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
.
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>.
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.
The Object
with the call method that is a completion for filename. This is sets by Readline.completion_proc=
method.
The Object
with the call method that is a completion for usernames. This is sets by Readline.completion_proc=
method.
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);
}
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_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;
}
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_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);
}
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_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;
}
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_get_completer_quote_characters(VALUE self)
{
if (rl_completer_quote_characters == NULL)
return Qnil;
return rb_locale_str_new_cstr(rl_completer_quote_characters);
}
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_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;
}
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_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);
}
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_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;
}
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_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);
}
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_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;
}
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_get_completion_case_fold(VALUE self)
{
return rb_attr_get(mReadline, completion_case_fold);
}
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_set_completion_case_fold(VALUE self, VALUE val)
{
return rb_ivar_set(mReadline, completion_case_fold, val);
}
Sets whether or not to ignore case on completion.
static VALUE
readline_s_get_completion_proc(VALUE self)
{
return rb_attr_get(mReadline, completion_proc);
}
Returns the completion Proc
object.
static VALUE
readline_s_set_completion_proc(VALUE self, VALUE proc)
{
mustbe_callable(proc);
return rb_ivar_set(mReadline, 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 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_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);
}
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_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;
}
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_emacs_editing_mode(VALUE self)
{
rl_emacs_editing_mode(1,0);
return Qnil;
}
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_p(VALUE self)
{
return rl_editing_mode == 1 ? Qtrue : Qfalse;
}
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_get_filename_quote_characters(VALUE self)
{
if (rl_filename_quote_characters == NULL)
return Qnil;
return rb_locale_str_new_cstr(rl_filename_quote_characters);
}
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_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;
}
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_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;
}
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_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;
}
Specifies a File
object input
that is input stream for Readline.readline
method.
static VALUE
readline_s_insert_text(VALUE self, VALUE str)
{
OutputStringValue(str);
rl_insert_text(RSTRING_PTR(str));
return self;
}
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_get_line_buffer(VALUE self)
{
if (rl_line_buffer == NULL)
return Qnil;
return rb_locale_str_new_cstr(rl_line_buffer);
}
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_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;
}
Specifies a File
object output
that is output stream for Readline.readline
method.
static VALUE
readline_s_get_point(VALUE self)
{
return INT2NUM(rl_point);
}
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_set_point(VALUE self, VALUE pos)
{
rl_point = NUM2INT(pos);
return pos;
}
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_get_pre_input_hook(VALUE self)
{
return rb_attr_get(mReadline, id_pre_input_hook);
}
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_set_pre_input_hook(VALUE self, VALUE proc)
{
mustbe_callable(proc);
return rb_ivar_set(mReadline, id_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 NotImplementedError
if the using readline library does not support.
static VALUE
readline_s_get_quoting_detection_proc(VALUE self)
{
return rb_attr_get(mReadline, quoting_detection_proc);
}
Returns the quoting detection Proc
object.
static VALUE
readline_s_set_quoting_detection_proc(VALUE self, VALUE proc)
{
mustbe_callable(proc);
return rb_ivar_set(mReadline, quoting_detection_proc, proc);
}
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_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;
}
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.
-
stdin was closed.
-
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_s_redisplay(VALUE self)
{
rl_redisplay();
return self;
}
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_refresh_line(VALUE self)
{
prepare_readline();
rl_refresh_line(0, 0);
return Qnil;
}
Clear the current input line.
static VALUE
readline_s_set_screen_size(VALUE self, VALUE rows, VALUE columns)
{
rl_set_screen_size(NUM2INT(rows), NUM2INT(columns));
return 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.
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;
}
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_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;
}
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_vi_editing_mode(VALUE self)
{
rl_vi_editing_mode(1,0);
return Qnil;
}
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_p(VALUE self)
{
return rl_editing_mode == 0 ? Qtrue : Qfalse;
}
Returns true if vi mode is active. Returns false if not.
Raises NotImplementedError
if the using readline library does not support.