Paren some expressions mate

src/musique.hh

@@ -317,6 +317,7 @@ struct Parser
 	Result<Ast> parse_binary_operator();
 	Result<Ast> parse_literal();
 
+	Result<Token::Type> peek_type() const;
 	Token consume();
 
 	// Tests if current token has given type

src/parser.cc

@@ -44,8 +44,28 @@ Result<Ast> Parser::parse_binary_operator()
 
 Result<Ast> Parser::parse_literal()
 {
-	Try(ensure(Token::Type::Numeric));
+	switch (Try(peek_type())) {
+	case Token::Type::Numeric:
 		return Ast::literal(consume());
+
+	case Token::Type::Open_Paren:
+		consume();
+		return parse_expression().and_then([&](Ast ast) -> tl::expected<Ast, Error> {
+			Try(ensure(Token::Type::Close_Paren));
+			consume();
+			return ast;
+		});
+
+	default:
+		unimplemented();
+	}
+}
+
+Result<Token::Type> Parser::peek_type() const
+{
+	return token_id >= tokens.size()
+		? errors::unexpected_end_of_source(tokens.back().location)
+		: Result<Token::Type>(tokens[token_id].type);
 }
 
 Token Parser::consume()

src/tests/parser.cc

@@ -56,4 +56,26 @@ suite parser_test = [] {
 				Ast::literal({ Token::Type::Numeric, "303", {} })
 		));
 	};
+
+	"Grouping expressions in parentheses"_test = [] {
+		expect_ast("(101 + 202) * 303", Ast::binary(
+				Token { Token::Type::Operator, "*", {} },
+				Ast::binary(
+							Token { Token::Type::Operator, "+", {} },
+							Ast::literal({ Token::Type::Numeric, "101", {} }),
+							Ast::literal({ Token::Type::Numeric, "202", {} })
+				),
+				Ast::literal({ Token::Type::Numeric, "303", {} })
+		));
+
+		expect_ast("101 * (202 + 303)", Ast::binary(
+				Token { Token::Type::Operator, "*", {} },
+				Ast::literal({ Token::Type::Numeric, "101", {} }),
+				Ast::binary(
+							Token { Token::Type::Operator, "+", {} },
+							Ast::literal({ Token::Type::Numeric, "202", {} }),
+							Ast::literal({ Token::Type::Numeric, "303", {} })
+				)
+		));
+	};
 };