)...);
+  }
+#else
+    using std::invoke;
+#endif
+} //  Namespace "detail"
+} //  Namespace "mingw_stdthread"
+
+#endif