[REBOL] Re: Parse problem
From: volker::nitsch::gmail::com at: 9-Oct-2005 14:29
On 10/9/05, [Patrick--Philipot--laposte--net] <[Patrick--Philipot--laposte--net]> wrote:
> Hi List,
>
> As I was testing my parse function, I have found an annoying problem
> with to-block! is this a bug ? how to workaround it ?
>
> My function use teh following line
>
> remove-each w bs [not parse to-block w [url!]]
>
> And it comes that to-block do not like parens. See
>
> >> to-block "(right"
> ** Syntax Error: Missing ) at end-of-script
> ** Near: (line 1) (right
>
> So there is some kind of evaluation
> here. On the other hand, this is ok.
>
> >> to-block "(right)"
> == [(right)]
>
> This is really bothering me, when Rebol is not fun at all :(
Remember to-block needs valid rebol-code, else it is helpless.
Catch the error.
!> attempt[to-block "(bang"]
== none
!> attempt[to-block "bang"]
== [bang]
!> if u: attempt[to-block "(bang"] [url? first u]
== none
!> if u: attempt[to-block "http://yep"] [url? u/1]
== true
!> attempt[load "http://yep"]
== http://yep
!> url? attempt[load "http://yep"]
== true
Some other versions to do it:
setup: does[
s: {Go see http://www.me.org, it is
fabulous. And http://aaa.mypicture.com with my photos.
ftp://aaa.mypicture.com too}
emit: func[val][repend "" val]
]
setup
; Simplest in this case:
while[ p: find s "http://" ][
emit copy/part s p
set[url s] load/next p
emit [build-tag [a href (url)] url </a>]
]
emit s
print emit ""
; Pure parse, but which chars allowed?
setup
url-chars: charset [#"a" - #"z" #"0" - #"9" "/.:"] ; which chars?
parse/all s[
some[
s: to http:// p: copy url any url-chars (
emit copy/part s p
emit [build-tag [a href (url)] url </a>]
)
] (emit s)
]
print emit ""
; Using load/next in parse is coomplex, but still:
setup
parse/all s [
some[
s: to http:// p: (
emit copy/part s p
set[url p] load/next p
emit [build-tag [a href (url)] url </a>]
) :p
] (emit s)
]
print emit ""
; With a kind of multiple 'to, different fonts for http/ftp, for demonstration :
setup
url-chars: charset [#"a" - #"z" #"0" - #"9" "/.:"] ; which chars?
parse/all s[
some[
s: "http://" any url-chars p: (
url: copy/part s p
emit [build-tag [a href (url)] <b> url </b> </a>]
)
|
s: "ftp://" any url-chars p: (
url: copy/part s p
emit [build-tag [a href (url)] <i> url </i> </a>]
)
| s: skip (emit s/1)
]
]
print emit ""
> Ideas and workaround appreciated.
>
> --
> Ciao
> Patrick
>
> --
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>
--
-Volker
Any problem in computer science can be solved with another layer of
indirection. But that usually will create another problem.
David
Wheeler
