ov-oncleanup.cc

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/*

Copyright (C) 2010-2015 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/>.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "defun.h"
#include "ov-oncleanup.h"
#include "ov-fcn.h"
#include "ov-usr-fcn.h"
#include "pt-misc.h"
#include "toplev.h"

DEFINE_OV_TYPEID_FUNCTIONS_AND_DATA (octave_oncleanup, "onCleanup",
                                     "onCleanup");

octave_oncleanup::octave_oncleanup (const octave_value& f)
  : fcn (f)
{
  if (f.is_function_handle ())
    {
      octave_function *fptr = f.function_value (true);
      if (fptr)
        {
          octave_user_function *uptr
            = dynamic_cast<octave_user_function *> (fptr);

          if (uptr != 0)
            {
              tree_parameter_list *pl = uptr->parameter_list ();

              if (pl != 0 && pl->length () > 0)
                warning ("onCleanup: cleanup action takes parameters");
            }
        }
      else
        error ("onCleanup: no default dispatch for function handle");
    }
  else
    {
      fcn = octave_value ();
      error ("onCleanup: argument must be a function handle");
    }
}

octave_oncleanup::~octave_oncleanup (void)
{
  if (fcn.is_undefined ())
    return;

  unwind_protect frame;

  // Clear interrupts.
  frame.protect_var (octave_interrupt_state);
  octave_interrupt_state = 0;

  // Disallow quit().
  frame.protect_var (quit_allowed);
  quit_allowed = false;

  // Clear errors.
  frame.protect_var (error_state);
  error_state = 0;

  try
    {
      // Run the actual code.
      fcn.do_multi_index_op (0, octave_value_list ());
    }
  catch (octave_interrupt_exception)
    {
      // Swallow the interrupt.
      warning ("onCleanup: interrupt occured in cleanup action");
    }
  catch (...) // Yes, the black hole. We're in a d-tor.
    {
      // This shouldn't happen, in theory.
      error ("onCleanup: internal error: unhandled exception in cleanup action");
    }

  // FIXME: can this happen now?
  if (error_state)
    frame.discard_first ();
}

octave_scalar_map
octave_oncleanup::scalar_map_value (void) const
{
  octave_scalar_map retval;
  retval.setfield ("task", fcn);
  return retval;
}

static void
warn_save_load (void)
{
  warning ("onCleanup: load and save not supported");
}

bool
octave_oncleanup::save_ascii (std::ostream& /* os */)
{
  warn_save_load ();
  return true;
}

bool
octave_oncleanup::load_ascii (std::istream& /* is */)
{
  warn_save_load ();
  return true;
}

bool
octave_oncleanup::save_binary (std::ostream& /* os */,
                               bool& /* save_as_floats */)
{
  warn_save_load ();
  return true;
}

bool
octave_oncleanup::load_binary (std::istream& /* is */, bool /* swap */,
                               oct_mach_info::float_format /* fmt */)
{
  warn_save_load ();
  return true;
}

bool
octave_oncleanup::save_hdf5 (octave_hdf5_id /* loc_id */,
                             const char * /* name */,
                             bool /* save_as_floats */)
{
  warn_save_load ();
  return true;
}

bool
octave_oncleanup::load_hdf5 (octave_hdf5_id /* loc_id */,
                             const char * /* name */)
{
  warn_save_load ();
  return true;
}

void
octave_oncleanup::print (std::ostream& os, bool pr_as_read_syntax)
{
  print_raw (os, pr_as_read_syntax);
  newline (os);
}

void
octave_oncleanup::print_raw (std::ostream& os, bool pr_as_read_syntax) const
{
  os << "onCleanup (";
  if (fcn.is_defined ())
    fcn.print_raw (os, pr_as_read_syntax);
  os << ")";
}

DEFUN (onCleanup, args, ,
       "-*- texinfo -*-\n\
@deftypefn {Built-in Function} {@var{obj} =} onCleanup (@var{function})\n\
Create a special object that executes a given function upon destruction.\n\
\n\
If the object is copied to multiple variables (or cell or struct array\n\
elements) or returned from a function, @var{function} will be executed after\n\
clearing the last copy of the object.  Note that if multiple local onCleanup\n\
variables are created, the order in which they are called is unspecified.\n\
For similar functionality @xref{The unwind_protect Statement}.\n\
@end deftypefn")
{
  octave_value retval;

  if (args.length () == 1)
    retval = octave_value (new octave_oncleanup (args(0)));
  else
    print_usage ();

  return retval;
}

/*
%!test
%! old_wstate = warning ("query");
%! unwind_protect
%!   trigger = onCleanup (@() warning ("on", "__MY_WARNING__"));
%!   warning ("off", "__MY_WARNING__");
%!   assert ((warning ("query", "__MY_WARNING__")).state, "off");
%!   clear trigger;
%!   assert ((warning ("query", "__MY_WARNING__")).state, "on");
%! unwind_protect_cleanup
%!   warning (old_wstate);
%! end_unwind_protect
*/