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pt-fcn.cc

/*

Copyright (C) 1996 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 <iostream.h>

#include <defaults.h>
#include "defun.h"
#include "error.h"
#include "gripes.h"
#include "help.h"
#include "input.h"
#include "pager.h"
#include "symtab.h"
#include "toplev.h"
#include "pt-exp.h"
#include "pt-fcn.h"
#include "pt-misc.h"
#include "pt-pr-code.h"
#include "pt-walk.h"
#include "unwind-prot.h"
#include "utils.h"
#include "ov.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;

// Maximum nesting level for functions called recursively.
static int Vmax_recursion_depth;

// If TRUE, the last computed value is returned from functions that
// don't actually define any return variables.
static bool Vreturn_last_computed_value;

// If TRUE, turn off printing of results in functions (as if a
// semicolon has been appended to each statement).
static bool Vsilent_functions;

// 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.

void
tree_function::install_nargin_and_nargout (void)
{
  nargin_sr = sym_tab->lookup ("nargin", 1, 0);
  nargout_sr = sym_tab->lookup ("nargout", 1, 0);
}

void
tree_function::bind_nargin_and_nargout (int nargin, int nargout)
{
  nargin_sr->define ((double) nargin);
  nargout_sr->define ((double) nargout);
}

tree_function::~tree_function (void)
{
  delete param_list;
  delete ret_list;
  delete sym_tab;
  delete cmd_list;
  delete vr_list;
}

tree_function *
tree_function::define_param_list (tree_parameter_list *t)
{
  param_list = t;

  if (param_list)
    {
      num_named_args = param_list->length ();
      curr_va_arg_number = num_named_args;
    }

  return this;
}

tree_function *
tree_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
tree_function::stash_fcn_file_name (void)
{
  if (fcn_name.empty ())
    file_name = "";
  else
    file_name = fcn_file_in_path (fcn_name);
}

void
tree_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
tree_function::takes_varargs (void) const
{
  return (param_list && param_list->takes_varargs ());
}

octave_value
tree_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
tree_function::octave_all_va_args (void)
{
  octave_value_list retval;

  int n = num_args_passed - num_named_args;

  if (n > 0)
    {
      retval.resize (n);

      int k = 0;
      for (int i = num_named_args; i < num_args_passed; i++)
      retval(k++) = args_passed(i);
    }

  return retval;
}

bool
tree_function::takes_var_return (void) const
{
  return (ret_list && ret_list->takes_varargs ());
}

void
tree_function::octave_vr_val (const octave_value& val)
{
  assert (vr_list);

  vr_list->append (val);
}

void
tree_function::stash_function_name (const string& s)
{
  fcn_name = s;
}

octave_value
tree_function::eval (bool print)
{
  octave_value retval;

  if (error_state || ! cmd_list)
    return retval;

  octave_value_list tmp_args;
  octave_value_list tmp = eval (print, 0, tmp_args);

  if (! error_state && tmp.length () > 0)
    retval = tmp(0);

  return retval;
}

// For unwind protect.

static void
pop_symbol_table_context (void *table)
{
  symbol_table *tmp = (symbol_table *) table;
  tmp->pop_context ();
}

static void
delete_vr_list (void *list)
{
  tree_va_return_list *tmp = (tree_va_return_list *) list;
  tmp->clear ();
  delete tmp;
}

static void
clear_symbol_table (void *table)
{
  symbol_table *tmp = (symbol_table *) table;
  tmp->clear ();
}

static void
clear_args_passed (void *fcn)
{
  tree_function *tmp = (tree_function *) fcn;

  if (tmp)
    tmp->clear_args_passed ();
}

octave_value_list
tree_function::eval (bool /* print */, 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 (call_depth > Vmax_recursion_depth)
    {
      ::error ("max_recursion_limit exceeded");
      run_unwind_frame ("func_eval");
      return retval;
    }

  if (call_depth > 1)
    {
      sym_tab->push_context ();
      add_unwind_protect (pop_symbol_table_context, (void *) 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, (void *) vr_list);
      }
    }

  if (vr_list)
    vr_list->clear ();

  // Force symbols to be undefined again when this function exits.

  add_unwind_protect (clear_symbol_table, (void *) 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;

  add_unwind_protect (::clear_args_passed, this);

  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_nargin_and_nargout (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.

    bool pf = ! Vsilent_functions;
    octave_value last_computed_value = cmd_list->eval (pf);

    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
tree_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
tree_function::print_code_function_header (void)
{
  tree_print_code tpc (octave_stdout, Vps4);

  tpc.visit_function_header (*this);
}

void
tree_function::print_code_function_trailer (void)
{
  tree_print_code tpc (octave_stdout, Vps4);

  tpc.visit_function_trailer (*this);
}

void
tree_function::accept (tree_walker& tw)
{
  tw.visit_function (*this);
}

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
max_recursion_depth (void)
{
  Vmax_recursion_depth = check_preference ("max_recursion_depth");

  return 0;
}

static int
return_last_computed_value (void)
{
  Vreturn_last_computed_value
    = check_preference ("return_last_computed_value");

  return 0;
}

static int
silent_functions (void)
{
  Vsilent_functions = check_preference ("silent_functions");

  return 0;
}

void
symbols_of_pt_fcn (void)
{
  DEFVAR (default_return_value, Matrix (), 0, 0,
    "the default for value for uninitialized variables returned from\n\
functions.  Only used if the variable initialize_return_values is\n\
nonzero.");

  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 (max_recursion_depth, 256.0, 0, max_recursion_depth,
    "maximum nesting level for functions called recursively.\n\
The default value is 256.");

  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");

  DEFVAR (silent_functions, 0.0, 0, silent_functions,
    "suppress printing results in called functions");
}

/*
;;; Local Variables: ***
;;; mode: C++ ***
;;; End: ***
*/

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