World: r3wp

Many of the requests here would be handled easily by the extensions 
we proposed last year.

it looks like that 3.0 won't have a new parse, but i don't have any 
details and i'm just guessing.

it's also true that some requests could be implemented rather easily... 
so maybe they can make it in for the first release.

Does that imply there won't be a Unicode Charset with which to parse 
unicode strings?

There is going to be a unicode! datatype

sorry.  Didn't finish...hit wrong key...


but I'm not sure what that means for charsets

Perhaps vector! will play a part in solving the unicode problem

having Unicode datytype does not mean we have unicode datatype ;-)

you can make a bitset with 65000 bits in r2... so why not in r3?

Gabriele - how do you create unicode (mostly 16bit, or varrying) 
charset in R2? :-)

btw - pity R3 does not integrate any parser helpers, which could 
make life easier

what do you mean by "does not integrate" and by "parser helpers"?

helpers = suggestions ... historically there were 2 or 3 lists with 
various suggestions, to some of them even Carl said he could consider 
to add them. First one was Robert's site, next one was yours, and 
several times ono various altme channels?

I don't know, as for me, I just wanted to|thru [a | b | c] :-)

I would let others more skilled parse gurus to raise their wishes 
...

petr, i didn't say r3 won't improve on parse, i said that the first 
release may not have the new features.

we won't stop at 3.0... there will be a 3.1 and so on... at least 
we hope so :)

(lost my connection yesterday night and the message i was typing...)

parsing utf-8 in r2 is easy. utf-16 and utf-32 are less confortable 
but should be easy too.

of course with r3 it's much easier because - i guess - you can just 
parse the unicode! string.

Is it possible to combine two bitset!s?

using  'union

great, thanks!

Is there some way to make this work: parse "aaa" [some "a" "a"] or 
PARSE just don't work this way?

What do you mean?
>> parse "aaa" [some "a"]
== true

Why the second "a"?

It may seem strange I know, but this is automaticaly created rule

Parsing for [some "a" "a"] will return false, because you've already 
parsed past the "a"s.

OK I need to find some other way :) Is it possible to go back in 
parse? -1 skip doesn't seem to work.

I was thinking the same. I seem to remember, that at some time (some 
version of REBOL), -1 skip did work!? Hmm...

Wasn't it just proposed for R3?

A clumsy way of doing it:
>> parse "aaa" [some "a" p: (p: skip p -1) :p "a"]
== true

OK thanks, that may help

That's not so clumsy. You want to backtrack and that's what you're 
doing.

obviously you could use (p: back p)

Even better. Thanks Anton. Seems that "-1 skip" should not be that 
hard to implement

parse "aaa" [some [p: "a"] :p "a"]

I think this needs (p: back p) before :p.

Not in my version. The p is set before the position advances past 
the "a", so it is already back.

The p is reset before "a" is consumed - that is why I put [p: "a"] 
in [].

So why it does return 'false here? p is empty on :p.

Interesting. It seems to be setting the last p before it fails on 
the last iteration of "a".

Clearly I need a temporary.

parse "aaa" [some [p1: "a" (p2: :p1)] :p2 "a"]

I have done this sort of thing before.

temporary, or step back

A temporary will work better with parts of unknown size, and be faster 
too.

OK

Still, you might want to apply rewrite rules to your generated parse 
rules - that code seems a little sloppy.

Peephole fixing?

rewrite rules?