added extensive testing for operator precedence

test/parser/expression.cpp

@@ -98,4 +98,111 @@ TEST_SUITE("Parser: expression") {
         CASE("Infix: '!='", "15 != 5;", 15, "!=", 5);
 #undef CASE
     }
+
+
+    TEST_CASE_FIXTURE(ParserFixture, "Slightly more complex infix expression") {
+        setup("5 - -15;");
+
+        REQUIRE(program->statements.size() == 1);
+        ast::expression_stmt* expression_stmt =
+            cast<ast::expression_stmt>(program->statements[0]);
+
+        ast::infix_expr* infix_expr =
+            cast<ast::infix_expr>(expression_stmt->expression);
+
+        test_integer_literal(infix_expr->left, 5);
+        CHECK(infix_expr->op == "-");
+
+        ast::prefix_expr* prefix_expr =
+            cast<ast::prefix_expr>(infix_expr->right);
+
+        CHECK(prefix_expr->op == "-");
+        test_integer_literal(prefix_expr->right, 15);
+    }
+
+    TEST_CASE_FIXTURE(
+        ParserFixture,
+        "Slightly even more complex infix expression"
+    ) {
+        setup("5 - -15 * 3;");
+
+        REQUIRE(program->statements.size() == 1);
+        ast::expression_stmt* expression_stmt =
+            cast<ast::expression_stmt>(program->statements[0]);
+
+        ast::infix_expr* infix_expr =
+            cast<ast::infix_expr>(expression_stmt->expression);
+
+        test_integer_literal(infix_expr->left, 5);
+        CHECK(infix_expr->op == "-");
+
+        ast::infix_expr* second_infix_expr =
+            cast<ast::infix_expr>(infix_expr->right);
+        CHECK(second_infix_expr->op == "*");
+
+        ast::prefix_expr* prefix_expr =
+            cast<ast::prefix_expr>(second_infix_expr->left);
+
+        CHECK(prefix_expr->op == "-");
+        test_integer_literal(prefix_expr->right, 15);
+
+        test_integer_literal(second_infix_expr->right, 3);
+    }
+
+    TEST_CASE_FIXTURE(
+        ParserFixture,
+        "Checking operator precedence with simple example"
+    ) {
+        setup("5 * -15 - 3;");
+
+        REQUIRE(program->statements.size() == 1);
+        ast::expression_stmt* expression_stmt =
+            cast<ast::expression_stmt>(program->statements[0]);
+
+        ast::infix_expr* infix_expr =
+            cast<ast::infix_expr>(expression_stmt->expression);
+
+
+        ast::infix_expr* second_infix_expr =
+            cast<ast::infix_expr>(infix_expr->left);
+        CHECK(second_infix_expr->op == "*");
+        test_integer_literal(second_infix_expr->left, 5);
+
+        ast::prefix_expr* prefix_expr =
+            cast<ast::prefix_expr>(second_infix_expr->right);
+
+        CHECK(prefix_expr->op == "-");
+        test_integer_literal(prefix_expr->right, 15);
+
+        CHECK(infix_expr->op == "-");
+        test_integer_literal(infix_expr->right, 3);
+    }
+
+    TEST_CASE_FIXTURE(ParserFixture, "Full Operator Precedence test") {
+        struct test {
+            std::string input;
+            std::string expected;
+        };
+
+        struct test tests[]{
+            {"-a * b", "((-a) * b)"},
+            {"!-a", "(!(-a))"},
+            {"a + b + c", "((a + b) + c)"},
+            {"a + b - c", "((a + b) - c)"},
+            {"a * b * c", "((a * b) * c)"},
+            {"a * b / c", "((a * b) / c)"},
+            {"a + b / c", "(a + (b / c))"},
+            {"a + b * c + d / e - f", "(((a + (b * c)) + (d / e)) - f)"},
+            {"3 + 4; -5 * 5", "(3 + 4)((-5) * 5)"},
+            {"5 > 4 == 3 < 4", "((5 > 4) == (3 < 4))"},
+            {"5 < 4 != 3 > 4", "((5 < 4) != (3 > 4))"},
+            {"3 + 4 * 5 == 3 * 1 + 4 * 5",
+             "((3 + (4 * 5)) == ((3 * 1) + (4 * 5)))"},
+        };
+
+        for (auto& t : tests) {
+            setup(t.input);
+            CHECK(program->str() == t.expected);
+        }
+    }
 }