cmd-edit.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1996-2022 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 <cstdlib>
#include <cstring>
 
#include <string>
 
#include "cmd-edit.h"
#include "cmd-hist.h"
#include "file-ops.h"
#include "file-stat.h"
#include "lo-error.h"
#include "lo-utils.h"
#include "oct-env.h"
#include "oct-mutex.h"
#include "oct-time.h"
#include "quit.h"
#include "singleton-cleanup.h"
#include "strdup-wrapper.h"
#include "unistd-wrappers.h"
 
#if defined (USE_READLINE)
#include <cstdio>
 
#include "oct-rl-edit.h"
#endif
 
namespace octave
{
  char * do_completer_word_break_hook ();
 
  command_editor *command_editor::s_instance = nullptr;
 
  std::set<command_editor::startup_hook_fcn> command_editor::m_startup_hook_set;
 
  std::set<command_editor::pre_input_hook_fcn> command_editor::m_pre_input_hook_set;
 
  std::set<command_editor::event_hook_fcn> command_editor::m_event_hook_set;
 
  static mutex event_hook_lock;
 
#if defined (USE_READLINE)
 
  class
  gnu_readline : public command_editor
  {
  public:
 
    typedef command_editor::startup_hook_fcn startup_hook_fcn;
 
    typedef command_editor::pre_input_hook_fcn pre_input_hook_fcn;
 
    typedef command_editor::event_hook_fcn event_hook_fcn;
 
    typedef command_editor::completion_fcn completion_fcn;
 
    gnu_readline (void);
 
    ~gnu_readline (void) = default;
 
    void do_set_name (const std::string& n);
 
    std::string do_readline (const std::string& prompt, bool& eof);
 
    void do_set_input_stream (FILE *f);
 
    FILE * do_get_input_stream (void);
 
    void do_set_output_stream (FILE *f);
 
    FILE * do_get_output_stream (void);
 
    void do_redisplay (void);
 
    int do_terminal_rows (void);
 
    int do_terminal_cols (void);
 
    void do_clear_screen (bool skip_redisplay);
 
    void do_resize_terminal (void);
 
    void do_set_screen_size (int ht, int wd);
 
    std::string newline_chars (void);
 
    void do_restore_terminal_state (void);
 
    void do_blink_matching_paren (bool flag);
 
    bool do_erase_empty_line (bool flag);
 
    void do_set_basic_word_break_characters (const std::string& s);
 
    void do_set_completer_word_break_characters (const std::string& s);
 
    void do_set_basic_quote_characters (const std::string& s);
 
    void do_set_filename_quote_characters (const std::string& s);
 
    void do_set_completer_quote_characters (const std::string& s);
 
    void do_set_completion_append_character (char c);
 
    void do_set_completion_function (completion_fcn f);
 
    void do_set_quoting_function (quoting_fcn f);
 
    void do_set_dequoting_function (dequoting_fcn f);
 
    void do_set_char_is_quoted_function (char_is_quoted_fcn f);
 
    void do_set_user_accept_line_function (user_accept_line_fcn f);
 
    completion_fcn do_get_completion_function (void) const;
 
    quoting_fcn do_get_quoting_function (void) const;
 
    dequoting_fcn do_get_dequoting_function (void) const;
 
    char_is_quoted_fcn do_get_char_is_quoted_function (void) const;
 
    user_accept_line_fcn do_get_user_accept_line_function (void) const;
 
    string_vector
    do_generate_filename_completions (const std::string& text);
 
    std::string do_get_line_buffer (void) const;
 
    std::string do_get_current_line (void) const;
 
    char do_get_prev_char (int) const;
 
    void do_replace_line (const std::string& text, bool clear_undo);
 
    void do_kill_full_line (void);
 
    void do_insert_text (const std::string& text);
 
    void do_newline (void);
 
    void do_accept_line (void);
 
    bool do_undo (void);
 
    void do_clear_undo_list (void);
 
    void set_startup_hook (startup_hook_fcn f);
 
    void restore_startup_hook (void);
 
    void set_pre_input_hook (pre_input_hook_fcn f);
 
    void restore_pre_input_hook (void);
 
    void set_event_hook (event_hook_fcn f);
 
    void restore_event_hook (void);
 
    void do_restore_event_hook (void);
 
    void do_read_init_file (const std::string& file);
 
    void do_re_read_init_file (void);
 
    bool do_filename_completion_desired (bool);
 
    bool do_filename_quoting_desired (bool);
 
    bool do_prefer_env_winsize (bool);
 
    void do_interrupt (bool);
 
    void do_handle_interrupt_signal (void);
 
    static int operate_and_get_next (int, int);
 
    static int history_search_backward (int, int);
 
    static int history_search_forward (int, int);
 
  private:
 
    static char * command_generator (const char *text, int state);
 
    static char * command_quoter (char *text, int match_type,
                                  char *quote_pointer);
 
    static char * command_dequoter (char *text, int match_type);
 
    static int command_char_is_quoted (char *text, int index);
 
    static int command_accept_line (int count, int key);
 
    static char ** command_completer (const char *text, int start, int end);
 
    static char * do_completer_word_break_hook ();
 
    startup_hook_fcn m_previous_startup_hook;
 
    pre_input_hook_fcn m_previous_pre_input_hook;
 
    event_hook_fcn m_previous_event_hook;
 
    completion_fcn m_completion_function;
 
    quoting_fcn m_quoting_function;
 
    dequoting_fcn m_dequoting_function;
 
    char_is_quoted_fcn m_char_is_quoted_function;
 
    user_accept_line_fcn user_accept_line_function;
 
    static std::string s_completer_quote_characters;
  };
 
  std::string gnu_readline::s_completer_quote_characters = "";
 
  gnu_readline::gnu_readline ()
    : command_editor (), m_previous_startup_hook (nullptr),
      m_previous_pre_input_hook (nullptr),
      m_previous_event_hook (nullptr), m_completion_function (nullptr),
      m_quoting_function (nullptr), m_dequoting_function (nullptr),
      m_char_is_quoted_function (nullptr), user_accept_line_function (nullptr)
  {
    // FIXME: need interface to rl_add_defun, rl_initialize, and
    // a function to set rl_terminal_name
 
    std::string term = sys::env::getenv ("TERM");
 
    octave_rl_set_terminal_name (term.c_str ());
 
    octave_rl_initialize ();
 
    do_blink_matching_paren (true);
 
    // Bind operate-and-get-next.
 
    octave_rl_add_defun ("operate-and-get-next",
                         gnu_readline::operate_and_get_next,
                         octave_rl_ctrl ('O'));
  }
 
  void
  gnu_readline::do_set_name (const std::string& nm)
  {
    ::octave_rl_set_name (nm.c_str ());
  }
 
  std::string
  gnu_readline::do_readline (const std::string& prompt, bool& eof)
  {
    std::string retval;
 
    eof = false;
 
    const char *p = prompt.c_str ();
 
    char *line = ::octave_rl_readline (p);
 
    if (line)
      {
        retval = line;
 
        free (line);
      }
    else
      eof = true;
 
    return retval;
  }
 
  void
  gnu_readline::do_set_input_stream (FILE *f)
  {
    ::octave_rl_set_input_stream (f);
  }
 
  FILE *
  gnu_readline::do_get_input_stream (void)
  {
    return ::octave_rl_get_input_stream ();
  }
 
  void
  gnu_readline::do_set_output_stream (FILE *f)
  {
    ::octave_rl_set_output_stream (f);
  }
 
  FILE *
  gnu_readline::do_get_output_stream (void)
  {
    return ::octave_rl_get_output_stream ();
  }
 
  void
  gnu_readline::do_redisplay (void)
  {
    ::octave_rl_redisplay ();
  }
 
  // GNU readline handles SIGWINCH, so these values have a good chance
  // of being correct even if the window changes size (they may be
  // wrong if, for example, the luser changes the window size while the
  // pager is running, and the signal is handled by the pager instead of
  // us.
 
  int
  gnu_readline::do_terminal_rows (void)
  {
    int sh = ::octave_rl_screen_height ();
 
    return sh > 0 ? sh : 24;
  }
 
  int
  gnu_readline::do_terminal_cols (void)
  {
    int sw = ::octave_rl_screen_width ();
 
    return sw > 0 ? sw : 80;
  }
 
  void
  gnu_readline::do_clear_screen (bool skip_redisplay)
  {
    ::octave_rl_clear_screen (skip_redisplay);
  }
 
  void
  gnu_readline::do_resize_terminal (void)
  {
    ::octave_rl_resize_terminal ();
  }
 
  void
  gnu_readline::do_set_screen_size (int ht, int wd)
  {
    ::octave_rl_set_screen_size (ht, wd);
  }
 
  std::string
  gnu_readline::newline_chars (void)
  {
    return "\r\n";
  }
 
  void
  gnu_readline::do_restore_terminal_state (void)
  {
    ::octave_rl_restore_terminal_state ();
  }
 
  void
  gnu_readline::do_blink_matching_paren (bool flag)
  {
    ::octave_rl_enable_paren_matching (flag ? 1 : 0);
  }
 
  bool
  gnu_readline::do_erase_empty_line (bool flag)
  {
    return ::octave_rl_erase_empty_line (flag ? 1 : 0);
  }
 
  void
  gnu_readline::do_set_basic_word_break_characters (const std::string& s)
  {
    ::octave_rl_set_basic_word_break_characters (s.c_str ());
  }
 
  void
  gnu_readline::do_set_completer_word_break_characters (const std::string& s)
  {
    ::octave_rl_set_completer_word_break_characters (s.c_str ());
 
    ::octave_rl_set_completion_word_break_hook
      (gnu_readline::do_completer_word_break_hook);
 
  }
 
  void
  gnu_readline::do_set_basic_quote_characters (const std::string& s)
  {
    ::octave_rl_set_basic_quote_characters (s.c_str ());
  }
 
  void
  gnu_readline::do_set_filename_quote_characters (const std::string& s)
  {
    ::octave_rl_set_filename_quote_characters (s.c_str ());
  }
 
  void
  gnu_readline::do_set_completer_quote_characters (const std::string& s)
  {
    s_completer_quote_characters = s;
  }
 
  void
  gnu_readline::do_set_completion_append_character (char c)
  {
    ::octave_rl_set_completion_append_character (c);
  }
 
  void
  gnu_readline::do_set_completion_function (completion_fcn f)
  {
    m_completion_function = f;
 
    rl_attempted_completion_fcn_ptr fp
      = (f ? gnu_readline::command_completer : nullptr);
 
    ::octave_rl_set_completion_function (fp);
  }
 
  void
  gnu_readline::do_set_quoting_function (quoting_fcn f)
  {
    m_quoting_function = f;
 
    rl_quoting_fcn_ptr fp
      = (f ? gnu_readline::command_quoter : nullptr);
 
    ::octave_rl_set_quoting_function (fp);
  }
 
  void
  gnu_readline::do_set_dequoting_function (dequoting_fcn f)
  {
    m_dequoting_function = f;
 
    rl_dequoting_fcn_ptr fp
      = (f ? gnu_readline::command_dequoter : nullptr);
 
    ::octave_rl_set_dequoting_function (fp);
  }
 
  void
  gnu_readline::do_set_char_is_quoted_function (char_is_quoted_fcn f)
  {
    m_char_is_quoted_function = f;
 
    rl_char_is_quoted_fcn_ptr fp
      = (f ? gnu_readline::command_char_is_quoted : nullptr);
 
    ::octave_rl_set_char_is_quoted_function (fp);
  }
 
  void
  gnu_readline::do_set_user_accept_line_function (user_accept_line_fcn f)
  {
    user_accept_line_function = f;
 
    if (f)
      octave_rl_add_defun ("accept-line", gnu_readline::command_accept_line,
                           ::octave_rl_ctrl ('M'));
    else
      octave_rl_add_defun ("accept-line", ::octave_rl_newline,
                           ::octave_rl_ctrl ('M'));
  }
 
  gnu_readline::completion_fcn
  gnu_readline::do_get_completion_function (void) const
  {
    return m_completion_function;
  }
 
  gnu_readline::quoting_fcn
  gnu_readline::do_get_quoting_function (void) const
  {
    return m_quoting_function;
  }
 
  gnu_readline::dequoting_fcn
  gnu_readline::do_get_dequoting_function (void) const
  {
    return m_dequoting_function;
  }
 
  gnu_readline::char_is_quoted_fcn
  gnu_readline::do_get_char_is_quoted_function (void) const
  {
    return m_char_is_quoted_function;
  }
 
  gnu_readline::user_accept_line_fcn
  gnu_readline::do_get_user_accept_line_function (void) const
  {
    return user_accept_line_function;
  }
 
  // True if the last "word" of the string line (delimited by delim) is
  // an existing directory.  Used by do_completer_word_break_hook.
 
  static bool
  looks_like_filename (const char *line, char delim)
  {
    bool retval = false;
 
    const char *s = strrchr (line, delim);
 
    if (s)
      {
        // Remove incomplete component.
        const char *f = strrchr (line, sys::file_ops::dir_sep_char ());
 
        if (f && (s[1] == '~' || f != s))
          {
            // For something like "A /b", f==s; don't assume a file.
 
            std::string candidate_filename = s+1;
 
            candidate_filename = candidate_filename.substr (0, f - s);
 
            // Handles any complete ~<username>, but doesn't expand usernames.
 
            if (candidate_filename[0] == '~')
              candidate_filename
                = sys::file_ops::tilde_expand (candidate_filename);
 
            sys::file_stat fs (candidate_filename);
 
            retval = fs.is_dir ();
          }
      }
 
    return retval;
  }
 
  // Decide whether to interpret partial commands like "abc/def" as a
  // filename or division.  Return the set of delimiters appropriate for
  // the decision.
 
  char *
  gnu_readline::do_completer_word_break_hook ()
  {
    static char *dir_sep = octave_strdup_wrapper (R"( '")");
 
    std::string word;
    std::string line = get_line_buffer ();
 
    // For now, assume space or quote delimiter for file names.
    const char *l = line.c_str ();
 
    if (looks_like_filename (l, ' ') || looks_like_filename (l, '\'')
        || looks_like_filename (l, '"'))
      {
        ::octave_rl_set_completer_quote_characters
          (s_completer_quote_characters.c_str ());
 
        return dir_sep;
      }
    else
      {
        ::octave_rl_set_completer_quote_characters ("");
 
        return octave_rl_get_completer_word_break_characters ();
      }
  }
 
  string_vector
  gnu_readline::do_generate_filename_completions (const std::string& text)
  {
    string_vector retval;
 
    int n = 0;
    int count = 0;
 
    char *fn = nullptr;
 
    while (1)
      {
        fn = ::octave_rl_filename_completion_function (text.c_str (), count);
 
        if (fn)
          {
            if (count == n)
              {
                // Famous last words:  Most large directories will not
                // have more than a few hundred files, so we should not
                // resize too many times even if the growth is linear...
                n += 100;
                retval.resize (n);
              }
 
            retval[count++] = fn;
 
            free (fn);
          }
        else
          break;
      }
 
    retval.resize (count);
 
    return retval;
  }
 
  std::string
  gnu_readline::do_get_line_buffer (void) const
  {
    return ::octave_rl_line_buffer ();
  }
 
  std::string
  gnu_readline::do_get_current_line (void) const
  {
    std::string retval;
    char *buf = ::octave_rl_copy_line ();
    retval = buf;
    free (buf);
    return retval;
  }
 
  // Return the character (offset+1) to the left of the cursor,
  // or '\0' if the cursor is at the start of the line.
  char
  gnu_readline::do_get_prev_char (int offset) const
  {
    const char *buf = ::octave_rl_line_buffer ();
    int p = ::octave_rl_point ();
 
    return p > offset ? buf[p - offset - 1] : '\0';
  }
 
  void
  gnu_readline::do_replace_line (const std::string& text, bool clear_undo)
  {
    ::octave_rl_replace_line (text.c_str (), clear_undo);
  }
 
  void
  gnu_readline::do_kill_full_line (void)
  {
    ::octave_rl_kill_full_line ();
  }
 
  void
  gnu_readline::do_insert_text (const std::string& text)
  {
    ::octave_rl_insert_text (text.c_str ());
  }
 
  void
  gnu_readline::do_newline (void)
  {
    ::octave_rl_newline (1, '\n');
  }
 
  void
  gnu_readline::do_accept_line (void)
  {
    command_accept_line (1, '\n');
  }
 
  bool
  gnu_readline::do_undo (void)
  {
    return ::octave_rl_do_undo ();
  }
 
  void
  gnu_readline::do_clear_undo_list ()
  {
    ::octave_rl_clear_undo_list ();
  }
 
  void
  gnu_readline::set_startup_hook (startup_hook_fcn f)
  {
    m_previous_startup_hook = ::octave_rl_get_startup_hook ();
 
    if (f != m_previous_startup_hook)
      ::octave_rl_set_startup_hook (f);
  }
 
  void
  gnu_readline::restore_startup_hook (void)
  {
    ::octave_rl_set_startup_hook (m_previous_startup_hook);
  }
 
  void
  gnu_readline::set_pre_input_hook (pre_input_hook_fcn f)
  {
    m_previous_pre_input_hook = ::octave_rl_get_pre_input_hook ();
 
    if (f != m_previous_pre_input_hook)
      ::octave_rl_set_pre_input_hook (f);
  }
 
  void
  gnu_readline::restore_pre_input_hook (void)
  {
    ::octave_rl_set_pre_input_hook (m_previous_pre_input_hook);
  }
 
  void
  gnu_readline::set_event_hook (event_hook_fcn f)
  {
    m_previous_event_hook = octave_rl_get_event_hook ();
 
    ::octave_rl_set_event_hook (f);
  }
 
  void
  gnu_readline::restore_event_hook (void)
  {
    ::octave_rl_set_event_hook (m_previous_event_hook);
  }
 
  void
  gnu_readline::do_read_init_file (const std::string& file)
  {
    ::octave_rl_read_init_file (file.c_str ());
  }
 
  void
  gnu_readline::do_re_read_init_file (void)
  {
    ::octave_rl_re_read_init_file ();
  }
 
  bool
  gnu_readline::do_filename_completion_desired (bool arg)
  {
    return ::octave_rl_filename_completion_desired (arg);
  }
 
  bool
  gnu_readline::do_filename_quoting_desired (bool arg)
  {
    return ::octave_rl_filename_quoting_desired (arg);
  }
 
  bool
  gnu_readline::do_prefer_env_winsize (bool arg)
  {
    return ::octave_rl_prefer_env_winsize (arg);
  }
 
  void
  gnu_readline::do_interrupt (bool arg)
  {
    ::octave_rl_done (arg);
  }
 
  void
  gnu_readline::do_handle_interrupt_signal (void)
  {
    octave_signal_caught = 0;
    octave_interrupt_state = 0;
 
    ::octave_rl_recover_from_interrupt ();
 
    throw interrupt_exception ();
  }
 
  int
  gnu_readline::operate_and_get_next (int /* count */, int /* c */)
  {
    // Accept the current line.
 
    command_editor::accept_line ();
 
    // Find the current line, and find the next line to use.
 
    int x_where = command_history::where ();
 
    int x_length = command_history::length ();
 
    if ((command_history::is_stifled ()
         && (x_length >= command_history::max_input_history ()))
        || (x_where >= x_length - 1))
      command_history::set_mark (x_where);
    else
      command_history::set_mark (x_where + 1);
 
    command_editor::add_startup_hook (command_history::goto_mark);
 
    return 0;
  }
 
  int
  gnu_readline::history_search_backward (int count, int c)
  {
    return octave_rl_history_search_backward (count, c);
  }
 
  int
  gnu_readline::history_search_forward (int count, int c)
  {
    return octave_rl_history_search_forward (count, c);
  }
 
  char *
  gnu_readline::command_generator (const char *text, int state)
  {
    char *retval = nullptr;
 
    completion_fcn f = command_editor::get_completion_function ();
 
    std::string tmp = f (text, state);
 
    std::size_t len = tmp.length ();
 
    if (len > 0)
      {
        retval = static_cast<char *> (std::malloc (len+1));
 
        if (retval)
          strcpy (retval, tmp.c_str ());
      }
 
    return retval;
  }
 
  char *
  gnu_readline::command_quoter (char *text, int matches, char *qcp)
  {
    char *retval = nullptr;
 
    quoting_fcn f = command_editor::get_quoting_function ();
 
    std::string tmp = f (text, matches, *qcp);
 
    std::size_t len = tmp.length ();
 
    if (len > 0)
      {
        retval = static_cast<char *> (std::malloc (len+1));
 
        if (retval)
          strcpy (retval, tmp.c_str ());
      }
 
    return retval;
  }
 
  char *
  gnu_readline::command_dequoter (char *text, int quote)
  {
    char *retval = nullptr;
 
    dequoting_fcn f = command_editor::get_dequoting_function ();
 
    std::string tmp = f (text, quote);
 
    std::size_t len = tmp.length ();
 
    if (len > 0)
      {
        retval = static_cast<char *> (std::malloc (len+1));
 
        if (retval)
          strcpy (retval, tmp.c_str ());
      }
 
    return retval;
  }
 
  int
  gnu_readline::command_char_is_quoted (char *text, int quote)
  {
    char_is_quoted_fcn f = command_editor::get_char_is_quoted_function ();
 
    return f (text, quote);
  }
 
  int
  gnu_readline::command_accept_line (int count, int key)
  {
    user_accept_line_fcn f = command_editor::get_user_accept_line_function ();
 
    if (f)
      f (::octave_rl_line_buffer ());
 
    ::octave_rl_redisplay ();
 
    return ::octave_rl_newline (count, key);
  }
 
  char **
  gnu_readline::command_completer (const char *text, int, int)
  {
    char **matches
      = ::octave_rl_completion_matches (text, gnu_readline::command_generator);
 
    return matches;
  }
 
#endif
 
  class
  default_command_editor : public command_editor
  {
  public:
 
    default_command_editor (void)
      : command_editor (), m_input_stream (stdin), m_output_stream (stdout) { }
 
    // No copying!
 
    default_command_editor (const default_command_editor&) = delete;
 
    default_command_editor& operator = (const default_command_editor&) = delete;
 
    ~default_command_editor (void) = default;
 
    std::string do_readline (const std::string& prompt, bool& eof);
 
    void do_set_input_stream (FILE *f);
 
    FILE * do_get_input_stream (void);
 
    void do_set_output_stream (FILE *f);
 
    FILE * do_get_output_stream (void);
 
    string_vector do_generate_filename_completions (const std::string& text);
 
    std::string do_get_line_buffer (void) const;
 
    std::string do_get_current_line (void) const;
 
    char do_get_prev_char (int) const;
 
    void do_replace_line (const std::string& text, bool clear_undo);
 
    void do_kill_full_line (void);
 
    void do_insert_text (const std::string& text);
 
    void do_newline (void);
 
    void do_accept_line (void);
 
  private:
 
    FILE *m_input_stream;
 
    FILE *m_output_stream;
  };
 
  std::string
  default_command_editor::do_readline (const std::string& prompt, bool& eof)
  {
    std::fputs (prompt.c_str (), m_output_stream);
    std::fflush (m_output_stream);
 
    return fgetl (m_input_stream, eof);
  }
 
  void
  default_command_editor::do_set_input_stream (FILE *f)
  {
    m_input_stream = f;
  }
 
  FILE *
  default_command_editor::do_get_input_stream (void)
  {
    return m_input_stream;
  }
 
  void
  default_command_editor::do_set_output_stream (FILE *f)
  {
    m_output_stream = f;
  }
 
  FILE *
  default_command_editor::do_get_output_stream (void)
  {
    return m_output_stream;
  }
 
  string_vector
  default_command_editor::do_generate_filename_completions (const std::string&)
  {
    // FIXME
    return string_vector ();
  }
 
  std::string
  default_command_editor::do_get_line_buffer (void) const
  {
    return "";
  }
 
  std::string
  default_command_editor::do_get_current_line (void) const
  {
    // FIXME
    return "";
  }
 
  char
  default_command_editor::do_get_prev_char (int) const
  {
    return '\0';
  }
 
  void
  default_command_editor::do_replace_line (const std::string&, bool)
  {
    // FIXME
  }
 
  void
  default_command_editor::do_kill_full_line (void)
  {
    // FIXME
  }
 
  void
  default_command_editor::do_insert_text (const std::string&)
  {
    // FIXME
  }
 
  void
  default_command_editor::do_newline (void)
  {
    // FIXME
  }
 
  void
  default_command_editor::do_accept_line (void)
  {
    // FIXME
  }
 
  bool
  command_editor::instance_ok (void)
  {
    bool retval = true;
 
    if (! s_instance)
      {
        make_command_editor ();
 
        if (s_instance)
          {
            s_instance->set_event_hook (event_handler);
 
            singleton_cleanup_list::add (cleanup_instance);
          }
      }
 
    if (! s_instance)
      (*current_liboctave_error_handler)
        ("unable to create command history object!");
 
    return retval;
  }
 
  void
  command_editor::make_command_editor (void)
  {
#if defined (USE_READLINE)
    s_instance = new gnu_readline ();
#else
    s_instance = new default_command_editor ();
#endif
  }
 
  void
  command_editor::force_default_editor (void)
  {
    delete s_instance;
    s_instance = new default_command_editor ();
  }
 
  void
  command_editor::set_initial_input (const std::string& text)
  {
    if (instance_ok ())
      s_instance->m_initial_input = text;
  }
 
  int
  command_editor::insert_initial_input (void)
  {
    return instance_ok () ? s_instance->do_insert_initial_input () : 0;
  }
 
  int
  command_editor::startup_handler (void)
  {
    // Iterate over a copy of the set to avoid problems if a hook
    // function attempts to remove itself from the startup_hook_set.
 
    std::set<startup_hook_fcn> hook_set = m_startup_hook_set;
 
    for (startup_hook_fcn f : hook_set)
      {
        if (f)
          f ();
      }
 
    return 0;
  }
 
  int
  command_editor::pre_input_handler (void)
  {
    // Iterate over copy of the set to avoid problems if a hook function
    // attempts to remove itself from the pre_input_hook_set.
 
    std::set<pre_input_hook_fcn> hook_set = m_pre_input_hook_set;
 
    for (pre_input_hook_fcn f : hook_set)
      {
        if (f)
          f ();
      }
 
    return 0;
  }
 
  int
  command_editor::event_handler (void)
  {
    if (octave_interrupt_state)
      handle_interrupt_signal ();
 
    event_hook_lock.lock ();
 
    std::set<event_hook_fcn> hook_set (m_event_hook_set);
 
    event_hook_lock.unlock ();
 
    for (event_hook_fcn f : hook_set)
      {
        if (f)
          f ();
      }
 
    return 0;
  }
 
  void
  command_editor::set_name (const std::string& n)
  {
    if (instance_ok ())
      s_instance->do_set_name (n);
  }
 
  std::string
  command_editor::readline (const std::string& prompt)
  {
    bool eof;
 
    return readline (prompt, eof);
  }
 
  std::string
  command_editor::readline (const std::string& prompt, bool& eof)
  {
    std::string retval;
 
    if (instance_ok ())
      {
        if (! s_instance->m_initial_input.empty ())
          add_pre_input_hook (command_editor::insert_initial_input);
 
        retval = s_instance->do_readline (prompt, eof);
      }
 
    return retval;
  }
 
  void
  command_editor::set_input_stream (FILE *f)
  {
    if (instance_ok ())
      s_instance->do_set_input_stream (f);
  }
 
  FILE *
  command_editor::get_input_stream (void)
  {
    return instance_ok () ? s_instance->do_get_input_stream () : nullptr;
  }
 
  void
  command_editor::set_output_stream (FILE *f)
  {
    if (instance_ok ())
      s_instance->do_set_output_stream (f);
  }
 
  FILE *
  command_editor::get_output_stream (void)
  {
    return instance_ok () ? s_instance->do_get_output_stream () : nullptr;
  }
 
  void
  command_editor::redisplay (void)
  {
    if (instance_ok ())
      s_instance->do_redisplay ();
  }
 
  int
  command_editor::terminal_rows (void)
  {
    return instance_ok () ? s_instance->do_terminal_rows () : -1;
  }
 
  int
  command_editor::terminal_cols (void)
  {
    return instance_ok () ? s_instance->do_terminal_cols () : -1;
  }
 
  void
  command_editor::clear_screen (bool skip_redisplay)
  {
    if (instance_ok ())
      s_instance->do_clear_screen (skip_redisplay);
  }
 
  void
  command_editor::resize_terminal (void)
  {
    if (instance_ok ())
      s_instance->do_resize_terminal ();
  }
 
  void
  command_editor::set_screen_size (int ht, int wd)
  {
    if (instance_ok ())
      s_instance->do_set_screen_size (ht, wd);
  }
 
  std::string
  command_editor::decode_prompt_string (const std::string& s)
  {
    return instance_ok () ? s_instance->do_decode_prompt_string (s) : "";
  }
 
  int
  command_editor::current_command_number (void)
  {
    return instance_ok () ? s_instance->m_command_number : 0;
  }
 
  void
  command_editor::reset_current_command_number (int n)
  {
    if (instance_ok ())
      s_instance->m_command_number = n;
  }
 
  void
  command_editor::increment_current_command_number (void)
  {
    if (instance_ok ())
      s_instance->m_command_number++;
  }
 
  void
  command_editor::restore_terminal_state (void)
  {
    if (instance_ok ())
      s_instance->do_restore_terminal_state ();
  }
 
  void
  command_editor::blink_matching_paren (bool flag)
  {
    if (instance_ok ())
      s_instance->do_blink_matching_paren (flag);
  }
 
  bool
  command_editor::erase_empty_line (bool flag)
  {
    return instance_ok () ? s_instance->do_erase_empty_line (flag) : false;
  }
 
  void
  command_editor::set_basic_word_break_characters (const std::string& s)
  {
    if (instance_ok ())
      s_instance->do_set_basic_word_break_characters (s);
  }
 
  void
  command_editor::set_completer_word_break_characters (const std::string& s)
  {
    if (instance_ok ())
      s_instance->do_set_completer_word_break_characters (s);
  }
 
  void
  command_editor::set_basic_quote_characters (const std::string& s)
  {
    if (instance_ok ())
      s_instance->do_set_basic_quote_characters (s);
  }
 
  void
  command_editor::set_filename_quote_characters (const std::string& s)
  {
    if (instance_ok ())
      s_instance->do_set_filename_quote_characters (s);
  }
 
  void
  command_editor::set_completer_quote_characters (const std::string& s)
  {
    if (instance_ok ())
      s_instance->do_set_completer_quote_characters (s);
  }
 
  void
  command_editor::set_completion_append_character (char c)
  {
    if (instance_ok ())
      s_instance->do_set_completion_append_character (c);
  }
 
  void
  command_editor::set_completion_function (completion_fcn f)
  {
    if (instance_ok ())
      s_instance->do_set_completion_function (f);
  }
 
  void
  command_editor::set_quoting_function (quoting_fcn f)
  {
    if (instance_ok ())
      s_instance->do_set_quoting_function (f);
  }
 
  void
  command_editor::set_dequoting_function (dequoting_fcn f)
  {
    if (instance_ok ())
      s_instance->do_set_dequoting_function (f);
  }
 
  void
  command_editor::set_char_is_quoted_function (char_is_quoted_fcn f)
  {
    if (instance_ok ())
      s_instance->do_set_char_is_quoted_function (f);
  }
 
  void
  command_editor::set_user_accept_line_function (user_accept_line_fcn f)
  {
    if (instance_ok ())
      s_instance->do_set_user_accept_line_function (f);
  }
 
  command_editor::completion_fcn
  command_editor::get_completion_function (void)
  {
    return instance_ok () ? s_instance->do_get_completion_function () : nullptr;
  }
 
  command_editor::quoting_fcn
  command_editor::get_quoting_function (void)
  {
    return instance_ok () ? s_instance->do_get_quoting_function () : nullptr;
  }
 
  command_editor::dequoting_fcn
  command_editor::get_dequoting_function (void)
  {
    return instance_ok () ? s_instance->do_get_dequoting_function () : nullptr;
  }
 
  command_editor::char_is_quoted_fcn
  command_editor::get_char_is_quoted_function (void)
  {
    return (instance_ok ()
            ? s_instance->do_get_char_is_quoted_function () : nullptr);
  }
 
  command_editor::user_accept_line_fcn
  command_editor::get_user_accept_line_function (void)
  {
    return (instance_ok ()
            ? s_instance->do_get_user_accept_line_function () : nullptr);
  }
 
  string_vector
  command_editor::generate_filename_completions (const std::string& text)
  {
    return (instance_ok ()
            ? s_instance->do_generate_filename_completions (text)
            : string_vector ());
  }
 
  std::string
  command_editor::get_line_buffer (void)
  {
    return instance_ok () ? s_instance->do_get_line_buffer () : "";
  }
 
  std::string
  command_editor::get_current_line (void)
  {
    return instance_ok () ? s_instance->do_get_current_line () : "";
  }
 
  // Return the character (offset+1) to the left of the cursor,
  // or '\0' if the cursor is at the start of the line.
  char
  command_editor::get_prev_char (int offset)
  {
    return instance_ok () ? s_instance->do_get_prev_char (offset) : '\0';
  }
 
  void
  command_editor::replace_line (const std::string& text, bool clear_undo)
  {
    if (instance_ok ())
      s_instance->do_replace_line (text, clear_undo);
  }
 
  void
  command_editor::kill_full_line (void)
  {
    if (instance_ok ())
      s_instance->do_kill_full_line ();
  }
 
  void
  command_editor::insert_text (const std::string& text)
  {
    if (instance_ok ())
      s_instance->do_insert_text (text);
  }
 
  void
  command_editor::newline (void)
  {
    if (instance_ok ())
      s_instance->do_newline ();
  }
 
  void
  command_editor::accept_line (void)
  {
    if (instance_ok ())
      s_instance->do_accept_line ();
  }
 
  bool
  command_editor::undo (void)
  {
    return instance_ok () ? s_instance->do_undo () : false;
  }
 
  void
  command_editor::clear_undo_list (void)
  {
    if (instance_ok ())
      s_instance->do_clear_undo_list ();
  }
 
  void
  command_editor::add_startup_hook (startup_hook_fcn f)
  {
    if (instance_ok ())
      {
        m_startup_hook_set.insert (f);
 
        s_instance->set_startup_hook (startup_handler);
      }
  }
 
  void
  command_editor::remove_startup_hook (startup_hook_fcn f)
  {
    if (instance_ok ())
      {
        auto p = m_startup_hook_set.find (f);
 
        if (p != m_startup_hook_set.end ())
          m_startup_hook_set.erase (p);
 
        if (m_startup_hook_set.empty ())
          s_instance->restore_startup_hook ();
      }
  }
 
  void
  command_editor::add_pre_input_hook (pre_input_hook_fcn f)
  {
    if (instance_ok ())
      {
        m_pre_input_hook_set.insert (f);
 
        s_instance->set_pre_input_hook (pre_input_handler);
      }
  }
 
  void
  command_editor::remove_pre_input_hook (pre_input_hook_fcn f)
  {
    if (instance_ok ())
      {
        auto p = m_pre_input_hook_set.find (f);
 
        if (p != m_pre_input_hook_set.end ())
          m_pre_input_hook_set.erase (p);
 
        if (m_pre_input_hook_set.empty ())
          s_instance->restore_pre_input_hook ();
      }
  }
 
  void
  command_editor::add_event_hook (event_hook_fcn f)
  {
    autolock guard (event_hook_lock);
 
    m_event_hook_set.insert (f);
  }
 
  void
  command_editor::remove_event_hook (event_hook_fcn f)
  {
    autolock guard (event_hook_lock);
 
    auto p = m_event_hook_set.find (f);
 
    if (p != m_event_hook_set.end ())
      m_event_hook_set.erase (p);
 
  }
 
  void
  command_editor::run_event_hooks (void)
  {
    event_handler ();
  }
 
  void
  command_editor::read_init_file (const std::string& file_arg)
  {
    if (instance_ok ())
      {
        std::string file = sys::file_ops::tilde_expand (file_arg);
 
        s_instance->do_read_init_file (file);
      }
  }
 
  void
  command_editor::re_read_init_file (void)
  {
    if (instance_ok ())
      s_instance->do_re_read_init_file ();
  }
 
  bool
  command_editor::filename_completion_desired (bool arg)
  {
    return (instance_ok ()
            ? s_instance->do_filename_completion_desired (arg) : false);
  }
 
  bool
  command_editor::filename_quoting_desired (bool arg)
  {
    return (instance_ok ())
           ? s_instance->do_filename_quoting_desired (arg) : false;
  }
 
  bool
  command_editor::prefer_env_winsize (bool arg)
  {
    return instance_ok () ? s_instance->do_prefer_env_winsize (arg) : false;
  }
 
  bool
  command_editor::interrupt (bool arg)
  {
    bool retval;
 
    if (instance_ok ())
      {
        // Return the current interrupt state.
        retval = s_instance->m_interrupted;
 
        s_instance->do_interrupt (arg);
 
        s_instance->m_interrupted = arg;
      }
    else
      retval = false;
 
    return retval;
  }
 
  void
  command_editor::interrupt_event_loop (bool arg)
  {
    if (instance_ok ())
      s_instance->do_interrupt_event_loop (arg);
  }
 
  bool
  command_editor::event_loop_interrupted (void)
  {
    return instance_ok () ? s_instance->do_event_loop_interrupted  () : false;
  }
 
  void
  command_editor::handle_interrupt_signal (void)
  {
    if (instance_ok ())
      s_instance->do_handle_interrupt_signal ();
  }
 
  // Return a string which will be printed as a prompt.  The string may
  // contain special characters which are decoded as follows:
  //
  //      \a      bell (ascii 07)
  //      \d      the date
  //      \e      escape (ascii 033)
  //      \h      the hostname up to the first '.'
  //      \H      the hostname
  //      \n      CRLF
  //      \r      CR
  //      \s      the name of the shell (program)
  //      \t      the time
  //      \T      the time in 12-hour hh:mm:ss format
  //      \@      the time in 12-hour hh:mm am/pm format
  //      \A      the time in 24-hour hh:mm format
  //      \u      your username
  //      \w      the current working directory
  //      \W      the last element of PWD
  //      \!      the history number of this command
  //      \#      the command number of this command
  //      \$      a $ or a # if you are root
  //      \nnn    character code nnn in octal
  //      \\      a backslash
  //      \[      begin a sequence of non-printing chars
  //      \]      end a sequence of non-printing chars
 
  std::string
  command_editor::do_decode_prompt_string (const std::string& s)
  {
    std::string retval;
    std::string tmpstr;
    std::size_t i = 0;
    std::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));
 
                  tmpstr = '\\';
 
                  if (n != -1)
                    {
                      tmpstr[0] = n;
                      i += 2;   // i++ makes this += 3 later
                    }
 
                  break;
                }
 
              case 'a':
                {
                  tmpstr = '\a';
 
                  break;
                }
 
              case 'd':
              case 't':
              case 'T':
              case '@':
              case 'A':
                // Make the current time/date into a string.
                {
                  sys::localtime now;
 
                  if (c == 'd')
                    tmpstr = now.strftime ("%a %b %d");
                  else if (c == 't')
                    tmpstr = now.strftime ("%H:%M:%S");
                  else if (c == 'T')
                    tmpstr = now.strftime ("%I:%M:%S");
                  else if (c == '@')
                    tmpstr = now.strftime ("%I:%M %p");
                  else // (c == 'A')
                    tmpstr = now.strftime ("%H:%M");
 
                  break;
                }
 
              case 'e':
                {
                  tmpstr = '\033';
 
                  break;
                }
 
              case 'h':
                {
                  tmpstr = sys::env::get_host_name ();
 
                  std::size_t pos = tmpstr.find ('.');
 
                  if (pos != std::string::npos)
                    tmpstr.resize (pos);
 
                  break;
                }
 
              case 'H':
                {
                  tmpstr = sys::env::get_host_name ();
 
                  break;
                }
 
              case 'n':
                {
                  tmpstr = newline_chars ();
 
                  break;
                }
 
              case 'r':
                {
                  tmpstr = '\r';
 
                  break;
                }
 
              case 's':
                {
                  tmpstr = sys::env::get_program_name ();
                  tmpstr = sys::env::base_pathname (tmpstr);
 
                  break;
                }
 
              case 'u':
                {
                  tmpstr = sys::env::get_user_name ();
 
                  break;
                }
 
              case 'w':
              case 'W':
                {
                  try
                    {
                      tmpstr = sys::env::get_current_directory ();
                    }
                  catch (const execution_exception&)
                    {
                      tmpstr = "";
                    }
 
                  std::string home_dir = sys::env::get_home_directory ();
 
                  if (c == 'W' && (home_dir.empty () || tmpstr != home_dir))
                    {
                      if (tmpstr != "/" && tmpstr != "//")
                        {
                          std::size_t pos = tmpstr.rfind ('/');
 
                          if (pos != std::string::npos && pos != 0)
                            tmpstr = tmpstr.substr (pos + 1);
                        }
                    }
                  else
                    tmpstr = sys::env::polite_directory_format (tmpstr);
 
                  break;
                }
 
              case '!':
                {
                  char number_buffer[32];
                  int num = command_history::current_number ();
                  if (num > 0)
                    sprintf (number_buffer, "%d", num);
                  else
                    strcpy (number_buffer, "!");
                  tmpstr = number_buffer;
 
                  break;
                }
 
              case '#':
                {
                  char number_buffer[32];
                  sprintf (number_buffer, "%d", m_command_number);
                  tmpstr = number_buffer;
 
                  break;
                }
 
              case '$':
                {
                  tmpstr = (octave_geteuid_wrapper () == 0 ? '#' : '$');
                  break;
                }
 
#if defined (USE_READLINE)
              case '[':
              case ']':
                {
                  tmpstr.resize (1);
 
                  tmpstr[0] = ((c == '[')
                               ? ::octave_rl_prompt_start_ignore ()
                               : ::octave_rl_prompt_end_ignore ());
 
                  break;
                }
#endif
 
              case '\\':
                {
                  tmpstr = '\\';
 
                  break;
                }
 
              default:
                {
                  tmpstr = "\\ ";
                  tmpstr[1] = c;
 
                  break;
                }
              }
 
            retval.append (tmpstr);
            i++;   // Move past processed escape character
          }
        else
          retval += c;
      }
 
    return retval;
  }
 
  int
  command_editor::do_insert_initial_input (void)
  {
    std::string input = m_initial_input;
 
    m_initial_input = "";
 
    do_insert_text (input);
 
    // Is it really right to redisplay here?
    do_redisplay ();
 
    return 0;
  }
 
  // Return the octal number parsed from STRING, or -1 to indicate that
  // the string contained a bad number.
 
  int
  command_editor::read_octal (const std::string& s)
  {
    int result = 0;
    int digits = 0;
 
    std::size_t i = 0;
    std::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;
  }
 
  void
  command_editor::error (int err_num)
  {
    (*current_liboctave_error_handler) ("%s", std::strerror (err_num));
  }
 
  void
  command_editor::error (const std::string& s)
  {
    (*current_liboctave_error_handler) ("%s", s.c_str ());
  }
}