xref: /onnv-gate/usr/src/cmd/perl/5.8.4/distrib/lib/Pod/Text/Overstrike.pm (revision 0:68f95e015346) 
1# Pod::Text::Overstrike -- Convert POD data to formatted overstrike text
2# $Id: Overstrike.pm,v 1.10 2002/08/04 03:35:01 eagle Exp $
3#
4# Created by Joe Smith <Joe.Smith@inwap.com> 30-Nov-2000
5#   (based on Pod::Text::Color by Russ Allbery <rra@stanford.edu>)
6#
7# This program is free software; you may redistribute it and/or modify it
8# under the same terms as Perl itself.
9#
10# This was written because the output from:
11#
12#     pod2text Text.pm > plain.txt; less plain.txt
13#
14# is not as rich as the output from
15#
16#     pod2man Text.pm | nroff -man > fancy.txt; less fancy.txt
17#
18# and because both Pod::Text::Color and Pod::Text::Termcap are not device
19# independent.
20
21##############################################################################
22# Modules and declarations
23##############################################################################
24
25package Pod::Text::Overstrike;
26
27require 5.004;
28
29use Pod::Text ();
30
31use strict;
32use vars qw(@ISA $VERSION);
33
34@ISA = qw(Pod::Text);
35
36# Don't use the CVS revision as the version, since this module is also in Perl
37# core and too many things could munge CVS magic revision strings.  This
38# number should ideally be the same as the CVS revision in podlators, however.
39$VERSION = 1.10;
40
41
42##############################################################################
43# Overrides
44##############################################################################
45
46# Make level one headings bold, overridding any existing formatting.
47sub cmd_head1 {
48    my ($self, $text, $line) = @_;
49    $text =~ s/\s+$//;
50    $text = $self->strip_format ($self->interpolate ($text, $line));
51    $text =~ s/(.)/$1\b$1/g;
52    $self->SUPER::cmd_head1 ($text);
53}
54
55# Make level two headings bold, overriding any existing formatting.
56sub cmd_head2 {
57    my ($self, $text, $line) = @_;
58    $text =~ s/\s+$//;
59    $text = $self->strip_format ($self->interpolate ($text, $line));
60    $text =~ s/(.)/$1\b$1/g;
61    $self->SUPER::cmd_head2 ($text);
62}
63
64# Make level three headings underscored, overriding any existing formatting.
65sub cmd_head3 {
66    my ($self, $text, $line) = @_;
67    $text =~ s/\s+$//;
68    $text = $self->strip_format ($self->interpolate ($text, $line));
69    $text =~ s/(.)/_\b$1/g;
70    $self->SUPER::cmd_head3 ($text);
71}
72
73# Level four headings look like level three headings.
74sub cmd_head4 {
75    my ($self, $text, $line) = @_;
76    $text =~ s/\s+$//;
77    $text = $self->strip_format ($self->interpolate ($text, $line));
78    $text =~ s/(.)/_\b$1/g;
79    $self->SUPER::cmd_head4 ($text);
80}
81
82# The common code for handling all headers.  We have to override to avoid
83# interpolating twice and because we don't want to honor alt.
84sub heading {
85    my ($self, $text, $line, $indent, $marker) = @_;
86    $self->item ("\n\n") if defined $$self{ITEM};
87    $text .= "\n" if $$self{loose};
88    my $margin = ' ' x ($$self{margin} + $indent);
89    $self->output ($margin . $text . "\n");
90}
91
92# Fix the various formatting codes.
93sub seq_b { local $_ = strip_format (@_); s/(.)/$1\b$1/g; $_ }
94sub seq_f { local $_ = strip_format (@_); s/(.)/_\b$1/g; $_ }
95sub seq_i { local $_ = strip_format (@_); s/(.)/_\b$1/g; $_ }
96
97# Output any included code in bold.
98sub output_code {
99    my ($self, $code) = @_;
100    $code =~ s/(.)/$1\b$1/g;
101    $self->output ($code);
102}
103
104# We unfortunately have to override the wrapping code here, since the normal
105# wrapping code gets really confused by all the backspaces.
106sub wrap {
107    my $self = shift;
108    local $_ = shift;
109    my $output = '';
110    my $spaces = ' ' x $$self{MARGIN};
111    my $width = $$self{width} - $$self{MARGIN};
112    while (length > $width) {
113        # This regex represents a single character, that's possibly underlined
114        # or in bold (in which case, it's three characters; the character, a
115        # backspace, and a character).  Use [^\n] rather than . to protect
116        # against odd settings of $*.
117        my $char = '(?:[^\n][\b])?[^\n]';
118        if (s/^((?>$char){0,$width})(?:\Z|\s+)//) {
119            $output .= $spaces . $1 . "\n";
120        } else {
121            last;
122        }
123    }
124    $output .= $spaces . $_;
125    $output =~ s/\s+$/\n\n/;
126    $output;
127}
128
129##############################################################################
130# Utility functions
131##############################################################################
132
133# Strip all of the formatting from a provided string, returning the stripped
134# version.
135sub strip_format {
136    my ($self, $text) = @_;
137    $text =~ s/(.)[\b]\1/$1/g;
138    $text =~ s/_[\b]//g;
139    return $text;
140}
141
142##############################################################################
143# Module return value and documentation
144##############################################################################
145
1461;
147__END__
148
149=head1 NAME
150
151Pod::Text::Overstrike - Convert POD data to formatted overstrike text
152
153=head1 SYNOPSIS
154
155    use Pod::Text::Overstrike;
156    my $parser = Pod::Text::Overstrike->new (sentence => 0, width => 78);
157
158    # Read POD from STDIN and write to STDOUT.
159    $parser->parse_from_filehandle;
160
161    # Read POD from file.pod and write to file.txt.
162    $parser->parse_from_file ('file.pod', 'file.txt');
163
164=head1 DESCRIPTION
165
166Pod::Text::Overstrike is a simple subclass of Pod::Text that highlights
167output text using overstrike sequences, in a manner similar to nroff.
168Characters in bold text are overstruck (character, backspace, character) and
169characters in underlined text are converted to overstruck underscores
170(underscore, backspace, character).  This format was originally designed for
171hardcopy terminals and/or lineprinters, yet is readable on softcopy (CRT)
172terminals.
173
174Overstruck text is best viewed by page-at-a-time programs that take
175advantage of the terminal's B<stand-out> and I<underline> capabilities, such
176as the less program on Unix.
177
178Apart from the overstrike, it in all ways functions like Pod::Text.  See
179L<Pod::Text> for details and available options.
180
181=head1 BUGS
182
183Currently, the outermost formatting instruction wins, so for example
184underlined text inside a region of bold text is displayed as simply bold.
185There may be some better approach possible.
186
187=head1 SEE ALSO
188
189L<Pod::Text>, L<Pod::Parser>
190
191The current version of this module is always available from its web site at
192L<http://www.eyrie.org/~eagle/software/podlators/>.  It is also part of the
193Perl core distribution as of 5.6.0.
194
195=head1 AUTHOR
196
197Joe Smith <Joe.Smith@inwap.com>, using the framework created by Russ Allbery
198<rra@stanford.edu>.
199
200=head1 COPYRIGHT AND LICENSE
201
202Copyright 2000 by Joe Smith <Joe.Smith@inwap.com>.
203Copyright 2001 by Russ Allbery <rra@stanford.edu>.
204
205This program is free software; you may redistribute it and/or modify it
206under the same terms as Perl itself.
207
208=cut
209