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 = '1.1';

=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 callback will be installed with the C<CallbackHandlerInstall>, which
means it handles history expansion and history, among other things.

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);

   $Term::ReadLine::Gnu::Attribs{term_set} = ["", "", "", ""];
   $self->CallbackHandlerInstall ($prompt, \&on_line);

   $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:	1.8
Committed:	Tue Dec 12 15:50:45 2017 UTC (6 years, 4 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_1, HEAD
Changes since 1.7:	+2 -2 lines
Log Message:	1.1
#	Content
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	my $rl = new AnyEvent::ReadLine::Gnu prompt => "hi> ", on_line => sub {
14	# 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	our $VERSION = '1.1';
62
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 callback will be installed with the C<CallbackHandlerInstall>, which
79	means it handles history expansion and history, among other things.
80
81	The following key-value pairs are supported:
82
83	=over 4
84
85	=item on_line => $cb->($string)
86
87	The only mandatory parameter - passes the callback that will receive lines
88	that are completed by the user.
89
90	The string will be in locale-encoding (a multibyte character string). For
91	example, in an utf-8 using locale it will be utf-8. There is no portable
92	way known to the author to convert this into e.g. a unicode string.
93
94	=item prompt => $string
95
96	The prompt string to use, defaults to C<< > >>.
97
98	=item name => $string
99
100	The readline application name, defaults to C<$0>.
101
102	=item in => $glob
103
104	The input filehandle (should be a glob): defaults to C<*STDIN>.
105
106	=item out => $glob
107
108	The output filehandle (should be a glob): defaults to C<*STDOUT>.
109
110	=back
111
112	=cut
113
114	our $self;
115	our $prompt;
116	our $cb;
117	our $hidden;
118	our $rw;
119	our ($in, $out);
120
121	our $saved_point;
122	our $saved_line;
123
124	# we postpone calling the user clalback here because readline
125	# still has the input buffer at this point, so calling hide and
126	# show might not have the desired effect.
127	sub on_line {
128	my $line = shift;
129	my $point = $self->{point};
130
131	AE::postpone sub {
132	$cb->($line, $point);
133	};
134	}
135
136	sub new {
137	my ($class, %arg) = @_;
138
139	$in = $arg{in} \|\| *STDIN;
140	$out = $arg{out} \|\| *STDOUT;
141	$prompt = $arg{prompt} // "> ";
142	$cb = $arg{on_line} \|\| $arg{cb}
143	or do { require Carp; Carp::croak ("AnyEvent::ReadLine::Gnu->new on_line callback argument mandatry, but missing") };
144
145	$self = $class->SUPER::new ($arg{name} \|\| $0, $in, $out);
146
147	$Term::ReadLine::Gnu::Attribs{term_set} = ["", "", "", ""];
148	$self->CallbackHandlerInstall ($prompt, \&on_line);
149
150	$hidden = 1;
151	$self->show;
152
153	$self
154	}
155
156	=item $rl->hide
157
158	=item AnyEvent::ReadLine::Gnu->hide
159
160	These methods I<hide> the readline prompt and text. Basically, it removes
161	the readline feedback from your terminal.
162
163	It is safe to call even when AnyEvent::ReadLine::Gnu has not yet been
164	initialised.
165
166	This is immensely useful in an event-based program when you want to output
167	some stuff to the terminal without disturbing the prompt - just C<hide>
168	readline, output your thing, then C<show> it again.
169
170	Since user input will not be processed while readline is hidden, you
171	should call C<show> as soon as possible.
172
173	=cut
174
175	sub hide {
176	return if !$self \|\| $hidden++;
177
178	undef $rw;
179
180	$saved_point = $self->{point};
181	$saved_line = $self->{line_buffer};
182
183	$self->rl_set_prompt ("");
184	$self->{line_buffer} = "";
185	$self->rl_redisplay;
186	}
187
188	=item $rl->show
189
190	=item AnyEvent::ReadLine::Gnu->show
191
192	Undos any hiding. Every call to C<hide> has to be followed to a call to
193	C<show>. The last call will redisplay the readline prompt, current input
194	line and cursor position. Keys entered while the prompt was hidden will be
195	processed again.
196
197	=cut
198
199	sub show {
200	return if !$self \|\| --$hidden;
201
202	if (defined $saved_point) {
203	$self->rl_set_prompt ($prompt);
204	$self->{line_buffer} = $saved_line;
205	$self->{point} = $saved_point;
206	$self->redisplay;
207	}
208
209	$rw = AE::io $in, 0, sub {
210	$self->rl_callback_read_char;
211	};
212	}
213
214	=item $rl->print ($string, ...)
215
216	=item AnyEvent::ReadLine::Gnu->print ($string, ...)
217
218	Prints the given strings to the terminal, by first hiding the readline,
219	printing the message, and showing it again.
220
221	This function can be called even when readline has never been initialised.
222
223	The last string should end with a newline.
224
225	=cut
226
227	sub print {
228	shift;
229
230	hide;
231	my $out = $out \|\| *STDOUT;
232	print $out @_;
233	show;
234	}
235
236	END {
237	return unless $self;
238
239	$self->hide;
240	$self->callback_handler_remove;
241	}
242
243	1;
244
245	=back
246
247	=head1 CAVEATS
248
249	There are some issues with readline that can be problematic in event-based
250	programs:
251
252	=over 4
253
254	=item blocking I/O
255
256	Readline uses blocking terminal I/O. Under most circumstances, this does
257	not cause big delays, but ttys have the potential to block programs
258	indefinitely (e.g. on XOFF).
259
260	=item unexpected disk I/O
261
262	By default, readline does filename completion on TAB, and reads its
263	config files.
264
265	Tab completion can be disabled by calling C<< $rl->unbind_key (9) >>.
266
267	=item tty settings
268
269	After readline has been initialised, it will mangle the termios tty
270	settings. This does not normally affect output very much, but should be
271	taken into consideration.
272
273	=item output intermixing
274
275	Your program might wish to print messages (for example, log messages) to
276	STDOUT or STDERR. This will usually cause confusion, unless readline is
277	hidden with the hide method.
278
279	=back
280
281	Oh, and the above list is probably not complete.
282
283	=head1 AUTHOR, CONTACT, SUPPORT
284
285	Marc Lehmann <schmorp@schmorp.de>
286	http://software.schmorp.de/pkg/AnyEvent-ReadLine-Gnu.html
287
288	=head1 SEE ALSO
289
290	L<rltelnet> - a simple tcp_connect-with-readline program using this module.
291
292	=cut
293