AnyEvent-ReadLine-Gnu/Gnu.pm

=head1 NAME

AnyEvent::ReadLine::Gnu - event-based interface to Term::ReadLine::Gnu

=head1 SYNOPSIS

 use AnyEvent::ReadLine::Gnu;

 # works always, prints message to stdout
 AnyEvent::ReadLine::Gnu->print ("message\n");

 # now initialise readline
 my $rl = new AnyEvent::ReadLine::Gnu prompt => "hi> ", on_line => sub {
    # called for each line entered by the user
    AnyEvent::ReadLine::Gnu->print ("you entered: $_[0]\n");
 };

 # asynchronously print something
 my $t = AE::timer 1, 1, sub {
    $rl->hide;
    print "async message 1\n"; # mind the \n
    $rl->show;

    # the same, but shorter:
    $rl->print ("async message 2\n");
 };

 # do other eventy stuff...
 AE::cv->recv;

=head1 DESCRIPTION

The L<Term::ReadLine> module family is bizarre (and you are encouraged not
to look at its sources unless you want to go blind). It does support
event-based operations, somehow, but it's hard to figure out.

It also has some utility functions for printing messages asynchronously,
something that, again, isn't obvious how to do.

This module has figured it all out for you, once and for all.

=over 4

=cut

package AnyEvent::ReadLine::Gnu;

use common::sense;
use AnyEvent;

BEGIN {
   # we try our best
   local $ENV{PERL_RL} = "Gnu";

   require Term::ReadLine;
   require Term::ReadLine::Gnu;
}

use base Term::ReadLine::;

our $VERSION = '0.2';

=item $rl = new AnyEvent::ReadLine::Gnu key => value...

Creates a new AnyEvent::ReadLine object.

Actually, it only configures readline and provides a convenient way to
call the show and hide methods, as well as readline methods - this is a
singleton.

The returned object is the standard L<Term::ReadLine::Gnu> object, all
methods that are documented (or working) for that module should work on
this object.

Once initialised, this module will also restore the terminal settings on a
normal program exit.

The following key-value pairs are supported:

=over 4

=item on_line => $cb->($string)

The only mandatory parameter - passes the callback that will receive lines
that are completed by the user.

The string will be in locale-encoding (a multibyte character string). For
example, in an utf-8 using locale it will be utf-8. There is no portable
way known to the author to convert this into e.g. a unicode string.

=item prompt => $string

The prompt string to use, defaults to C<< >  >>.

=item name => $string

The readline application name, defaults to C<$0>.

=item in => $glob

The input filehandle (should be a glob): defaults to C<*STDIN>.

=item out => $glob

The output filehandle (should be a glob): defaults to C<*STDOUT>.

=back

=cut

our $self;
our $prompt;
our $cb;
our $hidden;
our $rw;
our ($in, $out);

our $saved_point;
our $saved_line;

# we postpone calling the user clalback here because readline
# still has the input buffer at this point, so calling hide and
# show might not have the desired effect.
sub on_line {
   my $line = shift;
   my $point = $self->{point};

   AE::postpone sub {
      $cb->($line, $point);
   };
}

sub new {
   my ($class, %arg) = @_;

   $in     = $arg{in}  || *STDIN;
   $out    = $arg{out} || *STDOUT;
   $prompt = $arg{prompt} || "> ";
   $cb     = $arg{on_line} || $arg{cb}
      or do { require Carp; Carp::croak ("AnyEvent::ReadLine::Gnu->new on_line callback argument mandatry, but missing") };

   $self = $class->SUPER::new ($arg{name} || $0, $in, $out);

   $self->CallbackHandlerInstall ($prompt, \&on_line);
   # set the unadorned prompt
   $self->rl_set_prompt ($prompt);
   $self->redisplay;

   $hidden = 1;
   $self->show;

   $self
}

=item $rl->hide

=item AnyEvent::ReadLine::Gnu->hide

These methods I<hide> the readline prompt and text. Basically, it removes
the readline feedback from your terminal.

It is safe to call even when AnyEvent::ReadLine::Gnu has not yet been
initialised.

This is immensely useful in an event-based program when you want to output
some stuff to the terminal without disturbing the prompt - just C<hide>
readline, output your thing, then C<show> it again.

Since user input will not be processed while readline is hidden, you
should call C<show> as soon as possible.

=cut

sub hide {
   return if !$self || $hidden++;

   undef $rw;

   $saved_point = $self->{point};
   $saved_line  = $self->{line_buffer};

   $self->rl_set_prompt ("");
   $self->{line_buffer} = "";
   $self->rl_redisplay;
}

=item $rl->show

=item AnyEvent::ReadLine::Gnu->show

Undos any hiding. Every call to C<hide> has to be followed to a call to
C<show>. The last call will redisplay the readline prompt, current input
line and cursor position. Keys entered while the prompt was hidden will be
processed again.

=cut

sub show {
   return if !$self || --$hidden;

   if (defined $saved_point) {
      $self->rl_set_prompt ($prompt);
      $self->{line_buffer} = $saved_line;
      $self->{point}       = $saved_point;
      $self->redisplay;
   }

   $rw = AE::io $in, 0, sub {
      $self->rl_callback_read_char;
   };
}

=item $rl->print ($string, ...)

=item AnyEvent::ReadLine::Gnu->print ($string, ...)

Prints the given strings to the terminal, by first hiding the readline,
printing the message, and showing it again.

This function can be called even when readline has never been initialised.

The last string should end with a newline.

=cut

sub print {
   shift;

   hide;
   my $out = $out || *STDOUT;
   print $out @_;
   show;
}

END {
   return unless $self;

   $self->hide;
   $self->callback_handler_remove;
}

1;

=back

=head1 CAVEATS

There are some issues with readline that can be problematic in event-based
programs:

=over 4

=item blocking I/O

Readline uses blocking terminal I/O. Under most circumstances, this does
not cause big delays, but ttys have the potential to block programs
indefinitely (e.g. on XOFF).

=item unexpected disk I/O

By default, readline does filename completion on TAB, and reads its
config files.

Tab completion can be disabled by calling C<< $rl->unbind_key (9) >>.

=item tty settings

After readline has been initialised, it will mangle the termios tty
settings. This does not normally affect output very much, but should be
taken into consideration.

=item output intermixing

Your program might wish to print messages (for example, log messages) to
STDOUT or STDERR. This will usually cause confusion, unless readline is
hidden with the hide method.

=back

Oh, and the above list is probably not complete.

=head1 AUTHOR, CONTACT, SUPPORT

 Marc Lehmann <schmorp@schmorp.de>
 http://software.schmorp.de/pkg/AnyEvent-ReadLine-Gnu.html

=head1 SEE ALSO

L<rltelnet> - a simple tcp_connect-with-readline program using this module.

=cut

Revision:	1.6
Committed:	Fri May 11 00:30:20 2012 UTC (12 years ago) by root
Branch:	MAIN
Changes since 1.5:	+1 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			AnyEvent::ReadLine::Gnu - event-based interface to Term::ReadLine::Gnu
4
5			=head1 SYNOPSIS
6
7			use AnyEvent::ReadLine::Gnu;
8
9			# works always, prints message to stdout
10			AnyEvent::ReadLine::Gnu->print ("message\n");
11
12			# now initialise readline
13	root	1.2	my $rl = new AnyEvent::ReadLine::Gnu prompt => "hi> ", on_line => sub {
14	root	1.1	# called for each line entered by the user
15			AnyEvent::ReadLine::Gnu->print ("you entered: $_[0]\n");
16			};
17
18			# asynchronously print something
19			my $t = AE::timer 1, 1, sub {
20			$rl->hide;
21			print "async message 1\n"; # mind the \n
22			$rl->show;
23
24			# the same, but shorter:
25			$rl->print ("async message 2\n");
26			};
27
28			# do other eventy stuff...
29			AE::cv->recv;
30
31			=head1 DESCRIPTION
32
33			The L<Term::ReadLine> module family is bizarre (and you are encouraged not
34			to look at its sources unless you want to go blind). It does support
35			event-based operations, somehow, but it's hard to figure out.
36
37			It also has some utility functions for printing messages asynchronously,
38			something that, again, isn't obvious how to do.
39
40			This module has figured it all out for you, once and for all.
41
42			=over 4
43
44			=cut
45
46			package AnyEvent::ReadLine::Gnu;
47
48			use common::sense;
49			use AnyEvent;
50
51			BEGIN {
52			# we try our best
53			local $ENV{PERL_RL} = "Gnu";
54
55			require Term::ReadLine;
56			require Term::ReadLine::Gnu;
57			}
58
59			use base Term::ReadLine::;
60
61	root	1.2	our $VERSION = '0.2';
62	root	1.1
63			=item $rl = new AnyEvent::ReadLine::Gnu key => value...
64
65			Creates a new AnyEvent::ReadLine object.
66
67			Actually, it only configures readline and provides a convenient way to
68			call the show and hide methods, as well as readline methods - this is a
69			singleton.
70
71			The returned object is the standard L<Term::ReadLine::Gnu> object, all
72			methods that are documented (or working) for that module should work on
73			this object.
74
75			Once initialised, this module will also restore the terminal settings on a
76			normal program exit.
77
78			The following key-value pairs are supported:
79
80			=over 4
81
82			=item on_line => $cb->($string)
83
84			The only mandatory parameter - passes the callback that will receive lines
85			that are completed by the user.
86
87	root	1.2	The string will be in locale-encoding (a multibyte character string). For
88			example, in an utf-8 using locale it will be utf-8. There is no portable
89			way known to the author to convert this into e.g. a unicode string.
90
91	root	1.1	=item prompt => $string
92
93			The prompt string to use, defaults to C<< > >>.
94
95			=item name => $string
96
97			The readline application name, defaults to C<$0>.
98
99			=item in => $glob
100
101			The input filehandle (should be a glob): defaults to C<*STDIN>.
102
103			=item out => $glob
104
105			The output filehandle (should be a glob): defaults to C<*STDOUT>.
106
107			=back
108
109			=cut
110
111			our $self;
112			our $prompt;
113			our $cb;
114			our $hidden;
115			our $rw;
116			our ($in, $out);
117
118			our $saved_point;
119			our $saved_line;
120
121	root	1.2	# we postpone calling the user clalback here because readline
122			# still has the input buffer at this point, so calling hide and
123			# show might not have the desired effect.
124			sub on_line {
125			my $line = shift;
126			my $point = $self->{point};
127
128			AE::postpone sub {
129			$cb->($line, $point);
130			};
131			}
132
133	root	1.1	sub new {
134			my ($class, %arg) = @_;
135
136			$in = $arg{in} \|\| *STDIN;
137			$out = $arg{out} \|\| *STDOUT;
138			$prompt = $arg{prompt} \|\| "> ";
139	root	1.2	$cb = $arg{on_line} \|\| $arg{cb}
140			or do { require Carp; Carp::croak ("AnyEvent::ReadLine::Gnu->new on_line callback argument mandatry, but missing") };
141	root	1.1
142			$self = $class->SUPER::new ($arg{name} \|\| $0, $in, $out);
143
144	root	1.2	$self->CallbackHandlerInstall ($prompt, \&on_line);
145	root	1.1	# set the unadorned prompt
146			$self->rl_set_prompt ($prompt);
147	root	1.5	$self->redisplay;
148	root	1.1
149			$hidden = 1;
150			$self->show;
151
152			$self
153			}
154
155			=item $rl->hide
156
157			=item AnyEvent::ReadLine::Gnu->hide
158
159			These methods I<hide> the readline prompt and text. Basically, it removes
160			the readline feedback from your terminal.
161
162			It is safe to call even when AnyEvent::ReadLine::Gnu has not yet been
163			initialised.
164
165			This is immensely useful in an event-based program when you want to output
166			some stuff to the terminal without disturbing the prompt - just C<hide>
167			readline, output your thing, then C<show> it again.
168
169			Since user input will not be processed while readline is hidden, you
170			should call C<show> as soon as possible.
171
172			=cut
173
174			sub hide {
175			return if !$self \|\| $hidden++;
176
177			undef $rw;
178
179			$saved_point = $self->{point};
180			$saved_line = $self->{line_buffer};
181
182			$self->rl_set_prompt ("");
183			$self->{line_buffer} = "";
184			$self->rl_redisplay;
185			}
186
187			=item $rl->show
188
189			=item AnyEvent::ReadLine::Gnu->show
190
191			Undos any hiding. Every call to C<hide> has to be followed to a call to
192			C<show>. The last call will redisplay the readline prompt, current input
193			line and cursor position. Keys entered while the prompt was hidden will be
194			processed again.
195
196			=cut
197
198			sub show {
199			return if !$self \|\| --$hidden;
200
201			if (defined $saved_point) {
202			$self->rl_set_prompt ($prompt);
203			$self->{line_buffer} = $saved_line;
204			$self->{point} = $saved_point;
205			$self->redisplay;
206			}
207
208			$rw = AE::io $in, 0, sub {
209			$self->rl_callback_read_char;
210			};
211			}
212
213			=item $rl->print ($string, ...)
214
215			=item AnyEvent::ReadLine::Gnu->print ($string, ...)
216
217			Prints the given strings to the terminal, by first hiding the readline,
218			printing the message, and showing it again.
219
220	root	1.2	This function can be called even when readline has never been initialised.
221	root	1.1
222			The last string should end with a newline.
223
224			=cut
225
226			sub print {
227			shift;
228
229			hide;
230			my $out = $out \|\| *STDOUT;
231			print $out @_;
232			show;
233			}
234
235			END {
236			return unless $self;
237
238			$self->hide;
239			$self->callback_handler_remove;
240			}
241
242			1;
243
244			=back
245
246	root	1.3	=head1 CAVEATS
247
248			There are some issues with readline that can be problematic in event-based
249			programs:
250
251			=over 4
252
253			=item blocking I/O
254
255			Readline uses blocking terminal I/O. Under most circumstances, this does
256			not cause big delays, but ttys have the potential to block programs
257			indefinitely (e.g. on XOFF).
258
259			=item unexpected disk I/O
260
261	root	1.4	By default, readline does filename completion on TAB, and reads its
262			config files.
263	root	1.3
264	root	1.5	Tab completion can be disabled by calling C<< $rl->unbind_key (9) >>.
265
266	root	1.4	=item tty settings
267	root	1.3
268			After readline has been initialised, it will mangle the termios tty
269			settings. This does not normally affect output very much, but should be
270			taken into consideration.
271
272	root	1.4	=item output intermixing
273
274			Your program might wish to print messages (for example, log messages) to
275			STDOUT or STDERR. This will usually cause confusion, unless readline is
276			hidden with the hide method.
277
278	root	1.3	=back
279
280			Oh, and the above list is probably not complete.
281
282	root	1.1	=head1 AUTHOR, CONTACT, SUPPORT
283
284			Marc Lehmann <schmorp@schmorp.de>
285	root	1.6	http://software.schmorp.de/pkg/AnyEvent-ReadLine-Gnu.html
286	root	1.1
287	root	1.5	=head1 SEE ALSO
288
289			L<rltelnet> - a simple tcp_connect-with-readline program using this module.
290
291	root	1.1	=cut
292