[Pmwiki-users] Re: null characters or pattern breaking characters

[Christian Ridderström]

On Wed, 14 Jan 2004, Patrick R. Michaud wrote:

> > On Mon, 12 Jan 2004, Patrick R. Michaud wrote:
> > > 1.  It'd be really handy if the "null character" sequence began
> > > with a character that's already not considered to be part of a valid
> > > URI.  In PmWiki that set is currently
> > >         space  <  >  [  ]  "  '  (  )
> > 
> > Why would it be handy?
> 
> Because the null character could then be handled with one substitution (at 
> $InlineReplacements) instead of two.

I see, easier to implement --- although I'm not clear on the details, but 
never mind that (I'll have to read up on the internal workings of pmwiki 
soon).

But just to be on the safe side, you often refer to the URI pattern... 
are you aware that I'd like to be able to use the null token to break 
the matching of *any* pattern that looks for a specific range of 
characters?

Hmm... I wonder if I'm "breaking myself" here... would the above 
mean that this markup:

	''Here is some italic text [``[include:Main.HomePage]] bla.''

is *not* rendered in italics?

> > [...] OTOH, using some different alternative null tokens, 
> > any of these alternatives could be used:
> > 
> > token=	&NULL;			&;		    ``
> > 	[[&NULL;include:...]]	[[&;include:...]]   [[``include:...]]
> 
> I like the use of `` for a null token.  I think it would only cause
> difficulties in TeX documents that use it for leading double-quotes.

Yeah, that's my favourite ...
(I know that `` sometimes occur in Maple source files, the n:o times 
that'll occur in wiki markup should be few :-)

> &; is nice since it looks like a null character element, but has to be
> handled with two substitutions to keep it from appearing in a URI pattern.

There you go with 'two substitutions' again... ok, I guess I'll have to 
ask you to explain that...

Or is this simply equivlanet to what I wrote about first substituting 
the null token into a null-token-character, that's then removed just 
before output?

But if so, why is this bad from an implementation point of view... it 
wouldn't be that slow would it?

/Christian

-- 
Dr. Christian Ridderstr?m, +46-8-768 39 44       http://www.md.kth.se/~chr