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Index > Macroinstructions > How to get ' ' symbol in match?

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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
Is it possible to get ' ' character in match directive? Like so:
Code:
match a b, 2 2    

works OK, but if you write
Code:
match a b, 2+2    

works also, and I don't want it.. I want it to work ONLY when you put a space character, not any symbol. It seems the only way to do it is to check all the other symbols, and if it's false, then try with ' ' symbol.. It's quite a big overhead. Just wanted to know if it's possible.

Code:
false equ
define expr 2 2
irps symbol, ListOfSymbols  ; ListOfSymbols is +-<> ....
{
  match a#symbol#b, expr \{
   restore false
   define false +  ; just to signal it's false Smile
  \}
}

match , false {
 match a b, expr \{
  ; it worked
 \}
}    


Now, if you define expr 2+2 it will not work anymore, which is good.. sure, I also have to check separately for = and , symbols (since they must be preceeded by =), but I think you get the point.

Is it possible to do it in match directly? Thanks Smile


Last edited by Borsuc on 04 Jan 2006, 13:12; edited 1 time in total
Post 04 Jan 2006, 12:52
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7782
Location: Kraków, Poland
Tomasz Grysztar
For preprocessor the blanks are already non-existing (like the comments), the "2 2" is for preprocessor the sequence of two symbols just like "2+2" is the sequence of three (undistinguishable from "2 + 2").
If you want just two symbols, use "irps" and limit it to two first ones.
Post 04 Jan 2006, 13:01
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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
How can you limit it to first 2 symbols? does % work here (I think it works only for assembler).


maybe I'll need this: how to tell where a space ' ' has occured? Like

alpha beta
alpha+ss beta

and match to make it work, variable 1 contains alpha+ss and variable 2 beta? still, not even my previously posted macro will work Confused

If I do this:

match var1 var2

it will put alpha in var1 and ss in var2, which of course, it's not what I intended.

just wanted to know if it's possible to do it in some 'trick' or maybe something else. thx again

EDIT: oops, sorry.. I wrote the first code wrong.. It should've been match , false, not match +, false.. sorry Embarassed
Post 04 Jan 2006, 13:10
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7782
Location: Kraków, Poland
Tomasz Grysztar
Well, actually I perhaps misguided you a bit. To get the two symbols it's better to use just a few matches. Like:
Code:
define expr 2+2
match car cdr, expr 
{ define a car 
  define b cdr }
match car cdr, b
{ --error -- } ; more than two symbols    



And note once more: for preprocessor there are no spaces, "alpha+ss beta" is the sequence of "alpha", "+", "ss" and "beta" symbols, it doesn't matter whether there were some additional spaces between them or not.
Post 04 Jan 2006, 13:30
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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
Now it works.. why define a car? seems it not used.

thanks for the tip. I understand it better Smile
Post 04 Jan 2006, 13:33
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7782
Location: Kraków, Poland
Tomasz Grysztar
Well, you did "match a b" initially, so I defined the "a" and "b" symbols in this example.
Post 04 Jan 2006, 14:57
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Borsuc



Joined: 29 Dec 2005
Posts: 2466
Location: Bucharest, Romania
Borsuc
Ok, got it. Thanks Very Happy
Post 04 Jan 2006, 15:01
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Reverend



Joined: 24 Aug 2004
Posts: 408
Location: Poland
Reverend
Tomasz: Wouldn't it be better to make preprocessor work for symbols only separated with space? Coder can always write match '2 + 2' instead of '2+2'. It would be much easier and IMHO more intuitive. You would always know that '2+2' is one symbol and we would need no such (IMO) messy solutions to distinguish symbols.
Post 04 Jan 2006, 16:46
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Tomasz Grysztar



Joined: 16 Jun 2003
Posts: 7782
Location: Kraków, Poland
Tomasz Grysztar
Better or not, it would require completely different preprocessor philosophy, thus writing something completely different than flat assembler is now.

Also note that for assembler "2+not 2" is also a single token (single numerical expression). And for preprocessor it's just four tokens.
Post 04 Jan 2006, 17:08
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