Ada - Skipping Whitespace using look_ahead - whitespace

Question

I have a procedure, that in theory, should be skipping whitespace using a look_ahead loop. Problem is, it's not working, if there's any whitespace in the input file, it is adding it to the array of records. I think my logic is correct, but could use another pair of eyes to let me know what I'm missing, and why it's not working.
PROCEDURE Read(Calc: OUT Calculation) IS
EOL: Boolean;
C: Character;
I: Integer := 1;
BEGIN
LOOP
LOOP
Look_Ahead(C, EOL);
EXIT WHEN EOL or C /= ' ';
Get(C);
END LOOP;
EXIT WHEN ADA.Text_IO.END_OF_FILE;
Look_Ahead(C, EOL);
IF Is_Digit(C) THEN
Calc.Element(I).Kind := Number;
Get(Calc.Element(I).Int_Value);
ELSE
Calc.Element(I).Kind := Symbol;
Get(Calc.Element(I).Char_Value);
END IF;
Calc.Len := Calc.Len+1;
IF Calc.Element(I).Char_Value = '=' THEN
EXIT;
END IF;
I := I+1;
END LOOP;
END Read;
EDIT: If any of the other procedures, the code for the record etc is needed for an answer, let me know and I will post it.

Answer 1

For Ada.Text_IO.Look_Ahead, ARM A.10.7(8) says
Sets End_Of_Line to True if at end of line, including if at end of page or at end of file; in each of these cases the value of Item is not specified. Otherwise, End_Of_Line is set to False and Item is set to the next character (without consuming it) from the file.
(my emphasis) and I think the "without consuming it" is key. Once Look_Ahead has found an interesting character, you need to call Get to retrieve that character.
I hacked this little demo together: I left end-of-file to exception handling, and I called Skip_Line once end-of-line’s been seen because just Get wasn’t right (sorry not to be more precise!).
with Ada.Text_IO;
with Ada.IO_Exceptions;
procedure Justiciar is
procedure Read is
Eol: Boolean;
C: Character;
begin
-- Instead of useful processing, echo the input to the output
-- replacing spaces with periods.
Outer:
loop
Inner:
loop
Ada.Text_IO.Look_Ahead (C, Eol);
exit Outer when Eol; -- C is undefined
exit Inner when C /= ' ';
Ada.Text_IO.Get (C); -- consume the space
Ada.Text_IO.Put ('.'); -- instead of the space for visibility
end loop Inner;
Ada.Text_IO.Get (C); -- consume the character which isnt a space
Ada.Text_IO.Put (C); -- print it (or other processing!)
end loop Outer;
Ada.Text_IO.Skip_Line; -- consume the newline
Ada.Text_IO.New_Line; -- clear for next call
end Read;
begin
loop
Ada.Text_IO.Put ("reading: ");
Read;
end loop;
exception
when Ada.IO_Exceptions.End_Error =>
null;
end Justiciar;

Answer 2

Usually it's better to read an entire line and parse it than to try to parse character by character. The latter is usually more complex, harder to understand, and more error prone. So I'd suggest something like
function De_Space (Source : String) return String is
Line : Unbounded_String := To_Unbounded_String (Source);
begin -- De_Space
Remove : for I in reverse 1 .. Length (Line) loop
if Element (Line, I) = ' ' then
Delete (Source => Line, From => I, Through => I);
end if;
end loop Remove;
return To_String (Line);
end De_Space;
Line : constant String := De_Space (Get_Line);
You can then loop over Line'range and parse it. Since I'm not clear if
Get(C);
Get(Calc.Element(I).Int_Value);
Get(Calc.Element(I).Char_Value);
represent 1, 2, or 3 different procedures, I can't really help with that part.