I wish I could ...

I wish I could ...

[Björn Persson]

Right now I'm writing code like this in several places:

    case Going is
       when Forward =>
          for Pos in 1 .. Source.Last loop
             if Source.Reference.all (Pos) /= Character'Pos(Space) then
                return Pos;
             end if;
          end loop;
       when Backward =>
          for Pos in reverse 1 .. Source.Last loop
             if Source.Reference.all (Pos) /= Character'Pos(Space) then
                return Pos;
             end if;
          end loop;
    end case;

I wish I could just write:

    for Pos in Going 1 .. Source.Last loop
       if Source.Reference.all (Pos) /= Character'Pos(Space) then
          return Pos;
       end if;
    end loop;

-- 
Björn Persson                              PGP key A88682FD
                    omb jor ers @sv ge.
                    r o.b n.p son eri nu

Re: I wish I could ...

[Frank J. Lhota]

How about this:

    declare
        Direction_For : constant array ( Going_Type ) of
Ada.Strings.Direction :=
            (
            Forward  => Ada.Strings.Forward,
            Backward => Ada.Strings.Backward
            );
    begin
        return Ada.Strings.Fixed.Index
            (
            Source  => Source.Reference( 1 .. Source.Last ),
            Mapping => String'( 1 => Space ),
            Going   => Direction_For( Going )
            );
    end;

Re: I wish I could ...

[Björn Persson]

I can't call Index because I'm essentially writing Index (although this 
particular example was from Index_Non_Blank). I'm writing this for my 
EAstrings library (which is part of AdaCL). EAstrings works like 
Ada.Strings.Unbounded, but it keeps track of how the strings are encoded 
and transcodes them when necessary.

All I wanted to say was that it would be nice to be able to parameterize 
the "reverse" in a for loop.

-- 
Björn Persson                              PGP key A88682FD
                    omb jor ers @sv ge.
                    r o.b n.p son eri nu

Re: I wish I could ...

[Jeffrey Carter]

Bj�rn Persson wrote:

> Right now I'm writing code like this in several places:
> 
>    case Going is
>       when Forward =>
>          for Pos in 1 .. Source.Last loop
>             if Source.Reference.all (Pos) /= Character'Pos(Space) then
>                return Pos;
>             end if;
>          end loop;
>       when Backward =>
>          for Pos in reverse 1 .. Source.Last loop
>             if Source.Reference.all (Pos) /= Character'Pos(Space) then
>                return Pos;
>             end if;
>          end loop;
>    end case;

This looks like a function:

function Find_Other (Source : Whatever; Item : Whatever_Else)
return Thingy;

Where
Whatever      is the type of Source in your code
Whatever_Else is the type of Source.Reference (Pos)
Thingy        is the type of Pos

You would also want a similar function that uses "=" rather than "/=":

function Find_Equal (Source : Whatever; Item : Whatever_Else)
return Thingy;

Then all the cases where you're writing code like your example would be 
replaced by a call to one of these functions.

It's probably more complicated than that.

-- 
Jeff Carter
"The time has come to act, and act fast. I'm leaving."
Blazing Saddles
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