World: r3wp

Well, that would be up to Graham. His original description would 
seem to exclude such words.

means all uppercase?

As far as I can tell.

Yeah .. all uppercase ..

because " a: 5 capitals any capitals b:" stops at "g" and friends.

More importantly, it fails at "g" and friends, backtracks and proceeds 
to the next alternate action, some alpha.

Late, but got it. it would enclose "ABCDEF" but should ignore it 
because of the small letters..

Yup. Parse is fun.

You can drop one charset by changing [non-alpha | end] to [alpha 
end skip | end | none] .

would alpha break work?

No, that would break out of the enclosing all loop. The end skip 
will always fail and proceed to the next alternate.

capital: charset {ABCDEFGHIJKLMNOPQRSTUVWXYZ}
latipac: complement capital
rule: [
    any latipac here:
    copy token some capital there:
    (all[ 4 < length? token
        insert :there "</strong>"
        insert :here "<strong>"
        there: skip :there 16
    ])
    :there
]
parse/all/case txt [some rule]

problem is "Aa", thats aword, but notan all-uppcase-word. so it should 
be ignored.

capital: charset {ABCDEFGHIJKLMNOPQRSTUVWXYZ}
latipac:  complement capital
ws: charset { ^/^-}
rule: [
    any latipac here:
    copy token some capital there:
    opt [some ws
        (all[ 4 < length? token
            insert :there "</strong>"
            insert :here  "<strong>"
            there: skip :there 16]
        )
    ]
    :there
]
parse/all/case txt [some rule]

Fails on "aA".

The inserts are a nice touch though.

capital: charset {ABCDEFGHIJKLMNOPQRSTUVWXYZ}
ws: charset { ^/^-}
latipac: difference complement capital ws


sub-rule: [
	some capital there:
	[ws | end]
	(all[ 4 < length? copy/part :here :there
		insert :there "</strong>"
		insert :here  "<strong>"
		there: skip :there 17]
	)
]
rule: [
	any latipac 
	[	some ws here:
		sub-rule
	]|[skip there:]
	:there
]
parse/all/case txt [here: opt sub-rule some rule]

Doesn't take into account punctuation in the ws charset. This would 
fail on "HELLO, WORLD!"

left as an exercise for the reader

:-)

Of course mine doesn't handle words with apostrophes or hyphens in 
them either. Easy fix though, just add ' and - to the capitals charset.

Actually my further spec for this requires the parser to detect spaces 
between capitalised words :)

And do what?

treat the two capitalised words as one so <strong>HELLO DOLLY</strong>

What about "HELLO, DOLLY!" or such?

I think that punctuation is part of a word

For that matter, what about words in quotes?

only if capitalised

So, no difference.

I'll explain the purpose of all this.

A person is writing a text file.  It has headings which are denoted 
by caps, and terminating in ":".

But some headings are two or more words ... with the last terminating 
in ":" only.

Words inside the text, even in caps should not normally be highlighted.

that's the more complete spec.

Anyway, i have a working version now :)

Well, I hope I helped :)

Yep .. thanks all.

replace/all "</strong> <strong>" ""

What is the best description of Parse?  I would like to point some 
people to Parse as an example of the power of Rebol

reichart, I wrote one in the wikibook, don't know if it's useful.

Since you wrote one, do you know of a better one?  This is not a 
reflection on yours, but it is a great way to know what you considered 
the next best thing.

salvation from regular expressions

I may have added some the the rebol wikibook

To use the simpler of the CS terms:


Parse is a rule-based, recursive-descent string and structure parser 
with backtracking. It is not a parser generator (like Lex/Yacc) or 
compiler (like most regex engines) - the engine follows the rules 
directly. Since Parse is recursive-descent it can handle patterns 
that regular expressions wouldn't be able to. Since Parse backtracks 
it can handle patterns that ordinary recursive-descent parsers can't.


Basically, it puts the text and structure processing abilities of 
Perl 5 to shame, let alone those of the lesser regex engines.


In theory, Perl 6 has caught up with REBOL, but Perl 6 only exists 
in theory for now. By the time it becomes actual REBOL should surpass 
it (especially if I have anything to say about it).

It's pretty easy to demonstrate patterns that regular expressions 
can't handle. It's only somewhat difficult to demonstrate patterns 
that can't be handled by a recursive descent parser without backtracking 
or unlimited lookahead.


I have never run into a pattern that can't be handled by Parse in 
theory - its only limits are in implementation (available memory 
and recursion depth). I am not qualified to describe its limits. 
Still, you have to be careful about how you write the rules or they 
will trip you up.

A little dry as explanations go, I suppose. You may get better luck 
by showing some magic parse code tricks :)

Somewhat buzzy: Its a simplified compiler-compiler. Could be used 
to build a java-compiler (eg such complex syntax), but its also as 
easy as regex for simpler things. But still readable. (less buzzy: 
not always that easy due to the poorer lockahead).

Volker, it's more like it can do what a compiler-compiler can do 
without needing to compile :)

And backtracking is about the same as unlimited lookahead, but more 
powerful.

Thanks Brian, but as is the theme with questions I ask, I don't ask 
for myself, but rather that the "world" can learn what "we" know. 
 So perhaps you should add your 2 cents to Henriks, and Tom's in 
a public forum of the Wikibook.

the compiling is no big argument  as compiler-compilers are for compiled 
languages anyway ;) the point is, you can mix a grammar and actions 
for semantics easy.