ruby--ruby/ext/readline/readline.c

/************************************************

  readline.c - GNU Readline module

  $Author$
  created at: Wed Jan 20 13:59:32 JST 1999

  Copyright (C) 1997-2008  Shugo Maeda
  Copyright (C) 2008-2009  TAKAO Kouji

  $Id$

  Contact:
   - TAKAO Kouji <kouji at takao7 dot net> (current maintainer)

************************************************/

#ifdef RUBY_EXTCONF_H
#include RUBY_EXTCONF_H
#endif

#include "ruby/config.h"
#include <errno.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_READLINE_READLINE_H
#include <readline/readline.h>
#endif
#ifdef HAVE_READLINE_HISTORY_H
#include <readline/history.h>
#endif
#ifdef HAVE_EDITLINE_READLINE_H
#include <editline/readline.h>
#endif

#include "ruby/ruby.h"
#include "ruby/io.h"

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

static VALUE mReadline;

#define EDIT_LINE_LIBRARY_VERSION "EditLine wrapper"
#ifndef USE_INSERT_IGNORE_ESCAPE
# if !defined(HAVE_EDITLINE_READLINE_H) && defined(HAVE_RL_PROMPT_START_IGNORE) && defined(HAVE_RL_PROMPT_END_IGNORE)
#  define USE_INSERT_IGNORE_ESCAPE 1
# else
#  define USE_INSERT_IGNORE_ESCAPE 0
# endif
#endif

#define COMPLETION_PROC "completion_proc"
#define COMPLETION_CASE_FOLD "completion_case_fold"
static ID completion_proc, completion_case_fold;
#if USE_INSERT_IGNORE_ESCAPE
static ID id_orig_prompt, id_last_prompt;
#endif
#if defined(HAVE_RL_PRE_INPUT_HOOK)
static ID id_pre_input_hook;
#endif
#if defined(HAVE_RL_SPECIAL_PREFIXES)
static ID id_special_prefixes;
#endif

#ifndef HAVE_RL_FILENAME_COMPLETION_FUNCTION
# define rl_filename_completion_function filename_completion_function
#endif
#ifndef HAVE_RL_USERNAME_COMPLETION_FUNCTION
# define rl_username_completion_function username_completion_function
#endif
#ifndef HAVE_RL_COMPLETION_MATCHES
# define rl_completion_matches completion_matches
#endif

static int (*history_get_offset_func)(int);
static int (*history_replace_offset_func)(int);
#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
static int readline_completion_append_character;
#endif

static char **readline_attempted_completion_function(const char *text,
                                                     int start, int end);

#define OutputStringValue(str) do {\
    SafeStringValue(str);\
    (str) = rb_str_conv_enc((str), rb_enc_get(str), rb_locale_encoding());\
} while (0)\


/*
 * Document-class: Readline
 *
 * The Readline module provides interface for GNU Readline.
 * This module defines a number of methods to facilitate completion
 * and accesses input history from the Ruby interpreter.
 * This module supported Edit Line(libedit) too.
 * libedit is compatible with GNU Readline.
 *
 * GNU Readline:: http://www.gnu.org/directory/readline.html
 * libedit::      http://www.thrysoee.dk/editline/
 *
 * Reads one inputted line with line edit by Readline.readline method.
 * At this time, the facilitatation completion and the key
 * bind like Emacs can be operated like GNU Readline.
 *
 *   require "readline"
 *   while buf = Readline.readline("> ", true)
 *     p buf
 *   end
 *
 * The content that the user input can be recorded to the history.
 * The history can be accessed by Readline::HISTORY constant.
 *
 *   require "readline"
 *   while buf = Readline.readline("> ", true)
 *     p Readline::HISTORY.to_a
 *     print("-> ", buf, "\n")
 *   end
 *
 * Most of methods raise SecurityError exception if $SAFE is 4.
 *
 * Documented by TAKAO Kouji <kouji at takao7 dot net>.
 */

#if defined HAVE_RL_GETC_FUNCTION
static VALUE readline_instream;

#ifndef HAVE_RL_GETC
#define rl_getc(f) EOF
#endif

static int readline_getc(FILE *);
static int
readline_getc(FILE *input)
{
    rb_io_t *ifp = 0;
    VALUE c;
    if (!readline_instream) return rl_getc(input);
    GetOpenFile(readline_instream, ifp);
    if (rl_instream != ifp->stdio_file) return rl_getc(input);
#if defined(_WIN32)
    {
        INPUT_RECORD ir;
        int n;
        static int prior_key = '0';
        for (;;) {
            if (prior_key > 0xff) {
                prior_key = rl_getc(ifp->stdio_file);
                return prior_key;
            }
            if (PeekConsoleInput((HANDLE)_get_osfhandle(ifp->fd), &ir, 1, &n)) {
                if (n == 1) {
                    if (ir.EventType == KEY_EVENT && ir.Event.KeyEvent.bKeyDown) {
                        prior_key = rl_getc(ifp->stdio_file);
                        return prior_key;
                    } else {
                        ReadConsoleInput((HANDLE)_get_osfhandle(ifp->fd), &ir, 1, &n);
                    }
                } else {
                    HANDLE h = (HANDLE)_get_osfhandle(ifp->fd);
                    rb_w32_wait_events(&h, 1, INFINITE);
                }
            } else {
                break;
            }
        }
    }
#endif
    c = rb_io_getbyte(readline_instream);
    if (NIL_P(c)) return EOF;
#ifdef ESC
    if (c == INT2FIX(ESC) &&
	RL_ISSTATE(RL_STATE_ISEARCH) && /* isn't needed in other states? */
	rb_io_read_pending(ifp)) {
	int meta = 0;
	c = rb_io_getbyte(readline_instream);
	if (FIXNUM_P(c) && isascii(FIX2INT(c))) meta = 1;
	rb_io_ungetbyte(readline_instream, c);
	if (meta) rl_execute_next(ESC);
	return ESC;
    }
#endif
    return FIX2INT(c);
}
#elif defined HAVE_RL_EVENT_HOOK
#define BUSY_WAIT 0

static int readline_event(void);
static int
readline_event(void)
{
#if BUSY_WAIT
    rb_thread_schedule();
#else
    rb_wait_for_single_fd(fileno(rl_instream), RB_WAITFD_IN, NULL);
    return 0;
#endif
}
#endif

#if USE_INSERT_IGNORE_ESCAPE
static VALUE
insert_ignore_escape(VALUE self, VALUE prompt)
{
    VALUE last_prompt, orig_prompt = rb_attr_get(self, id_orig_prompt);
    int ignoring = 0;
    const char *s0, *s, *e;
    long len;
    static const char ignore_code[2] = {RL_PROMPT_START_IGNORE, RL_PROMPT_END_IGNORE};

    prompt = rb_str_new_shared(prompt);
    last_prompt = rb_attr_get(self, id_last_prompt);
    if (orig_prompt == prompt) return last_prompt;
    len = RSTRING_LEN(prompt);
    if (NIL_P(last_prompt)) {
	last_prompt = rb_str_tmp_new(len);
    }

    s = s0 = RSTRING_PTR(prompt);
    e = s0 + len;
    rb_str_set_len(last_prompt, 0);
    while (s < e && *s) {
	switch (*s) {
	  case RL_PROMPT_START_IGNORE:
	    ignoring = -1;
	    rb_str_cat(last_prompt, s0, ++s - s0);
	    s0 = s;
	    break;
	  case RL_PROMPT_END_IGNORE:
	    ignoring = 0;
	    rb_str_cat(last_prompt, s0, ++s - s0);
	    s0 = s;
	    break;
	  case '\033':
	    if (++s < e && *s == '[') {
		rb_str_cat(last_prompt, s0, s - s0 - 1);
		s0 = s - 1;
		while (++s < e && *s) {
		    if (ISALPHA(*s)) {
			if (!ignoring) {
			    ignoring = 1;
			    rb_str_cat(last_prompt, ignore_code+0, 1);
			}
			rb_str_cat(last_prompt, s0, ++s - s0);
			s0 = s;
			break;
		    }
		    else if (!('0' <= *s && *s <= '9' || *s == ';')) {
			break;
		    }
		}
	    }
	    break;
	  default:
	    if (ignoring > 0) {
		ignoring = 0;
		rb_str_cat(last_prompt, ignore_code+1, 1);
	    }
	    s++;
	    break;
	}
    }
    if (ignoring > 0) {
	ignoring = 0;
	rb_str_cat(last_prompt, ignore_code+1, 1);
    }
    rb_str_cat(last_prompt, s0, s - s0);

    rb_ivar_set(self, id_orig_prompt, prompt);
    rb_ivar_set(self, id_last_prompt, last_prompt);

    return last_prompt;
}
#endif

static VALUE
readline_get(VALUE prompt)
{
#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
    readline_completion_append_character = rl_completion_append_character;
#endif
    return (VALUE)readline((char *)prompt);
}

/*
 * call-seq:
 *   Readline.readline(prompt = "", add_hist = false) -> string or nil
 *
 * Shows the +prompt+ and reads the inputted line with line editing.
 * The inputted line is added to the history if +add_hist+ is true.
 *
 * Returns nil when the inputted line is empty and user inputs EOF
 * (Presses ^D on UNIX).
 *
 * Raises IOError exception if below conditions are satisfied.
 * 1. stdin is not tty.
 * 2. stdin was closed. (errno is EBADF after called isatty(2).)
 *
 * This method supports thread. Switchs the thread context when waits
 * inputting line.
 *
 * Supports line edit when inputs line. Provides VI and Emacs editing mode.
 * Default is Emacs editing mode.
 *
 * NOTE: Terminates ruby interpreter and does not return the terminal
 * status after user pressed '^C' when wait inputting line.
 * Give 3 examples that avoid it.
 *
 * * Catches the Interrupt exception by pressed ^C after returns
 *   terminal status:
 *
 *     require "readline"
 *
 *     stty_save = `stty -g`.chomp
 *     begin
 *       while buf = Readline.readline
 *           p buf
 *           end
 *         rescue Interrupt
 *           system("stty", stty_save)
 *           exit
 *         end
 *       end
 *     end
 *
 * * Catches the INT signal by pressed ^C after returns terminal
 *   status:
 *
 *     require "readline"
 *
 *     stty_save = `stty -g`.chomp
 *     trap("INT") { system "stty", stty_save; exit }
 *
 *     while buf = Readline.readline
 *       p buf
 *     end
 *
 * * Ignores pressing ^C:
 *
 *     require "readline"
 *
 *     trap("INT", "SIG_IGN")
 *
 *     while buf = Readline.readline
 *       p buf
 *     end
 *
 * Can make as follows with Readline::HISTORY constant.
 * It does not record to the history if the inputted line is empty or
 * the same it as last one.
 *
 *   require "readline"
 *
 *   while buf = Readline.readline("> ", true)
 *     # p Readline::HISTORY.to_a
 *     Readline::HISTORY.pop if /^\s*$/ =~ buf
 *
 *     begin
 *       if Readline::HISTORY[Readline::HISTORY.length-2] == buf
 *         Readline::HISTORY.pop
 *       end
 *     rescue IndexError
 *     end
 *
 *     # p Readline::HISTORY.to_a
 *     print "-> ", buf, "\n"
 *   end
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_readline(int argc, VALUE *argv, VALUE self)
{
    VALUE tmp, add_hist, result;
    char *prompt = NULL;
    char *buff;
    int status;

    rb_secure(4);
    if (rb_scan_args(argc, argv, "02", &tmp, &add_hist) > 0) {
	OutputStringValue(tmp);
#if USE_INSERT_IGNORE_ESCAPE
	tmp = insert_ignore_escape(self, tmp);
	rb_str_locktmp(tmp);
#endif
	prompt = RSTRING_PTR(tmp);
    }

    if (!isatty(fileno(rl_instream)) && errno == EBADF) rb_raise(rb_eIOError, "closed stdin");
    if (rl_outstream) {
	struct stat stbuf;
	int fd = fileno(rl_outstream);
	if (fd < 0 || fstat(fd, &stbuf) != 0) {
	    rb_raise(rb_eIOError, "closed stdout");
	}
    }

#ifdef _WIN32
    rl_prep_terminal(1);
#endif
    buff = (char*)rb_protect(readline_get, (VALUE)prompt, &status);
#if USE_INSERT_IGNORE_ESCAPE
    if (prompt) {
	rb_str_unlocktmp(tmp);
    }
#endif
    if (status) {
#if defined HAVE_RL_CLEANUP_AFTER_SIGNAL
        /* restore terminal mode and signal handler*/
#if defined HAVE_RL_FREE_LINE_STATE
        rl_free_line_state();
#endif
        rl_cleanup_after_signal();
#elif defined HAVE_RL_DEPREP_TERM_FUNCTION
        /* restore terminal mode */
	if (rl_deprep_term_function != NULL) /* NULL in libedit. [ruby-dev:29116] */
	    (*rl_deprep_term_function)();
	else
#else
        rl_deprep_terminal();
#endif
        rb_jump_tag(status);
    }

    if (RTEST(add_hist) && buff) {
	add_history(buff);
    }
    if (buff) {
	result = rb_locale_str_new_cstr(buff);
    }
    else
	result = Qnil;
    if (buff) free(buff);
    return result;
}

/*
 * call-seq:
 *   Readline.input = input
 *
 * Specifies a File object +input+ that is input stream for
 * Readline.readline method.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_input(VALUE self, VALUE input)
{
    rb_io_t *ifp;

    rb_secure(4);
    Check_Type(input, T_FILE);
    GetOpenFile(input, ifp);
    rl_instream = rb_io_stdio_file(ifp);
#ifdef HAVE_RL_GETC_FUNCTION
    readline_instream = input;
#endif
    return input;
}

/*
 * call-seq:
 *   Readline.output = output
 *
 * Specifies a File object +output+ that is output stream for
 * Readline.readline method.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_output(VALUE self, VALUE output)
{
    rb_io_t *ofp;

    rb_secure(4);
    Check_Type(output, T_FILE);
    GetOpenFile(output, ofp);
    rl_outstream = rb_io_stdio_file(ofp);
    return output;
}

#if defined(HAVE_RL_PRE_INPUT_HOOK)
/*
 * call-seq:
 *   Readline.pre_input_hook = proc
 *
 * Specifies a Proc object +proc+ to call after the first prompt has
 * been printed and just before readline starts reading input
 * characters.
 *
 * See GNU Readline's rl_pre_input_hook variable.
 *
 * Raises ArgumentError if +proc+ does not respond to the call method.
 *
 * Raises SecurityError if $SAFE is 4.
 */
static VALUE
readline_s_set_pre_input_hook(VALUE self, VALUE proc)
{
    rb_secure(4);
    if (!NIL_P(proc) && !rb_respond_to(proc, rb_intern("call")))
	rb_raise(rb_eArgError, "argument must respond to `call'");
    return rb_ivar_set(mReadline, id_pre_input_hook, proc);
}

/*
 * call-seq:
 *   Readline.pre_input_hook -> proc
 *
 * Returns a Proc object +proc+ to call after the first prompt has
 * been printed and just before readline starts reading input
 * characters. The default is nil.
 *
 * Raises SecurityError if $SAFE is 4.
 */
static VALUE
readline_s_get_pre_input_hook(VALUE self)
{
    rb_secure(4);
    return rb_attr_get(mReadline, id_pre_input_hook);
}

static int
readline_pre_input_hook(void)
{
    VALUE proc;

    proc = rb_attr_get(mReadline, id_pre_input_hook);
    if (!NIL_P(proc))
	rb_funcall(proc, rb_intern("call"), 0);
    return 0;
}
#else
#define readline_s_set_pre_input_hook rb_f_notimplement
#define readline_s_get_pre_input_hook rb_f_notimplement
#endif

#if defined(HAVE_RL_INSERT_TEXT)
/*
 * call-seq:
 *   Readline.insert_text(string) -> self
 *
 * Insert text into the line at the current cursor position.
 *
 * See GNU Readline's rl_insert_text function.
 *
 * Raises SecurityError if $SAFE is 4.
 */
static VALUE
readline_s_insert_text(VALUE self, VALUE str)
{
    rb_secure(4);
    OutputStringValue(str);
    rl_insert_text(RSTRING_PTR(str));
    return self;
}
#else
#define readline_s_insert_text rb_f_notimplement
#endif

#if defined(HAVE_RL_REDISPLAY)
/*
 * call-seq:
 *   Readline.redisplay -> self
 *
 * Change what's displayed on the screen to reflect the current
 * contents.
 *
 * See GNU Readline's rl_redisplay function.
 *
 * Raises SecurityError if $SAFE is 4.
 */
static VALUE
readline_s_redisplay(VALUE self)
{
    rb_secure(4);
    rl_redisplay();
    return self;
}
#else
#define readline_s_redisplay rb_f_notimplement
#endif

/*
 * call-seq:
 *   Readline.completion_proc = proc
 *
 * Specifies a Proc object +proc+ to determine completion behavior.  It
 * should take input string and return an array of completion candidates.
 *
 * The default completion is used if +proc+ is nil.
 *
 * The String that is passed to the Proc depends on the
 * Readline.completer_word_break_characters property.  By default the word
 * under the cursor is passed to the Proc.  For example, if the input is "foo
 * bar" then only "bar" would be passed to the completion Proc.
 *
 * Upon successful completion the Readline.completion_append_character will be
 * appended to the input so the user can start working on their next argument.
 *
 * = Examples
 *
 * == Completion for a Static List
 *
 *   require 'readline'
 *
 *   LIST = [
 *     'search', 'download', 'open',
 *     'help', 'history', 'quit',
 *     'url', 'next', 'clear',
 *     'prev', 'past'
 *   ].sort
 *
 *   comp = proc { |s| LIST.grep(/^#{Regexp.escape(s)}/) }
 *
 *   Readline.completion_append_character = " "
 *   Readline.completion_proc = comp
 *
 *   while line = Readline.readline('> ', true)
 *     p line
 *   end
 *
 * == Completion For Directory Contents
 *
 *   require 'readline'
 *
 *   Readline.completion_append_character = " "
 *   Readline.completion_proc = Proc.new do |str|
 *     Dir[str+'*'].grep(/^#{Regexp.escape(str)}/)
 *   end
 *
 *   while line = Readline.readline('> ', true)
 *     p line
 *   end
 *
 * = Autocomplete strategies
 *
 * When working with auto-complete there are some strategies that work well.
 * To get some ideas you can take a look at the
 * completion.rb[http://svn.ruby-lang.org/repos/ruby/trunk/lib/irb/completion.rb]
 * file for irb.
 *
 * The common strategy is to take a list of possible completions and filter it
 * down to those completions that start with the user input.  In the above
 * examples Enumerator.grep is used.  The input is escaped to prevent Regexp
 * special characters from interfering with the matching.
 *
 * It may also be helpful to use the Abbrev library to generate completions.
 *
 * Raises ArgumentError if +proc+ does not respond to the call method.
 *
 * Raises SecurityError if $SAFE is 4.
 */
static VALUE
readline_s_set_completion_proc(VALUE self, VALUE proc)
{
    rb_secure(4);
    if (!NIL_P(proc) && !rb_respond_to(proc, rb_intern("call")))
	rb_raise(rb_eArgError, "argument must respond to `call'");
    return rb_ivar_set(mReadline, completion_proc, proc);
}

/*
 * call-seq:
 *   Readline.completion_proc -> proc
 *
 * Returns the completion Proc object.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_completion_proc(VALUE self)
{
    rb_secure(4);
    return rb_attr_get(mReadline, completion_proc);
}

/*
 * call-seq:
 *   Readline.completion_case_fold = bool
 *
 * Sets whether or not to ignore case on completion.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_completion_case_fold(VALUE self, VALUE val)
{
    rb_secure(4);
    return rb_ivar_set(mReadline, completion_case_fold, val);
}

/*
 * call-seq:
 *   Readline.completion_case_fold -> bool
 *
 * Returns true if completion ignores case. If no, returns false.
 *
 * NOTE: Returns the same object that is specified by
 * Readline.completion_case_fold= method.
 *
 *   require "readline"
 *
 *   Readline.completion_case_fold = "This is a String."
 *   p Readline.completion_case_fold # => "This is a String."
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_completion_case_fold(VALUE self)
{
    rb_secure(4);
    return rb_attr_get(mReadline, completion_case_fold);
}

#ifdef HAVE_RL_LINE_BUFFER
/*
 * call-seq:
 *   Readline.line_buffer -> string
 *
 * Returns the full line that is being edited. This is useful from
 * within the complete_proc for determining the context of the
 * completion request.
 *
 * The length of +Readline.line_buffer+ and GNU Readline's rl_end are
 * same.
 */
static VALUE
readline_s_get_line_buffer(VALUE self)
{
    rb_secure(4);
    if (rl_line_buffer == NULL)
	return Qnil;
    return rb_locale_str_new_cstr(rl_line_buffer);
}
#else
#define readline_s_get_line_buffer rb_f_notimplement
#endif

#ifdef HAVE_RL_POINT
/*
 * call-seq:
 *   Readline.point -> int
 *
 * Returns the index of the current cursor position in
 * +Readline.line_buffer+.
 *
 * The index in +Readline.line_buffer+ which matches the start of
 * input-string passed to completion_proc is computed by subtracting
 * the length of input-string from +Readline.point+.
 *
 *   start = (the length of input-string) - Readline.point
 */
static VALUE
readline_s_get_point(VALUE self)
{
    rb_secure(4);
    return INT2NUM(rl_point);
}
#else
#define readline_s_get_point rb_f_notimplement
#endif

static char **
readline_attempted_completion_function(const char *text, int start, int end)
{
    VALUE proc, ary, temp;
    char **result;
    int case_fold;
    long i, matches;
    rb_encoding *enc;
    VALUE encobj;

    proc = rb_attr_get(mReadline, completion_proc);
    if (NIL_P(proc))
	return NULL;
#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
    rl_completion_append_character = readline_completion_append_character;
#endif
#ifdef HAVE_RL_ATTEMPTED_COMPLETION_OVER
    rl_attempted_completion_over = 1;
#endif
    case_fold = RTEST(rb_attr_get(mReadline, completion_case_fold));
    ary = rb_funcall(proc, rb_intern("call"), 1, rb_locale_str_new_cstr(text));
    if (!RB_TYPE_P(ary, T_ARRAY))
	ary = rb_Array(ary);
    matches = RARRAY_LEN(ary);
    if (matches == 0) return NULL;
    result = (char**)malloc((matches + 2)*sizeof(char*));
    if (result == NULL) rb_memerror();
    enc = rb_locale_encoding();
    encobj = rb_enc_from_encoding(enc);
    for (i = 0; i < matches; i++) {
	temp = rb_obj_as_string(RARRAY_PTR(ary)[i]);
	StringValueCStr(temp);	/* must be NUL-terminated */
	rb_enc_check(encobj, temp);
	result[i + 1] = (char*)malloc(RSTRING_LEN(temp) + 1);
	if (result[i + 1]  == NULL) rb_memerror();
	strcpy(result[i + 1], RSTRING_PTR(temp));
    }
    result[matches + 1] = NULL;

    if (matches == 1) {
        result[0] = strdup(result[1]);
    }
    else {
	const char *result1 = result[1];
	long low = strlen(result1);

	for (i = 1; i < matches; ++i) {
	    register int c1, c2;
	    long i1, i2, l2;
	    int n1, n2;
	    const char *p2 = result[i + 1];

	    l2 = strlen(p2);
	    for (i1 = i2 = 0; i1 < low && i2 < l2; i1 += n1, i2 += n2) {
		c1 = rb_enc_codepoint_len(result1 + i1, result1 + low, &n1, enc);
		c2 = rb_enc_codepoint_len(p2 + i2, p2 + l2, &n2, enc);
		if (case_fold) {
		    c1 = rb_tolower(c1);
		    c2 = rb_tolower(c2);
		}
		if (c1 != c2) break;
	    }

	    low = i1;
	}
	result[0] = (char*)malloc(low + 1);
	if (result[0]  == NULL) rb_memerror();
	strncpy(result[0], result[1], low);
	result[0][low] = '\0';
    }

    return result;
}

#ifdef HAVE_RL_SET_SCREEN_SIZE
/*
 * call-seq:
 *   Readline.set_screen_size(rows, columns) -> self
 *
 * Set terminal size to +rows+ and +columns+.
 *
 * See GNU Readline's rl_set_screen_size function.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_screen_size(VALUE self, VALUE rows, VALUE columns)
{
    rb_secure(4);
    rl_set_screen_size(NUM2INT(rows), NUM2INT(columns));
    return self;
}
#else
#define readline_s_set_screen_size rb_f_notimplement
#endif

#ifdef HAVE_RL_GET_SCREEN_SIZE
/*
 * call-seq:
 *   Readline.get_screen_size -> [rows, columns]
 *
 * Returns the terminal's rows and columns.
 *
 * See GNU Readline's rl_get_screen_size function.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_screen_size(VALUE self)
{
    int rows, columns;
    VALUE res;

    rb_secure(4);
    rl_get_screen_size(&rows, &columns);
    res = rb_ary_new();
    rb_ary_push(res, INT2NUM(rows));
    rb_ary_push(res, INT2NUM(columns));
    return res;
}
#else
#define readline_s_get_screen_size rb_f_notimplement
#endif

#ifdef HAVE_RL_VI_EDITING_MODE
/*
 * call-seq:
 *   Readline.vi_editing_mode -> nil
 *
 * Specifies VI editing mode. See the manual of GNU Readline for
 * details of VI editing mode.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_vi_editing_mode(VALUE self)
{
    rb_secure(4);
    rl_vi_editing_mode(1,0);
    return Qnil;
}
#else
#define readline_s_vi_editing_mode rb_f_notimplement
#endif

#ifdef HAVE_RL_EDITING_MODE
/*
 * call-seq:
 *   Readline.vi_editing_mode? -> bool
 *
 * Returns true if vi mode is active. Returns false if not.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_vi_editing_mode_p(VALUE self)
{
    rb_secure(4);
    return rl_editing_mode == 0 ? Qtrue : Qfalse;
}
#else
#define readline_s_vi_editing_mode_p rb_f_notimplement
#endif

#ifdef HAVE_RL_EMACS_EDITING_MODE
/*
 * call-seq:
 *   Readline.emacs_editing_mode -> nil
 *
 * Specifies Emacs editing mode. The default is this mode. See the
 * manual of GNU Readline for details of Emacs editing mode.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_emacs_editing_mode(VALUE self)
{
    rb_secure(4);
    rl_emacs_editing_mode(1,0);
    return Qnil;
}
#else
#define readline_s_emacs_editing_mode rb_f_notimplement
#endif

#ifdef  HAVE_RL_EDITING_MODE
/*
 * call-seq:
 *   Readline.emacs_editing_mode? -> bool
 *
 * Returns true if emacs mode is active. Returns false if not.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_emacs_editing_mode_p(VALUE self)
{
    rb_secure(4);
    return rl_editing_mode == 1 ? Qtrue : Qfalse;
}
#else
#define readline_s_emacs_editing_mode_p rb_f_notimplement
#endif

#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
/*
 * call-seq:
 *   Readline.completion_append_character = char
 *
 * Specifies a character to be appended on completion.
 * Nothing will be appended if an empty string ("") or nil is
 * specified.
 *
 * For example:
 *   require "readline"
 *
 *   Readline.readline("> ", true)
 *   Readline.completion_append_character = " "
 *
 * Result:
 *   >
 *   Input "/var/li".
 *
 *   > /var/li
 *   Press TAB key.
 *
 *   > /var/lib
 *   Completes "b" and appends " ". So, you can continuously input "/usr".
 *
 *   > /var/lib /usr
 *
 * NOTE: Only one character can be specified. When "string" is
 * specified, sets only "s" that is the first.
 *
 *   require "readline"
 *
 *   Readline.completion_append_character = "string"
 *   p Readline.completion_append_character # => "s"
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_completion_append_character(VALUE self, VALUE str)
{
    rb_secure(4);
    if (NIL_P(str)) {
	rl_completion_append_character = '\0';
    }
    else {
	OutputStringValue(str);
	if (RSTRING_LEN(str) == 0) {
	    rl_completion_append_character = '\0';
	} else {
	    rl_completion_append_character = RSTRING_PTR(str)[0];
	}
    }
    return self;
}
#else
#define readline_s_set_completion_append_character rb_f_notimplement
#endif

#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
/*
 * call-seq:
 *   Readline.completion_append_character -> char
 *
 * Returns a string containing a character to be appended on
 * completion. The default is a space (" ").
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_completion_append_character(VALUE self)
{
    char buf[1];

    rb_secure(4);
    if (rl_completion_append_character == '\0')
	return Qnil;

    buf[0] = (char) rl_completion_append_character;
    return rb_locale_str_new(buf, 1);
}
#else
#define readline_s_get_completion_append_character rb_f_notimplement
#endif

#ifdef HAVE_RL_BASIC_WORD_BREAK_CHARACTERS
/*
 * call-seq:
 *   Readline.basic_word_break_characters = string
 *
 * Sets the basic list of characters that signal a break between words
 * for the completer routine. The default is the characters which
 * break words for completion in Bash: " \t\n\"\\'`@$><=;|&{(".
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_basic_word_break_characters(VALUE self, VALUE str)
{
    static char *basic_word_break_characters = NULL;

    rb_secure(4);
    OutputStringValue(str);
    if (basic_word_break_characters == NULL) {
	basic_word_break_characters =
	    ALLOC_N(char, RSTRING_LEN(str) + 1);
    }
    else {
	REALLOC_N(basic_word_break_characters, char, RSTRING_LEN(str) + 1);
    }
    strncpy(basic_word_break_characters,
	    RSTRING_PTR(str), RSTRING_LEN(str));
    basic_word_break_characters[RSTRING_LEN(str)] = '\0';
    rl_basic_word_break_characters = basic_word_break_characters;
    return self;
}
#else
#define readline_s_set_basic_word_break_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_BASIC_WORD_BREAK_CHARACTERS
/*
 * call-seq:
 *   Readline.basic_word_break_characters -> string
 *
 * Gets the basic list of characters that signal a break between words
 * for the completer routine.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_basic_word_break_characters(VALUE self, VALUE str)
{
    rb_secure(4);
    if (rl_basic_word_break_characters == NULL)
	return Qnil;
    return rb_locale_str_new_cstr(rl_basic_word_break_characters);
}
#else
#define readline_s_get_basic_word_break_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_COMPLETER_WORD_BREAK_CHARACTERS
/*
 * call-seq:
 *   Readline.completer_word_break_characters = string
 *
 * Sets the basic list of characters that signal a break between words
 * for rl_complete_internal(). The default is the value of
 * Readline.basic_word_break_characters.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_completer_word_break_characters(VALUE self, VALUE str)
{
    static char *completer_word_break_characters = NULL;

    rb_secure(4);
    OutputStringValue(str);
    if (completer_word_break_characters == NULL) {
	completer_word_break_characters =
	    ALLOC_N(char, RSTRING_LEN(str) + 1);
    }
    else {
	REALLOC_N(completer_word_break_characters, char, RSTRING_LEN(str) + 1);
    }
    strncpy(completer_word_break_characters,
	    RSTRING_PTR(str), RSTRING_LEN(str));
    completer_word_break_characters[RSTRING_LEN(str)] = '\0';
    rl_completer_word_break_characters = completer_word_break_characters;
    return self;
}
#else
#define readline_s_set_completer_word_break_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_COMPLETER_WORD_BREAK_CHARACTERS
/*
 * call-seq:
 *   Readline.completer_word_break_characters -> string
 *
 * Gets the basic list of characters that signal a break between words
 * for rl_complete_internal().
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_completer_word_break_characters(VALUE self, VALUE str)
{
    rb_secure(4);
    if (rl_completer_word_break_characters == NULL)
	return Qnil;
    return rb_locale_str_new_cstr(rl_completer_word_break_characters);
}
#else
#define readline_s_get_completer_word_break_characters rb_f_notimplement
#endif

#if defined(HAVE_RL_SPECIAL_PREFIXES)
/*
 * call-seq:
 *   Readline.special_prefixes = string
 *
 * Sets the list of characters that are word break characters, but
 * should be left in text when it is passed to the completion
 * function. Programs can use this to help determine what kind of
 * completing to do. For instance, Bash sets this variable to "$@" so
 * that it can complete shell variables and hostnames.
 *
 * See GNU Readline's rl_special_prefixes variable.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_special_prefixes(VALUE self, VALUE str)
{
    rb_secure(4);
    if (!NIL_P(str)) {
	OutputStringValue(str);
	str = rb_str_dup_frozen(str);
	RBASIC(str)->klass = 0;
    }
    rb_ivar_set(mReadline, id_special_prefixes, str);
    if (NIL_P(str)) {
	rl_special_prefixes = NULL;
    }
    else {
	rl_special_prefixes = RSTRING_PTR(str);
    }
    return self;
}

/*
 * call-seq:
 *   Readline.special_prefixes -> string
 *
 * Gets the list of characters that are word break characters, but
 * should be left in text when it is passed to the completion
 * function.
 *
 * See GNU Readline's rl_special_prefixes variable.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_special_prefixes(VALUE self)
{
    VALUE str;
    rb_secure(4);
    if (rl_special_prefixes == NULL) return Qnil;
    str = rb_ivar_get(mReadline, id_special_prefixes);
    if (!NIL_P(str)) {
	str = rb_str_dup_frozen(str);
	RBASIC(str)->klass = rb_cString;
    }
    return str;
}
#else
#define readline_s_set_special_prefixes rb_f_notimplement
#define readline_s_get_special_prefixes rb_f_notimplement
#endif

#ifdef HAVE_RL_BASIC_QUOTE_CHARACTERS
/*
 * call-seq:
 *   Readline.basic_quote_characters = string
 *
 * Sets a list of quote characters which can cause a word break.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_basic_quote_characters(VALUE self, VALUE str)
{
    static char *basic_quote_characters = NULL;

    rb_secure(4);
    OutputStringValue(str);
    if (basic_quote_characters == NULL) {
	basic_quote_characters =
	    ALLOC_N(char, RSTRING_LEN(str) + 1);
    }
    else {
	REALLOC_N(basic_quote_characters, char, RSTRING_LEN(str) + 1);
    }
    strncpy(basic_quote_characters,
	    RSTRING_PTR(str), RSTRING_LEN(str));
    basic_quote_characters[RSTRING_LEN(str)] = '\0';
    rl_basic_quote_characters = basic_quote_characters;

    return self;
}
#else
#define readline_s_set_basic_quote_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_BASIC_QUOTE_CHARACTERS
/*
 * call-seq:
 *   Readline.basic_quote_characters -> string
 *
 * Gets a list of quote characters which can cause a word break.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_basic_quote_characters(VALUE self, VALUE str)
{
    rb_secure(4);
    if (rl_basic_quote_characters == NULL)
	return Qnil;
    return rb_locale_str_new_cstr(rl_basic_quote_characters);
}
#else
#define readline_s_get_basic_quote_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_COMPLETER_QUOTE_CHARACTERS
/*
 * call-seq:
 *   Readline.completer_quote_characters = string
 *
 * Sets a list of characters which can be used to quote a substring of
 * the line. Completion occurs on the entire substring, and within
 * the substring Readline.completer_word_break_characters are treated
 * as any other character, unless they also appear within this list.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_completer_quote_characters(VALUE self, VALUE str)
{
    static char *completer_quote_characters = NULL;

    rb_secure(4);
    OutputStringValue(str);
    if (completer_quote_characters == NULL) {
	completer_quote_characters =
	    ALLOC_N(char, RSTRING_LEN(str) + 1);
    }
    else {
	REALLOC_N(completer_quote_characters, char, RSTRING_LEN(str) + 1);
    }
    strncpy(completer_quote_characters, RSTRING_PTR(str), RSTRING_LEN(str));
    completer_quote_characters[RSTRING_LEN(str)] = '\0';
    rl_completer_quote_characters = completer_quote_characters;

    return self;
}
#else
#define readline_s_set_completer_quote_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_COMPLETER_QUOTE_CHARACTERS
/*
 * call-seq:
 *   Readline.completer_quote_characters -> string
 *
 * Gets a list of characters which can be used to quote a substring of
 * the line.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_completer_quote_characters(VALUE self, VALUE str)
{
    rb_secure(4);
    if (rl_completer_quote_characters == NULL)
	return Qnil;
    return rb_locale_str_new_cstr(rl_completer_quote_characters);
}
#else
#define readline_s_get_completer_quote_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_FILENAME_QUOTE_CHARACTERS
/*
 * call-seq:
 *   Readline.filename_quote_characters = string
 *
 * Sets a list of characters that cause a filename to be quoted by the completer
 * when they appear in a completed filename. The default is nil.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_set_filename_quote_characters(VALUE self, VALUE str)
{
    static char *filename_quote_characters = NULL;

    rb_secure(4);
    OutputStringValue(str);
    if (filename_quote_characters == NULL) {
	filename_quote_characters =
	    ALLOC_N(char, RSTRING_LEN(str) + 1);
    }
    else {
	REALLOC_N(filename_quote_characters, char, RSTRING_LEN(str) + 1);
    }
    strncpy(filename_quote_characters, RSTRING_PTR(str), RSTRING_LEN(str));
    filename_quote_characters[RSTRING_LEN(str)] = '\0';
    rl_filename_quote_characters = filename_quote_characters;

    return self;
}
#else
#define readline_s_set_filename_quote_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_FILENAME_QUOTE_CHARACTERS
/*
 * call-seq:
 *   Readline.filename_quote_characters -> string
 *
 * Gets a list of characters that cause a filename to be quoted by the completer
 * when they appear in a completed filename.
 *
 * Raises NotImplementedError if the using readline library does not support.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_get_filename_quote_characters(VALUE self, VALUE str)
{
    rb_secure(4);
    if (rl_filename_quote_characters == NULL)
	return Qnil;
    return rb_locale_str_new_cstr(rl_filename_quote_characters);
}
#else
#define readline_s_get_filename_quote_characters rb_f_notimplement
#endif

#ifdef HAVE_RL_REFRESH_LINE
/*
 * call-seq:
 *   Readline.refresh_line -> nil
 *
 * Clear the current input line.
 *
 * Raises SecurityError exception if $SAFE is 4.
 */
static VALUE
readline_s_refresh_line(VALUE self)
{
    rb_secure(4);
    rl_refresh_line(0, 0);
    return Qnil;
}
#else
#define readline_s_refresh_line rb_f_notimplement
#endif

static VALUE
hist_to_s(VALUE self)
{
    return rb_str_new_cstr("HISTORY");
}

static int
history_get_offset_history_base(int offset)
{
    return history_base + offset;
}

static int
history_get_offset_0(int offset)
{
    return offset;
}

static VALUE
hist_get(VALUE self, VALUE index)
{
    HIST_ENTRY *entry = NULL;
    int i;

    rb_secure(4);
    i = NUM2INT(index);
    if (i < 0) {
        i += history_length;
    }
    if (i >= 0) {
	entry = history_get(history_get_offset_func(i));
    }
    if (entry == NULL) {
	rb_raise(rb_eIndexError, "invalid index");
    }
    return rb_locale_str_new_cstr(entry->line);
}

#ifdef HAVE_REPLACE_HISTORY_ENTRY
static VALUE
hist_set(VALUE self, VALUE index, VALUE str)
{
    HIST_ENTRY *entry = NULL;
    int i;

    rb_secure(4);
    i = NUM2INT(index);
    OutputStringValue(str);
    if (i < 0) {
        i += history_length;
    }
    if (i >= 0) {
	entry = replace_history_entry(history_replace_offset_func(i), RSTRING_PTR(str), NULL);
    }
    if (entry == NULL) {
	rb_raise(rb_eIndexError, "invalid index");
    }
    return str;
}
#else
#define hist_set rb_f_notimplement
#endif

static VALUE
hist_push(VALUE self, VALUE str)
{
    rb_secure(4);
    OutputStringValue(str);
    add_history(RSTRING_PTR(str));
    return self;
}

static VALUE
hist_push_method(int argc, VALUE *argv, VALUE self)
{
    VALUE str;

    rb_secure(4);
    while (argc--) {
	str = *argv++;
	OutputStringValue(str);
	add_history(RSTRING_PTR(str));
    }
    return self;
}

static VALUE
rb_remove_history(int index)
{
#ifdef HAVE_REMOVE_HISTORY
    HIST_ENTRY *entry;
    VALUE val;

    rb_secure(4);
    entry = remove_history(index);
    if (entry) {
        val = rb_locale_str_new_cstr(entry->line);
        free((void *) entry->line);
        free(entry);
        return val;
    }
    return Qnil;
#else
    rb_notimplement();

    UNREACHABLE;
#endif
}

static VALUE
hist_pop(VALUE self)
{
    rb_secure(4);
    if (history_length > 0) {
	return rb_remove_history(history_length - 1);
    } else {
	return Qnil;
    }
}

static VALUE
hist_shift(VALUE self)
{
    rb_secure(4);
    if (history_length > 0) {
	return rb_remove_history(0);
    } else {
	return Qnil;
    }
}

static VALUE
hist_each(VALUE self)
{
    HIST_ENTRY *entry;
    int i;

    RETURN_ENUMERATOR(self, 0, 0);

    rb_secure(4);
    for (i = 0; i < history_length; i++) {
        entry = history_get(history_get_offset_func(i));
        if (entry == NULL)
            break;
	rb_yield(rb_locale_str_new_cstr(entry->line));
    }
    return self;
}

static VALUE
hist_length(VALUE self)
{
    rb_secure(4);
    return INT2NUM(history_length);
}

static VALUE
hist_empty_p(VALUE self)
{
    rb_secure(4);
    return history_length == 0 ? Qtrue : Qfalse;
}

static VALUE
hist_delete_at(VALUE self, VALUE index)
{
    int i;

    rb_secure(4);
    i = NUM2INT(index);
    if (i < 0)
        i += history_length;
    if (i < 0 || i > history_length - 1) {
	rb_raise(rb_eIndexError, "invalid index");
    }
    return rb_remove_history(i);
}

#ifdef HAVE_CLEAR_HISTORY
static VALUE
hist_clear(VALUE self)
{
    rb_secure(4);
    clear_history();
    return self;
}
#else
#define hist_clear rb_f_notimplement
#endif

static VALUE
filename_completion_proc_call(VALUE self, VALUE str)
{
    VALUE result;
    char **matches;
    int i;

    matches = rl_completion_matches(StringValuePtr(str),
				    rl_filename_completion_function);
    if (matches) {
	result = rb_ary_new();
	for (i = 0; matches[i]; i++) {
	    rb_ary_push(result, rb_locale_str_new_cstr(matches[i]));
	    free(matches[i]);
	}
	free(matches);
	if (RARRAY_LEN(result) >= 2)
	    rb_ary_shift(result);
    }
    else {
	result = Qnil;
    }
    return result;
}

static VALUE
username_completion_proc_call(VALUE self, VALUE str)
{
    VALUE result;
    char **matches;
    int i;

    matches = rl_completion_matches(StringValuePtr(str),
				    rl_username_completion_function);
    if (matches) {
	result = rb_ary_new();
	for (i = 0; matches[i]; i++) {
	    rb_ary_push(result, rb_locale_str_new_cstr(matches[i]));
	    free(matches[i]);
	}
	free(matches);
	if (RARRAY_LEN(result) >= 2)
	    rb_ary_shift(result);
    }
    else {
	result = Qnil;
    }
    return result;
}

void
Init_readline()
{
    VALUE history, fcomp, ucomp, version;

    /* Allow conditional parsing of the ~/.inputrc file. */
    rl_readline_name = (char *)"Ruby";

#if defined HAVE_RL_GETC_FUNCTION
    /* libedit check rl_getc_function only when rl_initialize() is called, */
    /* and using_history() call rl_initialize(). */
    /* This assignment should be placed before using_history() */
    rl_getc_function = readline_getc;
#elif defined HAVE_RL_EVENT_HOOK
    rl_event_hook = readline_event;
#endif

    using_history();

    completion_proc = rb_intern(COMPLETION_PROC);
    completion_case_fold = rb_intern(COMPLETION_CASE_FOLD);
#if defined(HAVE_RL_PRE_INPUT_HOOK)
    id_pre_input_hook = rb_intern("pre_input_hook");
#endif
#if defined(HAVE_RL_SPECIAL_PREFIXES)
    id_special_prefixes = rb_intern("special_prefixes");
#endif

    mReadline = rb_define_module("Readline");
    rb_define_module_function(mReadline, "readline",
			      readline_readline, -1);
    rb_define_singleton_method(mReadline, "input=",
			       readline_s_set_input, 1);
    rb_define_singleton_method(mReadline, "output=",
			       readline_s_set_output, 1);
    rb_define_singleton_method(mReadline, "completion_proc=",
			       readline_s_set_completion_proc, 1);
    rb_define_singleton_method(mReadline, "completion_proc",
			       readline_s_get_completion_proc, 0);
    rb_define_singleton_method(mReadline, "completion_case_fold=",
			       readline_s_set_completion_case_fold, 1);
    rb_define_singleton_method(mReadline, "completion_case_fold",
			       readline_s_get_completion_case_fold, 0);
    rb_define_singleton_method(mReadline, "line_buffer",
			       readline_s_get_line_buffer, 0);
    rb_define_singleton_method(mReadline, "point",
			       readline_s_get_point, 0);
    rb_define_singleton_method(mReadline, "set_screen_size",
			       readline_s_set_screen_size, 2);
    rb_define_singleton_method(mReadline, "get_screen_size",
			       readline_s_get_screen_size, 0);
    rb_define_singleton_method(mReadline, "vi_editing_mode",
			       readline_s_vi_editing_mode, 0);
    rb_define_singleton_method(mReadline, "vi_editing_mode?",
			       readline_s_vi_editing_mode_p, 0);
    rb_define_singleton_method(mReadline, "emacs_editing_mode",
			       readline_s_emacs_editing_mode, 0);
    rb_define_singleton_method(mReadline, "emacs_editing_mode?",
			       readline_s_emacs_editing_mode_p, 0);
    rb_define_singleton_method(mReadline, "completion_append_character=",
			       readline_s_set_completion_append_character, 1);
    rb_define_singleton_method(mReadline, "completion_append_character",
			       readline_s_get_completion_append_character, 0);
    rb_define_singleton_method(mReadline, "basic_word_break_characters=",
			       readline_s_set_basic_word_break_characters, 1);
    rb_define_singleton_method(mReadline, "basic_word_break_characters",
			       readline_s_get_basic_word_break_characters, 0);
    rb_define_singleton_method(mReadline, "completer_word_break_characters=",
			       readline_s_set_completer_word_break_characters, 1);
    rb_define_singleton_method(mReadline, "completer_word_break_characters",
			       readline_s_get_completer_word_break_characters, 0);
    rb_define_singleton_method(mReadline, "basic_quote_characters=",
			       readline_s_set_basic_quote_characters, 1);
    rb_define_singleton_method(mReadline, "basic_quote_characters",
			       readline_s_get_basic_quote_characters, 0);
    rb_define_singleton_method(mReadline, "completer_quote_characters=",
			       readline_s_set_completer_quote_characters, 1);
    rb_define_singleton_method(mReadline, "completer_quote_characters",
			       readline_s_get_completer_quote_characters, 0);
    rb_define_singleton_method(mReadline, "filename_quote_characters=",
			       readline_s_set_filename_quote_characters, 1);
    rb_define_singleton_method(mReadline, "filename_quote_characters",
			       readline_s_get_filename_quote_characters, 0);
    rb_define_singleton_method(mReadline, "refresh_line",
			       readline_s_refresh_line, 0);
    rb_define_singleton_method(mReadline, "pre_input_hook=",
			       readline_s_set_pre_input_hook, 1);
    rb_define_singleton_method(mReadline, "pre_input_hook",
			       readline_s_get_pre_input_hook, 0);
    rb_define_singleton_method(mReadline, "insert_text",
			       readline_s_insert_text, 1);
    rb_define_singleton_method(mReadline, "redisplay",
			       readline_s_redisplay, 0);
    rb_define_singleton_method(mReadline, "special_prefixes=",
 			       readline_s_set_special_prefixes, 1);
    rb_define_singleton_method(mReadline, "special_prefixes",
 			       readline_s_get_special_prefixes, 0);

#if USE_INSERT_IGNORE_ESCAPE
    CONST_ID(id_orig_prompt, "orig_prompt");
    CONST_ID(id_last_prompt, "last_prompt");
#endif

    history = rb_obj_alloc(rb_cObject);
    rb_extend_object(history, rb_mEnumerable);
    rb_define_singleton_method(history,"to_s", hist_to_s, 0);
    rb_define_singleton_method(history,"[]", hist_get, 1);
    rb_define_singleton_method(history,"[]=", hist_set, 2);
    rb_define_singleton_method(history,"<<", hist_push, 1);
    rb_define_singleton_method(history,"push", hist_push_method, -1);
    rb_define_singleton_method(history,"pop", hist_pop, 0);
    rb_define_singleton_method(history,"shift", hist_shift, 0);
    rb_define_singleton_method(history,"each", hist_each, 0);
    rb_define_singleton_method(history,"length", hist_length, 0);
    rb_define_singleton_method(history,"size", hist_length, 0);
    rb_define_singleton_method(history,"empty?", hist_empty_p, 0);
    rb_define_singleton_method(history,"delete_at", hist_delete_at, 1);
    rb_define_singleton_method(history,"clear", hist_clear, 0);

    /*
     * The history buffer. It extends Enumerable module, so it behaves
     * just like an array.
     * For example, gets the fifth content that the user input by
     * HISTORY[4].
     */
    rb_define_const(mReadline, "HISTORY", history);

    fcomp = rb_obj_alloc(rb_cObject);
    rb_define_singleton_method(fcomp, "call",
			       filename_completion_proc_call, 1);
    /*
     * The Object with the call method that is a completion for filename.
     * This is sets by Readline.completion_proc= method.
     */
    rb_define_const(mReadline, "FILENAME_COMPLETION_PROC", fcomp);

    ucomp = rb_obj_alloc(rb_cObject);
    rb_define_singleton_method(ucomp, "call",
			       username_completion_proc_call, 1);
    /*
     * The Object with the call method that is a completion for usernames.
     * This is sets by Readline.completion_proc= method.
     */
    rb_define_const(mReadline, "USERNAME_COMPLETION_PROC", ucomp);
    history_get_offset_func = history_get_offset_history_base;
    history_replace_offset_func = history_get_offset_0;
#if defined HAVE_RL_LIBRARY_VERSION
    version = rb_str_new_cstr(rl_library_version);
#if defined HAVE_CLEAR_HISTORY || defined HAVE_REMOVE_HISTORY
    if (strncmp(rl_library_version, EDIT_LINE_LIBRARY_VERSION,
		strlen(EDIT_LINE_LIBRARY_VERSION)) == 0) {
	add_history("1");
	if (history_get(history_get_offset_func(0)) == NULL) {
	    history_get_offset_func = history_get_offset_0;
	}
#ifdef HAVE_REPLACE_HISTORY_ENTRY
	if (replace_history_entry(0, "a", NULL) == NULL) {
	    history_replace_offset_func = history_get_offset_history_base;
	}
#endif
#ifdef HAVE_CLEAR_HISTORY
	clear_history();
#else
	{
	    HIST_ENTRY *entry = remove_history(0);
	    if (entry) {
		free((char *)entry->line);
		free(entry);
	    }
	}
#endif
    }
#endif
#else
    version = rb_str_new_cstr("2.0 or prior version");
#endif
    /* Version string of GNU Readline or libedit. */
    rb_define_const(mReadline, "VERSION", version);

    rl_attempted_completion_function = readline_attempted_completion_function;
#if defined(HAVE_RL_PRE_INPUT_HOOK)
    rl_pre_input_hook = (Function *)readline_pre_input_hook;
#endif
#ifdef HAVE_RL_CATCH_SIGNALS
    rl_catch_signals = 0;
#endif
#ifdef HAVE_RL_CLEAR_SIGNALS
    rl_clear_signals();
#endif

    readline_s_set_input(mReadline, rb_stdin);
}