World: r3wp

doc1: "start A 1 end start B 2 end"  how can you get value of  2 
out

It works with a because it's first , but becasuse it enters the "parse" 
with it and then doesn't match it doesn't again test the B 

>> parse doc1 [ "start" "A" copy R to "end" (print R) to end ]
 1
== true
>> parse doc1 [ "start" "B" copy R to "end" (print R) to end ]
== false

I thought it will recheck if I put it into something like SOME [ 
] but it doesn't 


parse doc1 [ SOME [ "start" "B" copy R to "end" (print R) to end 
] ]

Maybe ? parse/all doc1 [ thru "B" copy number to "end" (print number) 
]
But I'm beginning with parse, so I'm not an expert

This would work in this case but I need to get "2" only if sequence 
before it is exactly previous two "start" "B" XX "end" ...  there 
can be "B" in other places of the string and it musn't take that 
(I am used on using thru and to too but I musn't use them in this 
case for this reason as it might just skip to some "B"

>> doc1: "start A 1 end xyz B 2 end" ;; in this case it must not 
take 2
== "start A 1 end xyz B 2 end"

>> parse doc1 [ "start" thru "B" copy R to "end" (print R) to end 
] ;; but it will that's why I can't u
se to\thru
 2
== true

some ["start" ["A" | "B"] copy R to "end" "end"]

ups ... my example above is wrong .. just a sec

no, hang on...

Anton this would  return me 1 probably ?

(this is the right example .. I forgot to use thru above so second 
wouldn't pass anyway... but result is the same)

>> doc1: "start A 1 end start B 2 end"
== "start A 1 end start B 2 end"

>> parse doc1 [ thru "start" "A" copy R to "end" (print R) to end 
]
 1
== true

>> parse doc1 [ thru "start" "B" copy R to "end" (print R) to end 
]
== false

>> parse doc1 [ SOME [ thru "start" "B" copy R to "end" (print R) 
to end ] ]
== false

Is there anything expected between "start" and "A", for instance 
?

I know how to solve this by making it less robust (in this case relying 
that there is only one space between) but this doesn't solve my problem 
well 

>> parse doc1 [ thru "start B" copy R to "end" (print R) to end ]
 2
== true

No need for that.

1 or more spaces (to your question)

parse doc1 [some [thru "start" ["A" | "B"] copy R to "end" (?? R) 
"end"]]

hm.. just a sec so I try few things

PARSE without the /ALL refinement handles any amount of whitespace. 
(You will probably end up using parse/all, though. I usually do when 
parsing HTML.)

Your solution, I thought it won't work if I reverse order of A and 
B in the string but it seems it does.  I would need to know which 
one is A and B but I think this can be solved by setting some word 
( ) inside [ A | B] ...  so basically it seems to work... I think 
I can apply this way also to my concrete problem which is this

I don't understand why not simply : 

parse/all doc1 [ thru "start B" copy number to "end" (print number) 
]

You leave the pointer at beginning of "end" in the doc1 string. Look 
at my example, I move TO "end", then I also consume "end".

... to "end" (?? R) "end"]

kib2: becasue I don't know how many spaces are between start and 
B .. and in my concrete case I need to have multiple rules.. I will 
show concrete example

The second one actually consumes the "end", moving the pointer (the 
current parse index) through it.

Anton: Janko just said he wanted to extract the "2", so I don't care 
wheter the pointer is, no ?

Mmm.. probably true, but better to be neat and tidy with rules, then 
they can be reused in slightly different ways and still work as expected.

kib... because in concrete I think I need *complex rules* not just 
1 string for it to work .. it has to work on all sorts of pages written 
by anyone.. you will see once I show you real example .. right now

First define whitespace:
whsp: charset " ^-^/" ; Whitespace: space, tab, newline.

Ok, and if we define any space like this :

space: charset " ^-"

parse/all doc1 [ thru "start" any space thru "B" copy number to "end" 
(print number) to end]

( I need to parse meta tags description and keywords and abstract 
if they exist -- they can come in any order, there can be one or 
multiple spaces/newlines/tabs between tag arguments, there can be 
" or '  used as argument="asdasd" )
>> doc2: {<head>

{    <title>Dragonicum.com - making the right business connections 
!</title>

{    <meta name="keywords" content="Company Directory, Join Us, Advanced 
Search, Trade Leads, Forum, Trade S

{    hows, Advertising, Translation, fair trade, trade portal, business 
to business, trade leads, trade even
{    ts, china export, china manufacturer" />

{    <meta name="description" content="New international trade portal 
and company directory for Asia, Europe

{     and North America. Our priority No.1 is to create and maintain 
a safe, well lit business-to-business m

{    arketplace, by assisting our members in identifying new trustworthy 
business partners!" />

{    <link rel="stylesheet" href="style/blue_main.css" type="text/css" 
/>}
== {<head>

<title>Dragonicum.com - making the right business connections !</title>
<meta name="keywords" content="Company Directory...


>> T: "" parse doc [ thru "<meta" "name=" skip "keywords" skip "content=" 
m: skip (m1: first m ) copy T to m1  to end ] print T

Company Directory, Join Us, Advanced Search, Trade Leads, Forum, 
Trade Shows, Advertising, Translation, fair trade, trade portal, 
business to business, trade
leads, trade events, china export, china manufacturer

>> T: "" parse doc [ thru "<meta" "name=" skip "description" skip 
"content=" m: skip (m1: first m ) copy T to m1  to end ] print T

>>

( as you see because keywords are first it works for them , but doesn't 
for description , they can be in different order in other document 
etc)

I can't just use {<meta name="keywords content="} as rule because 
that would work just on some pages that use exactly one space and 
"

Yes, I know this problem.

I have been banging my head agains it for half of day :) .. now at 
least I know what exactly is the problem.. why it happens.. at first 
I had no clue.. but still have no idea how to solve it

I have solved similar parse job...

maybe your solution for A | B would work.. I will try

ha, yes it works .. briliant!

it does ?

yes :) thanks a lot!

>> T: K: D: "" parse doc [ SOME [ thru "<meta" "name=" skip [ "description" 
(V: 'D) | "keywords" (V: 'K)] skip "content=" m: skip (m1: first 
m ) copy T to m1
(set V T) ]  to end ] ?? K ?? D

K: {Company Directory, Join Us, Advanced Search, Trade Leads, Forum, 
Trade Shows, Advertising, Translation, fair trade, trade portal, 
business to business, tr
ade leads, trade events, china export, china manufacturer}

D: {New international trade portal and company directory for Asia, 
Europe and North America. Our priority No.1 is to create and maintain 
a safe, well lit busi

ness-to-business marketplace, by assisting our members in identifying 
new trustworthy business partners!}

== {New international trade portal and company directory for Asia, 
Europe and North America. Our priority No.1 is to create and mai...
>>

it is also not dependant on the order of things which I still have 
to figure out why is that .. it works no matter which one is before 
the other

I intended to make a blogpost .. "REBOL parse challenge" and present 
this problem and ask if people can provide solutions in other languages 
that would be more elgant ... (in similar note as the "arc challenge" 
... now that it seems even more hard nut to crack I should probably 
really do it .. does anyone think this would be easy to solve using 
the conventional language? (I think not)

I'm sure there are some elegant solutions in other languages too.

hm.. would this be nicely solvable with a regex? .. I think it would 
be quite a pain by using regular string functions like strpos substr 
etc... having the same requirenments (one or more spaces/tabs/newlines 
" or ' , undefined order)

I don't know - I only learn regex when I have to .. then a short 
time later I forget.

yes, me also

perl could do it pretty quick, I'm sure.

perl pro would certanly use regex (that is the initial home of it) 
:) ... I think parse and regex are best for some different problems, 
I am just not sure if this one is better solved with one or the other

regex I imagine sucks at structured stuff , where you have to make 
some sort of state machine , for example I don't think regex can 
well parse xml ... state machines are exelent at that but they do 
require more code than parse would

I will see with the "parse challenge" .. if I would want to be really 
*sneaky* I could ask if anyone can solve this in perl comunity .. 
and if their solution would suck more than rebol's then make the 
blogpost  :)

but I am not like that ;)