add boost on mac

macx64/include/boost/poly_collection/detail/callable_wrapper.hpp

@@ -0,0 +1,104 @@
+/* Copyright 2016-2017 Joaquin M Lopez Munoz.
+ * Distributed under the Boost Software License, Version 1.0.
+ * (See accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ * See http://www.boost.org/libs/poly_collection for library home page.
+ */
+
+#ifndef BOOST_POLY_COLLECTION_DETAIL_CALLABLE_WRAPPER_HPP
+#define BOOST_POLY_COLLECTION_DETAIL_CALLABLE_WRAPPER_HPP
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/poly_collection/detail/is_invocable.hpp>
+#include <functional>
+#include <type_traits>
+#include <typeinfo>
+
+namespace boost{
+
+namespace poly_collection{
+
+namespace detail{
+
+/* lightweight std::function look-alike over non-owned callable entities */
+
+template<typename Signature>
+class callable_wrapper;
+
+template<typename R,typename... Args>
+class callable_wrapper<R(Args...)>
+{
+public:
+  // TODO: we should prevent assignment by user code
+  template<
+    typename Callable,
+    typename std::enable_if<
+      !std::is_same<Callable,callable_wrapper>::value&&
+      is_invocable_r<R,Callable,Args...>::value
+    >::type* =nullptr
+  >
+  explicit callable_wrapper(Callable& x)noexcept:pt{info(x)},px{&x}{}
+  callable_wrapper(const callable_wrapper&)=default;
+  callable_wrapper& operator=(const callable_wrapper&)=default;
+
+  explicit operator bool()const noexcept{return true;}
+
+  R operator()(Args... args)const
+    {return pt->call(px,std::forward<Args>(args)...);}
+
+  const std::type_info& target_type()const noexcept{return pt->info;}
+
+  template<typename T>
+  T*       target()noexcept
+             {return typeid(T)==pt->info?static_cast<T*>(px):nullptr;}
+  template<typename T>
+  const T* target()const noexcept
+             {return typeid(T)==pt->info?static_cast<const T*>(px):nullptr;}
+
+  /* not in std::function interface */
+
+  operator std::function<R(Args...)>()const noexcept{return pt->convert(px);}
+
+  void*       data()noexcept{return px;}
+  const void* data()const noexcept{return px;}
+
+private:
+  struct table
+  {
+    R(*call)(void*,Args...);
+    const std::type_info& info;
+    std::function<R(Args...)> (*convert)(void*);
+  };
+
+  template<typename Callable>
+  static table* info(Callable&)noexcept
+  {
+    static table t={
+      [](void* p,Args... args){
+        auto r=std::ref(*static_cast<Callable*>(p));
+        return static_cast<R>(r(std::forward<Args>(args)...));
+      },
+      typeid(Callable),
+      [](void* p){
+        auto r=std::ref(*static_cast<Callable*>(p));
+        return std::function<R(Args...)>{r};
+      }
+    };
+    return &t;
+  }
+
+  table* pt;
+  void*  px;
+};
+
+} /* namespace poly_collection::detail */
+
+} /* namespace poly_collection */
+
+} /* namespace boost */
+
+#endif