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Re: SRFI-115 issues

This page is part of the web mail archives of SRFI 115 from before July 7th, 2015. The new archives for SRFI 115 contain all messages, not just those from before July 7th, 2015.

Alex Shinn scripsit:

> I actually need to separate the features better because things like
> "non-greedy" repetitions can actually be supported by non-backtracking
> implementations, "if" is just a shortcut for "or" with a look-ahead,
> and I have to think about whether it's possible for atomic/commit to
> be supported without backtracking.
> Ultimately with a little effort everything can be supported.  One
> trick to support backreferences in DFA impls is to replace them with
> .* and use post-processing to verify.  So it's more a matter of what's
> readily available, not what's possible.

In that case I think there should be a unified system and the feature
mechanism should be abandoned.

Editorially, you shouldn't say that backreferences are prohibitively
expensive: if you need them, you need them.  Just drop "prohibitively".

You escaped them by the will-death              John Cowan
and the Way of the Black Wheel.                 cowan@xxxxxxxx
I could not.  --Great-Souled Sam                http://www.ccil.org/~cowan