Re: saving struct data

[A Scott Hodel]

There was a patch to the octave sources posted awhile back that will
allow this.  I wrote scripts to convert  aribitrary variables to
a vector and back again for bleeding edge releases; includes lists.
If you're using octave-2.0.x, you'll need to remove references to the
list functions (is_list, nth, etc).

I've been using them for a couple of weeks sor so, so they're
"experimentally" bug free.  Here they are:

# Copyright (C) 1999 A. Scottedward Hodel 
#
# 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 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, 675 Mass Ave, Cambridge, MA 02139, USA. 
 
function vv = var2vec(var)
# function vv = var2vec(var)
# encode an arbitrary octave variable into a vector appropriate for
# octave save/load comands
# inputs: var: octave variable
# outputs: vec: vector encoding of vector value
#   encoding: 
#     1st number: variable type: 
#       0 numerical
#         followed by [rows columns vec(var)' ]
#       1 string
#         followed by [rows columns vec(1.0*var)' ]
#       2 structure
#         followed by [number_members member_name member value ...]
#       3 list
#         followed by [number_elements var2vec(nth(var,1)) ... ]

vartype = 3*is_list(var) + 2*is_struct(var) + 1*isstr(var);

switch(vartype)
case(0), # numerial
  vv = [ vartype; rows(var); columns(var) ];
  if(!isempty(var)) vv = [vv; vec(var)]; endif

case(1), # string
  save_val = implicit_str_to_num_ok;
  implicit_str_to_num_ok = 1;
  vv = var2vec(1.0*var);
  vv(1) = vartype;
  implicit_str_to_num_ok = save_val;

case(2),  # structure
  elems = struct_elements(var);
  nelems = rows(elems);
  vv = [vartype; nelems];
  for kk=1:nelems
    varname = deblank(elems(kk,:));
    vnvec = var2vec(varname);
    eval(sprintf("valvec = var2vec(var.%s);",varname));
    vv = [vv; vnvec; valvec];
  endfor

case(3), # list
  vv = [vartype; length(var)];
  for kk=1:length(var)
    vv = [vv; var2vec(nth(var,kk))];
  endfor

otherwise,
  error("vartype %d not implemented yet\n",vartype);
  vv = vartype;
endswitch

endfunction


# Copyright (C) 1999 A. Scottedward Hodel 
#
# 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 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, 675 Mass Ave, Cambridge, MA 02139, USA. 
 
function [var, vvrem] = vec2var(vv)
# function var = vec2var(vv)
# recover a variable from its var2vec encoding (see var2vec for format)
# inputs: vec: vector in var2vec output form
# outputs: var: corresponding octave variable
#          vvrem: remaining part of vector (unused portion)

vv = vec(vv);

vartype = vv(1);
switch(vartype)
case(0),
  # numerical value
  vrows = vv(2); vcols = vv(3); vend = 3+vrows*vcols ;
  if(vrows*vcols > 0) var = reshape( vv(4:vend), vrows,vcols );
  else                var = zeros(vrows,vcols);
  endif
  vvrem = vv((vend+1):length(vv));

case(1),
  # string value
  vv(1) = 0; 
  [var,vvrem] = vec2var(vv);
  var = setstr(var);

case(2),
  # structure value
  nelems = vv(2);
  vv = vv(3:length(vv),1);
  for kk=1:nelems
    [varname,vv] = vec2var(vv);
    [elemval,vv] = vec2var(vv);
    eval(sprintf("var.%s = elemval;",varname));
  endfor
  vvrem = vv;

case(3),
  # list
  var = list();
  nelems = vv(2);
  vv = vv(3:length(vv),1);

  for kk=1:nelems
    [var(kk), vv] = vec2var(vv);
  endfor
  vvrem = vv;

otherwise,
  error("vec2var: vartype %d not yet implemented\n",vartype);
endswitch

endfunction