added parsing of if statements

test/parser/if.cpp

@@ -0,0 +1,94 @@
+#include "ast/expressions/if_then_else.hpp"
+#include "ast/expressions/infix.hpp"
+#include "ast/statements/block.hpp"
+#include "ast/statements/expression.hpp"
+#include "utils.hpp"
+
+#include <doctest.h>
+
+TEST_SUITE("Parser: if") {
+    TEST_CASE("Malformed if then else (checking for memory leaks)") {}
+
+    TEST_CASE_FIXTURE(ParserFixture, "Parse well formed simple if ") {
+        setup("\
+if (x > 15) {\
+    return x;\
+}\
+");
+        REQUIRE(program->statements.size() == 1);
+        CHECK(program->statements[0]->token_literal() == "if");
+
+        ast::expression_stmt* expr_stmt =
+            cast<ast::expression_stmt>(program->statements[0]);
+
+        ast::if_then_else* if_stmt =
+            cast<ast::if_then_else>(expr_stmt->expression);
+
+        // condition
+        ast::infix_expr* cond = cast<ast::infix_expr>(if_stmt->condition);
+        test_infix_expression(cond, "x", ">", 15);
+        CHECK(if_stmt->condition->str() == "(x > 15)");
+
+        // consequence
+        REQUIRE(if_stmt->consequence->statements.size() == 1);
+        ast::return_stmt* ret_stmt =
+            cast<ast::return_stmt>(if_stmt->consequence->statements[0]);
+        test_identifier(ret_stmt->value, "x");
+        CHECK(if_stmt->consequence->str() == "{return x;}");
+
+        // alternative
+        CHECK(if_stmt->alternative == nullptr);
+
+        // full string
+        CHECK(if_stmt->str() == "if (x > 15){return x;}");
+    }
+
+    TEST_CASE_FIXTURE(ParserFixture, "Parse well formed if then else") {
+        setup("\
+if (x < 5) {\
+    return 15;\
+} else {\
+    let b = 1;\
+    return x;\
+}\
+");
+        REQUIRE(program->statements.size() == 1);
+        CHECK(program->statements[0]->token_literal() == "if");
+
+        ast::expression_stmt* expr_stmt =
+            cast<ast::expression_stmt>(program->statements[0]);
+
+        ast::if_then_else* if_stmt =
+            cast<ast::if_then_else>(expr_stmt->expression);
+
+        // condition
+        ast::infix_expr* cond = cast<ast::infix_expr>(if_stmt->condition);
+        test_infix_expression(cond, "x", "<", 5);
+        CHECK(if_stmt->condition->str() == "(x < 5)");
+
+        // consequence
+        REQUIRE(if_stmt->consequence->statements.size() == 1);
+        ast::return_stmt* ret_stmt =
+            cast<ast::return_stmt>(if_stmt->consequence->statements[0]);
+        test_integer_literal(ret_stmt->value, 15);
+        CHECK(if_stmt->consequence->str() == "{return 15;}");
+
+        // alternative
+        REQUIRE(if_stmt->alternative != nullptr);
+        REQUIRE(if_stmt->alternative->statements.size() == 2);
+        ast::let_stmt* let_stmt =
+            cast<ast::let_stmt>(if_stmt->alternative->statements[0]);
+        test_identifier(let_stmt->name, "b");
+        test_integer_literal(let_stmt->value, 1);
+
+        ast::return_stmt* ret_stmt2 =
+            cast<ast::return_stmt>(if_stmt->alternative->statements[1]);
+        test_identifier(ret_stmt2->value, "x");
+        CHECK(if_stmt->alternative->str() == "{let b = 1;return x;}");
+
+        // full string
+        CHECK(
+            if_stmt->str() == "if (x < 5){return 15;}else{let b = 1;return x;}"
+        );
+    }
+}