feat(lexer/parser): reconhecer sintaxe de if/else e gerar nós na AST

Author: Liviarodrigues1

src/lexer.l

@@ -157,6 +157,8 @@ static long long yy_parse_char_literal(const char *src)
 "return"                           { return RETURN; }
 "while"                            { return WHILE; }
 "for"                              { return FOR; }
+"if"                               { return IF; }
+"else"                             { return ELSE; }
 "true"                             { return TRUE; }
 "false"                            { return FALSE; }
 "\["                               { return LBRACKET; }

src/parser.y

@@ -50,6 +50,7 @@ static void parser_error_cleanup(AstProgram **out_program);
 %token KW_INT KW_CHAR KW_FLOAT KW_BOOL KW_VOID
 %token RETURN
 %token WHILE FOR
+%token IF ELSE
 %token TRUE FALSE
 %token PLUS MINUS TIMES DIVIDE MOD
 %token EQ NEQ LT LE GT GE
@@ -74,7 +75,7 @@ static void parser_error_cleanup(AstProgram **out_program);
 %type <param> parameter
 %type <param_list> parameter_list_nonempty parameter_list_opt
 %type <block> block
-%type <stmt> statement compound_statement declaration_statement assignment_statement return_statement expression_statement while_statement for_statement for_init_statement_opt for_post_statement_opt
+%type <stmt> statement compound_statement declaration_statement assignment_statement return_statement expression_statement while_statement for_statement if_statement for_init_statement_opt for_post_statement_opt
 %type <stmt_list> optional_statement_list statement_list
 %type <expr> expression logical_or_expression logical_and_expression equality_expression relational_expression additive_expression multiplicative_expression unary_expression postfix_expression primary_expression array_initializer expression_opt
 %type <expr_list> argument_expression_list argument_expression_list_opt initializer_list initializer_list_opt
@@ -189,8 +190,9 @@ statement
     | assignment_statement
     | return_statement
     | expression_statement
-  | while_statement
-  | for_statement
+    | while_statement
+    | for_statement
+    | if_statement
     ;
 
 compound_statement
@@ -262,6 +264,17 @@ for_statement
       }
     ;
 
+if_statement
+    : IF LPAREN expression RPAREN statement
+      {
+          $$ = ast_stmt_make_if($3, $5, NULL);
+      }
+    | IF LPAREN expression RPAREN statement ELSE statement
+      {
+          $$ = ast_stmt_make_if($3, $5, $7);
+      }
+    ;
+
 for_init_statement_opt
     : type_specifier IDENT ASSIGN expression
       {
@@ -578,4 +591,4 @@ AstProgram *c2lua_parse(FILE *input)
         return NULL;
     }
     return program;
-}
+}