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.
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]
Conceptually what I want is:
allowable: charset difference ['set of all chars'] [#"&" #"<"]
Help?
Gavin.
