xref: /dports/math/octave/octave-6.4.0/libinterp/corefcn/input.cc

////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

// Get command input interactively or from files.

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

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

#include <algorithm>
#include <iostream>
#include <queue>
#include <sstream>
#include <string>

#include "cmd-edit.h"
#include "file-ops.h"
#include "iconv-wrappers.h"
#include "localcharset-wrapper.h"
#include "oct-string.h"
#include "quit.h"
#include "str-vec.h"
#include "uniconv-wrappers.h"

#include "builtin-defun-decls.h"
#include "defun.h"
#include "error.h"
#include "errwarn.h"
#include "event-manager.h"
#include "help.h"
#include "hook-fcn.h"
#include "input.h"
#include "interpreter-private.h"
#include "interpreter.h"
#include "load-path.h"
#include "octave.h"
#include "oct-map.h"
#include "oct-hist.h"
#include "interpreter.h"
#include "event-manager.h"
#include "ovl.h"
#include "ov-fcn-handle.h"
#include "ov-usr-fcn.h"
#include "pager.h"
#include "parse.h"
#include "pt-eval.h"
#include "pt-stmt.h"
#include "sighandlers.h"
#include "sysdep.h"
#include "interpreter.h"
#include "unwind-prot.h"
#include "utils.h"
#include "variables.h"

// The time we last printed a prompt.
octave::sys::time Vlast_prompt_time = 0.0;

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

// TRUE if the plotting system has requested a call to drawnow at
// the next user prompt.
bool Vdrawnow_requested = false;

// TRUE if we are recording line numbers in a source file.
// Always true except when debugging and taking input directly from
// the terminal.
bool Vtrack_line_num = true;

namespace octave
{
  static std::string
  quoting_filename (const std::string& text, int, char quote)
  {
    if (quote)
      return text;
    else
      return ("'" + text);
  }

  // Try to parse a partial command line in reverse, excluding trailing TEXT.
  // If it appears a variable has been indexed by () or {},
  // return that expression,
  // to allow autocomplete of field names of arrays of structures.
  static std::string
  find_indexed_expression (const std::string& text)
  {
    std::string line = command_editor::get_line_buffer ();

    int pos = line.length () - text.length ();
    int curly_count = 0;
    int paren_count = 0;

    int last = --pos;

    while (pos >= 0 && (line[pos] == ')' || line[pos] == '}'))
      {
        if (line[pos] == ')')
          paren_count++;
        else
          curly_count++;

        while (curly_count + paren_count > 0 && --pos >= 0)
          {
            if (line[pos] == ')')
              paren_count++;
            else if (line[pos] == '(')
              paren_count--;
            else if (line[pos] == '}')
              curly_count++;
            else if (line[pos] == '{')
              curly_count--;
          }

        while (--pos >= 0 && line[pos] == ' ')
          ;
      }

    while (pos >= 0 && (isalnum (line[pos]) || line[pos] == '_'))
      pos--;

    if (++pos >= 0)
      return (line.substr (pos, last + 1 - pos));
    else
      return std::string ();
  }

  static string_vector
  generate_struct_completions (const std::string& text,
                               std::string& prefix, std::string& hint)
  {
    string_vector names;

    std::size_t pos = text.rfind ('.');
    bool array = false;

    if (pos != std::string::npos)
      {
        if (pos == text.length ())
          hint = "";
        else
          hint = text.substr (pos+1);

        prefix = text.substr (0, pos);

        if (prefix == "")
          {
            array = true;
            prefix = find_indexed_expression (text);
          }

        std::string base_name = prefix;

        pos = base_name.find_first_of ("{(. ");

        if (pos != std::string::npos)
          base_name = base_name.substr (0, pos);

        interpreter& interp
          = __get_interpreter__ ("generate_struct_completions");

        if (interp.is_variable (base_name))
          {
            int parse_status;

            error_system& es = interp.get_error_system ();

            unwind_protect frame;

            frame.add_method (es, &error_system::set_discard_warning_messages,
                              es.discard_warning_messages ());

            es.discard_warning_messages (true);

            try
              {
                octave_value tmp
                  = interp.eval_string (prefix, true, parse_status);

                frame.run ();

                if (tmp.is_defined ()
                    && (tmp.isstruct () || tmp.isjava () || tmp.is_classdef_object ()))
                  names = tmp.map_keys ();
              }
            catch (const execution_exception&)
              {
                interp.recover_from_exception ();
              }
          }
      }

    // Undo look-back that found the array expression,
    // but insert an extra "." to distinguish from the non-struct case.
    if (array)
      prefix = ".";

    return names;
  }

  // FIXME: this will have to be much smarter to work "correctly".
  static bool
  looks_like_struct (const std::string& text, char prev_char)
  {
    bool retval = (! text.empty ()
                   && (text != "." || prev_char == ')' || prev_char == '}')
                   && text.find_first_of (sys::file_ops::dir_sep_chars ()) == std::string::npos
                   && text.find ("..") == std::string::npos
                   && text.rfind ('.') != std::string::npos);

    return retval;
  }

  // FIXME: make this generate filenames when appropriate.

  static string_vector
  generate_possible_completions (const std::string& text, std::string& prefix,
                                 std::string& hint, bool& deemed_struct)
  {
    string_vector names;

    prefix = "";

    char prev_char = command_editor::get_prev_char (text.length ());
    deemed_struct = looks_like_struct (text, prev_char);

    if (deemed_struct)
      names = generate_struct_completions (text, prefix, hint);
    else
      names = make_name_list ();

    // Sort and remove duplicates.

    names.sort (true);

    return names;
  }

  static bool
  is_completing_dirfns (void)
  {
    static std::string dirfns_commands[] = {"cd", "isfile", "isfolder", "ls"};
    static const std::size_t dirfns_commands_length = 4;

    bool retval = false;

    std::string line = command_editor::get_line_buffer ();

    for (std::size_t i = 0; i < dirfns_commands_length; i++)
      {
        int index = line.find (dirfns_commands[i] + ' ');

        if (index == 0)
          {
            retval = true;
            break;
          }
      }

    return retval;
  }

  static std::string
  generate_completion (const std::string& text, int state)
  {
    std::string retval;

    static std::string prefix;
    static std::string hint;

    static std::size_t hint_len = 0;

    static int list_index = 0;
    static int name_list_len = 0;
    static int name_list_total_len = 0;
    static string_vector name_list;
    static string_vector file_name_list;

    static int matches = 0;

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

        prefix = "";

        hint = text;

        // No reason to display symbols while completing a
        // file/directory operation.

        bool deemed_struct = false;

        if (is_completing_dirfns ())
          name_list = string_vector ();
        else
          name_list = generate_possible_completions (text, prefix, hint,
                                                     deemed_struct);

        name_list_len = name_list.numel ();

        // If the line was something like "a{1}." then text = "." but
        // we don't want to expand all the . files.
        if (! deemed_struct)
          {

            file_name_list = command_editor::generate_filename_completions (text);

            name_list.append (file_name_list);

          }

        name_list_total_len = name_list.numel ();

        hint_len = hint.length ();

        matches = 0;

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

    if (name_list_total_len > 0 && matches > 0)
      {
        while (list_index < name_list_total_len)
          {
            std::string name = name_list[list_index];

            list_index++;

            if (hint == name.substr (0, hint_len))
              {
                // Special case: array reference forces prefix="."
                //               in generate_struct_completions ()
                if (list_index <= name_list_len && ! prefix.empty ())
                  retval = (prefix == "." ? "" : prefix) + '.' + name;
                else
                  retval = name;

                char prev_char =
                  command_editor::get_prev_char (text.length ());

                if (matches == 1 && looks_like_struct (retval, prev_char))
                  {
                    // Don't append anything, since we don't know
                    // whether it should be '(' or '.'.

                    command_editor::set_completion_append_character ('\0');
                  }
                else
                  {
                    input_system& input_sys
                      = __get_input_system__ ("generate_completion");

                    command_editor::set_completion_append_character
                      (input_sys.completion_append_char ());
                  }

                break;
              }
          }
      }

    return retval;
  }

  static int internal_input_event_hook_fcn (void)
  {
    octave_quit ();

    input_system& input_sys
      = __get_input_system__ ("internal_input_event_hook_fcn");

    input_sys.run_input_event_hooks ();

    return 0;
  }

  // Use literal "octave" in default setting for PS1 instead of
  // "\\s" to avoid setting the prompt to "octave.exe" or
  // "octave-gui", etc.

  input_system::input_system (interpreter& interp)
    : m_interpreter (interp), m_PS1 (R"(octave:\#> )"), m_PS2 ("> "),
      m_completion_append_char (' '), m_gud_mode (false),
      m_mfile_encoding ("system"), m_auto_repeat_debug_command (true),
      m_last_debugging_command ("\n"), m_input_event_hook_functions (),
      m_initialized (false)
  { }

  void input_system::initialize (bool line_editing)
  {
    if (m_initialized)
      return;

    // Force default line editor if we don't want readline editing.
    if (! line_editing)
      {
        command_editor::force_default_editor ();
        return;
      }

    // If we are using readline, this allows conditional parsing of the
    // .inputrc file.

    command_editor::set_name ("Octave");

    // FIXME: this needs to include a comma too, but that
    // causes trouble for the new struct element completion code.

    static const char *s = "\t\n !\"\'*+-/:;<=>(){}[\\]^`~";

    command_editor::set_basic_word_break_characters (s);

    command_editor::set_completer_word_break_characters (s);

    command_editor::set_basic_quote_characters (R"(")");

    command_editor::set_filename_quote_characters (" \t\n\\\"'@<>=;|&()#$`?*[!:{");

    command_editor::set_completer_quote_characters (R"('")");

    command_editor::set_completion_function (generate_completion);

    command_editor::set_quoting_function (quoting_filename);

    command_editor::add_event_hook (internal_input_event_hook_fcn);

    m_initialized = true;
  }

  octave_value
  input_system::PS1 (const octave_value_list& args, int nargout)
  {
    return set_internal_variable (m_PS1, args, nargout, "PS1");
  }

  octave_value
  input_system::PS2 (const octave_value_list& args, int nargout)
  {
    return set_internal_variable (m_PS2, args, nargout, "PS2");
  }

  octave_value
  input_system::completion_append_char (const octave_value_list& args,
                                        int nargout)
  {
    return set_internal_variable (m_completion_append_char, args, nargout,
                                  "completion_append_char");
  }

  octave_value
  input_system::gud_mode (const octave_value_list& args, int nargout)
  {
    return set_internal_variable (m_gud_mode, args, nargout, "__gud_mode__");
  }

  octave_value
  input_system::mfile_encoding (const octave_value_list& args, int nargout)
  {
    // Save current value in case there is an error in the additional
    // validation below.

    std::string saved_encoding = m_mfile_encoding;

    // We must pass the actual variable to change here for temporary
    // "local" settings to work properly.

    octave_value retval
      = set_internal_variable (m_mfile_encoding, args, nargout,
                               "__mfile_encoding__");

    // Additional validation if the encoding has changed.

    if (m_mfile_encoding != saved_encoding)
      {
        if (m_mfile_encoding.empty ())
          {
            m_mfile_encoding = "system";
          }
        else
          {
            std::transform (m_mfile_encoding.begin (),
                            m_mfile_encoding.end (),
                            m_mfile_encoding.begin (), ::tolower);

            std::string encoding = (m_mfile_encoding.compare ("system") == 0)
              ? octave_locale_charset_wrapper () : m_mfile_encoding;

            // Check for valid encoding name.
            void *codec
              = octave_iconv_open_wrapper (encoding.c_str (), "utf-8");

            if (codec == reinterpret_cast<void *> (-1))
              {
                m_mfile_encoding = saved_encoding;
                if (errno == EINVAL)
                  error ("__mfile_encoding__: conversion from encoding '%s' "
                         "not supported", encoding.c_str ());
                else
                  error ("__mfile_encoding__: error %d opening encoding '%s'.",
                         errno, encoding.c_str ());
              }
            else
              octave_iconv_close_wrapper (codec);
          }

      }

    // Synchronize the related gui preference for editor encoding
    feval ("__event_manager_gui_preference__",
           ovl ("editor/default_encoding", m_mfile_encoding));

    return retval;
  }

  octave_value
  input_system::auto_repeat_debug_command (const octave_value_list& args,
                                           int nargout)
  {
    return set_internal_variable (m_auto_repeat_debug_command, args, nargout,
                                  "auto_repeat_debug_command");
  }

  bool input_system::yes_or_no (const std::string& prompt)
  {
    std::string prompt_string = prompt + "(yes or no) ";

    while (1)
      {
        bool eof = false;

        std::string input_buf = interactive_input (prompt_string, eof);

        if (input_buf == "yes")
          return true;
        else if (input_buf == "no")
          return false;
        else
          message (nullptr, "Please answer yes or no.");
      }
  }

  std::string input_system::interactive_input (const std::string& s, bool& eof)
  {
    Vlast_prompt_time.stamp ();

    if (Vdrawnow_requested && m_interpreter.interactive ())
      {
        bool eval_error = false;

        try
          {
            Fdrawnow (m_interpreter);
          }
        catch (const execution_exception& e)
          {
            eval_error = true;

            m_interpreter.handle_exception (e);
          }

        flush_stdout ();

        // We set Vdrawnow_requested to false even if there is an error in
        // drawnow so that the error doesn't reappear at every prompt.

        Vdrawnow_requested = false;

        if (eval_error)
          return "\n";
      }

    return gnu_readline (s, eof);
  }

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

  octave_value_list
  input_system::get_user_input (const octave_value_list& args, int nargout)
  {
    octave_value_list retval;

    int read_as_string = 0;

    if (args.length () == 2)
      read_as_string++;

    std::string prompt = args(0).xstring_value ("input: unrecognized argument");

    output_system& output_sys = m_interpreter.get_output_system ();

    output_sys.reset ();

    octave_diary << prompt;

    bool eof = false;

    std::string input_buf = interactive_input (prompt.c_str (), eof);

    if (input_buf.empty ())
      error ("input: reading user-input failed!");

    std::size_t len = input_buf.length ();

    octave_diary << input_buf;

    if (input_buf[len - 1] != '\n')
      octave_diary << "\n";

    if (read_as_string)
      {
        // FIXME: fix gnu_readline and octave_gets instead!
        if (input_buf.length () == 1 && input_buf[0] == '\n')
          retval(0) = "";
        else
          retval(0) = input_buf;
      }
    else
      {
        int parse_status = 0;

        retval
          = m_interpreter.eval_string (input_buf, true, parse_status, nargout);

        tree_evaluator& tw = m_interpreter.get_evaluator ();

        if (! tw.in_debug_repl () && retval.empty ())
          retval(0) = Matrix ();
      }

    return retval;
  }

  bool input_system::have_input_event_hooks (void) const
  {
    return ! m_input_event_hook_functions.empty ();
  }

  void input_system::add_input_event_hook (const hook_function& hook_fcn)
  {
    m_input_event_hook_functions.insert (hook_fcn.id (), hook_fcn);
  }

  bool input_system::remove_input_event_hook (const std::string& hook_fcn_id)
  {
    hook_function_list::iterator p
      = m_input_event_hook_functions.find (hook_fcn_id);

    if (p == m_input_event_hook_functions.end ())
      return false;

    m_input_event_hook_functions.erase (p);
    return true;
  }

  void input_system::clear_input_event_hooks (void)
  {
    m_input_event_hook_functions.clear ();
  }

  void input_system::run_input_event_hooks (void)
  {
    m_input_event_hook_functions.run ();
  }

  std::string
  input_system::gnu_readline (const std::string& s, bool& eof) const
  {
    octave_quit ();

    eof = false;

    std::string retval = command_editor::readline (s, eof);

    if (! eof && retval.empty ())
      retval = "\n";

    return retval;
  }

  std::string base_reader::octave_gets (const std::string& prompt, bool& eof)
  {
    octave_quit ();

    eof = false;

    std::string retval;

    // Process pre input event hook function prior to flushing output and
    // printing the prompt.

    tree_evaluator& tw = m_interpreter.get_evaluator ();

    event_manager& evmgr = m_interpreter.get_event_manager ();

    if (m_interpreter.interactive ())
      {
        if (! tw.in_debug_repl ())
          evmgr.exit_debugger_event ();

        evmgr.pre_input_event ();

        evmgr.set_workspace ();
      }

    bool history_skip_auto_repeated_debugging_command = false;

    input_system& input_sys = m_interpreter.get_input_system ();

    pipe_handler_error_count = 0;

    output_system& output_sys = m_interpreter.get_output_system ();

    output_sys.reset ();

    octave_diary << prompt;

    retval = input_sys.interactive_input (prompt, eof);

    // There is no need to update the load_path cache if there is no
    // user input.
    if (retval != "\n"
        && retval.find_first_not_of (" \t\n\r") != std::string::npos)
      {
        load_path& lp = m_interpreter.get_load_path ();

        lp.update ();

        if (tw.in_debug_repl ())
          input_sys.last_debugging_command (retval);
        else
          input_sys.last_debugging_command ("\n");
      }
    else if (tw.in_debug_repl () && input_sys.auto_repeat_debug_command ())
      {
        retval = input_sys.last_debugging_command ();
        history_skip_auto_repeated_debugging_command = true;
      }

    if (retval != "\n")
      {
        if (! history_skip_auto_repeated_debugging_command)
          {
            if (command_history::add (retval))
              evmgr.append_history (retval);
          }

        octave_diary << retval;

        if (! retval.empty () && retval.back () != '\n')
          octave_diary << "\n";
      }
    else
      octave_diary << "\n";

    // Process post input event hook function after the internal history
    // list has been updated.

    if (m_interpreter.interactive ())
      evmgr.post_input_event ();

    return retval;
  }

  class
  terminal_reader : public base_reader
  {
  public:

    terminal_reader (interpreter& interp)
      : base_reader (interp), m_eof (false), m_input_queue ()
    { }

    std::string get_input (const std::string& prompt, bool& eof);

    std::string input_source (void) const { return s_in_src; }

    bool input_from_terminal (void) const { return true; }

  private:

    bool m_eof;
    std::queue<std::string> m_input_queue;

    static const std::string s_in_src;
  };

  class
  file_reader : public base_reader
  {
  public:

    file_reader (interpreter& interp, FILE *f_arg)
      : base_reader (interp), m_file (f_arg) { }

    std::string get_input (const std::string& prompt, bool& eof);

    std::string input_source (void) const { return s_in_src; }

    bool input_from_file (void) const { return true; }

  private:

    FILE *m_file;

    static const std::string s_in_src;
  };

  class
  eval_string_reader : public base_reader
  {
  public:

    eval_string_reader (interpreter& interp, const std::string& str)
      : base_reader (interp), m_eval_string (str)
    { }

    std::string get_input (const std::string& prompt, bool& eof);

    std::string input_source (void) const { return s_in_src; }

    bool input_from_eval_string (void) const { return true; }

  private:

    std::string m_eval_string;

    static const std::string s_in_src;
  };

  input_reader::input_reader (interpreter& interp)
    : m_rep (new terminal_reader (interp))
  { }

  input_reader::input_reader (interpreter& interp, FILE *file)
    : m_rep (new file_reader (interp, file))
  { }

  input_reader::input_reader (interpreter& interp, const std::string& str)
    : m_rep (new eval_string_reader (interp, str))
  { }

  const std::string base_reader::s_in_src ("invalid");

  const std::string terminal_reader::s_in_src ("terminal");

  // If octave_gets returns multiple lines, we cache the input and
  // return it one line at a time.  Multiple input lines may happen when
  // using readline and bracketed paste mode is enabled, for example.
  // Instead of queueing lines here, it might be better to modify the
  // grammar in the parser to handle multiple lines when working
  // interactively.  See also bug #59938.

  std::string
  terminal_reader::get_input (const std::string& prompt, bool& eof)
  {
    octave_quit ();

    eof = false;

    if (m_input_queue.empty ())
      {
        std::string input = octave_gets (prompt, m_eof);

        std::size_t len = input.size ();

        if (len == 0)
          {
            if (m_eof)
              {
                eof = m_eof;
                return input;
              }
            else
              {
                // Can this happen, or will the string returned from
                // octave_gets always end in a newline character?

                input = "\n";
                len = 1;
              }
          }

        std::size_t beg = 0;
        while (beg < len)
          {
            std::size_t end = input.find ('\n', beg);

            if (end == std::string::npos)
              {
                m_input_queue.push (input.substr (beg));
                break;
              }
            else
              {
                m_input_queue.push (input.substr (beg, end-beg+1));
                beg = end + 1;
              }
          }
      }

    std::string retval = m_input_queue.front ();
    m_input_queue.pop ();

    if (m_input_queue.empty ())
      eof = m_eof;

    return retval;
  }

  const std::string file_reader::s_in_src ("file");

  std::string
  file_reader::get_input (const std::string& /*prompt*/, bool& eof)
  {
    octave_quit ();

    eof = false;

    std::string src_str = octave_fgets (m_file, eof);

    input_system& input_sys = m_interpreter.get_input_system ();

    std::string mfile_encoding = input_sys.mfile_encoding ();

    std::string encoding;
    if (mfile_encoding.compare ("system") == 0)
      {
        encoding = octave_locale_charset_wrapper ();
        // encoding identifiers should consist of ASCII only characters
        std::transform (encoding.begin (), encoding.end (), encoding.begin (),
                        ::tolower);
      }
    else
      encoding = mfile_encoding;

    if (encoding.compare ("utf-8") == 0)
      {
        // Check for BOM and strip it
        if (src_str.compare (0, 3, "\xef\xbb\xbf") == 0)
          src_str.erase (0, 3);

        // replace invalid portions of the string
        // FIXME: Include file name that corresponds to m_file.
        if (string::u8_validate ("get_input", src_str) > 0)
          warning_with_id ("octave:get_input:invalid_utf8",
                           "Invalid UTF-8 byte sequences have been replaced.");
      }
    else
      {
        // convert encoding to UTF-8 before returning string
        const char *src = src_str.c_str ();
        std::size_t srclen = src_str.length ();

        std::size_t length;
        uint8_t *utf8_str;

        utf8_str = octave_u8_conv_from_encoding (encoding.c_str (), src, srclen,
                                                 &length);

        if (! utf8_str)
          error ("file_reader::get_input: "
                 "converting from codepage '%s' to UTF-8: %s",
                 encoding.c_str (), std::strerror (errno));

        unwind_protect frame;
        frame.add_fcn (::free, static_cast<void *> (utf8_str));

        src_str = std::string (reinterpret_cast<char *> (utf8_str), length);
      }

    return src_str;
  }

  const std::string eval_string_reader::s_in_src ("eval_string");

  std::string
  eval_string_reader::get_input (const std::string& /*prompt*/, bool& eof)
  {
    octave_quit ();

    eof = false;

    std::string retval;

    retval = m_eval_string;

    // Clear the eval string so that the next call will return
    // an empty character string with EOF = true.
    m_eval_string = "";

    if (retval.empty ())
      eof = true;

    return retval;
  }
}

DEFMETHOD (input, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{ans} =} input (@var{prompt})
@deftypefnx {} {@var{ans} =} input (@var{prompt}, "s")
Print @var{prompt} and wait for user input.

For example,

@example
input ("Pick a number, any number! ")
@end example

@noindent
prints the prompt

@example
Pick a number, any number!
@end example

@noindent
and waits for the user to enter a value.  The string entered by the user
is evaluated as an expression, so it may be a literal constant, a variable
name, or any other valid Octave code.

The number of return arguments, their size, and their class depend on the
expression entered.

If you are only interested in getting a literal string value, you can call
@code{input} with the character string @qcode{"s"} as the second argument.
This tells Octave to return the string entered by the user directly, without
evaluating it first.

Because there may be output waiting to be displayed by the pager, it is a
good idea to always call @code{fflush (stdout)} before calling @code{input}.
 This will ensure that all pending output is written to the screen before
your prompt.
@seealso{yes_or_no, kbhit, pause, menu, listdlg}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.get_user_input (args, std::max (nargout, 1));
}

DEFMETHOD (yes_or_no, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {@var{ans} =} yes_or_no ("@var{prompt}")
Ask the user a yes-or-no question.

Return logical true if the answer is yes or false if the answer is no.

Takes one argument, @var{prompt}, which is the string to display when asking
the question.  @var{prompt} should end in a space; @code{yes-or-no} adds the
string @samp{(yes or no) } to it.  The user must confirm the answer with
@key{RET} and can edit it until it has been confirmed.
@seealso{input}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin > 1)
    print_usage ();

  octave::input_system& input_sys = interp.get_input_system ();

  std::string prompt;

  if (nargin == 1)
    prompt = args(0).xstring_value ("yes_or_no: PROMPT must be a string");

  return ovl (input_sys.yes_or_no (prompt));
}

DEFMETHOD (keyboard, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} keyboard ()
@deftypefnx {} {} keyboard ("@var{prompt}")
Stop m-file execution and enter debug mode.

When the @code{keyboard} function is executed, Octave prints a prompt and
waits for user input.  The input strings are then evaluated and the results
are printed.  This makes it possible to examine the values of variables
within a function, and to assign new values if necessary.  To leave the
prompt and return to normal execution type @samp{return} or @samp{dbcont}.
The @code{keyboard} function does not return an exit status.

If @code{keyboard} is invoked without arguments, a default prompt of
@samp{debug> } is used.
@seealso{dbstop, dbcont, dbquit}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin > 1)
    print_usage ();

  octave::tree_evaluator& tw = interp.get_evaluator ();

  if (nargin == 1)
    {
      std::string prompt
        = args(0).xstring_value ("keyboard: PROMPT must be a string");

      tw.keyboard (prompt);
    }
  else
    tw.keyboard ();

  return ovl ();
}

DEFUN (completion_matches, args, nargout,
       doc: /* -*- texinfo -*-
@deftypefn {} {} completion_matches (@var{hint})
Generate possible completions given @var{hint}.

This function is provided for the benefit of programs like Emacs which
might be controlling Octave and handling user input.  The current
command number is not incremented when this function is called.  This is
a feature, not a bug.
@end deftypefn */)
{
  if (args.length () != 1)
    print_usage ();

  octave_value retval;

  std::string hint = args(0).string_value ();

  int n = 32;

  string_vector list (n);

  int k = 0;

  for (;;)
    {
      std::string cmd = octave::generate_completion (hint, k);

      if (! cmd.empty ())
        {
          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.numel ();

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

  octave_completion_matches_called = true;

  return retval;
}

/*
%!assert (ischar (completion_matches ("")))
%!assert (ischar (completion_matches ("a")))
%!assert (ischar (completion_matches (" ")))
%!assert (isempty (completion_matches (" ")))
%!assert (any (strcmp ("abs", deblank (cellstr (completion_matches (""))))))
%!assert (any (strcmp ("abs", deblank (cellstr (completion_matches ("a"))))))
%!assert (any (strcmp ("abs", deblank (cellstr (completion_matches ("ab"))))))
%!assert (any (strcmp ("abs", deblank (cellstr (completion_matches ("abs"))))))
%!assert (! any (strcmp ("abs", deblank (cellstr (completion_matches ("absa"))))))

%!error completion_matches ()
%!error completion_matches (1, 2)
*/

DEFUN (readline_read_init_file, args, ,
       doc: /* -*- texinfo -*-
@deftypefn {} {} readline_read_init_file (@var{file})
Read the readline library initialization file @var{file}.

If @var{file} is omitted, read the default initialization file
(normally @file{~/.inputrc}).

@xref{Readline Init File, , , readline, GNU Readline Library},
for details.
@seealso{readline_re_read_init_file}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin > 1)
    print_usage ();

  if (nargin == 0)
    octave::command_editor::read_init_file ();
  else
    {
      std::string file = args(0).string_value ();

      octave::command_editor::read_init_file (file);
    }

  return ovl ();
}

DEFUN (readline_re_read_init_file, args, ,
       doc: /* -*- texinfo -*-
@deftypefn {} {} readline_re_read_init_file ()
Re-read the last readline library initialization file that was read.

@xref{Readline Init File, , , readline, GNU Readline Library},
for details.
@seealso{readline_read_init_file}
@end deftypefn */)
{
  if (args.length () != 0)
    print_usage ();

  octave::command_editor::re_read_init_file ();

  return ovl ();
}

DEFMETHOD (add_input_event_hook, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{id} =} add_input_event_hook (@var{fcn})
@deftypefnx {} {@var{id} =} add_input_event_hook (@var{fcn}, @var{data})
Add the named function or function handle @var{fcn} to the list of functions
to call periodically when Octave is waiting for input.

The function should have the form

@example
@var{fcn} (@var{data})
@end example

If @var{data} is omitted, Octave calls the function without any arguments.

The returned identifier may be used to remove the function handle from the
list of input hook functions.
@seealso{remove_input_event_hook}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  octave_value user_data;

  if (nargin == 2)
    user_data = args(1);

  octave::input_system& input_sys = interp.get_input_system ();

  hook_function hook_fcn (args(0), user_data);

  input_sys.add_input_event_hook (hook_fcn);

  return ovl (hook_fcn.id ());
}

DEFMETHOD (remove_input_event_hook, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} remove_input_event_hook (@var{name})
@deftypefnx {} {} remove_input_event_hook (@var{fcn_id})
Remove the named function or function handle with the given identifier
from the list of functions to call periodically when Octave is waiting
for input.
@seealso{add_input_event_hook}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  std::string hook_fcn_id = args(0).xstring_value ("remove_input_event_hook: argument not valid as a hook function name or id");

  bool warn = (nargin < 2);

  octave::input_system& input_sys = interp.get_input_system ();

  if (! input_sys.remove_input_event_hook (hook_fcn_id) && warn)
    warning ("remove_input_event_hook: %s not found in list",
             hook_fcn_id.c_str ());

  return ovl ();
}

DEFMETHOD (PS1, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} PS1 ()
@deftypefnx {} {@var{old_val} =} PS1 (@var{new_val})
@deftypefnx {} {} PS1 (@var{new_val}, "local")
Query or set the primary prompt string.

When executing interactively, Octave displays the primary prompt when it is
ready to read a command.

The default value of the primary prompt string is @qcode{'octave:\#> '}.
To change it, use a command like

@example
PS1 ("\\u@@\\H> ")
@end example

@noindent
which will result in the prompt @samp{boris@@kremvax> } for the user
@samp{boris} logged in on the host @samp{kremvax.kgb.su}.  Note that two
backslashes are required to enter a backslash into a double-quoted
character string.  @xref{Strings}.

You can also use ANSI escape sequences if your terminal supports them.
This can be useful for coloring the prompt.  For example,

@example
PS1 ('\[\033[01;31m\]\s:\#> \[\033[0m\]')
@end example

@noindent
will give the default Octave prompt a red coloring.

When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{PS2, PS4}
@end deftypefn */)
{
  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.PS1 (args, nargout);
}

DEFMETHOD (PS2, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} PS2 ()
@deftypefnx {} {@var{old_val} =} PS2 (@var{new_val})
@deftypefnx {} {} PS2 (@var{new_val}, "local")
Query or set the secondary prompt string.

The secondary prompt is printed when Octave is expecting additional input to
complete a command.  For example, if you are typing a @code{for} loop that
spans several lines, Octave will print the secondary prompt at the beginning
of each line after the first.  The default value of the secondary prompt
string is @qcode{"> "}.

When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{PS1, PS4}
@end deftypefn */)
{
  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.PS2 (args, nargout);
}

DEFMETHOD (completion_append_char, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} completion_append_char ()
@deftypefnx {} {@var{old_val} =} completion_append_char (@var{new_val})
@deftypefnx {} {} completion_append_char (@var{new_val}, "local")
Query or set the internal character variable that is appended to
successful command-line completion attempts.

The default value is @qcode{" "} (a single space).

When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@end deftypefn */)
{
  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.completion_append_char (args, nargout);
}

DEFMETHOD (__request_drawnow__, , args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} __request_drawnow__ ()
@deftypefnx {} {} __request_drawnow__ (@var{flag})
Undocumented internal function.
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin > 1)
    print_usage ();

  if (nargin == 0)
    Vdrawnow_requested = true;
  else
    Vdrawnow_requested = args(0).bool_value ();

  return ovl ();
}

DEFMETHOD (__gud_mode__, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn {} {} __gud_mode__ ()
Undocumented internal function.
@end deftypefn */)
{
  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.gud_mode (args, nargout);
}

DEFMETHOD (__mfile_encoding__, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn {} {@var{current_encoding} =} __mfile_encoding__ (@var{new_encoding})
Set and query the codepage that is used for reading .m files.
@end deftypefn */)
{
  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.mfile_encoding (args, nargout);
}

DEFMETHOD (auto_repeat_debug_command, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} auto_repeat_debug_command ()
@deftypefnx {} {@var{old_val} =} auto_repeat_debug_command (@var{new_val})
@deftypefnx {} {} auto_repeat_debug_command (@var{new_val}, "local")
Query or set the internal variable that controls whether debugging
commands are automatically repeated when the input line is empty (typing
just @key{RET}).

When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@end deftypefn */)
{
  octave::input_system& input_sys = interp.get_input_system ();

  return input_sys.auto_repeat_debug_command (args, nargout);
}

// Always define these functions.  The macro is intended to allow the
// declarations to be hidden, not so that Octave will not provide the
// functions if they are requested.

// #if defined (OCTAVE_USE_DEPRECATED_FUNCTIONS)

bool
octave_yes_or_no (const std::string& prompt)
{
  octave::input_system& input_sys
    = octave::__get_input_system__ ("set_default_prompts");

  return input_sys.yes_or_no (prompt);
}

void
remove_input_event_hook_functions (void)
{
  octave::input_system& input_sys
    = octave::__get_input_system__ ("remove_input_event_hook_functions");

  input_sys.clear_input_event_hooks ();
}

// 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)
{
  octave::command_editor::set_input_stream (stdin);
  return octave::command_editor::get_input_stream ();
}

// #endif