World: r3wp

It wouldn't have to be industrial-strength, but it would like a security 
blanket for developers experimenting with the new language. PCRE 
is found all over the place in languages on Linux machines, and the 
absence makes some developers uncomfortable - despite the fact that 
Parse is better.

yea but then rebol programs would start getting comtaminated with 
unfriendly gobbeldy gook and rebol developers would have to learn 
pcre

Good point. One article I was thinking would be along the lines of 
a "phrasebook", translating PCRE concepts to Parse equivalents.

sometimes it is just is too hard to get parse working ...an alternative 
would be nice

What about a parse rule that takes pcre strings as input and produces 
a parse rule as output?

I've got this rule to parse email headers which only works some of 
the time.

				header-rule: [
					thru "^/Date:" copy m-date to newline |
					thru "^/From:" copy m-from to newline |
					thru "^/Subject:" copy m-subject to newline |
					thru "^/To:" copy m-to to newline |
					thru "^/Return-path: "
				]
				m-subject: m-date: m-from: m-to: none

				parse header [some header-rule]

I am not totatly against REs I use them all the time in shells, and 
having them built in would make writing "work alike" programs easier 
but over all , it  seems to me like a step down

(you can garuntee the order in which the header lines come?

No, order may vary.

no, that's why I use  "some"

but it will only work when order is the same

I was under the impression that it would keep applying the rule ...

thru "^To:"  is thru to even if you bypass other valid lined to get 
there

So how would he say "Any of these in any order?"

you should only go 'thru the common line start. try something like:
header-rule: [
    "Date:" copy ... to newline |
    "From:" copy ... to newline |
...
]
parse header [some [thru "^/" header-rule]

I will be a few to make concreat but basicly you work with what is 
common to all lines , in this case colons and newlines

Hmm.  Works so far :)

sorry, I missed a problem in this expression: the header must start 
with a newline, so
parse header [header-rule some [thru "^/" header-rule]]
is better

might have to be careful if you want the first line

ahh

got you caught it

Ahh...well, invariablly the first line of the header is "Return-path:" 
so i'ts not a problem.

invariable because if it's not there, I add it!

Thanks, I should asked much sooner rather than struggling with it.

what about when you get novel headders? do you care?

no, these are the ones I display when reading an email ...

If the user requests full header display, I just show them raw.

I need the "^/... as nowadays, there's email coming thru with authentication 
signatures that contain the headers in a block

so once you have done some header-lines  and got the ones you are 
interested in you skip the rest with thru "^/^/"

actually, I copy the header  and body out first and process them 
separately.

parse msg [ copy header thru {^/^} copy body to end ]

actually I use this: parse msg [copy header thru {^M^/^M^/} copy 
body to end]

the last line matching rule in  header-rule  should be   |  to newline

sorry?

to not break out of the rules before you reach the end of the header

if you came accross a novel header line before you came across  the 
To: line you would not get to the To: line

header-rule: [
					thru "Date:" copy m-date to newline |
					thru "From:" copy m-from to newline |
					thru "Subject:" copy m-subject to newline |
					thru "To:" copy m-to to newline
				]
				m-subject: m-date: m-from: m-to: none

				parse header [header-rule some [ thru "^/" header-rule]]

that's what I have at present ...

just making it explicit

I should remove those "thru"s I've got there.

this header-rule should now be applied each time I get  a "^/" ...

and if you had a header with a line that did not begin with  'Date, 
From, Subject or To  then you could prematurely break out of header-rule 
 before you got all your bits

How ?

header-rule: [
    "Date:" copy m-date to newline |
    "From:" copy m-from to newline |
    "Subject:" copy m-subject to newline |
    "To:" copy m-to to newline |
    to newline
]
m-subject: m-date: m-from: m-to: none

parse header [header-rule some [ thru "^/" header-rule]]

oh, I see ...

else
Date: ...
X-Something: ...   ; break the rule
To: ...
From: ...

If you are testing "^/" I would think that you need to use parse/all.


You may find my script helpful for visualising the effect of your 
rules:


http://www.rebol.org/cgi-bin/cgiwrap/rebol/documentation.r?script=parse-analysis-view.r

oops - you're right, I missed the big one.

so, is PCRE easier to understand ??

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