I'm using Perl for this regular expression question, but it would be good to know if it applies to PHP, as well.
I need to comment out all print statements or all things that start with print in a PHP file. It looks something like this:
<?php
// Description of file
...
print("Foobar");
// print("Foo");
//print("bar");
// Open and print file
function printtemplate($file) {
...
}
...
printtemplate($file);
...
?>
To start with, I formulated a regular expression like this:
((?<!function )|(?<!//))print
It obviously does not work because the | is an OR. I'm looking for an AND so that both negative look-behind assertions need to be true. Does the AND construct exist in some form in regular expressions or is there a way to simulate one?
Ultimately, I want the php file to look like the following, after the regular expression is applied:
<?php
// Description of file
...
//print("Foobar");
// print("Foo");
//print("bar");
// Open and print file
function printtemplate($file) {
...
}
...
//printtemplate($file);
...
?>
Any help would be appreciated. Thank you.
Just put them next to each other. That's it. It will create AND effect, since you need to pass both look-around before being able to match anything that comes after them.
In your case, it would be:
(?<!function )(?<!//)print
However, note that the regex above will return false positive, which causes more comments to be added than necessary. Demo.
For PCRE (used in PHP), look-behind assertion requires the pattern to be strictly fixed-length, so it is not possible to use look-behind assertion to check in all cases whether print is being commented out or not to exclude it. @mpapec's answer gives one solution that is applicable for well-written code, and has better coverage than your regex with look-behind.