On Sun, 31 Oct 1999 [EMAIL PROTECTED] wrote:
>
> Lookin' for help again...
>
> I am building up a parser for XML, and now that I know how to use 'parse' it
> is actually a straightforward matter of taking the production rules out of
> the XML spec and putting them in Rebol.
>
> But I need to be able to test that a string conforms to a set of characters.
> For instance, that a string contains any valid character except some special
> characters which are not allowed un-escaped in XML, like ampersand and
> less-than.
Just in case you didn't know, there already is an XML parser in
Rebol. :-) (but it's not a validating parser)
>> help parse-xml
Parses XML code and returns a tree of blocks.
Arguments:
code -- XML code to parse (string)
> It feels like there should be an easy way to build a charset, and them maybe
> do arithmetic on it using 'difference'.
>
> You know how you can do this...
>
> allowable: charset [#"A" - #"Z"]
>
> well I really want to be able to something do this:
>
> allowable: charset [#00 - #FF]
>
Try this:
>> charset [#"^(00)" - #"^(FF)"]
> Conceptually what I want is:
>
> allowable: charset difference ['set of all chars'] [#"&" #"<"]
>
Something like this?
>> difference charset [#"^(00)" - #"^(FF)"] charset [#"&" #"<"]
Or even easier:
>> complement charset [#"&" #"<"]
/Martin Johannesson, [EMAIL PROTECTED]
