fix: added new ast type and moved parsing functions to a different header

src/parser/parsing_utils.c

@@ -0,0 +1,35 @@
+struct ast *parse_simple_command(void)
+{
+    struct list *cmd_elements = NULL;
+    char *token = pop_token();
+    if (token == NULL) // just in case ?
+    {
+        puts("Internal error: cannot get the following token");
+        return NULL;
+    }
+
+    while (token != NULL && !isterminator(token[0]))
+    {
+        cmd_elements = list_append(cmd_elements, token);
+        token = pop_token();
+    }
+
+    if (token == NULL)
+    {
+        puts("Internal error: cannot get the following token");
+        return NULL;
+    }
+
+    struct ast *result = ast_create_cmd(cmd_elements);
+    return result;
+}
+
+struct ast *parse_if_rule(void)
+{
+    return NULL;
+}
+
+struct ast *parse_shell_command(void)
+{
+    return parse_if_rule();
+}