[Ur] Regular expressions DSEL?

[Artyom Shalkhakov]

Hello all,

2017-02-23 21:55 GMT+06:00, Artyom Shalkhakov <artyom.shalkhakov at gmail.com>:
> Hello Benjamin, Ziv,
>
> I wrote a very rough approximation to the idea that Ziv proposed, here's
> the code (currently, it does not do much):
>
> https://github.com/ashalkhakov/urweb-regex/tree/typed-regex
>
> At first I was thinking that it would be better to introduce named groups,
> but now I'm wondering how to handle positional groups, instead?
>
> Tangentially, I also noticed that JS does not handle capture groups mixed
> with repetition, e.g.
>
> 'xabxabxab'.match(/(xab){3}/) // or with /(xab)*/
>
> gives: ["xabxabxab", "xab"] (would it be worth it to try to rule out cases
> like this statically? probably not?)
>

I guess I figured it out. The idea is to keep track of index for every
group as well as the total count of groups in a regular expression.
Then, when constructing a capture:

> capture [#Name] E

the group indexes in E get incremented by 1, a new group is added:
{Name=0}, and the total count of groups is increased by 1.

Similarly, when concatenating two expressions in

> concat E1 E2

the group indexes in E2 will all get incremented by N, where N is the
count of groups of E1.

I think it should work.

>
> 2017-02-21 21:21 GMT+06:00 Benjamin Barenblat <bbaren at mit.edu>:
>
>> On Mon, Feb 20, 2017 at 10:27 PM, Artyom Shalkhakov
>> <artyom.shalkhakov at gmail.com> wrote:
>> > Thank you for the pointer. I guess creating a new package that depends
>> > on
>> > urweb-regex is the way to go.
>>
>> I’m also happy to merge changes to urweb-regex. I think a richly-typed
>> API like the one you’re looking for would be quite valuable in the
>> regex library.
>>
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>
>
>
> --
> Cheers,
> Artyom Shalkhakov
>


-- 
Cheers,
Artyom Shalkhakov