There are two methods
First of which works as
preg_quote() is supposed to
work (except for the fact that
preg_quote() is broken before PHP 7.1.3 version, and
Pattern::quote() fixes it)...
Pattern::quote("Welcome\How are you?");
Welcome\\How are you\?
...second of which is the direct opposite:
Pattern::unquote("Welcome\\How are you\?");
Welcome\How are you?
Please, keep in mind that this is not a safe way to create patterns with unsafe characters - for that, consider using Prepared Patterns.
These two methods should be transitive, so:
$output = Pattern::unquote(Pattern::quote($input));
The contract is
$input === $output for any