module Readline - RDoc Documentation

# module 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`

  www.gnu.org/directory/readline.html

libedit

  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

Documented by Kouji Takao <kouji dot takao at gmail dot com>.

### Constants

FILENAME_COMPLETION_PROC

  The `Object` with the call method that is a completion for filename. This is sets by `Readline.completion_proc=` method.

HISTORY

  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]`.

USERNAME_COMPLETION_PROC

  The `Object` with the call method that is a completion for usernames. This is sets by `Readline.completion_proc=` method.

VERSION

  Version string of GNU `Readline` or libedit.

### Public Class Methods

basic_quote_characters → string click to toggle source

Gets a list of quote characters which can cause a word break.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_get_basic_quote_characters(VALUE self)
    {
        if (rl_basic_quote_characters == NULL)
            return Qnil;
        return rb_locale_str_new_cstr(rl_basic_quote_characters);
    }

basic_quote_characters = string click to toggle source

Sets a list of quote characters which can cause a word break.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_set_basic_quote_characters(VALUE self, VALUE str)
    {
        static char *basic_quote_characters = NULL;

        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;
    }

basic_word_break_characters → string click to toggle source

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.

    static VALUE
    readline_s_get_basic_word_break_characters(VALUE self)
    {
        if (rl_basic_word_break_characters == NULL)
            return Qnil;
        return rb_locale_str_new_cstr(rl_basic_word_break_characters);
    }

basic_word_break_characters = string click to toggle source

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: “ tn"\‘`@$><=;|&{(”.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_set_basic_word_break_characters(VALUE self, VALUE str)
    {
        static char *basic_word_break_characters = NULL;

        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;
    }

completer_quote_characters → string click to toggle source

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.

    static VALUE
    readline_s_get_completer_quote_characters(VALUE self)
    {
        if (rl_completer_quote_characters == NULL)
            return Qnil;
        return rb_locale_str_new_cstr(rl_completer_quote_characters);
    }

completer_quote_characters = string click to toggle source

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.

    static VALUE
    readline_s_set_completer_quote_characters(VALUE self, VALUE str)
    {
        static char *completer_quote_characters = NULL;

        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;
    }

completer_word_break_characters → string click to toggle source

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.

    static VALUE
    readline_s_get_completer_word_break_characters(VALUE self)
    {
        if (rl_completer_word_break_characters == NULL)
            return Qnil;
        return rb_locale_str_new_cstr(rl_completer_word_break_characters);
    }

completer_word_break_characters = string click to toggle source

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.

    static VALUE
    readline_s_set_completer_word_break_characters(VALUE self, VALUE str)
    {
        static char *completer_word_break_characters = NULL;

        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;
    }

completion_append_character → char click to toggle source

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.

    static VALUE
    readline_s_get_completion_append_character(VALUE self)
    {
        char buf[1];

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

        buf[0] = (char) rl_completion_append_character;
        return rb_locale_str_new(buf, 1);
    }

completion_append_character = char click to toggle source

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.

    static VALUE
    readline_s_set_completion_append_character(VALUE self, VALUE str)
    {
        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;
    }

completion_case_fold → bool click to toggle source

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."

    static VALUE
    readline_s_get_completion_case_fold(VALUE self)
    {
        return rb_attr_get(mReadline, completion_case_fold);
    }

completion_case_fold = bool click to toggle source

Sets whether or not to ignore case on completion.

    static VALUE
    readline_s_set_completion_case_fold(VALUE self, VALUE val)
    {
        return rb_ivar_set(mReadline, completion_case_fold, val);
    }

completion_proc → proc click to toggle source

Returns the completion `Proc` object.

    static VALUE
    readline_s_get_completion_proc(VALUE self)
    {
        return rb_attr_get(mReadline, completion_proc);
    }

completion_proc = proc click to toggle source

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 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.

    static VALUE
    readline_s_set_completion_proc(VALUE self, VALUE proc)
    {
        mustbe_callable(proc);
        return rb_ivar_set(mReadline, completion_proc, proc);
    }

completion_quote_character → char click to toggle source

When called during a completion (e.g. from within your `completion_proc`), it will return a string containing the character used to quote the argument being completed, or nil if the argument is unquoted.

When called at other times, it will always return nil.

Note that `Readline.completer_quote_characters` must be set, or this method will always return nil.

    static VALUE
    readline_s_get_completion_quote_character(VALUE self)
    {
        char buf[1];

        if (rl_completion_quote_character == '\0')
            return Qnil;

        buf[0] = (char) rl_completion_quote_character;
        return rb_locale_str_new(buf, 1);
    }

delete_text([start[, length]]) → self click to toggle source
delete_text(start..end) → self
delete_text() → self

Delete text between start and end in the current line.

See GNU Readline’s rl_delete_text function.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_delete_text(int argc, VALUE *argv, VALUE self)
    {
        rb_check_arity(argc, 0, 2);
        if (rl_line_buffer) {
            const char *p, *ptr = rl_line_buffer;
            long beg = 0, len = strlen(ptr);
            const char *end = ptr + len;
            rb_encoding *enc = rb_locale_encoding();
            if (argc == 2) {
                beg = NUM2LONG(argv[0]);
                len = NUM2LONG(argv[1]);
              num_pos:
                p = str_subpos(ptr, end, beg, &len, enc);
                if (!p) rb_raise(rb_eArgError, "invalid index");
                beg = p - ptr;
            }
            else if (argc == 1) {
                len = rb_enc_strlen(ptr, ptr + len, enc);
                if (!rb_range_beg_len(argv[0], &beg, &len, len, 1)) {
                    beg = NUM2LONG(argv[0]);
                    goto num_pos;
                }
            }
            rl_delete_text(rb_long2int(beg), rb_long2int(beg + len));
        }
        return self;
    }

emacs_editing_mode → nil click to toggle source

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.

    static VALUE
    readline_s_emacs_editing_mode(VALUE self)
    {
        rl_emacs_editing_mode(1,0);
        return Qnil;
    }

emacs_editing_mode? → bool click to toggle source

Returns true if emacs mode is active. Returns false if not.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_emacs_editing_mode_p(VALUE self)
    {
        return rl_editing_mode == 1 ? Qtrue : Qfalse;
    }

filename_quote_characters → string click to toggle source

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.

    static VALUE
    readline_s_get_filename_quote_characters(VALUE self)
    {
        if (rl_filename_quote_characters == NULL)
            return Qnil;
        return rb_locale_str_new_cstr(rl_filename_quote_characters);
    }

filename_quote_characters = string click to toggle source

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.

    static VALUE
    readline_s_set_filename_quote_characters(VALUE self, VALUE str)
    {
        static char *filename_quote_characters = NULL;

        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;
    }

get_screen_size → [rows, columns] click to toggle source

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.

    static VALUE
    readline_s_get_screen_size(VALUE self)
    {
        int rows, columns;
        VALUE res;

        rl_get_screen_size(&rows, &columns);
        res = rb_ary_new();
        rb_ary_push(res, INT2NUM(rows));
        rb_ary_push(res, INT2NUM(columns));
        return res;
    }

input = input click to toggle source

Specifies a `File` object `input` that is input stream for `Readline.readline` method.

    static VALUE
    readline_s_set_input(VALUE self, VALUE input)
    {
        rb_io_t *ifp;
        int fd;
        FILE *f;

        if (NIL_P(input)) {
            clear_rl_instream();
        }
        else {
            Check_Type(input, T_FILE);
            GetOpenFile(input, ifp);
            clear_rl_instream();
            fd = rb_cloexec_dup(ifp->fd);
            if (fd == -1)
                rb_sys_fail("dup");
            f = fdopen(fd, "r");
            if (f == NULL) {
                int save_errno = errno;
                close(fd);
                rb_syserr_fail(save_errno, "fdopen");
            }
            rl_instream = readline_rl_instream = f;
            readline_instream = input;
        }
        return input;
    }

insert_text(string) → self click to toggle source

Insert text into the line at the current cursor position.

See GNU Readline’s rl_insert_text function.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_insert_text(VALUE self, VALUE str)
    {
        OutputStringValue(str);
        rl_insert_text(RSTRING_PTR(str));
        return self;
    }

line_buffer → string click to toggle source

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.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_get_line_buffer(VALUE self)
    {
        if (rl_line_buffer == NULL)
            return Qnil;
        return rb_locale_str_new_cstr(rl_line_buffer);
    }

output = output click to toggle source

Specifies a `File` object `output` that is output stream for `Readline.readline` method.

    static VALUE
    readline_s_set_output(VALUE self, VALUE output)
    {
        rb_io_t *ofp;
        int fd;
        FILE *f;

        if (NIL_P(output)) {
            clear_rl_outstream();
        }
        else {
            Check_Type(output, T_FILE);
            GetOpenFile(output, ofp);
            clear_rl_outstream();
            fd = rb_cloexec_dup(ofp->fd);
            if (fd == -1)
                rb_sys_fail("dup");
            f = fdopen(fd, "w");
            if (f == NULL) {
                int save_errno = errno;
                close(fd);
                rb_syserr_fail(save_errno, "fdopen");
            }
            rl_outstream = readline_rl_outstream = f;
            readline_outstream = output;
        }
        return output;
    }

point → int click to toggle source

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

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_get_point(VALUE self)
    {
        return INT2NUM(rl_point);
    }

point = int click to toggle source

`Set` the index of the current cursor position in `Readline.line_buffer`.

Raises `NotImplementedError` if the using readline library does not support.

See `Readline.point`.

    static VALUE
    readline_s_set_point(VALUE self, VALUE pos)
    {
        rl_point = NUM2INT(pos);
        return pos;
    }

pre_input_hook → proc click to toggle source

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 `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_get_pre_input_hook(VALUE self)
    {
        return rb_attr_get(mReadline, id_pre_input_hook);
    }

pre_input_hook = proc click to toggle source

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 `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_set_pre_input_hook(VALUE self, VALUE proc)
    {
        mustbe_callable(proc);
        return rb_ivar_set(mReadline, id_pre_input_hook, proc);
    }

quoting_detection_proc → proc click to toggle source

Returns the quoting detection `Proc` object.

    static VALUE
    readline_s_get_quoting_detection_proc(VALUE self)
    {
        return rb_attr_get(mReadline, quoting_detection_proc);
    }

quoting_detection_proc = proc click to toggle source

Specifies a `Proc` object `proc` to determine if a character in the user’s input is escaped. It should take the user’s input and the index of the character in question as input, and return a boolean (true if the specified character is escaped).

`Readline` will only call this proc with characters specified in `completer_quote_characters`, to discover if they indicate the end of a quoted argument, or characters specified in `completer_word_break_characters`, to discover if they indicate a break between arguments.

If `completer_quote_characters` is not set, or if the user input doesn’t contain one of the `completer_quote_characters` or a ++ character, `Readline` will not attempt to use this proc at all.

Raises `ArgumentError` if `proc` does not respond to the call method.

    static VALUE
    readline_s_set_quoting_detection_proc(VALUE self, VALUE proc)
    {
        mustbe_callable(proc);
        return rb_ivar_set(mReadline, quoting_detection_proc, proc);
    }

readline(prompt = "", add_hist = false) → string or nil click to toggle source

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 one of below conditions are satisfied.

1. stdin was closed.

2. stdout was closed.

This method supports thread. Switches 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

    static VALUE
    readline_readline(int argc, VALUE *argv, VALUE self)
    {
        VALUE tmp, add_hist, result;
        char *prompt = NULL;
        char *buff;
        int status;

        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);
        }

        prepare_readline();

    #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;
    }

redisplay → self click to toggle source

Change what’s displayed on the screen to reflect the current contents.

See GNU Readline’s rl_redisplay function.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_redisplay(VALUE self)
    {
        rl_redisplay();
        return self;
    }

refresh_line → nil click to toggle source

Clear the current input line.

    static VALUE
    readline_s_refresh_line(VALUE self)
    {
        prepare_readline();
        rl_refresh_line(0, 0);
        return Qnil;
    }

set_screen_size(rows, columns) → self click to toggle source

`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.

    static VALUE
    readline_s_set_screen_size(VALUE self, VALUE rows, VALUE columns)
    {
        rl_set_screen_size(NUM2INT(rows), NUM2INT(columns));
        return self;
    }

special_prefixes → string click to toggle source

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.

    static VALUE
    readline_s_get_special_prefixes(VALUE self)
    {
        VALUE str;
        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);
            rb_obj_reveal(str, rb_cString);
        }
        return str;
    }

special_prefixes = string click to toggle source

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.

    static VALUE
    readline_s_set_special_prefixes(VALUE self, VALUE str)
    {
        if (!NIL_P(str)) {
            OutputStringValue(str);
            str = rb_str_dup_frozen(str);
            rb_obj_hide(str);
        }
        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;
    }

vi_editing_mode → nil click to toggle source

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.

    static VALUE
    readline_s_vi_editing_mode(VALUE self)
    {
        rl_vi_editing_mode(1,0);
        return Qnil;
    }

vi_editing_mode? → bool click to toggle source

Returns true if vi mode is active. Returns false if not.

Raises `NotImplementedError` if the using readline library does not support.

    static VALUE
    readline_s_vi_editing_mode_p(VALUE self)
    {
        return rl_editing_mode == 0 ? Qtrue : Qfalse;
    }