Use arena in parser

Signed-off-by: CHatingPython <chatingpython@gmail.com>

furc/include/furc/ast/declaration.hpp

@@ -62,6 +62,23 @@ class function_definition_node : public function_declarartion_node {
 public:
     function_definition_node(front::token name, function_body_handle&& body)
       : function_declarartion_node(name), m_body(std::move(body)) {}
+
+    ~function_definition_node() override = default;
+
+    function_definition_node(function_definition_node&& other) noexcept
+      : function_declarartion_node(std::move(other)), m_name(other.m_name), m_body(std::move(other.m_body)) {}
+
+    function_definition_node(const function_definition_node&) = delete;
+
+    function_definition_node& operator=(function_definition_node&& other) noexcept {
+        if (this == &other) return *this;
+        function_declarartion_node::operator=(std::move(other));
+        m_name = other.m_name;
+        m_body = std::move(other.m_body);
+        return *this;
+    }
+
+    function_definition_node& operator=(const function_definition_node&) = delete;
 public:
     declaration_node_t type() const override { return declaration_node_t::FunctionDefinition; }
 

furc/include/furc/ast/statement.hpp

@@ -35,14 +35,14 @@ public:
 class declaration_node;
 class declaration_statement_node : public statement_node {
 public:
-    declaration_statement_node(declaration_node* declaration)
-      : m_declaration(declaration) {}
+    declaration_statement_node(node_handle<declaration_node>&& declaration)
+      : m_declaration(std::move(declaration)) {}
 public:
     statement_node_t type() const override { return statement_node_t::Declaration; }
 
     std::ostream& print(std::ostream& os) const override { return os; }
 private:
-    declaration_node* m_declaration = nullptr;
+    node_handle<declaration_node> m_declaration;
 };
 
 class return_statement_node : public statement_node {