tools/perl-5.8.0/lib/5.8.0/Text/Tabs.pm


package Text::Tabs;

require Exporter;

@ISA = (Exporter);
@EXPORT = qw(expand unexpand $tabstop);

use vars qw($VERSION $tabstop $debug);
$VERSION = 98.112801;

use strict;

BEGIN   {
        $tabstop = 8;
        $debug = 0;
}

sub expand
{
        my (@l) = @_;
        for $_ (@l) {
                1 while s/(^|\n)([^\t\n]*)(\t+)/
                        $1. $2 . (" " x
                                ($tabstop * length($3)
                                - (length($2) % $tabstop)))
                        /sex;
        }
        return @l if wantarray;
        return $l[0];
}

sub unexpand
{
        my (@l) = @_;
        my @e;
        my $x;
        my $line;
        my @lines;
        my $lastbit;
        for $x (@l) {
                @lines = split("\n", $x, -1);
                for $line (@lines) {
                        $line = expand($line);
                        @e = split(/(.{$tabstop})/,$line,-1);
                        $lastbit = pop(@e);
                        $lastbit = '' unless defined $lastbit;
                        $lastbit = "\t"
                                if $lastbit eq " "x$tabstop;
                        for $_ (@e) {
                                if ($debug) {
                                        my $x = $_;
                                        $x =~ s/\t/^I\t/gs;
                                        print "sub on '$x'\n";
                                }
                                s/  +$/\t/;
                        }
                        $line = join('',@e, $lastbit);
                }
                $x = join("\n", @lines);
        }
        return @l if wantarray;
        return $l[0];
}

1;
__END__


=head1 NAME

Text::Tabs -- expand and unexpand tabs per the unix expand(1) and unexpand(1)

=head1 SYNOPSIS

  use Text::Tabs;

  $tabstop = 4;
  @lines_without_tabs = expand(@lines_with_tabs);
  @lines_with_tabs = unexpand(@lines_without_tabs);

=head1 DESCRIPTION

Text::Tabs does about what the unix utilities expand(1) and unexpand(1)
do.  Given a line with tabs in it, expand will replace the tabs with
the appropriate number of spaces.  Given a line with or without tabs in
it, unexpand will add tabs when it can save bytes by doing so.  Invisible
compression with plain ascii!

=head1 BUGS

expand doesn't handle newlines very quickly -- do not feed it an
entire document in one string.  Instead feed it an array of lines.

=head1 AUTHOR

David Muir Sharnoff <muir@idiom.com>