Re: FAQ and string functions

[lutz@iks-jena.de (Lutz Donnerhacke)]

* Oleg Goodyckov wrote:
>Perl we say @list=split(/ /,String) and that's all.  Is this Perl's own
>especiality? No. It can be realized in Ada. And I say more - without this
>Ada will never be convinient language. While for splitting string like
>"x=2*3" people will must be to write program enstead split("=","x=2*3"),
>people will write in Perl, not Ada.

Split is a library function in Perl, not a system call. You can have this
library call in Ada, too. Do you consider Perl unusable because MIME::Parser
is not in the core language?

\f
with Split, Ada.Text_IO, Whole;

procedure Test_Split is
   function Get_Whole_Line is new Whole.Line (Ada.Text_IO.Get_Line);
begin
   loop
      declare
         line : constant String := Get_Whole_Line;
         rang : constant Split.String_Ranges := Split.Split (' ', line);
      begin
         Ada.Text_IO.Put_Line ("Words:" & Integer'Image (rang'Length));
         for i in rang'Range loop
            Ada.Text_IO.Put (line (rang (i).first .. rang (i).last));
            if i < rang'Last then
               Ada.Text_IO.Put (", ");
            end if;
         end loop;
         Ada.Text_IO.New_Line;
      end;
   end loop;
exception
   when Ada.Text_IO.End_Error => null;
end Test_Split;
\f
with Ada.Strings.Maps;

package Split is
   pragma Preelaborate (Split);

   type Ranges is record
      first : Positive;
      last  : Positive;
   end record;
   type String_Ranges is array (Positive range <>) of Ranges;

   function Split (
     Source : String;
     Set    : Ada.Strings.Maps.Character_Set;
     Test   : Ada.Strings.Membership
   ) return String_Ranges;

   function Split (Terminator : Character; Source : String)
     return String_Ranges;
end Split;
\f
with Ada.Strings.Fixed;

package body Split is
   Null_Ranges : String_Ranges (Positive'First .. Positive'First - 1);

   function Split (Source : String;
     Set    : Ada.Strings.Maps.Character_Set;
     Test   : Ada.Strings.Membership) return String_Ranges is
      First, Last : Natural;
   begin
      Ada.Strings.Fixed.Find_Token (Source, Set, Test, First, Last);
      if Last = Natural'First then
         return Null_Ranges;
      else
         return Ranges'(First, Last) &
           Split (Source (Last + 1 .. Source'Last), Set, Test);
      end if;
   end Split;

   function Split (Terminator : Character; Source : String)
     return String_Ranges is
   begin
      return Split (Source,
        Ada.Strings.Maps.To_Set (Terminator), Ada.Strings.Outside);
   end Split;
end Split;
\f
package Whole is
   pragma Preelaborate (Whole);

   buffsize : Positive := 80;

   generic
      with procedure Get (buff : out String; last : out Natural);
   function Line return String;
end Whole;
\f
package body Whole is
   function Line return String is
      buff : String (Positive'First .. Positive'First + buffsize);
      last : Natural;
   begin
      Get (buff, last);
      if last < buff'Last then
         return buff (buff'First .. last);
      else
         return buff & Line;
      end if;
   end Line;
end Whole;