Cream of the Crop 26/Cream of the Crop 26.iso/os2/octa209s.zip/octave-2.09/src/input.cc

C/C++ Source or Header | 1997-05-28 | 27KB | 1,387 lines

/*

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.

*/

/*

The 2 functions listed below were adapted from similar functions
from GNU Bash, the Bourne Again SHell, copyright (C) 1987, 1989, 1991
Free Software Foundation, Inc.

  read_octal    decode_prompt_string

*/

/* Modified by Klaus Gebhardt, 1996 */

// Use the GNU readline library for command line editing and hisory.

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

#include <ctime>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <csignal>

#include <string>

#include <iostream.h>

#ifdef HAVE_UNISTD_H
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <unistd.h>
#endif

#if defined (USE_READLINE)
#include <readline/readline.h>
#include <readline/history.h>
#endif

#include "str-vec.h"

#include "defun.h"
#include "dirfns.h"
#include "error.h"
#include "gripes.h"
#include "help.h"
#include "input.h"
#include "oct-map.h"
#include "oct-hist.h"
#include "toplev.h"
#include "oct-obj.h"
#include "pager.h"
#include "parse.h"
#include "pathlen.h"
#include "pt-const.h"
#include "sighandlers.h"
#include "symtab.h"
#include "sysdep.h"
#include "utils.h"
#include "variables.h"

// Primary prompt string.
static string Vps1;

// Secondary prompt string.
static string Vps2;

// String printed before echoed input (enabled by --echo-input).
string Vps4;

// Character to append after successful command-line completion attempts.
static char Vcompletion_append_char;

// Global pointer for eval().
string current_eval_string;

// Nonzero means get input from current_eval_string.
int get_input_from_eval_string = 0;

// Nonzero means we're parsing a function file.
int reading_fcn_file = 0;

// Simple name of function file we are reading.
string curr_fcn_file_name;

// Full name of file we are reading.
string curr_fcn_file_full_name;

// Nonzero means we're parsing a script file.
int reading_script_file = 0;

// If we are reading from an M-file, this is it.
FILE *ff_instream = 0;

// Nonzero means this is an interactive shell.
int interactive = 0;

// Nonzero means the user forced this shell to be interactive (-i).
int forced_interactive = 0;

// Nonzero means the user forced this shell to be really interactive (-i),
// but without using the pager.
int really_forced_interactive = 0;

// Should we issue a prompt?
int promptflag = 1;

// The current line of input, from wherever.
string current_input_line;

// TRUE after a call to completion_matches().
bool octave_completion_matches_called = false;

// Return the octal number parsed from STRING, or -1 to indicate that
// the string contained a bad number.

static int
read_octal (const string& s)
{
  int result = 0;
  int digits = 0;

  size_t i = 0;
  size_t slen = s.length ();

  while (i < slen && s[i] >= '0' && s[i] < '8')
    {
      digits++;
      result = (result * 8) + s[i] - '0';
      i++;
    }

  if (! digits || result > 0777 || i < slen)
    result = -1;

  return result;
}

// Return a string which will be printed as a prompt.  The string may
// contain special characters which are decoded as follows:
//
//    \t    the time
//    \d    the date
//    \n    CRLF
//    \s    the name of the shell (program)
//    \w    the current working directory
//    \W    the last element of PWD
//    \u    your username
//    \h    the hostname
//    \#    the command number of this command
//    \!    the history number of this command
//    \$    a $ or a # if you are root
//    \<octal> character code in octal
//    \\    a backslash

static string
decode_prompt_string (const string& s)
{
  string result;
  string temp;
  size_t i = 0;
  size_t slen = s.length ();
  int c;

  while (i < slen)
    {
      c = s[i];

      i++;

      if (c == '\\')
    {
      c = s[i];

      switch (c)
        {
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
          // Maybe convert an octal number.
          {
        int n = read_octal (s.substr (i, 3));

        temp = "\\";

        if (n != -1)
          {
            i += 3;
            temp[0] = n;
          }

        c = 0;
        goto add_string;
          }

        case 't':
        case 'd':
          // Make the current time/date into a string.
          {
        time_t now = time (0);

        temp = ctime (&now);

        if (c == 't')
          {
            temp = temp.substr (11);
            temp.resize (8);
          }
        else
          temp.resize (10);

        goto add_string;
          }

        case 'n':
          {
        if (using_readline)
          temp = "\r\n";
        else
          temp = "\n";

        goto add_string;
          }

        case 's':
          {
        temp = base_pathname (Vprogram_name);

        goto add_string;
          }

        case 'w':
        case 'W':
          {
#define EFFICIENT
#ifdef EFFICIENT
        // Use the value of PWD because it is much more
        // effecient.

        temp = Vcurrent_directory;

        if (temp.empty ())
          temp = octave_getcwd ();
#else
        temp = octave_getcwd ();
#endif    /* EFFICIENT */

        if (c == 'W')
          {
            size_t pos = temp.rfind ('/');

            if (pos != NPOS && pos != 0)
              temp = temp.substr (pos + 1);
          }
        else
          temp = polite_directory_format (temp);

        goto add_string;
          }

        case 'u':
          {
        temp = Vuser_name;

        goto add_string;
          }

        case 'H':
          {
        temp = Vhost_name;

        goto add_string;
          }

        case 'h':
          {
        temp = Vhost_name;

        size_t pos = temp.find ('.');

        if (pos != NPOS)
          temp.resize (pos);

        goto add_string;
          }

        case '#':
          {
        char number_buffer[128];
        sprintf (number_buffer, "%d", current_command_number);
        temp = number_buffer;

        goto add_string;
          }

        case '!':
          {
        char number_buffer[128];
        int num = octave_command_history.current_number ();
        if (num > 0)
                  sprintf (number_buffer, "%d", num);
        else
          strcpy (number_buffer, "!");
        temp = number_buffer;

        goto add_string;
          }

        case '$':
          {
        temp = (geteuid () == 0 ? "#" : "$");

        goto add_string;
          }

        case '[':
        case ']':
          {
        temp.resize (2);

        temp[0] = '\001';
        temp[1] = ((c == '[')
               ? RL_PROMPT_START_IGNORE
               : RL_PROMPT_END_IGNORE);

        goto add_string;
          }

        case '\\':
          {
        temp = "\\";

        goto add_string;
          }

        default:
          {
        temp = "\\ ";
        temp[1] = c;

        goto add_string;
          }

        add_string:
          {
        if (c)
          i++;

        result.append (temp);

        break;
          }
        }
    }
      else
    result += c;
    }

  return result;
}

static void
do_input_echo (const string& input_string)
{
  int do_echo = reading_script_file ?
    (Vecho_executing_commands & ECHO_SCRIPTS)
      : (Vecho_executing_commands & ECHO_CMD_LINE) && ! forced_interactive;

  if (do_echo)
    {
      if (forced_interactive)
    {
      if (promptflag > 0)
        octave_stdout << decode_prompt_string (Vps1);
      else
        octave_stdout << decode_prompt_string (Vps2);
    }
      else
    octave_stdout << decode_prompt_string (Vps4);

      if (! input_string.empty ())
    {
      octave_stdout << input_string;

      if (input_string[input_string.length () - 1] != '\n')
        octave_stdout << "\n";
    }
    }
}

char *
gnu_readline (const char *s, bool force_readline)
{
  char *retval = 0;

  if (using_readline || force_readline)
    {
      char *tmp = retval = ::readline (s);

      if (tmp && strlen (tmp) == 0)
    {
      retval = (char *) malloc (2);
      retval[0] = '\n';
      retval[1] = '\0';
    }
    }
  else
    {
      if (s && *s &&
      (interactive || forced_interactive || really_forced_interactive))
    {
      fprintf (rl_outstream, s);
      fflush (rl_outstream);
    }

      FILE *curr_stream = rl_instream;
      if (reading_fcn_file || reading_script_file)
    curr_stream = ff_instream;

      int grow_size = 1024;
      int max_size = grow_size;

      char *buf = (char *) malloc (max_size);
      char *bufptr = buf;
      int len = 0;

      do
    {
      if (fgets (bufptr, grow_size, curr_stream))
        {
          len = strlen (bufptr);

          if (len == grow_size - 1)
        {
          int tmp = bufptr - buf + grow_size - 1;
          grow_size *= 2;
          max_size += grow_size;
          buf = (char *) realloc (buf, max_size);
          bufptr = buf + tmp;

          if (*(bufptr-1) == '\n')
            {
              *bufptr = '\0';
              retval = buf;
            }
        }
          else if (bufptr[len-1] != '\n')
        {
          bufptr[len++] = '\n';
          bufptr[len] = '\0';
          retval = buf;
        }
          else
        retval = buf;
        }
      else
        {
          if (len == 0)
        free (buf);

          break;
        }
    }
      while (! retval);
    }

  return retval;
}

static char *
octave_gets (void)
{
  char *retval = 0;

  if ((interactive || forced_interactive || really_forced_interactive)
      && (! (reading_fcn_file || reading_script_file)))
    {
      const char *ps = (promptflag > 0) ? Vps1.c_str () :
    Vps2.c_str ();

      string prompt = decode_prompt_string (ps);

      pipe_handler_error_count = 0;

      flush_octave_stdout ();

      octave_diary << prompt;

      retval = gnu_readline (prompt.c_str ());
    }
  else
    retval = gnu_readline ("");

  if (retval)
    current_input_line = retval;
  else
    current_input_line = "";

  if (! current_input_line.empty ())
    {
      if (! input_from_startup_file)
    octave_command_history.add (current_input_line);

      octave_diary << current_input_line;

      do_input_echo (current_input_line);
    }

  octave_diary << "\n";

  return retval;
}

// Read a line from the input stream.

static char *
get_user_input (void)
{
  char *retval = 0;

  if (get_input_from_eval_string)
    {
      size_t len = current_eval_string.length ();

      retval = (char *) malloc (len + 2);

      strcpy (retval, current_eval_string.c_str ());

      retval[len++] = '\n';
      retval[len] = '\0';    // Paranoia.
    }
  else
    retval = octave_gets ();

  if (retval)
    current_input_line = retval;

  if (! get_input_from_eval_string)
    input_line_number++;

  return retval;
}

int
octave_read (char *buf, unsigned max_size)
{
  static char *input_buf = 0;
  static char *cur_pos = 0;
  static int chars_left = 0;

  int status = 0;

  if (! input_buf)
    {
      cur_pos = input_buf = get_user_input ();

      chars_left = input_buf ? strlen (input_buf) : 0;
    }

  if (chars_left > 0)
    {
      buf[0] = '\0';

      int len = max_size - 2;

      strncpy (buf, cur_pos, len);

      if (chars_left > len)
    {
      chars_left -= len;

      cur_pos += len;

      buf[len] = '\0';

      status = len;
    }
      else
    {
      free (input_buf);
      input_buf = 0;

      len = chars_left;

      if (buf[len-1] != '\n')
        buf[len++] = '\n';

      buf[len] = '\0';

      status = len;
    }
    }
  else if (chars_left == 0)
    {
      if (input_buf)
    {
      free (input_buf);
      input_buf = 0;
    }

      status = 0;
    }
  else
    status = -1;

  return status;
}

// Fix things up so that input can come from file `name', printing a
// warning if the file doesn't exist.

FILE *
get_input_from_file (const string& name, int warn)
{
  FILE *instream = 0;

  if (name.length () > 0)
    instream = fopen (name.c_str (), "rb");

  if (! instream && warn)
    warning ("%s: no such file or directory", name.c_str ());

  if (reading_fcn_file || reading_script_file)
    ff_instream = instream;
  else
    rl_instream = instream;

  return instream;
}

// Fix things up so that input can come from the standard input.  This
// may need to become much more complicated, which is why it's in a
// separate function.

FILE *
get_input_from_stdin (void)
{
  rl_instream = stdin;
  return rl_instream;
}

static string_vector
generate_struct_completions (const char *text, char *& prefix,
                 char *& hint)
{
  string_vector names;

  assert (text);

  char *id = strsave (text);
  char *ptr = strchr (id, '.');
  *ptr = '\0';

  char *elts = ptr + 1;
  ptr = strrchr (elts, '.');
  if (ptr)
    *ptr = '\0';
  else
    elts = 0;

  prefix = strsave (text);
  ptr = strrchr (prefix, '.');
  *ptr = '\0';

  delete [] hint;
  hint = strsave (ptr + 1);

  symbol_record *sr = curr_sym_tab->lookup (id, 0, 0);
  if (! sr)
    sr = global_sym_tab->lookup (id, 0, 0);

  if (sr && sr->is_defined ())
    {
      tree_fvc *tmp_fvc = sr->def ();

      tree_constant *def = 0;
      if (tmp_fvc->is_constant ())
    def = (tree_constant *) tmp_fvc;

      if (def && def->is_map ())
    {
      if (elts && *elts)
        {
          octave_value ult = def->lookup_map_element (elts, 0, 1);

          if (ult.is_map ())
        {
          Octave_map m = ult.map_value ();
          names = m.make_name_list ();
        }
        }
      else
        {
          Octave_map m = def->map_value ();
          names = m.make_name_list ();
        }
    }
    }

  delete [] id;

  return names;
}

// XXX FIXME XXX -- make this generate file names when appropriate.

static string_vector
generate_possible_completions (const char *text, char *& prefix,
                   char *& hint)
{
  string_vector names;

  prefix = 0;

  if (text && *text && *text != '.' && strrchr (text, '.'))
    names = generate_struct_completions (text, prefix, hint);
  else
    names = make_name_list ();

  names.qsort ();

  // Remove duplicates.

  // XXX FIXME XXX -- maybe this should be defined for all Array objects.

  int k = 0;

  int len = names.length ();

  for (int i = 1; i < len; i++)
    {
      if (names[i] != names[k])
    {
      k++;

      if (k != i)
        names[k] = names[i];
    }
    }

  names.resize (k+1);

  return names;
}

static int
looks_like_struct (const char *nm)
{
  int retval = 0;

  assert (nm);

  char *id = strsave (nm);
  char *elts = 0;
  char *ptr = strchr (id, '.');
  if (ptr)
    {
      *ptr = '\0';
      elts = ptr + 1;
    }

  symbol_record *sr = curr_sym_tab->lookup (id, 0, 0);
  if (! sr)
    sr = global_sym_tab->lookup (id, 0, 0);

  if (sr && sr->is_defined ())
    {
      tree_fvc *tmp_fvc = sr->def ();

      tree_constant *def = 0;
      if (tmp_fvc->is_constant ())
    def = (tree_constant *) tmp_fvc;

      if (def && def->is_map ())
    {
      if (elts && *elts)
        {
          octave_value ult = def->lookup_map_element (elts, 0, 1);

          if (ult.is_map ())
        retval = 1;
        }
      else
        retval = 1;
    }
    }

  delete [] id;

  return retval;
}

// XXX FIXME XXX -- this has to return a pointer to char, but it
// should be converted to use a generating function that returns a
// string_vector.

static char *
command_generator (const char *text, int state)
{
  static char *prefix = 0;
  static char *hint = 0;

  static int prefix_len = 0;
  static int hint_len = 0;

  static int list_index = 0;
  static int list_length = 0;
  static string_vector name_list;

  static int matches = 0;

  if (state == 0)
    {
      list_index = 0;

      delete [] prefix;
      prefix = 0;

      delete [] hint;
      hint = strsave (text);

      name_list = generate_possible_completions (text, prefix, hint);

      prefix_len = 0;
      if (prefix)
    prefix_len = strlen (prefix);

      assert (hint);
      hint_len = strlen (hint);

      matches = 0;

      list_length = name_list.length ();

      for (int i = 0; i < list_length; i++)
    if (name_list[i].compare (hint, 0, hint_len))
      matches++;
    }

  if (list_length > 0 && matches > 0)
    {
      const char *name;

      while (list_index < list_length)
    {
      name = name_list[list_index].c_str ();

      list_index++;

      if (strncmp (name, hint, hint_len) == 0)
        {
          int len = 2 + prefix_len + strlen (name);
          char *buf = (char *) malloc (len);

          if (prefix)
        {
          strcpy (buf, prefix);
          strcat (buf, ".");
          strcat (buf, name);
        }
          else
        strcpy (buf, name);

          if (matches == 1 && looks_like_struct (buf))
        rl_completion_append_character = '.';
          else
        rl_completion_append_character = Vcompletion_append_char;

          return buf;
        }
    }
    }

  return 0;
}

static char **
command_completer (char *text, int /* start */, int /* end */)
{
  char **matches = 0;
  matches = completion_matches (text, command_generator);
  return matches;
}

// The next two functions implement the equivalent of the K*rn shell
// C-o operate-and-get-next-history-line editing command.  Stolen from
// the GNU Bourne Again SHell.

// ??
static int saved_history_line_to_use = 0;

// ??
static Function *old_rl_startup_hook = 0;

static void
set_saved_history (void)
{
  HIST_ENTRY *h;

  if (saved_history_line_to_use)
    {
      if (history_set_pos (saved_history_line_to_use))
    {
      h = current_history ();
      if (h)
        {
          rl_insert_text (h->line);

          // Get rid of any undo list created by the previous
          // insert, so the line won't totally be erased when the
          // edits are undone (they will be normally, because this
          // is a history  line -- cf. readline.c: line 380 or
          // so).

          if (rl_undo_list)
        {
          free_undo_list ();
          rl_undo_list = 0;
        }
        }
    }
    }
  saved_history_line_to_use = 0;
  rl_startup_hook = old_rl_startup_hook;
}

static void
operate_and_get_next (int /* count */, int /* c */)
{
  int where;

  // Accept the current line.

  rl_newline ();

  // Find the current line, and find the next line to use.

  where = where_history ();

  if ((history_is_stifled () && (history_length >= max_input_history))
      || (where >= history_length - 1))
    saved_history_line_to_use = where;
  else
    saved_history_line_to_use = where + 1;

  old_rl_startup_hook = rl_startup_hook;
  rl_startup_hook = (Function *) set_saved_history;
}

void
initialize_readline (void)
{
  // Set things up internally in case some function that uses readline
  // (currently Fclc(), maybe others) is called before readline().

  rl_initialize ();

  // Allow conditional parsing of the ~/.inputrc file

  rl_readline_name = "Octave";

  // Tell the completer that we want to try first.

  rl_attempted_completion_function = (CPPFunction *) command_completer;

  // Bind operate-and-get-next.

  rl_add_defun ("operate-and-get-next",
        (Function *) operate_and_get_next, CTRL ('O'));


  // And the history search functions.

  rl_add_defun ("history-search-backward",
        (Function *) rl_history_search_backward, META ('p'));

  rl_add_defun ("history-search-forward",
        (Function *) rl_history_search_forward, META ('n'));

  // Don't treat single quotes as string delimiters when doing paren
  // matching.

  rl_paren_string_delimiters = "\"";
}

static int
match_sans_spaces (const char *standard, const char *test)
{
  char *tmp = strsave (test);

  char *tp = tmp;
  while (*tp == ' ' || *tp == '\t')
    tp++;

  char *ep = tmp + strlen (tmp) - 1;
  while (*ep == ' ' || *ep == '\t')
    ep--;

  *(ep+1) = '\0';

  int retval = strcmp (standard, tp) == 0;

  delete [] tmp;

  return retval;

}

// If the user simply hits return, this will produce an empty matrix.

static octave_value_list
get_user_input (const octave_value_list& args, bool debug = false)
{
  octave_value retval;

  int nargin = args.length ();

  int read_as_string = 0;

  if (nargin == 2)
    read_as_string++;

  string prompt ("debug> ");

  if (nargin > 0)
   {
     prompt = args(0).string_value ();

     if (error_state)
       {
     error ("input: unrecognized argument");
     return retval;
       }
    }

 again:

  flush_octave_stdout ();

  char *input_buf = gnu_readline (prompt.c_str (), true);

  if (input_buf)
    {
      if (! input_from_startup_file)
    octave_command_history.add (input_buf);

      int len = strlen (input_buf);

      if (len < 1)
    {
      if (debug)
        goto again;
      else
        {
          if (read_as_string)
        return "";
          else
        return Matrix ();
        }
    }

      if (match_sans_spaces ("exit", input_buf)
      || match_sans_spaces ("quit", input_buf)
      || match_sans_spaces ("return", input_buf))
    {
      return retval;
    }
      else if (read_as_string)
    {
      retval = input_buf;
    }
      else
    {
      int parse_status = 0;

      retval = eval_string (input_buf, 0, parse_status);

      if (retval.is_defined ())
        {
          if (debug)
        retval.print ();
        }
      else
        retval = Matrix ();
    }
    }
  else
    error ("input: reading user-input failed!");

  if (debug)
    goto again;

  return retval;
}

DEFUN (input, args, ,
  "input (PROMPT [, S])\n\
\n\
Prompt user for input.  If the second argument is present, return\n\
value as a string.")
{
  octave_value_list retval;

  int nargin = args.length ();

  if (nargin == 1 || nargin == 2)
    retval = get_user_input (args);
  else
    print_usage ("input");

  return retval;
}

DEFUN (keyboard, args, ,
  "keyboard (PROMPT)\n\
\n\
maybe help in debugging function files")
{
  octave_value_list retval;

  int nargin = args.length ();

  if (nargin == 0 || nargin == 1)
    retval = get_user_input (args, true);
  else
    print_usage ("keyboard");

  return retval;
}

DEFUN_TEXT(echo, args, ,
  "echo [options]\n\
\n\
  echo [on|off]         -- enable or disable echoing of commands as\n\
                           they are executed in script files\n\
\n\
  echo [on all|off all] -- enable or disable echoing of commands as they\n\
                           are executed in script files and functions\n\
\n\
Without any arguments, toggle the current echo state.")
{
  octave_value_list retval;

  int argc = args.length () + 1;

  string_vector argv = args.make_argv ("echo");

  if (error_state)
    return retval;

  switch (argc)
    {
    case 1:
      {
    if ((Vecho_executing_commands & ECHO_SCRIPTS)
        || (Vecho_executing_commands & ECHO_FUNCTIONS))
      bind_builtin_variable ("echo_executing_commands",
                 (double) ECHO_OFF);
    else
      bind_builtin_variable ("echo_executing_commands",
                 (double) ECHO_SCRIPTS);
      }
      break;

    case 2:
      {
    string arg = argv[1];

    if (arg == "on")
      bind_builtin_variable ("echo_executing_commands",
                 (double) ECHO_SCRIPTS);
    else if (arg == "off")
      bind_builtin_variable ("echo_executing_commands",
                 (double) ECHO_OFF);
    else
      print_usage ("echo");
      }
      break;

    case 3:
      {
    string arg = argv[1];

    if (arg == "on" && argv[2] == "all")
      bind_builtin_variable ("echo_executing_commands",
                 (double) (ECHO_SCRIPTS | ECHO_FUNCTIONS));
    else if (arg == "off" && argv[2] == "all")
      bind_builtin_variable ("echo_executing_commands",
                 (double) ECHO_OFF);
    else
      print_usage ("echo");
      }
      break;

    default:
      print_usage ("echo");
      break;
    }

  return retval;
}

DEFUN (completion_matches, args, nargout,
  "completion_matches (HINT): generate possible completions given HINT\n\
\n\
This function is provided for the benefit of programs like Emacs which\n\
might be controlling Octave and handling user input.  The current command\n\
number is not incremented when this function is called.  This is a feature,\n\
not a bug.")
{
  octave_value retval;

  int nargin = args.length ();

  if (nargin == 1)
    {
      string hint_string = args(0).string_value ();

      if (! error_state)
    {
      int n = 32;

      string_vector list (n);

      const char *hint = hint_string.c_str ();

      int k = 0;

      for (;;)
        {
          const char *cmd = command_generator (hint, k);

          if (cmd)
        {
          if (*cmd)
            {
              if (k == n)
            {
              n *= 2;
              list.resize (n);
            }

              list[k++] = cmd;
            }
        }
          else
        {
          list.resize (k);
          break;
        }
        }

      if (nargout > 0)
        {
          if (! list.empty ())
        retval = list;
          else
        retval = "";
        }
      else
        {
          // We don't use string_vector::list_in_columns here
          // because it will be easier for Emacs if the names
          // appear in a single column.

          int len = list.length ();

          for (int i = 0; i < len; i++)
        octave_stdout << list[i] << "\n";
        }

      octave_completion_matches_called = true;
    }
    }
  else
    print_usage ("completion_matches");

  return retval;
}

static int
ps1 (void)
{
  int status = 0;

  Vps1 = builtin_string_variable ("PS1");

  return status;
}

static int
ps2 (void)
{
  int status = 0;

  Vps2 = builtin_string_variable ("PS2");

  return status;
}

static int
ps4 (void)
{
  int status = 0;

  Vps4 = builtin_string_variable ("PS4");

  return status;
}

static int
completion_append_char (void)
{
  int status = 0;

  string s = builtin_string_variable ("completion_append_char");

  switch (s.length ())
    {
    case 1:
      Vcompletion_append_char = s[0];
      break;

    case 0:
      Vcompletion_append_char = '\0';
      break;

    default:
      warning ("completion_append_char must be a single character");
      status = -1;
      break;
    }

  return status;
}

void
symbols_of_input (void)
{
  DEFVAR (PS1, "\\s:\\#> ", 0, ps1,
    "primary prompt string");

  DEFVAR (PS2, "> ", 0, ps2,
    "secondary prompt string");

  DEFVAR (PS4, "+ ", 0, ps4,
    "string printed before echoed input (enabled by --echo-input)");

  DEFVAR (completion_append_char, " ", 0, completion_append_char,
    "the string to append after successful command-line completion attempts");
}

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