1
2package Text::Tabs;
3
4require Exporter;
5
6@ISA = (Exporter);
7@EXPORT = qw(expand unexpand $tabstop);
8
9use vars qw($VERSION $tabstop $debug);
10$VERSION = 2005.0824;
11
12use strict;
13
14BEGIN	{
15	$tabstop = 8;
16	$debug = 0;
17}
18
19sub expand {
20	my @l;
21	my $pad;
22	for ( @_ ) {
23		my $s = '';
24		for (split(/^/m, $_, -1)) {
25			my $offs = 0;
26			s{\t}{
27				$pad = $tabstop - (pos() + $offs) % $tabstop;
28				$offs += $pad - 1;
29				" " x $pad;
30			}eg;
31			$s .= $_;
32		}
33		push(@l, $s);
34	}
35	return @l if wantarray;
36	return $l[0];
37}
38
39sub unexpand
40{
41	my (@l) = @_;
42	my @e;
43	my $x;
44	my $line;
45	my @lines;
46	my $lastbit;
47	for $x (@l) {
48		@lines = split("\n", $x, -1);
49		for $line (@lines) {
50			$line = expand($line);
51			@e = split(/(.{$tabstop})/,$line,-1);
52			$lastbit = pop(@e);
53			$lastbit = '' unless defined $lastbit;
54			$lastbit = "\t"
55				if $lastbit eq " "x$tabstop;
56			for $_ (@e) {
57				if ($debug) {
58					my $x = $_;
59					$x =~ s/\t/^I\t/gs;
60					print "sub on '$x'\n";
61				}
62				s/  +$/\t/;
63			}
64			$line = join('',@e, $lastbit);
65		}
66		$x = join("\n", @lines);
67	}
68	return @l if wantarray;
69	return $l[0];
70}
71
721;
73__END__
74
75sub expand
76{
77	my (@l) = @_;
78	for $_ (@l) {
79		1 while s/(^|\n)([^\t\n]*)(\t+)/
80			$1. $2 . (" " x
81				($tabstop * length($3)
82				- (length($2) % $tabstop)))
83			/sex;
84	}
85	return @l if wantarray;
86	return $l[0];
87}
88
89
90=head1 NAME
91
92Text::Tabs -- expand and unexpand tabs per the unix expand(1) and unexpand(1)
93
94=head1 SYNOPSIS
95
96  use Text::Tabs;
97
98  $tabstop = 4;
99  @lines_without_tabs = expand(@lines_with_tabs);
100  @lines_with_tabs = unexpand(@lines_without_tabs);
101
102=head1 DESCRIPTION
103
104Text::Tabs does about what the unix utilities expand(1) and unexpand(1)
105do.  Given a line with tabs in it, expand will replace the tabs with
106the appropriate number of spaces.  Given a line with or without tabs in
107it, unexpand will add tabs when it can save bytes by doing so.  Invisible
108compression with plain ascii!
109
110=head1 BUGS
111
112expand doesn't handle newlines very quickly -- do not feed it an
113entire document in one string.  Instead feed it an array of lines.
114
115=head1 LICENSE
116
117Copyright (C) 1996-2002,2005 David Muir Sharnoff.
118Copyright (C) 2005 Aristotle Pagaltzis
119This module may be modified, used, copied, and redistributed at your own risk.
120Publicly redistributed modified versions must use a different name.
121
122