[M3devel] m3core: TextCat.m3: MultiCat

[Rodney M. Bates]

It looks wrong to me too.  But once messing with it, how about
treeing the concatenations, something like:

; PROCEDURE MultiCat ( READONLY x : ARRAY OF TEXT ) : TEXT

   = VAR Num := NUMBER ( x )
   ; VAR Half : CARDINAL

   ; BEGIN (* MultiCat *)
       IF Num <= 0
       THEN
         RETURN ""
       ELSIF Num = 1
       THEN
         RETURN x [ 0 ]
       ELSE
         Half := Num DIV 2
       ; RETURN
           Concat
             ( MultiCat ( SUBARRAY ( x , 0 , Half ) )
             , MultiCat ( SUBARRAY ( x , Half , Num - Half ) )
             )
       END (* IF *)
     END MultiCat

It would reduce heap space overhead, allocation time, Multicat
execution time, and maybe collection time (if that has a nonzero
constant factor) from linear to logarithmic.  On the downside,
stack space would increase from constant to logarithmic, which
might hurt in case stack was very tight and heap was not.

dirk muysers wrote:
> ....
>      result := NEW (T, a := x[i], b := result);
> ....
> What about the initialisation of a_len, b_len, and a_or_b_wide ??
> Shouldn't it rather be:
> ....
>      result := Concat (x [i], result)
> ....
> This is almost certainly a bug.
> 
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-- 
-------------------------------------------------------------
Rodney M. Bates, retired assistant professor
Dept. of Computer Science, Wichita State University
Wichita, KS 67260-0083
316-978-3922
rodney.bates at wichita.edu