Add cpp_using_declaration

include/cppast/cpp_entity_type.hpp

@@ -17,6 +17,7 @@ namespace cppast
         namespace_t,
         namespace_alias_t,
         using_directive_t,
+        using_declaration_t,
 
         count,
     };

include/cppast/cpp_namespace.hpp

@@ -117,7 +117,7 @@ namespace cppast
             return std::unique_ptr<cpp_using_directive>(new cpp_using_directive(target));
         }
 
-        /// \returns The [cppast::cpp_namespace_ref]() that is exposed.
+        /// \returns The [cppast::cpp_namespace_ref]() that is being used.
         /// \notes The name of the reference is the same as the name of this entity.
         cpp_namespace_ref target() const
         {
@@ -137,6 +137,41 @@ namespace cppast
 
         cpp_entity_id target_;
     };
+
+    /// A [cppast::cpp_entity]() modelling a using declaration.
+    ///
+    /// A using declaration is `using std::vector`, for example.
+    class cpp_using_declaration final : public cpp_entity
+    {
+    public:
+        /// \returns A newly created using declaration.
+        /// \notes It is not meant to be registered at the [cppast::cpp_entity_index](),
+        /// as nothing can refer to it.
+        static std::unique_ptr<cpp_using_declaration> build(const cpp_entity_ref& target)
+        {
+            return std::unique_ptr<cpp_using_declaration>(new cpp_using_declaration(target));
+        }
+
+        /// \returns The [cppast::cpp_entity_ref]() that is being used.
+        /// \notes The name of the reference is the same as the name of this entity.
+        cpp_entity_ref target() const
+        {
+            return {target_, name()};
+        }
+
+    private:
+        cpp_using_declaration(const cpp_entity_ref& target)
+        : cpp_entity(target.name()), target_(target.id())
+        {
+        }
+
+        cpp_entity_type do_get_entity_type() const noexcept override
+        {
+            return cpp_entity_type::using_declaration_t;
+        }
+
+        cpp_entity_id target_;
+    };
 } // namespace cppast
 
 #endif // CPPAST_CPP_NAMESPACE_HPP_INCLUDED

src/cpp_entity_type.cpp

@@ -16,6 +16,7 @@ bool cppast::is_scope(cpp_entity_type type) noexcept
     case cpp_entity_type::file_t:
     case cpp_entity_type::namespace_alias_t:
     case cpp_entity_type::using_directive_t:
+    case cpp_entity_type::using_declaration_t:
     case cpp_entity_type::count:
         break;
     }