Add basic entity

include/cppast/cpp_entity.hpp

@@ -0,0 +1,61 @@
+// Copyright (C) 2017 Jonathan Müller <jonathanmueller.dev@gmail.com>
+// This file is subject to the license terms in the LICENSE file
+// found in the top-level directory of this distribution.
+
+#ifndef CPPAST_CPP_ENTITY_HPP_INCLUDED
+#define CPPAST_CPP_ENTITY_HPP_INCLUDED
+
+#include <type_safe/optional_ref.hpp>
+
+#include <cppast/detail/intrusive_list.hpp>
+
+namespace cppast
+{
+    enum class cpp_entity_type;
+
+    /// The base class for all entities in the C++ AST.
+    class cpp_entity : detail::intrusive_list_node<cpp_entity>
+    {
+    public:
+        cpp_entity(const cpp_entity&) = delete;
+        cpp_entity& operator=(const cpp_entity&) = delete;
+
+        virtual ~cpp_entity() noexcept = default;
+
+        /// \returns The type of the entity.
+        cpp_entity_type type() const noexcept
+        {
+            return do_get_entity_type();
+        }
+
+        /// \returns The name of the entity.
+        /// The name is the string associated with the entity's declaration.
+        const std::string& name() const noexcept
+        {
+            return name_;
+        }
+
+        /// \returns A [ts::optional_ref]() to the parent entity in the AST.
+        type_safe::optional_ref<cpp_entity> parent() const noexcept
+        {
+            return parent_;
+        }
+
+    protected:
+        /// \effects Creates it giving it the parent entity and the name.
+        cpp_entity(type_safe::optional_ref<cpp_entity> parent, std::string name)
+        : parent_(std::move(parent)), name_(std::move(name))
+        {
+        }
+
+    private:
+        virtual cpp_entity_type do_get_entity_type() const noexcept = 0;
+
+        type_safe::optional_ref<cpp_entity> parent_;
+        std::string                         name_;
+
+        friend detail::intrusive_list_access<cpp_entity>;
+    };
+} // namespace cppast
+
+#endif // CPPAST_CPP_ENTITY_HPP_INCLUDED