xref: /openbsd-src/gnu/usr.bin/perl/cpan/podlators/lib/Pod/Text/Overstrike.pm (revision c90a81c56dcebd6a1b73fe4aff9b03385b8e63b3) 
1# Pod::Text::Overstrike -- Convert POD data to formatted overstrike text
2#
3# This was written because the output from:
4#
5#     pod2text Text.pm > plain.txt; less plain.txt
6#
7# is not as rich as the output from
8#
9#     pod2man Text.pm | nroff -man > fancy.txt; less fancy.txt
10#
11# and because both Pod::Text::Color and Pod::Text::Termcap are not device
12# independent.
13#
14# Created by Joe Smith <Joe.Smith@inwap.com> 30-Nov-2000
15#   (based on Pod::Text::Color by Russ Allbery <rra@cpan.org>)
16# Copyright 2000 Joe Smith <Joe.Smith@inwap.com>.
17# Copyright 2001, 2004, 2008, 2014 Russ Allbery <rra@cpan.org>.
18#
19# This program is free software; you may redistribute it and/or modify it
20# under the same terms as Perl itself.
21
22##############################################################################
23# Modules and declarations
24##############################################################################
25
26package Pod::Text::Overstrike;
27
28use 5.006;
29use strict;
30use warnings;
31
32use vars qw(@ISA $VERSION);
33
34use Pod::Text ();
35
36@ISA = qw(Pod::Text);
37
38$VERSION = '4.07';
39
40##############################################################################
41# Overrides
42##############################################################################
43
44# Make level one headings bold, overridding any existing formatting.
45sub cmd_head1 {
46    my ($self, $attrs, $text) = @_;
47    $text =~ s/\s+$//;
48    $text = $self->strip_format ($text);
49    $text =~ s/(.)/$1\b$1/g;
50    return $self->SUPER::cmd_head1 ($attrs, $text);
51}
52
53# Make level two headings bold, overriding any existing formatting.
54sub cmd_head2 {
55    my ($self, $attrs, $text) = @_;
56    $text =~ s/\s+$//;
57    $text = $self->strip_format ($text);
58    $text =~ s/(.)/$1\b$1/g;
59    return $self->SUPER::cmd_head2 ($attrs, $text);
60}
61
62# Make level three headings underscored, overriding any existing formatting.
63sub cmd_head3 {
64    my ($self, $attrs, $text) = @_;
65    $text =~ s/\s+$//;
66    $text = $self->strip_format ($text);
67    $text =~ s/(.)/_\b$1/g;
68    return $self->SUPER::cmd_head3 ($attrs, $text);
69}
70
71# Level four headings look like level three headings.
72sub cmd_head4 {
73    my ($self, $attrs, $text) = @_;
74    $text =~ s/\s+$//;
75    $text = $self->strip_format ($text);
76    $text =~ s/(.)/_\b$1/g;
77    return $self->SUPER::cmd_head4 ($attrs, $text);
78}
79
80# The common code for handling all headers.  We have to override to avoid
81# interpolating twice and because we don't want to honor alt.
82sub heading {
83    my ($self, $text, $indent, $marker) = @_;
84    $self->item ("\n\n") if defined $$self{ITEM};
85    $text .= "\n" if $$self{opt_loose};
86    my $margin = ' ' x ($$self{opt_margin} + $indent);
87    $self->output ($margin . $text . "\n");
88    return '';
89}
90
91# Fix the various formatting codes.
92sub cmd_b { local $_ = $_[0]->strip_format ($_[2]); s/(.)/$1\b$1/g; $_ }
93sub cmd_f { local $_ = $_[0]->strip_format ($_[2]); s/(.)/_\b$1/g; $_ }
94sub cmd_i { local $_ = $_[0]->strip_format ($_[2]); s/(.)/_\b$1/g; $_ }
95
96# Output any included code in bold.
97sub output_code {
98    my ($self, $code) = @_;
99    $code =~ s/(.)/$1\b$1/g;
100    $self->output ($code);
101}
102
103# Strip all of the formatting from a provided string, returning the stripped
104# version.
105sub strip_format {
106    my ($self, $text) = @_;
107    $text =~ s/(.)[\b]\1/$1/g;
108    $text =~ s/_[\b]//g;
109    return $text;
110}
111
112# We unfortunately have to override the wrapping code here, since the normal
113# wrapping code gets really confused by all the backspaces.
114sub wrap {
115    my $self = shift;
116    local $_ = shift;
117    my $output = '';
118    my $spaces = ' ' x $$self{MARGIN};
119    my $width = $$self{opt_width} - $$self{MARGIN};
120    while (length > $width) {
121        # This regex represents a single character, that's possibly underlined
122        # or in bold (in which case, it's three characters; the character, a
123        # backspace, and a character).  Use [^\n] rather than . to protect
124        # against odd settings of $*.
125        my $char = '(?:[^\n][\b])?[^\n]';
126        if (s/^((?>$char){0,$width})(?:\Z|\s+)//) {
127            $output .= $spaces . $1 . "\n";
128        } else {
129            last;
130        }
131    }
132    $output .= $spaces . $_;
133    $output =~ s/\s+$/\n\n/;
134    return $output;
135}
136
137##############################################################################
138# Module return value and documentation
139##############################################################################
140
1411;
142__END__
143
144=head1 NAME
145
146=for stopwords
147overstrike
148
149Pod::Text::Overstrike - Convert POD data to formatted overstrike text
150
151=for stopwords
152overstruck Overstruck Allbery terminal's
153
154=head1 SYNOPSIS
155
156    use Pod::Text::Overstrike;
157    my $parser = Pod::Text::Overstrike->new (sentence => 0, width => 78);
158
159    # Read POD from STDIN and write to STDOUT.
160    $parser->parse_from_filehandle;
161
162    # Read POD from file.pod and write to file.txt.
163    $parser->parse_from_file ('file.pod', 'file.txt');
164
165=head1 DESCRIPTION
166
167Pod::Text::Overstrike is a simple subclass of Pod::Text that highlights
168output text using overstrike sequences, in a manner similar to nroff.
169Characters in bold text are overstruck (character, backspace, character)
170and characters in underlined text are converted to overstruck underscores
171(underscore, backspace, character).  This format was originally designed
172for hard-copy terminals and/or line printers, yet is readable on soft-copy
173(CRT) terminals.
174
175Overstruck text is best viewed by page-at-a-time programs that take
176advantage of the terminal's B<stand-out> and I<underline> capabilities, such
177as the less program on Unix.
178
179Apart from the overstrike, it in all ways functions like Pod::Text.  See
180L<Pod::Text> for details and available options.
181
182=head1 BUGS
183
184Currently, the outermost formatting instruction wins, so for example
185underlined text inside a region of bold text is displayed as simply bold.
186There may be some better approach possible.
187
188=head1 SEE ALSO
189
190L<Pod::Text>, L<Pod::Simple>
191
192The current version of this module is always available from its web site at
193L<http://www.eyrie.org/~eagle/software/podlators/>.  It is also part of the
194Perl core distribution as of 5.6.0.
195
196=head1 AUTHOR
197
198Joe Smith <Joe.Smith@inwap.com>, using the framework created by Russ Allbery
199<rra@cpan.org>.
200
201=head1 COPYRIGHT AND LICENSE
202
203Copyright 2000 by Joe Smith <Joe.Smith@inwap.com>.
204Copyright 2001, 2004, 2008 by Russ Allbery <rra@cpan.org>.
205
206This program is free software; you may redistribute it and/or modify it
207under the same terms as Perl itself.
208
209=cut
210