Parse binop expressions

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

furc/include/furc/ast/literal.hpp

@@ -48,6 +48,8 @@ public:
     literal_node_t literal_type() const override { return literal_node_t::Integer; }
 
     const handle<front::integer_token>& value() const { return m_value; }
+
+    bool operator==(front::integer_token integer) const { return m_value == integer; }
 public:
     std::ostream& print(std::ostream& os) const override;
 protected:

furc/include/furc/front/parser.hpp

@@ -33,6 +33,9 @@ private:
     ast::node_handle<ast::expression_node>  parse_expression();
     ast::node_handle<ast::literal_node>     parse_literal();
 
+    ast::expression_node_h parse_expression_primary();
+    ast::expression_node_h parse_expression_rhs(const ast::expression_node_h& init, std::uint32_t precedence);
+
     ast::function_body_handle parse_body();
 private:
     token_handle<>        next_token();

furc/include/furc/front/token.hpp

@@ -26,6 +26,12 @@ enum class token_t {
     Colon,
     Comma,
     Dot,
+
+    Plus,
+    Minus,
+    Star,
+    Slash,
+    Percent,
 };
 
 static inline std::ostream& operator<<(std::ostream& os, token_t type) {
@@ -45,7 +51,13 @@ static inline std::ostream& operator<<(std::ostream& os, token_t type) {
     case token_t::Colon: return os << "':'";
     case token_t::Comma: return os << "','";
     case token_t::Dot: return os << "'.'";
+    case token_t::Plus: return os << "'+'";
+    case token_t::Minus: return os << "'-'";
+    case token_t::Star: return os << "'*'";
+    case token_t::Slash: return os << "'/'";
+    case token_t::Percent: return os << "'%'";
     }
+    return os;
 }
 
 static inline std::string operator+(const std::string& str, token_t type) {
@@ -65,7 +77,13 @@ static inline std::string operator+(const std::string& str, token_t type) {
     case token_t::Colon: return str + "':'";
     case token_t::Comma: return str + "','";
     case token_t::Dot: return str + "'.'";
+    case token_t::Plus: return str + "'+'";
+    case token_t::Minus: return str + "'-'";
+    case token_t::Star: return str + "'*'";
+    case token_t::Slash: return str + "'/'";
+    case token_t::Percent: return str + "'%'";
     }
+    return str;
 }
 
 enum class keyword_token {
@@ -144,7 +162,12 @@ struct token {
         case token_t::Semicolon:
         case token_t::Colon:
         case token_t::Comma:
-        case token_t::Dot: return true;
+        case token_t::Dot:
+        case token_t::Plus:
+        case token_t::Minus:
+        case token_t::Star:
+        case token_t::Slash:
+        case token_t::Percent: return true;
         }
     }
 };