Move type traits to its own header and clean up code using the traits

sol/stack.hpp

@@ -24,18 +24,12 @@
 
 #include "reference.hpp"
 #include "tuple.hpp"
+#include "traits.hpp"
 #include <utility>
-#include <type_traits>
 #include <array>
 #include <cstring>
 
 namespace sol {
-template<typename T, typename R = void>
-using EnableIf = typename std::enable_if<T::value, R>::type;
-
-template<typename T, typename R = void>
-using DisableIf = typename std::enable_if<!T::value, R>::type;
-
 namespace stack {
 namespace detail {
 template<typename T>

sol/table.hpp

@@ -29,15 +29,15 @@
 
 namespace sol {
 namespace detail {
-    template<typename T>
+template<typename T>
-    T* get_ptr(T& val) {
+T* get_ptr(T& val) {
     return std::addressof(val);
-    }
+}
 
-    template<typename T>
+template<typename T>
-    T* get_ptr(T* val) {
+T* get_ptr(T* val) {
     return val;
-    }
+}
 } // detail
 
 class table : virtual public reference {
@@ -71,13 +71,13 @@ public:
 
     template<typename T, typename TFx>
     table& set_function(T&& key, TFx&& fx) {
-        typedef typename std::remove_pointer<typename std::decay<TFx>::type>::type clean_fx;
+        typedef typename std::remove_pointer<Decay<TFx>>::type clean_fx;
         return set_isfunction_fx(std::is_function<clean_fx>(), std::forward<T>(key), std::forward<TFx>(fx));
     }
 
     template<typename T, typename TFx, typename TObj>
     table& set_function(T&& key, TFx&& fx, TObj&& obj) {
-        return set_lvalue_fx(std::integral_constant<bool, std::is_lvalue_reference<TObj>::value || std::is_pointer<TObj>::value>(),
+        return set_lvalue_fx(Bool<std::is_lvalue_reference<TObj>::value || std::is_pointer<TObj>::value>(),
             std::forward<T>(key), std::forward<TFx>(fx), std::forward<TObj>(obj));
     }
 
@@ -98,7 +98,7 @@ private:
 
     template<typename T, typename TFx>
     table& set_isfunction_fx(std::false_type, T&& key, TFx&& fx) {
-        typedef typename std::decay<TFx>::type clean_lambda;
+        typedef Decay<TFx> clean_lambda;
         typedef typename detail::function_traits<decltype(&clean_lambda::operator())>::free_function_pointer_type raw_func_t;
         typedef std::is_convertible<clean_lambda, raw_func_t> isconvertible;
         return set_isconvertible_fx(isconvertible(), std::forward<T>(key), std::forward<TFx>(fx));
@@ -106,14 +106,14 @@ private:
 
     template<typename T, typename TFx>
     table& set_isconvertible_fx(std::true_type, T&& key, TFx&& fx) {
-        typedef typename std::decay<TFx>::type clean_lambda;
+        typedef Decay<TFx> clean_lambda;
         typedef typename detail::function_traits<decltype(&clean_lambda::operator())>::free_function_pointer_type raw_func_t;
         return set_isfunction_fx(std::true_type(), std::forward<T>(key), raw_func_t(std::forward<TFx>(fx)));
     }
 
     template<typename T, typename TFx>
     table& set_isconvertible_fx(std::false_type, T&& key, TFx&& fx) {
-        typedef typename std::remove_pointer<typename std::decay<TFx>::type>::type clean_fx;
+        typedef typename std::remove_pointer<Decay<TFx>>::type clean_fx;
         std::unique_ptr<lua_func> sptr(new lambda_lua_func<clean_fx>(std::forward<TFx>(fx)));
         return set_fx(std::forward<T>(key), std::move(sptr));
     }
@@ -125,16 +125,13 @@ private:
 
     template<typename T, typename TFx, typename TObj>
     table& set_lvalue_fx(std::false_type, T&& key, TFx&& fx, TObj&& obj) {
-        typedef typename std::remove_pointer<typename std::decay<TFx>::type>::type clean_fx;
+        typedef typename std::remove_pointer<Decay<TFx>>::type clean_fx;
         std::unique_ptr<lua_func> sptr(new explicit_lua_func<clean_fx, TObj>(std::forward<TObj>(obj), std::forward<TFx>(fx)));
         return set_fx(std::forward<T>(key), std::move(sptr));
     }
 
     template<typename T, typename TFx, typename TObj>
     table& set_fx(std::true_type, T&& key, TFx&& fx, TObj&& obj) {
-        typedef typename std::decay<TObj>::type decay_of_to;
-        typedef typename std::decay<TFx>::type decay_of_tfx;
-        
         std::string fkey(key);
 
         // Layout: 
@@ -142,9 +139,9 @@ private:
         // idx n + 1: is the object's void pointer
         // We don't need to store the size, because the other side is templated
         // with the same member function pointer type
-        decay_of_tfx fxptr(std::forward<TFx>(fx));
+        Decay<TFx> fxptr(std::forward<TFx>(fx));
         void* userobjdata = static_cast<void*>(detail::get_ptr(obj));
-        lua_CFunction freefunc = &static_object_lua_func<decay_of_to, TFx>::call;
+        lua_CFunction freefunc = &static_object_lua_func<Decay<TObj>, TFx>::call;
         const char* freefuncname = fkey.c_str();
         const luaL_Reg funcreg[ 2 ] = {
             { freefuncname, freefunc },
@@ -164,9 +161,8 @@ private:
 
     template<typename T, typename TFx>
     table& set_fx(std::false_type, T&& key, TFx&& fx) {
-        typedef typename std::decay<TFx>::type ptr_fx;
         std::string fkey(key);
-        ptr_fx target(std::forward<TFx>(fx));
+        Decay<TFx> target(std::forward<TFx>(fx));
         lua_CFunction freefunc = &static_lua_func<TFx>::call;
         const char* freefuncname = fkey.c_str();
         const luaL_Reg funcreg[ 2 ] = {
@@ -208,7 +204,6 @@ private:
         push();
         stack::push_user(state(), userdata, metatablename);
         luaL_setfuncs(state(), funcreg, 1);
-
         lua_pop(state(), 1);
         return *this;
     }

sol/traits.hpp

@@ -0,0 +1,72 @@
+// The MIT License (MIT)
+
+// Copyright (c) 2013 Danny Y., Rapptz
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software is furnished to do so,
+// subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#ifndef SOL_TRAITS_HPP
+#define SOL_TRAITS_HPP
+
+#include <type_traits>
+
+namespace sol {
+template<typename T, typename R = void>
+using EnableIf = typename std::enable_if<T::value, R>::type;
+
+template<typename T, typename R = void>
+using DisableIf = typename std::enable_if<!T::value, R>::type;
+
+template<typename T>
+using Unqualified = typename std::remove_reference<typename std::remove_cv<T>::type>::type;
+
+namespace detail {
+// code borrowed from Gears 
+// https://github.com/Rapptz/Gears/
+template<typename T, typename = void>
+struct is_function_impl : std::is_function<T> {};
+
+template<typename T>
+struct is_function_impl<T, EnableIf<std::is_class<Unqualified<T>>>> {
+    using yes = char;
+    using no = struct { char s[2]; };
+
+    struct F { void operator()(); };
+    struct Derived : T, F { };
+    template<typename U, U> struct Check;
+
+    template<typename V>
+    static no test(Check<void (F::*)(), &V::operator()>*);
+
+    template<typename>
+    static yes test(...);
+
+    static const bool value = sizeof(test<Derived>(0)) == sizeof(yes);
+};
+} // detail
+
+template<bool B>
+using Bool = std::integral_constant<bool, B>;
+
+template<typename T>
+struct Function : Bool<detail::is_function_impl<T>::value> {};
+
+template<typename T>
+using Decay = typename std::decay<T>::type;
+} // sol
+
+#endif // SOL_TRAITS_HPP