Thinking about practical use cases. With the proposed changes, doing a submatch is quite overcomplicated:
(*:A)submatch(*:B)(*MOVE:A)(*SETEND:B)match-submatch-again(*MOVE:B)(*SETEND) Perhaps the other idea, use capturing brackets for this purpose could be better. Something like this: (submatch)(*match:{1}pattern) is easier. Inside the {}, a name can be presented as well. The (*MOVE) could be kept for moving the string pointer around. Let me know your opinion. Regards, Zoltan -------- Eredeti levél -------- Feladó: Zoltán Herczeg < hzmes...@freemail.hu (Link -> mailto:hzmes...@freemail.hu) > Dátum: 2019 július 29 18:51:34 Tárgy: Re: [pcre-dev] Remove some restrictions of lookbehind assertions Címzett: pcre-dev@exim.org < pcre-dev@exim.org (Link -> mailto:pcre-dev@exim.org) > > > (*SETEND:mark_name) > > - This verb changes the end position to the position recorded by the last > > mark which name is > mark_name. If the position is smaller than the current string position, it is > set to the current string > position. > By "end position" do you mean "end of subject"? I'm misunderstanding > something here because won't a MARK name usually be earlier than the > current position? Or do you envisage using this in some kind of loop? In > the interpreter, this will be easy to implement only if the MARK is > earlier on the matching path. Oh, are you thinking of something like > this? > (*MARK:A)<stuff>(*MARK:B)<stuff>(*MOVE:A)(SETEND:B)<more stuff> > That would be straightforward in the interpreter, I think. Exactly. Usually (*MOVE:A)(SETEND:B) would be in an assertion to check something which should be somewhere before, kind of a generic lookbehind assertion. Maybe we could use capturing blocks for that, which require far less text (and a bit less flexible). Anyway we should not forget about the flags (noteol and friends I think) which controls \z (and friends). Anyway before we implement anything lets discuss it. I think we can figure out something which is: - Easy to maintain: I suspect not many people will use this (at least not now), so an easier approach is less likely introduce a lot of new bugs - Flexible enough in practice: moving string pointers and do a sub-match looks a valid use case. However, since perl does not have have this feature, it is likely that very few practical use cases actually requires it. Regards, Zoltan -- ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev