Re: Pretty printing the pretty print.

[Mike H <postmaster@ada-augusta.demon.co.uk>]

In message <20140104121332.22310cd2@vostro>, Oliver Kleinke
<oliver.kleinke@c-01a.de> writes
>Do you by chance remember the task?
As far as I remember the original "specification" was a requirement to
split an array at an arbitrary point and re-join the two parts (first
and last) in the reverse order (last then first). Spotting that what was
actually required was a circular shift changed the game somewhat. By
some odd coincidence, before Christmas I stumbled across the following
(see below). It seems to fit the bill. I also seem to remember that
turning it into a generic was not as sweet and clean as I expected.

function Shift_right_circular
     (A      : in Array_type;
      Places : in Natural) return Array_type is

      P : Natural := Places rem A'LENGTH;

      -- Array will be split into two slices (I1 .. I2) & (I3 .. I4) and
      -- re-made as (I3 .. I4) & (I1 .. I2). The values of I2 and I3 are
      -- derived from their position numbers, P2 and P3.
      P1 : Natural := Index_type'POS (A'FIRST); --  position number of
I1
      P2 : Natural := P1 + P - 1;                        --  position
number of I2
      P3 : Natural := P1 + P;                             --  position
number of I3
      --
      -- I1 is A'FIRST
      I2 : Index_type := Index_type'VAL(P2);
      I3 : Index_type := Index_type'VAL(P3);
      -- I4 is A'LAST

begin

      if Places = 0 then
         -- no shifting to be done
         return A;
      else
         return A (I3 .. A'LAST) & A (A'FIRST .. I2);
      end if;

end Shift_right_circular;


-- 
Mike
Swim? Naturally at Severn Vale
<http://www.severnvalesc.org/>