Added boost header

test/external/boost/signals/detail/signals_common.hpp

@@ -0,0 +1,162 @@
+// Boost.Signals library
+
+// Copyright Douglas Gregor 2001-2004. Use, modification and
+// distribution is subject to 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)
+
+// For more information, see http://www.boost.org
+
+#ifndef BOOST_SIGNALS_COMMON_HEADER
+#define BOOST_SIGNALS_COMMON_HEADER
+
+#ifndef BOOST_SIGNALS_NAMESPACE
+#  define BOOST_SIGNALS_NAMESPACE signals
+#endif
+
+#include <boost/type_traits/conversion_traits.hpp>
+#include <boost/ref.hpp>
+#include <boost/signals/detail/config.hpp>
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_PREFIX
+#endif
+
+namespace boost {
+  namespace BOOST_SIGNALS_NAMESPACE {
+    namespace detail {
+      // The unusable class is a placeholder for unused function arguments
+      // It is also completely unusable except that it constructable from
+      // anything. This helps compilers without partial specialization
+      // handle slots returning void.
+      struct unusable {
+        unusable() {}
+      };
+
+      // Determine the result type of a slot call
+      template<typename R>
+      struct slot_result_type {
+        typedef R type;
+      };
+
+      template<>
+      struct slot_result_type<void> {
+        typedef unusable type;
+      };
+
+      // Determine if the given type T is a signal
+      class signal_base;
+
+      template<typename T>
+      struct is_signal {
+        BOOST_STATIC_CONSTANT(bool,
+          value = (is_convertible<T*, signal_base*>::value));
+      };
+
+      /*
+       * The IF implementation is temporary code. When a Boost metaprogramming
+       * library is introduced, Boost.Signals will use it instead.
+       */
+      namespace intimate {
+        struct SelectThen
+        {
+          template<typename Then, typename Else>
+          struct Result
+          {
+            typedef Then type;
+          };
+        };
+
+        struct SelectElse
+        {
+          template<typename Then, typename Else>
+          struct Result
+          {
+            typedef Else type;
+          };
+        };
+
+        template<bool Condition>
+        struct Selector
+        {
+          typedef SelectThen type;
+        };
+
+        template<>
+        struct Selector<false>
+        {
+          typedef SelectElse type;
+        };
+      } // end namespace intimate
+
+      template<bool Condition, typename Then, typename Else>
+      struct IF
+      {
+        typedef typename intimate::Selector<Condition>::type select;
+        typedef typename select::template Result<Then,Else>::type type;
+      };
+
+      // Determine if the incoming argument is a reference_wrapper
+#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+      template<typename T>
+      struct is_ref
+      {
+        BOOST_STATIC_CONSTANT(bool, value = false);
+      };
+
+      template<typename T>
+      struct is_ref<reference_wrapper<T> >
+      {
+        BOOST_STATIC_CONSTANT(bool, value = true);
+      };
+#else // no partial specialization
+      typedef char yes_type;
+      typedef double no_type;
+
+      no_type is_ref_tester(...);
+
+      template<typename T>
+      yes_type is_ref_tester(reference_wrapper<T>*);
+
+      template<typename T>
+      struct is_ref
+      {
+        static T* t;
+        BOOST_STATIC_CONSTANT(bool,
+          value = (sizeof(is_ref_tester(t)) == sizeof(yes_type)));
+      };
+#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+
+      // A slot can be a signal, a reference to a function object, or a
+      // function object.
+      struct signal_tag {};
+      struct reference_tag {};
+      struct value_tag {};
+
+      // Classify the given slot as a signal, a reference-to-slot, or a
+      // standard slot
+      template<typename S>
+      class get_slot_tag {
+        typedef typename IF<(is_signal<S>::value),
+                            signal_tag,
+                            value_tag>::type signal_or_value;
+
+      public:
+        typedef typename IF<(is_ref<S>::value),
+                            reference_tag,
+                            signal_or_value>::type type;
+      };
+
+      // Forward declaration needed in lots of places
+      class signal_base_impl;
+      class bound_objects_visitor;
+      class slot_base;
+    } // end namespace detail
+  } // end namespace BOOST_SIGNALS_NAMESPACE
+} // end namespace boost
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_SUFFIX
+#endif
+
+#endif // BOOST_SIGNALS_COMMON_HEADER