World: r3wp

Anton, I used to use a character rather than a string too, because 
of the memory issue. But it turned out to be slower that way. I think 
parse only matches on strings, and single characters have to be converted 
to one-character strings before they can be passed to the matcher. 
At least that would explain the speed discrepancy.

Anton, for me it is a wrong behaviour of parse.

I also have some doubts about the corretness of this:
var: 123 probe parse/all "" [copy var ""] var; false == 123

Graham: two points of trouble
1; you loose the order of the segments with your approach, 

eg NTE can be at different positions in the message, set-id is not 
always used in the same way.

2; are you sure that the values of different laboratories can be 
compared? 
are they using the same test kits, do they do ring tests ?

I would agree with romano. Anton please reported this inconsistent 
behaviour to RAMBO.

sqlab, doesn't my last parse account for the possibility of NET segment 
being anywhere in the message ?

currently I only have data from one laboratory - I'll have to contact 
some others to get theirs to see what their messages are like.

Yes, you get the NTEs, but you do not retain the information, which 
OBR,  which OBX  they comment or if the follow even the PID.


That's why I use just one block for all segments retaining the order.

Perhaps I can get around that by instantiating a new hl7object with 
each MSH segment...

Or not ...

Brian, yes! You remind me of that finding, long ago... I now remember 
thinking how it was good because of less syntax.

Romano, I don't think it is an error anymore. Note my examples contain 
the pipe |, which allows the rule to succeed on none input. eg, these 
rules are equivalent:
[copy var "a" | none]
[copy var "a" | ]

Your example, however, looks like an edge case... Probably parse 
checks for the end of the input before trying to match a string.

The 'to position' thing, we talk about in the RAMBO group also works 
with blocks:
>> parse ["string" 123 [me-:-server-:-dagobah]] [to 2 mk: (print mk)]
123 [me-:-server-:-dagobah]
== false


TO also works with datatypes, as explained in the Core documentation:

>> parse ["string" 123 [me-:-server-:-dagobah]] [to email! mk: (print mk)]
[me-:-server-:-dagobah]
== false

(Right brackets are left out just after the email address by Altme.)

geomol, out of curiosity, have you tried those incidents where parse 
will lock up and you need to quit REBOL? Have you tried to keep it 
running for a few minutes and see what happens?

nope

just wondering if that is a known behaviour. it returns to the console 
on its own

Strange and funny. Like it has it's own personality. ;-)

after about 5-7 minutes or so...

it's in one of the examples in the wikibook group

It an almost infinite loop then. Takes all the cpu.

Yes, it reply == false after some time here too.

good, then I'm not crazy :-)

wondering if there is some sanity limit on a billion loops or something

:-) Maybe integer overflow?

possibly if there is something that needs counting...

Anyway, parse works in a certain (and you could say special) way, 
when dealing with strings:
>> parse "a" [char!]
== false
>> parse "a" [string!]
== false
>> parse "a" [#"a"]
== true
>> parse "a" ["a"]
== true

So parsing a string for [any string!] maybe doesn't make much sense.

And parsing strings and chars within blocks give more meaning, when 
looking for datatypes:
>> parse ["a"] [char!]
== false
>> parse ["a"] [string!]
== true
>> parse [#"a"] [string!]
== false
>> parse [#"a"] [char!]
== true

using datatypes as rules, I think only work with blocks, not strings, 
which is why it returns false in the first two cases with "a"

Sadly, in string mode you can't use -- to charset!

Be great if you could:
>> chars: charset "ab"
== make bitset! 64#{AAAAAAAAAAAAAAAABgAAAAAAAAAAAAAAAAAAAAAAAAA=}
>> parse "1234ab" [to chars]

** Script Error: Invalid argument: make bitset! 64#{AAAAAAAAAAAAAAAABgAAAAAAAAAAAAAAAAAAAAAAAAA=}
** Near: parse "1234ab" [to chars]

You can with a little trick:

>> no-chars: complement charset "ab"
== make bitset! #{
FFFFFFFFFFFFFFFFFFFFFFFFF9FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
}
>> parse "1234ab" [some no-chars mk: (print mk) to end]
ab
== true

Yep, that's the workaround I use, but it can get complex...

I seem to remember Carl S. saying something about adding a safety 
check to parse to jump out of infinite loops...

Hi, I am checking the example in the parse chapter, section 7.3 copying 
the output , but I don't get it !!

parse {<h1>title</h1>}  [copy heading ["H" [ "1"  |  "2"  |  "3" 
]] (print heading)]

the text seems to imply that heading should contain the "title" string, 
but it doesn't work for me. any ideas ?

It's not a good example. You could do something like:


>> parse {<H1>A heading</H1>} [copy heading ["<H" ["1" | "2" | "3"] 
">" to "</"]]
== false
>> heading
== "<H1>A heading"

yes,  this makes sense but it doesn't handle opening and closing 
tags as the example seems to imply. I'll report to rambo so the docs 
get updated

thanks

Something I will never understand about parse:  

digit: charset [#"0" - #"9"]
parse "123" [ any [ digit | end ] ]

I hit the end of the damn string, SO QUIT!  *&(%@$(*&($#*%

NM...  I got it.  Parse is tricksy.

solution?

parse "123" [ any [ digit | thru end ] ]

yeah, each rule stop at a position, not going past it. that way you 
wouldn't be able to reach the tail of the series. THRU will get you 
to the tale

tail

The problem wasn't really that I wasn't so much not hitting the end 
as it was figuring out how to keep all of my data.  I'm breaking 
up some text using a semi-dynamic set of recursive rules and I kept 
loosing my last bit of data or hanging the interpreter...

Ah, recursive rules. :) I pushed my variables onto a stack when recursing, 
then popped them off when returning.

That tends to bloat the code a fair bit. ( push-vars [a b c] recursive-rule 
pop-vars [a b c] )

so then you get to thinking to generate this code automatically with 
a make-recursive-rule function, which takes a 

parse rule, looks for recursion in it, then surrounds it with push-vars 
and pop-vars for you (kind of macro expansion).
Or I did something like that, anyway.