program number(input, output);
(* number: add line numbers to a file

  Dr. Thomas D. Schneider, Ph.D.
  National Institutes of Health
  schneidt@mail.nih.gov
  toms@alum.mit.edu (permanent)
  http://alum.mit.edu/www/toms (permanent)

 *)

label 1; (* end of program *)

const
(* begin module version *)
   version = 1.10; (* of number.p 2010 Mar 01
2010 Mar 01, 1.10 remove blanks before numbers
2001 Sep 13, 1.09 link to cumulative.p
1991 Sep 16, 1.08 origin
*)
(* end module version *)

(* begin module describe.number *)
(*
name
   number: add line numbers to a file

synopsis
   number(input: in, output: out)

files
   input:  input file
   output: input file with line numbers at the start

description
   Add line numbers to the input file.

examples

documentation

see also

   {A slow but effective solution to the technical note below is in:}
   cumulative.p

author
   Thomas Dana Schneider

bugs

technical notes
   Perhaps the program should have an option to define the number of columns
   for the line numbers.  An earlier version computed this.  However, to do
   that requires resetting the file and prevents the program from being used
   as part of a pipe.  The current program simply uses a default value for
   the number of columns so that number can be used as part of a pipe.

   See cumulative.p for a solution, not yet implemented.

*)
(* end module describe.number *)

(* begin module halt *)
procedure halt;
(* stop the program.  the procedure performs a goto to the end of the
   program.  you must have a label:
      label 1;
   declared, and also the end of the program must have this label:
      1: end.
   examples are in the module libraries.
   this is the only goto in the delila system. *)
begin
      writeln(output,' program halt.');
      goto 1
end;
(* end module halt version = 4.11; (@ of prgmod.p 1991 Apr 22 *)

(* begin module copyaline *)
procedure copyaline(var fin, fout: text);
(* copy a line from file fin to file fout *)
begin (* copyaline *)
      while not eoln(fin) do begin
         fout^ := fin^;
         put(fout);
         get(fin)
      end;
      readln(fin);
      writeln(fout);
end; (* copyaline *)
(* end module copyaline version = 4.11; (@ of prgmod.p 1991 Apr 22 *)

(* begin module number.themain *)
procedure themain(var fin,fout: text);
(* the main procedure of the program *)
const
{
   decimals = 5; (* that should be sufficient for most files! *)
}
   decimals = 1; (* No blanks before numbers! *)
var
   count: integer; (* count of the lines produces so far *)
{
   decimals: integer; (* decimal places to express the value of lines in *)
   lines: integer; (* total lines in the file *)
}
begin
{ this is crazy.  the extra reset prevents
this from being used in pipes.  
   (* determine number of lines in the file *)
   lines := -1; (* don't count the line that has the eof on it! *)
   reset(fin);
   while not eof(fin) do begin
      lines := lines + 1;
      readln(fin)
   end;

   if lines > 0 then begin
      (* determine how many decimal places to put out for line numbers *)
      decimals := trunc(ln(lines)/ln(10))+1;

      (* copy the file *)
      reset(fin);
      for count := 1 to lines do begin
         write(fout,count:decimals,' ');
         copyaline(fin,fout)
      end;
   end;
}

   count := 0;
{
   reset(fin);
}
   while not eof(fin) do begin
      count := succ(count);
      write(fout,count:decimals,' ');
      copyaline(fin,fout)
   end;

end;
(* end module number.themain *)

begin
   themain(input,output);
1: end.