Re: Squid 3.4.0.1 configurator problems

On 09/27/2013 09:39 AM, Amos Jeffries wrote:
> On 28/09/2013 3:18 a.m., Tsantilas Christos wrote:
>> On 09/27/2013 08:23 AM, Alex Rousskov wrote:
>>> Using approach (2) with flexible RE delimiter, we could write
>>>
>>> acl foo url_regex /ends[) (]/
>>> or
>>> acl foo url_regex {ends[) (]}
>>> or
>>> acl foo url_regex @ends[) (]@
>>>
>>> and it will all work without double escaping.
>>
>>
>> Alex, in the "Revised approach to fixing configuration syntax" mail
>> thread you are proposing to use "regex::" prefix for regular
>> expressions. This is required for grammar consistency.
>> This is means that the regex should like :
>>
>> acl foo url_regex regex::/ends[) (]/
>> or
>> acl foo url_regex regex::{ends[) (]}
>> or
>> acl foo url_regex regex::@ends[) (]@

Yes, IF that syntax is adopted.

> Okay Alex I think we can agree on that flexible-delimiter syntax to
> avoid escaping.
>
> I also agree with that regex:: prefix.
>
> Is there anything else we have been disagreeing on?

As far as REs are concerned, we need to decide

1) Whether we want to support the new regex:: syntax at all or keep
using spaceless REs as before (at least for now) while reserving the
regex:: prefix.

2) If we want to support the new regex:: syntax:

2a) What characters do we allow as RE delimiters? Perl allows virtually
any non-whitespace character, even #, but we probably want to be more
restrictive.

2b) Do we add support for escaping sequences? As discussed a few emails
back, that support is necessary if we want to support arbitrary REs,
which is somewhat important for automated config generators. It is also
needed for (2c).

2c) Do we add support for character sequences so that one can add
special characters and such? This also requires a form of escaping. For
example, here are some of the sequences supported by Perl (we do not
support all of them immediately, of course, but we need to reserve
\-escape if we want them in the future):

> Sequence Description
> \t tab (HT, TAB)
> \n newline (NL)
> \r return (CR)
> \f form feed (FF)
> \b backspace (BS)
> \a alarm (bell) (BEL)
> \e escape (ESC)
> \x{263A} hex char (example: SMILEY)
> \x1b restricted range hex char (example: ESC)
> \N{name} named Unicode character or character sequence
> \N{U+263D} Unicode character (example: FIRST QUARTER MOON)
> \c[ control char (example: chr(27))
> \o{23072} octal char (example: SMILEY)
> \033 restricted range octal char (example: ESC)

We could also try to abuse existing character class [[:class:]] syntax
for those. For example, we can find and replace [[:squid::octal(32):]]
sequences with a space character.

Note that (2c) applies to "strings" as well, IMO.

Alex.
Received on Fri Sep 27 2013 - 17:47:43 MDT