[squid-dev] RFC: Adding a new line to a regex

[Amos Jeffries]

On 21/01/22 07:27, Eduard Bagdasaryan wrote:
> I would concur with Alex that (4) is preferable: It does not break old 
> configurations, re-uses existing mechanisms and allows to apply it only 
> when/where required. I have one more option for your consideration: 
> escaping with a backtick (e.g., `n) instead of a backslash. This 
> approach is used, e.g., in PowerShell.
> 
> 5a. Recognize just `n escape sequence in squid.conf regexes.
> 
> 5b. Recognize all '`'-based escape sequences in squid.conf regexes.
> 
> Pros:  Easier upgrade: backtick is rare in regular expressions (compared 
> to '%' or '/'), probably there is no need to convert old regexes at all.
> Pros:  Simplicity: no double-escaping is required (as in (1b)).
> Cons: Though it should be straightforward to specify common escape 
> sequences, such as `n, `r or `t, we still need to devise a way of 
> providing arbitrary character (i.e., its code) in this way.
> 

You are mixing up different features offered by several of the *many* 
different languages people call "regex".

Squid regex patterns are written in GNU Regular Expression language. 
None of those commonly expected things are features in that ancient 
language.


Amos