new file mode 100644
--- /dev/null
+++ b/src/ov-usr-fcn.cc
@@ -0,0 +1,563 @@
+/*
+
+Copyright (C) 1996, 1997 John W. Eaton
+
+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, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+*/
+
+#if defined (__GNUG__)
+#pragma implementation
+#endif
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "str-vec.h"
+
+#include <defaults.h>
+#include "defun.h"
+#include "error.h"
+#include "help.h"
+#include "input.h"
+#include "oct-obj.h"
+#include "ov-usr-fcn.h"
+#include "ov.h"
+#include "pager.h"
+#include "pt-misc.h"
+#include "pt-pr-code.h"
+#include "pt-walk.h"
+#include "symtab.h"
+#include "toplev.h"
+#include "unwind-prot.h"
+#include "utils.h"
+#include "variables.h"
+
+// If TRUE, variables returned from functions have default values even
+// if they are not explicitly initialized.
+static bool Vdefine_all_return_values;
+
+// If TRUE, the last computed value is returned from functions that
+// don't actually define any return variables.
+static bool Vreturn_last_computed_value;
+
+// Nonzero means we're breaking out of a loop or function body.
+extern int breaking;
+
+// Nonzero means we're returning from a function.
+extern int returning;
+
+// User defined functions.
+
+octave_allocator
+octave_user_function::allocator (sizeof (octave_user_function));
+
+int
+octave_user_function::t_id (-1);
+
+const string
+octave_user_function::t_name ("user-defined function");
+
+// Ugh.  This really needs to be simplified (code/data?
+// extrinsic/intrinsic state?).
+
+octave_user_function::octave_user_function
+  (tree_parameter_list *pl, tree_parameter_list *rl,
+   tree_statement_list *cl, symbol_table *st)
+  : octave_function (string (), string ()),
+    param_list (pl), ret_list (rl), cmd_list (cl),
+    sym_tab (st), file_name (), fcn_name (), t_parsed (0),
+    system_fcn_file (false), call_depth (0), num_named_args (0),
+    args_passed (), num_args_passed (0), curr_va_arg_number (0),
+    vr_list (0), symtab_entry (0), argn_sr (0), nargin_sr (0),
+    nargout_sr (0)
+{
+  install_automatic_vars ();
+
+  if (param_list)
+    {
+      num_named_args = param_list->length ();
+      curr_va_arg_number = num_named_args;
+    }
+}
+
+octave_user_function::~octave_user_function (void)
+{
+  delete param_list;
+  delete ret_list;
+  delete sym_tab;
+  delete cmd_list;
+  delete vr_list;
+}
+
+octave_user_function *
+octave_user_function::define_ret_list (tree_parameter_list *t)
+{
+  ret_list = t;
+
+  if (ret_list && ret_list->takes_varargs ())
+    vr_list = new tree_va_return_list;
+ 
+  return this;
+}
+
+void
+octave_user_function::stash_fcn_file_name (void)
+{
+  if (fcn_name.empty ())
+    file_name = "";
+  else
+    file_name = fcn_file_in_path (fcn_name);
+}
+
+void
+octave_user_function::mark_as_system_fcn_file (void)
+{
+  if (! file_name.empty ())
+    {
+      // We really should stash the whole path to the file we found,
+      // when we looked it up, to avoid possible race conditions...
+      // XXX FIXME XXX
+      //
+      // We probably also don't need to get the library directory
+      // every time, but since this function is only called when the
+      // function file is parsed, it probably doesn't matter that
+      // much.
+
+      string ff_name = fcn_file_in_path (file_name);
+
+      if (Vfcn_file_dir.compare (ff_name, 0, Vfcn_file_dir.length ()) == 0)
+	system_fcn_file = 1;
+    }
+  else
+    system_fcn_file = 0;
+}
+
+bool
+octave_user_function::takes_varargs (void) const
+{
+  return (param_list && param_list->takes_varargs ());
+}
+
+octave_value
+octave_user_function::octave_va_arg (void)
+{
+  octave_value retval;
+
+  if (curr_va_arg_number < num_args_passed)
+    retval = args_passed (curr_va_arg_number++);
+  else
+    ::error ("va_arg: error getting arg number %d -- only %d provided",
+	     curr_va_arg_number + 1, num_args_passed);
+
+  return retval;
+}
+
+octave_value_list
+octave_user_function::octave_all_va_args (void)
+{
+  octave_value_list retval;
+
+  retval.resize (num_args_passed - num_named_args);
+
+  int k = 0;
+  for (int i = num_named_args; i < num_args_passed; i++)
+    retval(k++) = args_passed(i);
+
+  return retval;
+}
+
+bool
+octave_user_function::takes_var_return (void) const
+{
+  return (ret_list && ret_list->takes_varargs ());
+}
+
+void
+octave_user_function::octave_vr_val (const octave_value& val)
+{
+  assert (vr_list);
+
+  vr_list->append (val);
+}
+
+void
+octave_user_function::stash_function_name (const string& s)
+{
+  fcn_name = s;
+}
+
+// For unwind protect.
+
+static void
+pop_symbol_table_context (void *table)
+{
+  symbol_table *tmp = static_cast<symbol_table *> (table);
+  tmp->pop_context ();
+}
+
+static void
+delete_vr_list (void *list)
+{
+  tree_va_return_list *tmp = static_cast<tree_va_return_list *> (list);
+  tmp->clear ();
+  delete tmp;
+}
+
+static void
+clear_symbol_table (void *table)
+{
+  symbol_table *tmp = static_cast<symbol_table *> (table);
+  tmp->clear ();
+}
+
+static void
+unprotect_function (void *sr_arg)
+{
+  symbol_record *sr = static_cast<symbol_record *> (sr_arg);
+  sr->unprotect ();
+}
+
+octave_value_list
+octave_user_function::do_index_op (int nargout, const octave_value_list& args)
+{
+  octave_value_list retval;
+
+  if (error_state)
+    return retval;
+
+  if (! cmd_list)
+    return retval;
+
+  int nargin = args.length ();
+
+  begin_unwind_frame ("func_eval");
+
+  unwind_protect_int (call_depth);
+  call_depth++;
+
+  if (symtab_entry && ! symtab_entry->is_read_only ())
+    {
+      symtab_entry->protect ();
+      add_unwind_protect (unprotect_function, symtab_entry);
+    }
+
+  if (call_depth > 1)
+    {
+      sym_tab->push_context ();
+      add_unwind_protect (pop_symbol_table_context, sym_tab);
+
+      if (vr_list)
+	{
+	  // Push new vr_list.
+
+	  unwind_protect_ptr (vr_list);
+	  vr_list = new tree_va_return_list;
+
+	  // Clear and delete the new one before restoring the old
+	  // one.
+
+	  add_unwind_protect (delete_vr_list, vr_list);
+	}
+    }
+
+  if (vr_list)
+    vr_list->clear ();
+
+  // Force symbols to be undefined again when this function exits.
+
+  add_unwind_protect (clear_symbol_table, sym_tab);
+
+  // Save old and set current symbol table context, for
+  // eval_undefined_error().
+
+  unwind_protect_ptr (curr_sym_tab);
+  curr_sym_tab = sym_tab;
+
+  unwind_protect_ptr (curr_function);
+  curr_function = this;
+
+  // XXX FIXME XXX -- ???
+  // unwind_protect_ptr (args_passed);
+
+  args_passed = args;
+
+  string_vector arg_names = args.name_tags ();
+
+  unwind_protect_int (num_args_passed);
+  num_args_passed = nargin;
+
+  unwind_protect_int (num_named_args);
+  unwind_protect_int (curr_va_arg_number);
+
+  if (param_list && ! param_list->varargs_only ())
+    {
+      param_list->define_from_arg_vector (args);
+      if (error_state)
+	goto abort;
+    }
+
+  if (ret_list && Vdefine_all_return_values)
+    {
+      octave_value tmp = builtin_any_variable ("default_return_value");
+
+      if (tmp.is_defined ())
+	ret_list->initialize_undefined_elements (tmp);
+    }
+
+  // The following code is in a separate scope to avoid warnings from
+  // G++ about `goto abort' crossing the initialization of some
+  // variables.
+
+  {
+    bind_automatic_vars (arg_names, nargin, nargout);
+
+    bool echo_commands = (Vecho_executing_commands & ECHO_FUNCTIONS);
+
+    if (echo_commands)
+      print_code_function_header ();
+
+    // Evaluate the commands that make up the function.
+
+    octave_value_list tmp = cmd_list->eval ();
+
+    octave_value last_computed_value;
+
+    if (! tmp.empty ())
+      last_computed_value = tmp(0);
+
+    if (echo_commands)
+      print_code_function_trailer ();
+
+    if (returning)
+      returning = 0;
+
+    if (breaking)
+      breaking--;
+
+    if (error_state)
+      {
+	traceback_error ();
+	goto abort;
+      }
+    
+    // Copy return values out.
+
+    if (ret_list)
+      retval = ret_list->convert_to_const_vector (vr_list);
+    else if (Vreturn_last_computed_value)
+      retval(0) = last_computed_value;
+  }
+
+ abort:
+  run_unwind_frame ("func_eval");
+
+  return retval;
+}
+
+void
+octave_user_function::traceback_error (void)
+{
+  if (error_state >= 0)
+    error_state = -1;
+
+  if (fcn_name.empty ())
+    {
+      if (file_name.empty ())
+	::error ("called from `?unknown?'");
+      else
+	::error ("called from file `%s'", file_name.c_str ());
+    }
+  else
+    {
+      if (file_name.empty ())
+	::error ("called from `%s'", fcn_name.c_str ());
+      else 
+	::error ("called from `%s' in file `%s'",
+		 fcn_name.c_str (), file_name.c_str ());
+    }
+}
+
+void
+octave_user_function::accept (tree_walker& tw)
+{
+  tw.visit_octave_user_function (*this);
+}
+
+void
+octave_user_function::print_code_function_header (void)
+{
+  tree_print_code tpc (octave_stdout, Vps4);
+
+  tpc.visit_octave_user_function_header (*this);
+}
+
+void
+octave_user_function::print_code_function_trailer (void)
+{
+  tree_print_code tpc (octave_stdout, Vps4);
+
+  tpc.visit_octave_user_function_trailer (*this);
+}
+
+void
+octave_user_function::install_automatic_vars (void)
+{
+  argn_sr = sym_tab->lookup ("argn", true);
+  nargin_sr = sym_tab->lookup ("nargin", true);
+  nargout_sr = sym_tab->lookup ("nargout", true);
+}
+
+void
+octave_user_function::bind_automatic_vars
+  (const string_vector& arg_names, int nargin, int nargout)
+{
+  if (! arg_names.empty ())
+    argn_sr->define (arg_names);
+
+  nargin_sr->define (static_cast<double> (nargin));
+  nargout_sr->define (static_cast<double> (nargout));
+}
+
+DEFUN (va_arg, args, ,
+  "va_arg (): return next argument in a function that takes a\n\
+variable number of parameters")
+{
+  octave_value_list retval;
+
+  int nargin = args.length ();
+
+  if (nargin == 0)
+    {
+      if (curr_function)
+	{
+	  if (curr_function->takes_varargs ())
+	    retval = curr_function->octave_va_arg ();
+	  else
+	    {
+	      ::error ("va_arg only valid within function taking variable");
+	      ::error ("number of arguments");
+	    }
+	}
+      else
+	::error ("va_arg only valid within function body");
+    }
+  else
+    print_usage ("va_arg");
+
+  return retval;
+}
+
+DEFUN (va_start, args, ,
+  "va_start (): reset the pointer to the list of optional arguments\n\
+to the beginning")
+{
+  octave_value_list retval;
+
+  int nargin = args.length ();
+
+  if (nargin == 0)
+    {
+      if (curr_function)
+	{
+	  if (curr_function->takes_varargs ())
+	    curr_function->octave_va_start ();
+	  else
+	    {
+	      ::error ("va_start only valid within function taking variable");
+	      ::error ("number of arguments");
+	    }
+	}
+      else
+	::error ("va_start only valid within function body");
+    }
+  else
+    print_usage ("va_start");
+
+  return retval;
+}
+
+DEFUN (vr_val, args, ,
+  "vr_val (X): append X to the list of optional return values for a\n\
+function that allows a variable number of return values")
+{
+  octave_value_list retval;
+
+  int nargin = args.length ();
+
+  if (nargin == 1)
+    {
+      if (curr_function)
+	{
+	  if (curr_function->takes_var_return ())
+	    curr_function->octave_vr_val (args(0));
+	  else
+	    {
+	      ::error ("vr_val only valid within function declared to");
+	      ::error ("produce a variable number of values");
+	    }
+	}
+      else
+	::error ("vr_val only valid within function body");
+    }
+  else
+    print_usage ("vr_val");
+
+  return retval;
+}
+
+static int
+define_all_return_values (void)
+{
+  Vdefine_all_return_values = check_preference ("define_all_return_values");
+
+  return 0;
+}
+
+static int
+return_last_computed_value (void)
+{
+  Vreturn_last_computed_value
+    = check_preference ("return_last_computed_value");
+
+  return 0;
+}
+
+void
+symbols_of_ov_usr_fcn (void)
+{
+  DEFVAR (default_return_value, Matrix (), 0, 0,
+    "the default for value for unitialized variables returned from\n\
+functions.  Only used if the variable initialize_return_values is\n\
+set to \"true\".");
+
+  DEFVAR (define_all_return_values, 0.0, 0, define_all_return_values,
+    "control whether values returned from functions should have a\n\
+value even if one has not been explicitly assigned.  See also\n\
+default_return_value");
+
+  DEFVAR (return_last_computed_value, 0.0, 0, return_last_computed_value,
+    "if a function does not return any values explicitly, return the\n\
+  last computed value");
+}
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; End: ***
+*/