World: r3wp

It looks, that I could have used:

    C: [while [and [A | B] accept | skip | reject]]

Janko, charset is short for make bitset! so you can call them bitsets 
or charsets :)

Ladislav, what 'choice operator?

|

Help!  Still struggling to understand parse.  How could I replace 
any and all SINGLE occurrences of  the single-quote character anywhere 
in a string (beginning, middle or end) with TWO single-quotes?  But 
if there are already TWO single-quotes together, I want to leave 
them alone.

TIA for any and all help for a newbie!

easy, actually.  you match double quotes first then fallback to single 
quotes, adding a new one and skiping one char... 

give me a minute I should get something working...

R2?

yes, View 2.7.6 under Windows XP

>> parse/all str [ any [thru {"} [{"} | p: (insert p {"} skip) ]]]
something like this (not tested)

i think i misunderstood something, replace {"} by {'} maybe

>> str: {1 ''2 '3 4 ' '5 ''6 '7 8 9 '0'}

>> parse/all str [some [{''} | [{'} here: (insert here {'}) skip] 
| skip]]
>> print str
== {1 ''2 ''3 4 '' ''5 ''6 ''7 8 9 ''0''}

note all ticks... ( ' ) are single quote chars in the above.

same as mine, except i use THRU to speed up the process

Thanks!  I'm going to have to look @ this for awhile to understand 
why you even need to worry about the double-quote character.  Much 
to learn....

Thanks Maxim and Steeve for the prompt replies!

print it out in the rebol console... you will see that my exampe 
doesn't nave any double quote characters.. they just look like so 
in altme's font  ;-)

corrected version with thru:

>> parse/all str [ any [thru {'} [{'} | p: (insert p {'} ) skip ]]]

Ah!  when you said "...you match double quotes first then fallback 
to single quotes, ..." I was thinking double-quote character, not 
double single-quotes.  Need more coffee...

Thanks very much!

( I can see that being misleading when read hehehe :-)

Just curious, I tested both versions and Steeve's version is about 
2times faster than Maxim's :)

we should add a DONATE account somewhere, linked with Altme.

I'm sure people would be glad to add 1 dollar for such fast assistance.
Then, we could finance some interesting projects

actually, having a paypal account linked with your login and a "donate" 
button would be really nice :-)  right in the chat tool.

I sure would use it... some people have helped save days of work 
with free code and insight.

I'd gladly give back a few $ for their efforts

Jack, Parse is my fav REBOL command.  If I ever have time, this is 
the one funciton I would like to create hundreds of examples for 
in a Wiki.

newbie's solution,without  PARSE:
>> s2: {1 ''2 '3 4 ' '5 ''6 '7 8 9 '0'}

>> replace/all s2 {''} {'}     replace/all s2 {'} {''}      print 
str
1 ''2 ''3 4 '' ''5 ''6 ''7 8 9 ''0''
>> str == s2
== true

I just adopted a new notation standard for parse rules... the goal 
is to make rules a bit more verbose as to the type of each rule token... 
I find this reads well in any direction, since we encouter the "=" 
character when reading from left to right or right to left... and 
parse rules often have to be read from right to left.

example:

=terminal=: [

 =quote= copy terminal to =quote= skip (print ["found terminal: " 
 terminal])
]


on very large rules, and with the syntax highlighting in my editor 
making the "=" signs very distinct, I can instantly detect what parts 
of my rules are other rules or character patterns... it also helps 
out in the declarations... I see when blocks are intended to be used 
as rules quite instantly where ever they are in my code.


in my current little parser, I find I can edit my rules almost twice 
as fast and loose MUCH less time scanning my blocks to find the rule 
tokens, and switching them around.

wonder what you guys think about it...

another example.... in this dense block of text, I can spot the =eol= 
 (end of line) token instantly in both x and y dimensions of the 
rule paragraph:

=line-comment=: [
	=comment-symbol= [
		[thru =eol= (print "comment to end of line")]
		|[to end]
	]
	(print "success")
]

when using rules in other contexts, they also stick out...

=alphabet=: rejoin [=digit= =letter= bits "_"]


here I immediately see that bits isn't a rule, but a function or 
a word.

with syntax highlighting it's quite amazing how    bits   stands 
out. ... in my editor at least.

use color instead :)

what do you mean color?

Use an editor that colorises the words

Gab uses the == in his literate editor ..

Chuck Moore uses color extensively in his color forth .. to replace 
other types of syntactic markup.

syntax highlighting colorizes words ... stuff is colorized... but 
user words aren't colorised and they all get mixed up between functions, 
variables and rules... and having colors which are two strong next 
to each other and in relative distribution ... cancels out.

stuff is colorized... (*in my editor*)

so you could write a parser that reads your rules and colorises them 
...

without the need for all those = signs everywhere

but not while I'm coding... this is not for presentation, its for 
coding... I'm writing rules twice as fast now... just cause I'm not 
waisting time "searching" for the keywords within all of that text.

exactly ... for coding.

unfortunately what you say isn't feasible, even if you can technically 
do it.  who is going to program a parser to colorise code which is 
usefull for only one application? its actually going to take more 
time to write your  color parser for each piece of code than write 
the code itself  :-P


so bottom line, Graham doesn't like this syntax. any others care 
to comment?

Max, just do what ever suits you.

I'm just trying to get a feel for what others think about the idea. 
 and sharing a bit of a discovery at the same time, if it may help 
others. the goal isn't to be popular or convince others... and sorry, 
if my last line may have looked harsh, it wasn't.  :-)


I was just resuming your reaction plainly and  relaunching the question 
to be sure others realize I want a few opinions.

it's not a syntax  but a convention ...

true  :-)

any others care to comment?


I'm afraid t looks very messy to me and reminded me of Perl for some 
reasion.

yay,  I've got the BNF grammar done... its ripping through a C language 
BNF grammar definition...  :-)

now I've just got to make a parse rule emitter ... easy enough.

(all in R3, but not using newer parse stuff, cause its not required)

the new parse rejection system is VERY cool.    ( can simplify the 
structure of some rules a lot  :-)

For a long time I've added = to the end of my parse rules, and = 
to the beginning of parse variables. I think it matches the production 
rule grammar well, and also emulates set-word/get-word syntax.