Introduce binop_expression_node

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

furc/include/furc/ast/expression.hpp

@@ -8,7 +8,8 @@ namespace furc {
 namespace ast {
 
 enum class expression_node_t {
-    Literal
+    Literal,
+    Binop
 };
 
 class expression_node : public statement_node {
@@ -22,6 +23,38 @@ protected:
     bool equal(const node& rhs) const override;
 };
 
+using expression_node_h = node_handle<expression_node>;
+
+enum class binop_expression_node_t {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Mod,
+};
+
+class binop_expression_node : public expression_node {
+public:
+    binop_expression_node(binop_expression_node_t type, expression_node_h&& lhs, expression_node_h&& rhs)
+      : m_type(type), m_lhs(std::move(lhs)), m_rhs(std::move(rhs)) {}
+
+    binop_expression_node_t  type() const { return m_type; };
+    const expression_node_h& lhs() const { return m_lhs; };
+    const expression_node_h& rhs() const { return m_rhs; };
+public:
+    expression_node_t expression_type() const override { return expression_node_t::Binop; }
+
+    std::ostream& print(std::ostream& os) const override;
+protected:
+    bool equal(const node& rhs) const override;
+private:
+    binop_expression_node_t m_type;
+    expression_node_h       m_lhs;
+    expression_node_h       m_rhs;
+};
+
+using binop_expression_node_h = node_handle<binop_expression_node>;
+
 } // namespace ast
 } // namespace furc