interpreter.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2021 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 <cstdio>
 
#include <set>
#include <string>
#include <iostream>
 
#include "cmd-edit.h"
#include "cmd-hist.h"
#include "file-ops.h"
#include "file-stat.h"
#include "file-ops.h"
#include "fpucw-wrappers.h"
#include "lo-blas-proto.h"
#include "lo-error.h"
#include "oct-env.h"
#include "str-vec.h"
#include "signal-wrappers.h"
#include "unistd-wrappers.h"
 
#include "builtin-defun-decls.h"
#include "defaults.h"
#include "Cell.h"
#include "defun.h"
#include "display.h"
#include "error.h"
#include "event-manager.h"
#include "file-io.h"
#include "graphics.h"
#include "help.h"
#include "input.h"
#include "interpreter-private.h"
#include "interpreter.h"
#include "load-path.h"
#include "load-save.h"
#include "octave.h"
#include "oct-hist.h"
#include "oct-map.h"
#include "oct-mutex.h"
#include "ovl.h"
#include "ov.h"
#include "ov-classdef.h"
#include "parse.h"
#include "pt-classdef.h"
#include "pt-eval.h"
#include "pt-jump.h"
#include "pt-stmt.h"
#include "settings.h"
#include "sighandlers.h"
#include "sysdep.h"
#include "unwind-prot.h"
#include "utils.h"
#include "variables.h"
#include "version.h"
 
// TRUE means the quit() call is allowed.
bool quit_allowed = true;
 
// TRUE means we are ready to interpret commands, but not everything
// is ready for interactive use.
bool octave_interpreter_ready = false;
 
// TRUE means we've processed all the init code and we are good to go.
bool octave_initialized = false;
 
DEFUN (__version_info__, args, ,
       doc: /* -*- texinfo -*-
@deftypefn {} {retval =} __version_info__ (@var{name}, @var{version}, @var{release}, @var{date})
Undocumented internal function.
@end deftypefn */)
{
  static octave_map vinfo;
 
  int nargin = args.length ();
 
  if (nargin != 0 && nargin != 4)
    print_usage ();
 
  octave_value retval;
 
  if (nargin == 0)
    retval = vinfo;
  else if (nargin == 4)
    {
      if (vinfo.nfields () == 0)
        {
          vinfo.assign ("Name", args(0));
          vinfo.assign ("Version", args(1));
          vinfo.assign ("Release", args(2));
          vinfo.assign ("Date", args(3));
        }
      else
        {
          octave_idx_type n = vinfo.numel () + 1;
 
          vinfo.resize (dim_vector (n, 1));
 
          octave_value idx (n);
 
          vinfo.assign (idx, "Name", Cell (octave_value (args(0))));
          vinfo.assign (idx, "Version", Cell (octave_value (args(1))));
          vinfo.assign (idx, "Release", Cell (octave_value (args(2))));
          vinfo.assign (idx, "Date", Cell (octave_value (args(3))));
        }
    }
 
  return retval;
}
 
DEFMETHOD (quit, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} quit
@deftypefnx {} {} quit cancel
@deftypefnx {} {} quit force
@deftypefnx {} {} quit ("cancel")
@deftypefnx {} {} quit ("force")
@deftypefnx {} {} quit (@var{status})
@deftypefnx {} {} quit (@var{status}, "force")
Quit the current Octave session.
 
The @code{exit} function is an alias for @code{quit}.
 
If the optional integer value @var{status} is supplied, pass that value to
the operating system as Octave's exit status.  The default value is zero.
 
When exiting, Octave will attempt to run the m-file @file{finish.m} if it
exists.  User commands to save the workspace or clean up temporary files
may be placed in that file.  Alternatively, another m-file may be scheduled
to run using @code{atexit}.  If an error occurs while executing the
@file{finish.m} file, Octave does not exit and control is returned to
the command prompt.
 
If the optional argument @qcode{"cancel"} is provided, Octave does not
exit and control is returned to the command prompt.  This feature allows
the @code{finish.m} file to cancel the quit process.
 
If the user preference to request confirmation before exiting, Octave
will display a dialog and give the user an option to cancel the exit
process.
 
If the optional argument @qcode{"force"} is provided, no confirmation is
requested, and the execution of the @file{finish.m} file is skipped.
@seealso{atexit}
@end deftypefn */)
{
  int numel = args.length ();
 
  if (numel > 2)
    print_usage ();
 
  int exit_status = 0;
 
  bool force = false;
  bool cancel = false;
 
  if (numel == 2)
    {
      exit_status = args(0).xnint_value ("quit: STATUS must be an integer");
      std::string frc
        = args(1).xstring_value ("quit: second argument must be a string");
 
      if (frc == "force")
        force = true;
      else
        error (R"(quit: second argument must be string "force")");
    }
  else if (numel == 1)
    {
      if (args(0).is_string ())
        {
          const char *msg
            = R"(quit: option must be string "cancel" or "force")";
 
          std::string opt = args(0).xstring_value (msg);
 
          if (opt == "cancel")
            cancel = true;
          else if (opt == "force")
            force = true;
          else
            error ("%s", msg);
        }
      else
        exit_status = args(0).xnint_value ("quit: STATUS must be an integer");
    }
 
  if (cancel)
    {
      // No effect if "quit cancel" appears outside of finish script.
 
      if (interp.executing_finish_script ())
        interp.cancel_quit (true);
 
      return ovl ();
    }
 
  interp.quit (exit_status, force);
 
  return ovl ();
}
 
DEFALIAS (exit, quit);
 
DEFMETHOD (atexit, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} atexit (@var{fcn})
@deftypefnx {} {} atexit (@var{fcn}, @var{flag})
Register a function to be called when Octave exits.
 
For example,
 
@example
@group
function last_words ()
  disp ("Bye bye");
endfunction
atexit ("last_words");
@end group
@end example
 
@noindent
will print the message @qcode{"Bye bye"} when Octave exits.
 
The additional argument @var{flag} will register or unregister @var{fcn}
from the list of functions to be called when Octave exits.  If @var{flag} is
true, the function is registered, and if @var{flag} is false, it is
unregistered.  For example, after registering the function @code{last_words}
above,
 
@example
atexit ("last_words", false);
@end example
 
@noindent
will remove the function from the list and Octave will not call
@code{last_words} when it exits.
 
Note that @code{atexit} only removes the first occurrence of a function
from the list, so if a function was placed in the list multiple times with
@code{atexit}, it must also be removed from the list multiple times.
@seealso{quit}
@end deftypefn */)
{
  int nargin = args.length ();
 
  if (nargin < 1 || nargin > 2)
    print_usage ();
 
  std::string arg = args(0).xstring_value ("atexit: FCN argument must be a string");
 
  bool add_mode = (nargin == 2)
    ? args(1).xbool_value ("atexit: FLAG argument must be a logical value")
    : true;
 
  octave_value_list retval;
 
  if (add_mode)
    interp.add_atexit_fcn (arg);
  else
    {
      bool found = interp.remove_atexit_fcn (arg);
 
      if (nargout > 0)
        retval = ovl (found);
    }
 
  return retval;
}
 
namespace octave
{
  temporary_file_list::~temporary_file_list (void)
  {
    cleanup ();
  }
 
  void temporary_file_list::insert (const std::string& file)
  {
    m_files.insert (file);
  }
 
  void temporary_file_list::cleanup (void)
  {
    while (! m_files.empty ())
      {
        auto it = m_files.begin ();
 
        octave_unlink_wrapper (it->c_str ());
 
        m_files.erase (it);
      }
  }
 
  // The time we last time we changed directories.
  sys::time Vlast_chdir_time = 0.0;
 
  // Execute commands from a file and catch potential exceptions in a consistent
  // way.  This function should be called anywhere we might parse and execute
  // commands from a file before we have entered the main loop in
  // toplev.cc.
 
  static int safe_source_file (const std::string& file_name,
                               const std::string& context = "",
                               bool verbose = false,
                               bool require_file = true)
  {
    interpreter& interp = __get_interpreter__ ("safe_source_file");
 
    try
      {
        source_file (file_name, context, verbose, require_file);
      }
    catch (const interrupt_exception&)
      {
        interp.recover_from_exception ();
 
        return 1;
      }
    catch (const execution_exception& e)
      {
        interp.handle_exception (e);
 
        return 1;
      }
 
    return 0;
  }
 
  static void initialize_version_info (void)
  {
    octave_value_list args;
 
    args(3) = OCTAVE_RELEASE_DATE;
    args(2) = config::release ();
    args(1) = OCTAVE_VERSION;
    args(0) = "GNU Octave";
 
    F__version_info__ (args, 0);
  }
 
  static void xerbla_abort (void)
  {
    error ("Fortran procedure terminated by call to XERBLA");
  }
 
  static void initialize_xerbla_error_handler (void)
  {
    // The idea here is to force xerbla to be referenced so that we will
    // link to our own version instead of the one provided by the BLAS
    // library.  But numeric_limits<double>::NaN () should never be -1, so
    // we should never actually call xerbla.  FIXME (again!): If this
    // becomes a constant expression the test might be optimized away and
    // then the reference to the function might also disappear.
 
    if (numeric_limits<double>::NaN () == -1)
      F77_FUNC (xerbla, XERBLA) ("octave", 13 F77_CHAR_ARG_LEN (6));
 
    typedef void (*xerbla_handler_ptr) (void);
 
    typedef void (*octave_set_xerbla_handler_ptr) (xerbla_handler_ptr);
 
    dynamic_library libs ("");
 
    if (libs)
      {
        octave_set_xerbla_handler_ptr octave_set_xerbla_handler
          = reinterpret_cast<octave_set_xerbla_handler_ptr>
              (libs.search ("octave_set_xerbla_handler"));
 
        if (octave_set_xerbla_handler)
          octave_set_xerbla_handler (xerbla_abort);
      }
  }
 
  OCTAVE_NORETURN static void
  lo_error_handler (const char *fmt, ...)
  {
    va_list args;
    va_start (args, fmt);
    verror_with_cfn (fmt, args);
    va_end (args);
 
    throw execution_exception ();
  }
 
  OCTAVE_NORETURN static void
  lo_error_with_id_handler (const char *id, const char *fmt, ...)
  {
    va_list args;
    va_start (args, fmt);
    verror_with_id_cfn (id, fmt, args);
    va_end (args);
 
    throw execution_exception ();
  }
 
  static void initialize_error_handlers (void)
  {
    set_liboctave_error_handler (lo_error_handler);
    set_liboctave_error_with_id_handler (lo_error_with_id_handler);
    set_liboctave_warning_handler (warning);
    set_liboctave_warning_with_id_handler (warning_with_id);
  }
 
  // Create an interpreter object and perform initialization up to the
  // point of setting reading command history and setting the load
  // path.
 
  interpreter::interpreter (application *app_context)
    : m_app_context (app_context),
      m_tmp_files (),
      m_atexit_fcns (),
      m_display_info (),
      m_environment (),
      m_settings (),
      m_error_system (*this),
      m_help_system (*this),
      m_input_system (*this),
      m_output_system (*this),
      m_history_system (*this),
      m_dynamic_loader (*this),
      m_load_path (*this),
      m_load_save_system (*this),
      m_type_info (),
      m_symbol_table (*this),
      m_evaluator (*this),
      m_stream_list (*this),
      m_child_list (),
      m_url_handle_manager (),
      m_cdef_manager (*this),
      m_gtk_manager (),
      m_event_manager (*this),
      m_gh_manager (nullptr),
      m_interactive (false),
      m_read_site_files (true),
      m_read_init_files (m_app_context != nullptr),
      m_verbose (false),
      m_inhibit_startup_message (false),
      m_load_path_initialized (false),
      m_history_initialized (false),
      m_in_top_level_repl (false),
      m_cancel_quit (false),
      m_executing_finish_script (false),
      m_executing_atexit (false),
      m_initialized (false)
  {
    // FIXME: When thread_local storage is used by default, this message
    // should change to say something like
    //
    //   only one Octave interpreter may be active in any given thread
 
    if (instance)
      throw std::runtime_error
        ("only one Octave interpreter may be active");
 
    instance = this;
 
    // Matlab uses "C" locale for LC_NUMERIC class regardless of local setting
    setlocale (LC_ALL, "");
    setlocale (LC_NUMERIC, "C");
    setlocale (LC_TIME, "C");
    sys::env::putenv ("LC_NUMERIC", "C");
    sys::env::putenv ("LC_TIME", "C");
 
    // Initialize the default floating point unit control state.
    octave_set_default_fpucw ();
 
    thread::init ();
 
    octave_ieee_init ();
 
    initialize_xerbla_error_handler ();
 
    initialize_error_handlers ();
 
    if (m_app_context)
      {
        install_signal_handlers ();
        octave_unblock_signal_by_name ("SIGTSTP");
      }
    else
      quit_allowed = false;
 
    if (! m_app_context)
      m_display_info.initialize ();
 
    bool line_editing = false;
    bool traditional = false;
 
    if (m_app_context)
      {
        // Embedded interpreters don't execute command line options.
        const cmdline_options& options = m_app_context->options ();
 
        // Make all command-line arguments available to startup files,
        // including PKG_ADD files.
 
        string_vector args = options.all_args ();
 
        m_app_context->intern_argv (args);
        intern_nargin (args.numel () - 1);
 
        bool is_octave_program = m_app_context->is_octave_program ();
 
        std::list<std::string> command_line_path = options.command_line_path ();
 
        for (const auto& pth : command_line_path)
          m_load_path.set_command_line_path (pth);
 
        std::string exec_path = options.exec_path ();
        if (! exec_path.empty ())
          m_environment.exec_path (exec_path);
 
        std::string image_path = options.image_path ();
        if (! image_path.empty ())
          m_environment.image_path (image_path);
 
        if (! options.no_window_system ())
          m_display_info.initialize ();
 
        // Is input coming from a terminal?  If so, we are probably
        // interactive.
 
        // If stdin is not a tty, then we are reading commands from a
        // pipe or a redirected file.
        bool stdin_is_tty = octave_isatty_wrapper (fileno (stdin));
 
        m_interactive = (! is_octave_program && stdin_is_tty
                         && octave_isatty_wrapper (fileno (stdout)));
 
        // Check if the user forced an interactive session.
        if (options.forced_interactive ())
          m_interactive = true;
 
        line_editing = options.line_editing ();
        if ((! m_interactive || options.forced_interactive ())
            && ! options.forced_line_editing ())
          line_editing = false;
 
        traditional = options.traditional ();
 
        // FIXME: if possible, perform the following actions directly
        // instead of using the interpreter-level functions.
 
        if (options.echo_commands ())
          m_evaluator.echo
            (tree_evaluator::ECHO_SCRIPTS | tree_evaluator::ECHO_FUNCTIONS
             | tree_evaluator::ECHO_ALL);
 
        std::string docstrings_file = options.docstrings_file ();
        if (! docstrings_file.empty ())
          Fbuilt_in_docstrings_file (*this, octave_value (docstrings_file));
 
        std::string doc_cache_file = options.doc_cache_file ();
        if (! doc_cache_file.empty ())
          Fdoc_cache_file (*this, octave_value (doc_cache_file));
 
        std::string info_file = options.info_file ();
        if (! info_file.empty ())
          Finfo_file (*this, octave_value (info_file));
 
        std::string info_program = options.info_program ();
        if (! info_program.empty ())
          Finfo_program (*this, octave_value (info_program));
 
        if (options.debug_jit ())
          Fdebug_jit (octave_value (true));
 
        if (options.jit_compiler ())
          Fjit_enable (octave_value (true));
 
        std::string texi_macros_file = options.texi_macros_file ();
        if (! texi_macros_file.empty ())
          Ftexi_macros_file (*this, octave_value (texi_macros_file));
      }
 
    // FIXME: we defer creation of the gh_manager object because it
    // creates a root_figure object that requires the display_info
    // object, but that is currently only accessible through the global
    // interpreter object and that is not available until after the
    // interpreter::instance pointer is set (above).  It would be better
    // if m_gh_manager could be an object value instead of a pointer and
    // created as part of the interpreter initialization.  To do that,
    // we should either make the display_info object independent of the
    // interpreter object (does it really need to cache any
    // information?) or defer creation of the root_figure object until
    // it is actually needed.
    m_gh_manager = new gh_manager (*this);
 
    m_input_system.initialize (line_editing);
 
    // These can come after command line args since none of them set any
    // defaults that might be changed by command line options.
 
    initialize_version_info ();
 
    // This should be done before initializing the load path because
    // some PKG_ADD files might need --traditional behavior.
 
    if (traditional)
      maximum_braindamage ();
 
    octave_interpreter_ready = true;
  }
 
  OCTAVE_THREAD_LOCAL interpreter *interpreter::instance = nullptr;
 
  interpreter::~interpreter (void)
  {
    delete m_gh_manager;
  }
 
  void interpreter::intern_nargin (octave_idx_type nargs)
  {
    m_evaluator.set_auto_fcn_var (stack_frame::NARGIN, nargs);
  }
 
  // Read the history file unless a command-line option inhibits that.
 
  void interpreter::initialize_history (bool read_history_file)
  {
    if (! m_history_initialized)
      {
        // Allow command-line option to override.
 
        if (m_app_context)
          {
            const cmdline_options& options = m_app_context->options ();
 
            read_history_file = options.read_history_file ();
 
            if (! read_history_file)
              command_history::ignore_entries ();
          }
 
        m_history_system.initialize (read_history_file);
 
        if (! m_app_context)
          command_history::ignore_entries ();
 
        m_history_initialized = true;
      }
  }
 
  // Set the initial path to the system default unless command-line
  // option says to leave it empty.
 
  void interpreter::initialize_load_path (bool set_initial_path)
  {
    if (! m_load_path_initialized)
      {
        // Allow command-line option to override.
 
        if (m_app_context)
          {
            const cmdline_options& options = m_app_context->options ();
 
            set_initial_path = options.set_initial_path ();
          }
 
        // Temporarily set the execute_pkg_add function to one that
        // catches exceptions.  This is better than wrapping
        // load_path::initialize in a try-catch block because it will
        // not stop executing PKG_ADD files at the first exception.
        // It's also better than changing the default execute_pkg_add
        // function to use safe_source file because that will normally
        // be evaluated from the normal interpreter loop where exceptions
        // are already handled.
 
        unwind_protect frame;
 
        frame.add_method (m_load_path, &load_path::set_add_hook,
                          m_load_path.get_add_hook ());
 
        m_load_path.set_add_hook ([this] (const std::string& dir)
                                  { this->execute_pkg_add (dir); });
 
        m_load_path.initialize (set_initial_path);
 
        m_load_path_initialized = true;
      }
  }
 
  // This may be called separately from execute
 
  void interpreter::initialize (void)
  {
    if (m_initialized)
      return;
 
    display_startup_message ();
 
    // Wait to read the history file until the interpreter reads input
    // files and begins evaluating commands.
 
    initialize_history ();
 
    // Initializing the load path may execute PKG_ADD files, so can't be
    // done until the interpreter is ready to execute commands.
 
    // Deferring it to the execute step also allows the path to be
    // initialized between creating and execute the interpreter, for
    // example, to set a custom path for an embedded interpreter.
 
    initialize_load_path ();
 
    octave_save_signal_mask ();
 
    can_interrupt = true;
 
    octave_signal_hook = respond_to_pending_signals;
    octave_interrupt_hook = nullptr;
 
    catch_interrupts ();
 
    // FIXME: could we eliminate this variable or make it not be global?
    // Global used to communicate with signal handler.
    octave_initialized = true;
 
    m_initialized = true;
  }
 
  // FIXME: this function is intended to be executed only once.  Should
  // we enforce that restriction?
 
  int interpreter::execute (void)
  {
    int exit_status = 0;
 
    try
      {
        initialize ();
 
        execute_startup_files ();
 
        if (m_app_context)
          {
            const cmdline_options& options = m_app_context->options ();
 
            if (m_app_context->have_eval_option_code ())
              {
                int status = execute_eval_option_code ();
 
                if (status )
                  exit_status = status;
 
                if (! options.persist ())
                  return exit_status;
              }
 
            // If there is an extra argument, see if it names a file to
            // read.  Additional arguments are taken as command line options
            // for the script.
 
            if (m_app_context->have_script_file ())
              {
                int status = execute_command_line_file ();
 
                if (status)
                  exit_status = status;
 
                if (! options.persist ())
                  return exit_status;
              }
 
            if (options.forced_interactive ())
              command_editor::blink_matching_paren (false);
 
            exit_status = main_loop ();
          }
      }
    catch (const exit_exception& ex)
      {
        return ex.exit_status ();
      }
 
    return exit_status;
  }
 
  // Call a function with exceptions handled to avoid problems with
  // errors while shutting down.
 
#define OCTAVE_IGNORE_EXCEPTION(E)                                      \
  catch (E)                                                             \
    {                                                                   \
      recover_from_exception ();                                        \
                                                                        \
      std::cerr << "error: ignoring " #E " while preparing to exit"     \
                << std::endl;                                           \
    }
 
#define OCTAVE_SAFE_CALL(F, ARGS)                                       \
  do                                                                    \
    {                                                                   \
      try                                                               \
        {                                                               \
          unwind_protect frame;                                         \
                                                                        \
          frame.add_method (m_error_system,                             \
                            &error_system::set_debug_on_error,          \
                            m_error_system.debug_on_error ());          \
          frame.add_method (m_error_system,                             \
                            &error_system::set_debug_on_warning,        \
                            m_error_system.debug_on_warning ());        \
                                                                        \
          m_error_system.debug_on_error (false);                        \
          m_error_system.debug_on_warning (false);                      \
                                                                        \
          F ARGS;                                                       \
        }                                                               \
      OCTAVE_IGNORE_EXCEPTION (const exit_exception&)                   \
      OCTAVE_IGNORE_EXCEPTION (const interrupt_exception&)              \
      OCTAVE_IGNORE_EXCEPTION (const execution_exception&)              \
      OCTAVE_IGNORE_EXCEPTION (const std::bad_alloc&)                   \
    }                                                                   \
  while (0)
 
  void interpreter::shutdown (void)
  {
    OCTAVE_SAFE_CALL (feval, ("close", ovl ("all"), 0));
 
    // If we are attached to a GUI, process pending events and
    // disable the link.
 
    OCTAVE_SAFE_CALL (m_event_manager.process_events, (true));
    OCTAVE_SAFE_CALL (m_event_manager.disable, ());
 
    OCTAVE_SAFE_CALL (m_input_system.clear_input_event_hooks, ());
 
    // Any atexit functions added after this function call won't be
    // executed.  Each atexit function is executed with
    // OCTAVE_SAFE_CALL, so we don't need that here.
 
    execute_atexit_fcns ();
 
    // Clear all functions and variables.
 
    // Note that we don't force symbols to be cleared, so we will
    // respect mlock at this point.  Later, we'll force all variables
    // and functions to be cleared.
 
    OCTAVE_SAFE_CALL (clear_all, ());
 
    // We may still have some figures.  Close them.
 
    OCTAVE_SAFE_CALL (feval, ("close", ovl ("all"), 0));
 
    // What is supposed to happen if a figure has a closerequestfcn or
    // deletefcn callback registered that creates other figures or
    // variables?  What if those variables are classdef objects with
    // destructors that can create figures?  The possibilities are
    // endless.  At some point, we have to give up and force execution
    // to end.
 
    // Note that we again don't force symbols to be cleared, so we
    // continue to respect mlock here.  Later, we'll force all variables
    // and functions to be cleared.
 
    OCTAVE_SAFE_CALL (clear_all, ());
 
    // Do this explicitly so that destructors for mex file objects
    // are called, so that functions registered with mexAtExit are
    // called.
 
    OCTAVE_SAFE_CALL (m_symbol_table.clear_mex_functions, ());
 
    OCTAVE_SAFE_CALL (command_editor::restore_terminal_state, ());
 
    OCTAVE_SAFE_CALL (m_history_system.write_timestamp, ());
 
    if (! command_history::ignoring_entries ())
      OCTAVE_SAFE_CALL (command_history::clean_up_and_save, ());
 
    OCTAVE_SAFE_CALL (m_gtk_manager.unload_all_toolkits, ());
 
    // Now that the graphics toolkits have been unloaded, force all
    // symbols to be cleared.
 
    OCTAVE_SAFE_CALL (clear_all, (true));
 
    // FIXME:  May still need something like this to ensure that
    // destructors for class objects will run properly.  Should that be
    // done earlier?  Before or after atexit functions are executed?
    // What will happen if the destructor for an obect attempts to
    // display a figure?
 
    OCTAVE_SAFE_CALL (m_symbol_table.cleanup, ());
 
    OCTAVE_SAFE_CALL (sysdep_cleanup, ());
 
    OCTAVE_SAFE_CALL (flush_stdout, ());
 
    // Don't call singleton_cleanup_list::cleanup until we have the
    // problems with registering/unregistering types worked out.  For
    // example, uncomment the following line, then use the make_int
    // function from the examples directory to create an integer
    // object and then exit Octave.  Octave should crash with a
    // segfault when cleaning up the typinfo singleton.  We need some
    // way to force new octave_value_X types that are created in
    // .oct files to be unregistered when the .oct file shared library
    // is unloaded.
    //
    // OCTAVE_SAFE_CALL (singleton_cleanup_list::cleanup, ());
  }
 
  void interpreter::execute_atexit_fcns (void)
  {
    // Prevent atexit functions from adding new functions to the list.
    m_executing_atexit = true;
 
    while (! m_atexit_fcns.empty ())
      {
        std::string fcn = m_atexit_fcns.front ();
 
        m_atexit_fcns.pop_front ();
 
        OCTAVE_SAFE_CALL (feval, (fcn, octave_value_list (), 0));
 
        OCTAVE_SAFE_CALL (flush_stdout, ());
      }
  }
 
  void interpreter::display_startup_message (void) const
  {
    bool inhibit_startup_message = false;
 
    if (m_app_context)
      {
        const cmdline_options& options = m_app_context->options ();
 
        inhibit_startup_message = options.inhibit_startup_message ();
      }
 
    if (m_interactive && ! inhibit_startup_message)
      std::cout << octave_startup_message () << "\n" << std::endl;
  }
 
  // Initialize by reading startup files.  Return non-zero if an exception
  // occurs when reading any of them, but don't exit early because of an
  // exception.
 
  int interpreter::execute_startup_files (void)
  {
    bool read_site_files = m_read_site_files;
    bool read_init_files = m_read_init_files;
    bool verbose = m_verbose;
    bool inhibit_startup_message = m_inhibit_startup_message;
 
    if (m_app_context)
      {
        const cmdline_options& options = m_app_context->options ();
 
        read_site_files = options.read_site_files ();
        read_init_files = options.read_init_files ();
        verbose = options.verbose_flag ();
        inhibit_startup_message = options.inhibit_startup_message ();
      }
 
    verbose = (verbose && ! inhibit_startup_message);
 
    bool require_file = false;
 
    std::string context;
 
    int exit_status = 0;
 
    if (read_site_files)
      {
        // Execute commands from the site-wide configuration file.
        // First from the file $(prefix)/lib/octave/site/m/octaverc
        // (if it exists), then from the file
        // $(prefix)/share/octave/$(version)/m/octaverc (if it exists).
 
        int status = safe_source_file (config::local_site_defaults_file (),
                                       context, verbose, require_file);
 
        if (status)
          exit_status = status;
 
        status = safe_source_file (config::site_defaults_file (),
                                   context, verbose, require_file);
 
        if (status)
          exit_status = status;
      }
 
    if (read_init_files)
      {
        // Try to execute commands from the Matlab compatible startup.m file
        // if it exists anywhere in the load path when starting Octave.
        std::string ff_startup_m = file_in_path ("startup.m", "");
 
        if (! ff_startup_m.empty ())
          {
            int parse_status = 0;
 
            try
              {
                eval_string (std::string ("startup"), false, parse_status, 0);
              }
            catch (const interrupt_exception&)
              {
                recover_from_exception ();
              }
            catch (const execution_exception& e)
              {
                handle_exception (e);
              }
          }
 
        // Try to execute commands from $CONFIG/octave/octaverc, where
        // $CONFIG is the platform-dependent location for user local
        // configuration files.
 
        std::string user_config_dir = sys::env::get_user_config_directory ();
 
        std::string cfg_dir = user_config_dir + sys::file_ops::dir_sep_str ()
                              + "octave";
 
        std::string cfg_rc = sys::env::make_absolute ("octaverc", cfg_dir);
 
        if (! cfg_rc.empty ())
          {
            int status = safe_source_file (cfg_rc, context, verbose,
                                           require_file);
 
            if (status)
              exit_status = status;
          }
 
        // Try to execute commands from $HOME/$OCTAVE_INITFILE and
        // $OCTAVE_INITFILE.  If $OCTAVE_INITFILE is not set,
        // .octaverc is assumed.
 
        bool home_rc_already_executed = false;
 
        std::string initfile = sys::env::getenv ("OCTAVE_INITFILE");
 
        if (initfile.empty ())
          initfile = ".octaverc";
 
        std::string home_dir = sys::env::get_home_directory ();
 
        std::string home_rc = sys::env::make_absolute (initfile, home_dir);
 
        std::string local_rc;
 
        if (! home_rc.empty ())
          {
            int status = safe_source_file (home_rc, context, verbose,
                                           require_file);
 
            if (status)
              exit_status = status;
 
            // Names alone are not enough.
 
            sys::file_stat fs_home_rc (home_rc);
 
            if (fs_home_rc)
              {
                // We want to check for curr_dir after executing home_rc
                // because doing that may change the working directory.
 
                local_rc = sys::env::make_absolute (initfile);
 
                home_rc_already_executed = same_file (home_rc, local_rc);
              }
          }
 
        if (! home_rc_already_executed)
          {
            if (local_rc.empty ())
              local_rc = sys::env::make_absolute (initfile);
 
            int status = safe_source_file (local_rc, context, verbose,
                                           require_file);
 
            if (status)
              exit_status = status;
          }
      }
 
    if (m_interactive && verbose)
      std::cout << std::endl;
 
    return exit_status;
  }
 
  // Execute any code specified with --eval 'CODE'
 
  int interpreter::execute_eval_option_code (void)
  {
    if (! m_app_context)
      return 0;
 
    const cmdline_options& options = m_app_context->options ();
 
    std::string code_to_eval = options.code_to_eval ();
 
    unwind_protect_var<bool> upv (m_interactive, false);
 
    int parse_status = 0;
 
    try
      {
        eval_string (code_to_eval, false, parse_status, 0);
      }
    catch (const interrupt_exception&)
      {
        recover_from_exception ();
 
        return 1;
      }
    catch (const execution_exception& e)
      {
        handle_exception (e);
 
        return 1;
      }
 
    return parse_status;
  }
 
  int interpreter::execute_command_line_file (void)
  {
    if (! m_app_context)
      return 0;
 
    const cmdline_options& options = m_app_context->options ();
 
    unwind_protect frame;
 
    frame.add_method (this, &interpreter::interactive, m_interactive);
 
    string_vector args = options.all_args ();
 
    frame.add_method (m_app_context, &application::intern_argv, args);
 
    frame.add_method (this, &interpreter::intern_nargin, args.numel () - 1);
 
    frame.add_method (m_app_context,
                      &application::program_invocation_name,
                      application::program_invocation_name ());
 
    frame.add_method (m_app_context,
                      &application::program_name,
                      application::program_name ());
 
    m_interactive = false;
 
    // If we are running an executable script (#! /bin/octave) then
    // we should only see the args passed to the script.
 
    string_vector script_args = options.remaining_args ();
 
    m_app_context->intern_argv (script_args);
    intern_nargin (script_args.numel () - 1);
 
    std::string fname = script_args[0];
 
    m_app_context->set_program_names (fname);
 
    std::string context;
    bool verbose = false;
    bool require_file = true;
 
    return safe_source_file (fname, context, verbose, require_file);
  }
 
  int interpreter::main_loop (void)
  {
    // The big loop.  Read, Eval, Print, Loop.  Normally user
    // interaction at the command line in a terminal session, but we may
    // also end up here when reading from a pipe or when stdin is
    // connected to a file by the magic of input redirection.
 
    int exit_status = 0;
 
    // FIXME: should this choice be a command-line option?  Note that we
    // intend that the push parser interface only be used for
    // interactive sessions.
 
#if defined (OCTAVE_ENABLE_COMMAND_LINE_PUSH_PARSER)
    static bool use_command_line_push_parser = true;
#else
    static bool use_command_line_push_parser = false;
#endif
 
    // The following logic is written as it is to allow easy transition
    // to setting USE_COMMAND_LINE_PUSH_PARSER at run time and to
    // simplify the logic of the main loop below by using the same
    // base_parser::run interface for both push and pull parsers.
 
    std::shared_ptr<base_parser> repl_parser;
 
    if (m_interactive)
      {
        if (use_command_line_push_parser)
          {
            push_parser *pp = new push_parser (*this, new input_reader (*this));
            repl_parser = std::shared_ptr<base_parser> (pp);
          }
        else
          {
            parser *pp = new parser (new lexer (*this));
            repl_parser = std::shared_ptr<base_parser> (pp);
          }
      }
    else
      {
        parser *pp = new parser (new lexer (stdin, *this));
        repl_parser = std::shared_ptr<base_parser> (pp);
      }
 
    do
      {
        try
          {
            unwind_protect_var<bool> upv (m_in_top_level_repl, true);
 
            repl_parser->reset ();
 
            if (m_evaluator.at_top_level ())
              {
                m_evaluator.dbstep_flag (0);
                m_evaluator.reset_debug_state ();
              }
 
            exit_status = repl_parser->run ();
 
            if (exit_status == 0)
              {
                std::shared_ptr<tree_statement_list>
                  stmt_list = repl_parser->statement_list ();
 
                if (stmt_list)
                  {
                    command_editor::increment_current_command_number ();
 
                    m_evaluator.eval (stmt_list, m_interactive);
                  }
                else if (repl_parser->at_end_of_input ())
                  {
                    exit_status = EOF;
                    break;
                  }
              }
          }
        catch (const interrupt_exception&)
          {
            recover_from_exception ();
 
            // Required newline when the user does Ctrl+C at the prompt.
            if (m_interactive)
              octave_stdout << "\n";
          }
        catch (const index_exception& e)
          {
            recover_from_exception ();
 
            std::cerr << "error: unhandled index exception: "
                      << e.message () << " -- trying to return to prompt"
                      << std::endl;
          }
        catch (const execution_exception& ee)
          {
            m_error_system.save_exception (ee);
            m_error_system.display_exception (ee, std::cerr);
 
            if (m_interactive)
              recover_from_exception ();
            else
              {
                // We should exit with a nonzero status.
                exit_status = 1;
                break;
              }
          }
        catch (const std::bad_alloc&)
          {
            recover_from_exception ();
 
            std::cerr << "error: out of memory -- trying to return to prompt"
                      << std::endl;
          }
      }
    while (exit_status == 0);
 
    if (exit_status == EOF)
      {
        if (m_interactive)
          octave_stdout << "\n";
 
        exit_status = 0;
      }
 
    return exit_status;
  }
 
  tree_evaluator& interpreter::get_evaluator (void)
  {
    return m_evaluator;
  }
 
  stream_list& interpreter::get_stream_list (void)
  {
    return m_stream_list;
  }
 
  url_handle_manager& interpreter::get_url_handle_manager (void)
  {
    return m_url_handle_manager;
  }
 
  symbol_scope
  interpreter::get_top_scope (void) const
  {
    return m_evaluator.get_top_scope ();
  }
 
  symbol_scope
  interpreter::get_current_scope (void) const
  {
    return m_evaluator.get_current_scope ();
  }
 
  symbol_scope
  interpreter::require_current_scope (const std::string& who) const
  {
    symbol_scope scope = get_current_scope ();
 
    if (! scope)
      error ("%s: symbol table scope missing", who.c_str ());
 
    return scope;
  }
 
  profiler& interpreter::get_profiler (void)
  {
    return m_evaluator.get_profiler ();
  }
 
  int interpreter::chdir (const std::string& dir)
  {
    std::string xdir = sys::file_ops::tilde_expand (dir);
 
    int cd_ok = sys::env::chdir (xdir);
 
    if (! cd_ok)
      error ("%s: %s", dir.c_str (), std::strerror (errno));
 
    Vlast_chdir_time.stamp ();
 
    // FIXME: should these actions be handled as a list of functions
    // to call so users can add their own chdir handlers?
 
    m_load_path.update ();
 
    m_event_manager.directory_changed (sys::env::get_current_directory ());
 
    return cd_ok;
  }
 
  void interpreter::mlock (bool skip_first) const
  {
    m_evaluator.mlock (skip_first);
  }
 
  void interpreter::munlock (bool skip_first) const
  {
    m_evaluator.munlock (skip_first);
  }
 
  bool interpreter::mislocked (bool skip_first) const
  {
    return m_evaluator.mislocked (skip_first);
  }
 
  void interpreter::munlock (const char *nm)
  {
    if (! nm)
      error ("munlock: invalid value for NAME");
 
    munlock (std::string (nm));
  }
 
  void interpreter::munlock (const std::string& nm)
  {
    octave_value val = m_symbol_table.find_function (nm);
 
    if (val.is_defined ())
      {
        octave_function *fcn = val.function_value ();
 
        if (fcn)
          fcn->unlock ();
      }
  }
 
  bool interpreter::mislocked (const char *nm)
  {
    if (! nm)
      error ("mislocked: invalid value for NAME");
 
    return mislocked (std::string (nm));
  }
 
  bool interpreter::mislocked (const std::string& nm)
  {
    bool retval = false;
 
    octave_value val = m_symbol_table.find_function (nm);
 
    if (val.is_defined ())
      {
        octave_function *fcn = val.function_value ();
 
        if (fcn)
          retval = fcn->islocked ();
      }
 
    return retval;
  }
 
  std::string interpreter::mfilename (const std::string& opt) const
  {
    return m_evaluator.mfilename (opt);
  }
 
  octave_value_list interpreter::eval_string (const std::string& eval_str,
                                              bool silent, int& parse_status,
                                              int nargout)
  {
    return m_evaluator.eval_string (eval_str, silent, parse_status, nargout);
  }
 
  octave_value interpreter::eval_string (const std::string& eval_str,
                                         bool silent, int& parse_status)
  {
    return m_evaluator.eval_string (eval_str, silent, parse_status);
  }
 
  octave_value_list interpreter::eval_string (const octave_value& arg,
                                              bool silent, int& parse_status,
                                              int nargout)
  {
    return m_evaluator.eval_string (arg, silent, parse_status, nargout);
  }
 
  octave_value_list interpreter::eval (const std::string& try_code,
                                       int nargout)
  {
    return m_evaluator.eval (try_code, nargout);
  }
 
  octave_value_list interpreter::eval (const std::string& try_code,
                                       const std::string& catch_code,
                                       int nargout)
  {
    return m_evaluator.eval (try_code, catch_code, nargout);
  }
 
  octave_value_list interpreter::evalin (const std::string& context,
                                         const std::string& try_code,
                                         int nargout)
  {
    return m_evaluator.evalin (context, try_code, nargout);
  }
 
  octave_value_list interpreter::evalin (const std::string& context,
                                         const std::string& try_code,
                                         const std::string& catch_code,
                                         int nargout)
  {
    return m_evaluator.evalin (context, try_code, catch_code, nargout);
  }
 
  //! Evaluate an Octave function (built-in or interpreted) and return
  //! the list of result values.
  //!
  //! @param name The name of the function to call.
  //! @param args The arguments to the function.
  //! @param nargout The number of output arguments expected.
  //! @return A list of output values.  The length of the list is not
  //!         necessarily the same as @c nargout.
 
  octave_value_list interpreter::feval (const char *name,
                                        const octave_value_list& args,
                                        int nargout)
  {
    return feval (std::string (name), args, nargout);
  }
 
  octave_value_list interpreter::feval (const std::string& name,
                                        const octave_value_list& args,
                                        int nargout)
  {
    octave_value fcn = m_symbol_table.find_function (name, args);
 
    if (fcn.is_undefined ())
      error ("feval: function '%s' not found", name.c_str ());
 
    octave_function *of = fcn.function_value ();
 
    return of->call (m_evaluator, nargout, args);
  }
 
  octave_value_list interpreter::feval (octave_function *fcn,
                                        const octave_value_list& args,
                                        int nargout)
  {
    if (fcn)
      return fcn->call (m_evaluator, nargout, args);
 
    return octave_value_list ();
  }
 
  octave_value_list interpreter::feval (const octave_value& val,
                                        const octave_value_list& args,
                                        int nargout)
  {
    // FIXME: do we really want to silently return an empty ovl if
    // the function object is undefined?  It's essentially what the
    // version above that accepts a pointer to an octave_function
    // object does and some code was apparently written to rely on it
    // (for example, __ode15__).
 
    if (val.is_undefined ())
      return ovl ();
 
    if (val.is_function ())
      {
        return feval (val.function_value (), args, nargout);
      }
    else if (val.is_function_handle () || val.is_inline_function ())
      {
        // This covers function handles, inline functions, and anonymous
        //  functions.
 
        std::list<octave_value_list> arg_list;
        arg_list.push_back (args);
 
        // FIXME: could we make octave_value::subsref a const method?
        // It would be difficult because there are instances of
        // incrementing the reference count inside subsref methods,
        // which means they can't be const with the current way of
        // handling reference counting.
 
        octave_value xval = val;
        return xval.subsref ("(", arg_list, nargout);
      }
    else if (val.is_string ())
      {
        return feval (val.string_value (), args, nargout);
      }
    else
      error ("feval: first argument must be a string, inline function, or a function handle");
 
    return ovl ();
  }
 
  //! Evaluate an Octave function (built-in or interpreted) and return
  //! the list of result values.
  //!
  //! @param args The first element of @c args is the function to call.
  //!             It may be the name of the function as a string, a function
  //!             handle, or an inline function.  The remaining arguments are
  //!             passed to the function.
  //! @param nargout The number of output arguments expected.
  //! @return A list of output values.  The length of the list is not
  //!         necessarily the same as @c nargout.
 
  octave_value_list interpreter::feval (const octave_value_list& args,
                                        int nargout)
  {
    if (args.length () == 0)
      error ("feval: first argument must be a string, inline function, or a function handle");
 
    octave_value f_arg = args(0);
 
    octave_value_list tmp_args = args.slice (1, args.length () - 1, true);
 
    return feval (f_arg, tmp_args, nargout);
  }
 
  octave_value interpreter::make_function_handle (const std::string& name)
  {
    return m_evaluator.make_fcn_handle (name);
  }
 
  void interpreter::install_variable (const std::string& name,
                                      const octave_value& value, bool global)
  {
    m_evaluator.install_variable (name, value, global);
  }
 
  octave_value interpreter::global_varval (const std::string& name) const
  {
    return m_evaluator.global_varval (name);
  }
 
  void interpreter::global_assign (const std::string& name,
                                   const octave_value& val)
  {
    m_evaluator.global_assign (name, val);
  }
 
  octave_value interpreter::top_level_varval (const std::string& name) const
  {
    return m_evaluator.top_level_varval (name);
  }
 
  void interpreter::top_level_assign (const std::string& name,
                                      const octave_value& val)
  {
    m_evaluator.top_level_assign (name, val);
  }
 
  bool interpreter::is_variable (const std::string& name) const
  {
    return m_evaluator.is_variable (name);
  }
 
  bool interpreter::is_local_variable (const std::string& name) const
  {
    return m_evaluator.is_local_variable (name);
  }
 
  octave_value interpreter::varval (const std::string& name) const
  {
    return m_evaluator.varval (name);
  }
 
  void interpreter::assign (const std::string& name,
                            const octave_value& val)
  {
    m_evaluator.assign (name, val);
  }
 
  void interpreter::assignin (const std::string& context,
                              const std::string& name,
                              const octave_value& val)
  {
    m_evaluator.assignin (context, name, val);
  }
 
  void interpreter::source_file (const std::string& file_name,
                                 const std::string& context, bool verbose,
                                 bool require_file)
  {
    m_evaluator.source_file (file_name, context, verbose, require_file);
  }
 
  bool interpreter::at_top_level (void) const
  {
    return m_evaluator.at_top_level ();
  }
 
  bool interpreter::isglobal (const std::string& name) const
  {
    return m_evaluator.is_global (name);
  }
 
  octave_value interpreter::find (const std::string& name)
  {
    return m_evaluator.find (name);
  }
 
  void interpreter::clear_all (bool force)
  {
    m_evaluator.clear_all (force);
  }
 
  void interpreter::clear_objects (void)
  {
    m_evaluator.clear_objects ();
  }
 
  void interpreter::clear_variable (const std::string& name)
  {
    m_evaluator.clear_variable (name);
  }
 
  void interpreter::clear_variable_pattern (const std::string& pattern)
  {
    m_evaluator.clear_variable_pattern (pattern);
  }
 
  void interpreter::clear_variable_regexp (const std::string& pattern)
  {
    m_evaluator.clear_variable_regexp (pattern);
  }
 
  void interpreter::clear_variables (void)
  {
    m_evaluator.clear_variables ();
  }
 
  void interpreter::clear_global_variable (const std::string& name)
  {
    m_evaluator.clear_global_variable (name);
  }
 
  void interpreter::clear_global_variable_pattern (const std::string& pattern)
  {
    m_evaluator.clear_global_variable_pattern (pattern);
  }
 
  void interpreter::clear_global_variable_regexp (const std::string& pattern)
  {
    m_evaluator.clear_global_variable_regexp (pattern);
  }
 
  void interpreter::clear_global_variables (void)
  {
    m_evaluator.clear_global_variables ();
  }
 
  void interpreter::clear_functions (bool force)
  {
    m_symbol_table.clear_functions (force);
  }
 
  void interpreter::clear_function (const std::string& name)
  {
    m_symbol_table.clear_function (name);
  }
 
  void interpreter::clear_symbol (const std::string& name)
  {
    m_evaluator.clear_symbol (name);
  }
 
  void interpreter::clear_function_pattern (const std::string& pat)
  {
    m_symbol_table.clear_function_pattern (pat);
  }
 
  void interpreter::clear_function_regexp (const std::string& pat)
  {
    m_symbol_table.clear_function_regexp (pat);
  }
 
  void interpreter::clear_symbol_pattern (const std::string& pat)
  {
    return m_evaluator.clear_symbol_pattern (pat);
  }
 
  void interpreter::clear_symbol_regexp (const std::string& pat)
  {
    return m_evaluator.clear_symbol_regexp (pat);
  }
 
  std::list<std::string> interpreter::global_variable_names (void)
  {
    return m_evaluator.global_variable_names ();
  }
 
  std::list<std::string> interpreter::top_level_variable_names (void)
  {
    return m_evaluator.top_level_variable_names ();
  }
 
  std::list<std::string> interpreter::variable_names (void)
  {
    return m_evaluator.variable_names ();
  }
 
  std::list<std::string> interpreter::user_function_names (void)
  {
    return m_symbol_table.user_function_names ();
  }
 
  std::list<std::string> interpreter::autoloaded_functions (void) const
  {
    return m_evaluator.autoloaded_functions ();
  }
 
  void interpreter::handle_exception (const execution_exception& e)
  {
    m_error_system.save_exception (e);
 
    // FIXME: use a separate stream instead of std::cerr directly so that
    // error messages can be redirected more easily?  Pass the message
    // to an event manager function?
    m_error_system.display_exception (e, std::cerr);
 
    recover_from_exception ();
  }
 
  void interpreter::recover_from_exception (void)
  {
    can_interrupt = true;
    octave_interrupt_state = 0;
    octave_signal_caught = 0;
    octave_restore_signal_mask ();
    catch_interrupts ();
  }
 
  void interpreter::mark_for_deletion (const std::string& file)
  {
    m_tmp_files.insert (file);
  }
 
  void interpreter::cleanup_tmp_files (void)
  {
    m_tmp_files.cleanup ();
  }
 
  void interpreter::quit (int exit_status, bool force, bool confirm)
  {
    if (! force)
      {
        try
          {
            bool cancel = false;
 
            if (symbol_exist ("finish.m", "file"))
              {
                unwind_protect_var<bool> upv1 (m_executing_finish_script, true);
                unwind_protect_var<bool> upv2 (m_cancel_quit);
 
                evalin ("base", "finish", 0);
 
                cancel = m_cancel_quit;
              }
 
            if (cancel)
              return;
 
            // Check for confirmation.
 
            if (confirm && ! m_event_manager.confirm_shutdown ())
              return;
          }
        catch (const execution_exception&)
          {
            // Catch execution_exceptions so we don't throw an
            // exit_exception if there is an in finish.m.  But throw it
            // again so that will be handled as any other
            // execution_exception by the evaluator.  This way, errors
            // will be ignored properly and we won't exit if quit is
            // called recursively from finish.m.
 
            throw;
          }
      }
 
    throw exit_exception (exit_status);
  }
 
  void interpreter::add_atexit_fcn (const std::string& fname)
  {
    if (m_executing_atexit)
      return;
 
    m_atexit_fcns.push_front (fname);
  }
 
  bool interpreter::remove_atexit_fcn (const std::string& fname)
  {
    bool found = false;
 
    for (auto it = m_atexit_fcns.begin ();
         it != m_atexit_fcns.end (); it++)
      {
        if (*it == fname)
          {
            m_atexit_fcns.erase (it);
            found = true;
            break;
          }
      }
 
    return found;
  }
 
  void interpreter::add_atexit_function (const std::string& fname)
  {
    interpreter& interp
      = __get_interpreter__ ("interpreter::add_atexit_function");
 
    interp.add_atexit_fcn (fname);
  }
 
  bool interpreter::remove_atexit_function (const std::string& fname)
  {
    interpreter& interp
      = __get_interpreter__ ("interpreter::remove_atexit_function");
 
    return interp.remove_atexit_fcn (fname);
  }
 
  // What internal options get configured by --traditional.
 
  void interpreter::maximum_braindamage (void)
  {
    m_input_system.PS1 (">> ");
    m_input_system.PS2 ("");
 
    m_evaluator.PS4 ("");
 
    m_load_save_system.crash_dumps_octave_core (false);
    m_load_save_system.save_default_options ("-mat-binary");
 
    m_history_system.timestamp_format_string ("%%-- %D %I:%M %p --%%");
 
    m_error_system.beep_on_error (true);
    Fconfirm_recursive_rmdir (octave_value (false));
 
    Fdisable_diagonal_matrix (octave_value (true));
    Fdisable_permutation_matrix (octave_value (true));
    Fdisable_range (octave_value (true));
    Ffixed_point_format (octave_value (true));
    Fprint_empty_dimensions (octave_value (false));
    Fstruct_levels_to_print (octave_value (0));
 
    disable_warning ("Octave:abbreviated-property-match");
    disable_warning ("Octave:colon-nonscalar-argument");
    disable_warning ("Octave:data-file-in-path");
    disable_warning ("Octave:function-name-clash");
    disable_warning ("Octave:possible-matlab-short-circuit-operator");
  }
 
  void interpreter::execute_pkg_add (const std::string& dir)
  {
    try
      {
        m_load_path.execute_pkg_add (dir);
      }
    catch (const interrupt_exception&)
      {
        recover_from_exception ();
      }
    catch (const execution_exception& e)
      {
        handle_exception (e);
      }
  }
}