Is there a way to do balanced match with std.regex?

Example (from [1]):

test -> funcPow((3),2) * (9+1)

I want to match the funcPow((3),2) bit, regardless of the depth of the expression in funcPow(*).

https://stackoverflow.com/questions/7898310/using-regex-to-balance-match-parenthesis [1]

On Tue, 15 Dec 2015 00:16:41 +0000, Jakob Ovrum wrote:

> Is there a way to do balanced match with std.regex?
> 
> Example (from [1]):
> 
> test -> funcPow((3),2) * (9+1)
> 
> I want to match the funcPow((3),2) bit, regardless of the depth of the
> expression in funcPow(*).
> 
> https://stackoverflow.com/questions/7898310/using-regex-to-balance-
match-parenthesis
> [1]

I don't think so.

std.regex looks like it implements only a deterministic finite automaton, whereas what you are looking for requires a push-down automaton. It just so happens that a few popular regex libraries implement PDAs rather than DFAs (and have associated changes to their regex syntax to make it work, albeit inelegantly).

On Tuesday, 15 December 2015 at 01:07:32 UTC, Chris Wright wrote:
> I don't think so.
>
> std.regex looks like it implements only a deterministic finite automaton, whereas what you are looking for requires a push-down automaton. It just so happens that a few popular regex libraries implement PDAs rather than DFAs (and have associated changes to their regex syntax to make it work, albeit inelegantly).

Thanks, that makes sense.

String manipulation in D without regex is pretty nice anyway, so it's not a big loss.

On Tuesday, 15 December 2015 at 01:29:39 UTC, Jakob Ovrum wrote:
> Thanks, that makes sense.
>
> String manipulation in D without regex is pretty nice anyway, so it's not a big loss.

There is a library named Pegged which can match against balanced parens:

https://github.com/PhilippeSigaud/Pegged

On Tuesday, 15 December 2015 at 00:16:41 UTC, Jakob Ovrum wrote:
> Is there a way to do balanced match with std.regex?

It's only possible with (?R) implemented: http://php.net/manual/en/regexp.reference.recursive.php
But there is no (?R) in D regex implementation.

On Tuesday, 15 December 2015 at 02:35:34 UTC, Xinok wrote:
> On Tuesday, 15 December 2015 at 01:29:39 UTC, Jakob Ovrum wrote:
>> Thanks, that makes sense.
>>
>> String manipulation in D without regex is pretty nice anyway, so it's not a big loss.
>
> There is a library named Pegged which can match against balanced parens:
>
> https://github.com/PhilippeSigaud/Pegged

Pegged is amazeballs.
Can build some v cool things with it. Particularly with some CTFE abuse!