## Copyright (C) 2006-2012 John W. Eaton
## Copyright (C) 2010 VZLU Prague
##
## This file is 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 3 of the License, 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, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} {} substruct (@var{type}, @var{subs}, @dots{})
## Create a subscript structure for use with @code{subsref} or
## @code{subsasgn}.  For example:
##
## @example
## @group
## idx = substruct ("()", @{3, ":"@})
##      @result{}
##        idx =
##        @{
##          type = ()
##          subs =
##          @{
##            [1,1] =  3
##            [1,2] = :
##          @}
##        @}
## x = [1, 2, 3; 4, 5, 6; 7, 8, 9];
## subsref (x, idx)
##    @result{} 7  8  9
## @end group
## @end example
## @seealso{subsref, subsasgn}
## @end deftypefn

## Author:  jwe

function retval = substruct (varargin)

  nargs = nargin;

  if (nargs > 1 && mod (nargs, 2) == 0)
    typ = varargin(1:2:nargs);
    sub = varargin(2:2:nargs);
    braces = strcmp (typ, "()") | strcmp (typ, "{}");
    dots = strcmp (typ, ".");
    if (all (braces | dots))
      cells = cellfun ("isclass", sub, "cell");
      chars = cellfun ("isclass", sub, "char");
      if (any (braces &! cells))
        error ("substruct: for TYPE == () or {}, SUBS must be a cell array");
      elseif (any (dots &! chars))
        error ("substruct: for TYPE == ., SUBS must be a character string");
      endif
    else
      error ("substruct: expecting TYPE to be one of \"()\", \"{}\", or \".\"");
    endif

    retval = struct ("type", typ, "subs", sub);
  else
    print_usage ();
  endif

endfunction

%!test
%! x(1,1).type = "()";
%! x(1,2).type = "{}";
%! x(1,3).type = ".";
%! x(1,1).subs = {1,2,3};
%! x(1,2).subs = {":"};
%! x(1,3).subs = "foo";
%! y = substruct ("()", {1,2,3}, "{}", {":"}, ".", "foo");
%! assert(x,y);
%!error assert(substruct);
%!error assert(substruct (1, 2, 3));
%!error assert(substruct ("x", 1));
%!error assert(substruct ("()", [1,2,3]));
%!error assert(substruct (".", {1,2,3}));