How can PHP include or require functions be modified to include a parsed version of a file instead of the file itself?

To include a parsed version of a file instead of the file itself using PHP's include or require functions, you can use output buffering. This involves capturing the output of the included file using ob_start(), ob_get_clean(), and eval() functions.

ob_start();
include 'file.php';
$parsed_content = ob_get_clean();
eval("?>" . $parsed_content);