[REBOL] Re: 'Parse is peculiar! - more details
From: ingo:2b1 at: 14-Dec-2000 13:53
Hi Brett,
here's my take, assuming that "<WON:" is sure not to be in the name-string
(and it is the only thing you can be sure about ...
line1: {Lets find "Ju<l>ie<1234><WON:90966776>"}
main-rule: [ (next-part: "") thru {"} copy name to {<} some sub-rule to end ]
sub-rule: [ "<WON:" (print name) to end
| (if next-part <> "" [append name join "<" next-part] ) skip copy next-part to "<" ]
>> parse line1 main-rule
Ju<l>i<97868769>
OK, what do I do?
in main-rule first create an empty-string next-part (no copy needed, as the
string is not changed, the word gets assigned to new strings later on)
Up to copy name it's the same as before, but then we go into the sub-rule.
when entering sub-rule we are right before the "<" so we can test if it is
<WON:
by chance, if it is, w're done, print the name, and go to the end.
If it's not "<WON:" we first test if next-part is still "" (first pass) and
we either do nothing, or append a "<" and next-part to the name", then we
skip over the "<" (remember? that's where we entered the sub-rule!) and then
we copy the next-part of the name to the next "<" the rule ends here, but
we've told parse to check this rule multiple times (some), so we just reenter
the sub-rule ...
I hope this helps,
Ingo
Once upon a time Brett Handley spoketh thus:
> > L 09/22/2000 - 15:37:25: "*`Ultimate_Master`*<4718>" <WON:26073391>"
> connected, ip
> > "202.54.232.2"
> > L 09/22/2000 - 15:43:10: "[IMPREA]Smart-Gun!!<4723><WON:23014199>"
> connected, ip
> > "220.34.24.3"
> > L 09/22/2000 - 15:47:30: "{[FrAg]}-MaN-<4727><WON:19220729>" connected, ip
> "132.76.43.24"
> >
> > L 09/22/2000 - 15:49:22: "<Usyd> H4XX0R<124><WON:20007739>" connected, ip
> "160.34.64.112"
> >
> > As you can see the game appears to impose few restrictions on the range of
> characters and
> > spaces allowed in a name. It's also a stupid log format.
>
> Hmm. I agree really ugly log format...
>
> It really isn't the best example for getting confident on parse.
>
> But I can see it would be really good to get it to work :)
>
> >Therefore I need the
> > following behavoir from 'parse:
> >
> > go thru {"} then copy all text to name until the UID pattern "< some
> digits >" is found.
> > I don't want the UID included in 'name though. In the lines above that
> would mean 'name
> > is set to "*`Ultimate_Master`*", "[IMPREA]Smart-Gun!!", "{[FrAg]}-MaN-"
> and "<Usyd>
> > H4XX0R" respectively.
> >
> > I don't want to go thru the UID I want to go 'to it, but still get a 'true
> result.
>
> Is that log line you gave for Ultimate_Master accurate? There seems to be a
> double-quote after the UID.
>
> The problem that I can see is that somebody might have a name like <4444>.
> They might get really wierd and do something like <4444><4444> as a name as
> well.
>
> The only consistency I can see for determining what is really after the name
> is the string that starts <WON:
>
> So I reckon on the basis of what I've seen, the only way to get the name
> accurately is to find the UID accurately and to do that requires searching
> backwards from before the <WON: for a <UID>.
>
> The problem here is parse won't do this neatly in one go.
>
> One idea then is to get parse to caputure from the beginning of the name
> throught to the <WON and then call itself to process the internal bit - my
> worry with this is to know if parse is reenterant or not.
>
> Or better use parse to do as before but instead of calling itself, use find
> instead. I know you are trying to avoid find, but it may actually be the
> simplest to code and understand.
>
> Alternatively you could probably get parse to backtrack in a fashion by
> creating a truly evil parse rule. I managed to do this once but as I said -
> it is truly evil (modifies the input stream and other horrors). :)
>
> Anyway I'll wait to hear your thoughts and to find out if that double-quote
> was real or not.
>
> Brett.
>
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