Re: Array index overloading

[Shark8 <OneWingedShark@gmail.com>]

On 06-Aug-14 11:38, marmaduke.woodman@univ-amu.fr wrote:
> So V(2 .. 4) is possible, but is the equivalent V((2, 3, 4)) ?


Kinda; the following should show how you'd do your select-by-vector sort 
of thing:

     -- This is your index-type, and a 'vector' thereof.
     Subtype Index_Type is Positive;
     Type Index_Array is Array(Positive range <>) of Index_Type;

     -- This is the Array-type you're interested in.
     Type Collection_Array is Array(Index_Type range <>) of Float;

     -- This is how you can apply a 'vector' to that array to select
     -- disjoint components.
     Function Get_Items( Indices  : Index_Array;
                         From     : Collection_Array
                       ) return Collection_Array is
     Begin
         Return Result: Collection_Array(1..Indices'Length) do
             for Index in Indices'Range loop
                 Offsets:
                 declare
                     From_Index : Constant Positive := Indices(Index);
                     To_Index   : Constant Positive := 
Result'First+Index-Indices'First;
                 begin
                     Result(To_Index) := From(From_Index);
                 end Offsets;
             end loop;
         end return;
     End Get_Items;