## Copyright (C) 1996, 1997 John W. Eaton
## Copyright (C) 2003 Miquel E Cabanas
##
## This program is free software ...
##    though it is not (yet) part of Octave
##
## Octave is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.

## -*- texinfo -*-
## @deftypefn {Function File} {} mult_choice (@var{title}, @var{opt1}, @dots{})
##  Print a title string followed by a series of options.  Each
## option will be printed along with a number.  More than one option can
## be selected at the same time, and the return value is a sorted vector
## containing the number of the option(s) selected by the user.  This
## function is useful for interactive programs.  There is no limit to
## the number of options that may be passed in, but it may be confusing
## to present more than will fit easily on one screen.
## @end deftypefn
## @seealso{menu, disp, printf, and input}

## Author: jwe, mce

function num = mult_choice (t, ...)

  if (nargin < 2)
    usage ("mult_choice (title, opt1, ...)");
  endif

  ## Force pending output to appear before the menu.

  fflush (stdout);

  ## Don't send the menu through the pager since doing that can cause
  ## major confusion.

  save_page_screen_output = page_screen_output;

  unwind_protect

    page_screen_output = 0;

    if (! isempty (t))
      printf ("\n");
      disp (t);
      printf ("\n");
    endif

    nopt = nargin - 1;

    while (1)
      va_start ();
      for i = 1:nopt
        printf ("  [%2d] ", i);
        disp (va_arg ());
      endfor
      printf ("\n");
      s = input ("pick one or more numbers separated by spaces: ", "s");
      ## now check that s is a string, split it into substrings,
      ## convert the substrings to numbers, and then check that
      ## values are valid
      ## printf ("\n");
      ## printf ("you have selected options: %s\n", s);

      eval (sprintf ("num = str2num (s);"), "num = [];");
      if (! any (is_vector (num)) || any (num < 1) || any(num > nopt))
        printf ("\nerror: some input invalid or out of range\n\n");
      else
	num = sort (num);
        break;
      endif
    endwhile

  unwind_protect_cleanup

    page_screen_output = save_page_screen_output;

  end_unwind_protect

endfunction