ov-oncleanup.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2010-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// 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
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include "defun.h"
#include "interpreter.h"
#include "interpreter-private.h"
#include "ov-oncleanup.h"
#include "ov-fcn.h"
#include "ov-usr-fcn.h"
#include "parse.h"
#include "pt-misc.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)
        error ("onCleanup: no default dispatch for function handle");
 
      octave_user_function *uptr
        = dynamic_cast<octave_user_function *> (fptr);
 
      if (uptr != nullptr)
        {
          octave::tree_parameter_list *pl = uptr->parameter_list ();
 
          if (pl != nullptr && pl->length () > 0)
            warning ("onCleanup: cleanup action takes parameters");
        }
    }
  else
    {
      fcn = octave_value ();
      error ("onCleanup: argument must be a function handle");
    }
}
 
octave_oncleanup::~octave_oncleanup (void)
{
  call_object_destructor ();
}
 
octave_scalar_map
octave_oncleanup::scalar_map_value (void) const
{
  octave_scalar_map retval;
  retval.setfield ("task", fcn);
  return retval;
}
 
bool
octave_oncleanup::save_ascii (std::ostream& /* os */)
{
  warning ("save: unable to save onCleanup variables, skipping");
 
  return true;
}
 
bool
octave_oncleanup::load_ascii (std::istream& /* is */)
{
  // Silently skip object that was not saved
  return true;
}
 
bool
octave_oncleanup::save_binary (std::ostream& /* os */,
                               bool /* save_as_floats */)
{
  warning ("save: unable to save onCleanup variables, skipping");
 
  return true;
}
 
bool
octave_oncleanup::load_binary (std::istream& /* is */, bool /* swap */,
                               octave::mach_info::float_format /* fmt */)
{
  // Silently skip object that was not saved
  return true;
}
 
bool
octave_oncleanup::save_hdf5 (octave_hdf5_id /* loc_id */,
                             const char * /* name */,
                             bool /* save_as_floats */)
{
  warning ("save: unable to save onCleanup variables, skipping");
 
  return true;
}
 
bool
octave_oncleanup::load_hdf5 (octave_hdf5_id /* loc_id */,
                             const char * /* name */)
{
  // Silently skip object that was not saved
  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 << ')';
}
 
void
octave_oncleanup::call_object_destructor (void)
{
  if (fcn.is_undefined ())
    return;
 
  octave_value the_fcn = fcn;
  fcn = octave_value ();
 
  octave::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;
 
  octave::interpreter& interp
    = octave::__get_interpreter__ ("octave_oncleanup::call_object_destructor");
 
  interpreter_try (frame);
 
  try
    {
      // Run the actual code.
      octave::feval (the_fcn);
    }
  catch (const octave::interrupt_exception&)
    {
      interp.recover_from_exception ();
 
      warning ("onCleanup: interrupt occurred in cleanup action");
    }
  catch (const octave::execution_exception& ee)
    {
      interp.recover_from_exception ();
 
      std::string msg = ee.message ();
 
      warning ("onCleanup: error caught while executing cleanup function:\n%s\n",
               msg.c_str ());
 
    }
  catch (const octave::exit_exception&)
    {
      // This shouldn't happen since we disabled quit above.
      warning ("onCleanup: exit disabled while executing cleanup function");
    }
  catch (...) // Yes, the black hole.  We're in a d-tor.
    {
      // This shouldn't happen, in theory.
      warning ("onCleanup: internal error: unhandled exception in cleanup action");
    }
}
 
DEFUN (onCleanup, args, ,
       doc: /* -*- texinfo -*-
@deftypefn {} {@var{obj} =} onCleanup (@var{function})
Create a special object that executes a given function upon destruction.
 
If the object is copied to multiple variables (or cell or struct array
elements) or returned from a function, @var{function} will be executed after
clearing the last copy of the object.  Note that if multiple local onCleanup
variables are created, the order in which they are called is unspecified.
For similar functionality @xref{The unwind_protect Statement}.
@end deftypefn */)
{
  if (args.length () != 1)
    print_usage ();
 
  return ovl (new octave_oncleanup (args(0)));
}
 
/*
%!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
*/