--- /dev/null
+#ifndef __NEST_EXPR_ADD_NODE_H__
+#define __NEST_EXPR_ADD_NODE_H__
+
+#include "nest/expr/Node.h"
+
+#include <memory>
+
+namespace nest
+{
+namespace expr
+{
+
+class AddNode final : public Node
+{
+public:
+ AddNode(const std::shared_ptr<expr::Node> &lhs, const std::shared_ptr<expr::Node> &rhs)
+ : _lhs{lhs}, _rhs{rhs}
+ {
+ // DO NOTHING
+ }
+
+public:
+ const AddNode *asAdd(void) const override { return this; }
+
+public:
+ const std::shared_ptr<expr::Node> &lhs(void) const { return _lhs; }
+ const std::shared_ptr<expr::Node> &rhs(void) const { return _rhs; }
+
+private:
+ std::shared_ptr<expr::Node> const _lhs;
+ std::shared_ptr<expr::Node> const _rhs;
+};
+
+} // namespace expr
+} // namespace nest
+
+#endif // __NEST_EXPR_ADD_NODE_H__
--- /dev/null
+#include "nest/expr/AddNode.h"
+
+#include <memory>
+
+#include <gtest/gtest.h>
+
+namespace
+{
+struct DummyNode final : public nest::expr::Node
+{
+};
+}
+
+TEST(ADD_NODE, cast)
+{
+ auto left = std::make_shared<DummyNode>();
+ auto right = std::make_shared<DummyNode>();
+
+ auto derived = std::make_shared<nest::expr::AddNode>(left, right);
+ std::shared_ptr<nest::expr::Node> base = derived;
+
+ ASSERT_NE(derived.get(), nullptr);
+ ASSERT_EQ(base->asAdd(), derived.get());
+
+ ASSERT_EQ(derived->lhs().get(), left.get());
+ ASSERT_EQ(derived->rhs().get(), right.get());
+}