xref: /onnv-gate/usr/src/cmd/perl/5.8.4/distrib/lib/Pod/ParseLink.pm (revision 0:68f95e015346) 
1# Pod::ParseLink -- Parse an L<> formatting code in POD text.
2# $Id: ParseLink.pm,v 1.6 2002/07/15 05:46:00 eagle Exp $
3#
4# Copyright 2001 by Russ Allbery <rra@stanford.edu>
5#
6# This program is free software; you may redistribute it and/or modify it
7# under the same terms as Perl itself.
8#
9# This module implements parsing of the text of an L<> formatting code as
10# defined in perlpodspec.  It should be suitable for any POD formatter.  It
11# exports only one function, parselink(), which returns the five-item parse
12# defined in perlpodspec.
13#
14# Perl core hackers, please note that this module is also separately
15# maintained outside of the Perl core as part of the podlators.  Please send
16# me any patches at the address above in addition to sending them to the
17# standard Perl mailing lists.
18
19##############################################################################
20# Modules and declarations
21##############################################################################
22
23package Pod::ParseLink;
24
25require 5.004;
26
27use strict;
28use vars qw(@EXPORT @ISA $VERSION);
29
30use Exporter;
31@ISA    = qw(Exporter);
32@EXPORT = qw(parselink);
33
34# Don't use the CVS revision as the version, since this module is also in Perl
35# core and too many things could munge CVS magic revision strings.  This
36# number should ideally be the same as the CVS revision in podlators, however.
37$VERSION = 1.06;
38
39
40##############################################################################
41# Implementation
42##############################################################################
43
44# Parse the name and section portion of a link into a name and section.
45sub _parse_section {
46    my ($link) = @_;
47    $link =~ s/^\s+//;
48    $link =~ s/\s+$//;
49
50    # If the whole link is enclosed in quotes, interpret it all as a section
51    # even if it contains a slash.
52    return (undef, $1) if ($link =~ /^"\s*(.*?)\s*"$/);
53
54    # Split into page and section on slash, and then clean up quoting in the
55    # section.  If there is no section and the name contains spaces, also
56    # guess that it's an old section link.
57    my ($page, $section) = split (/\s*\/\s*/, $link, 2);
58    $section =~ s/^"\s*(.*?)\s*"$/$1/ if $section;
59    if ($page && $page =~ / / && !defined ($section)) {
60        $section = $page;
61        $page = undef;
62    } else {
63        $page = undef unless $page;
64        $section = undef unless $section;
65    }
66    return ($page, $section);
67}
68
69# Infer link text from the page and section.
70sub _infer_text {
71    my ($page, $section) = @_;
72    my $inferred;
73    if ($page && !$section) {
74        $inferred = $page;
75    } elsif (!$page && $section) {
76        $inferred = '"' . $section . '"';
77    } elsif ($page && $section) {
78        $inferred = '"' . $section . '" in ' . $page;
79    }
80    return $inferred;
81}
82
83# Given the contents of an L<> formatting code, parse it into the link text,
84# the possibly inferred link text, the name or URL, the section, and the type
85# of link (pod, man, or url).
86sub parselink {
87    my ($link) = @_;
88    $link =~ s/\s+/ /g;
89    if ($link =~ /\A\w+:[^:\s]\S*\Z/) {
90        return (undef, $link, $link, undef, 'url');
91    } else {
92        my $text;
93        if ($link =~ /\|/) {
94            ($text, $link) = split (/\|/, $link, 2);
95        }
96        my ($name, $section) = _parse_section ($link);
97        my $inferred = $text || _infer_text ($name, $section);
98        my $type = ($name && $name =~ /\(\S*\)/) ? 'man' : 'pod';
99        return ($text, $inferred, $name, $section, $type);
100    }
101}
102
103
104##############################################################################
105# Module return value and documentation
106##############################################################################
107
108# Ensure we evaluate to true.
1091;
110__END__
111
112=head1 NAME
113
114Pod::ParseLink - Parse an LE<lt>E<gt> formatting code in POD text
115
116=head1 SYNOPSIS
117
118    use Pod::ParseLink;
119    my ($text, $inferred, $name, $section, $type) = parselink ($link);
120
121=head1 DESCRIPTION
122
123This module only provides a single function, parselink(), which takes the
124text of an LE<lt>E<gt> formatting code and parses it.  It returns the anchor
125text for the link (if any was given), the anchor text possibly inferred from
126the name and section, the name or URL, the section if any, and the type of
127link.  The type will be one of 'url', 'pod', or 'man', indicating a URL, a
128link to a POD page, or a link to a Unix manual page.
129
130Parsing is implemented per L<perlpodspec>.  For backward compatibility,
131links where there is no section and name contains spaces, or links where the
132entirety of the link (except for the anchor text if given) is enclosed in
133double-quotes are interpreted as links to a section (LE<lt>/sectionE<gt>).
134
135The inferred anchor text is implemented per L<perlpodspec>:
136
137    L<name>         =>  L<name|name>
138    L</section>     =>  L<"section"|/section>
139    L<name/section> =>  L<"section" in name|name/section>
140
141The name may contain embedded EE<lt>E<gt> and ZE<lt>E<gt> formatting codes,
142and the section, anchor text, and inferred anchor text may contain any
143formatting codes.  Any double quotes around the section are removed as part
144of the parsing, as is any leading or trailing whitespace.
145
146If the text of the LE<lt>E<gt> escape is entirely enclosed in double quotes,
147it's interpreted as a link to a section for backwards compatibility.
148
149No attempt is made to resolve formatting codes.  This must be done after
150calling parselink (since EE<lt>E<gt> formatting codes can be used to escape
151characters that would otherwise be significant to the parser and resolving
152them before parsing would result in an incorrect parse of a formatting code
153like:
154
155    L<verticalE<verbar>barE<sol>slash>
156
157which should be interpreted as a link to the C<vertical|bar/slash> POD page
158and not as a link to the C<slash> section of the C<bar> POD page with an
159anchor text of C<vertical>.  Note that not only the anchor text will need to
160have formatting codes expanded, but so will the target of the link (to deal
161with EE<lt>E<gt> and ZE<lt>E<gt> formatting codes), and special handling of
162the section may be necessary depending on whether the translator wants to
163consider markup in sections to be significant when resolving links.  See
164L<perlpodspec> for more information.
165
166=head1 SEE ALSO
167
168L<Pod::Parser>
169
170The current version of this module is always available from its web site at
171L<http://www.eyrie.org/~eagle/software/podlators/>.
172
173=head1 AUTHOR
174
175Russ Allbery <rra@stanford.edu>.
176
177=head1 COPYRIGHT AND LICENSE
178
179Copyright 2001 by Russ Allbery <rra@stanford.edu>.
180
181This program is free software; you may redistribute it and/or modify it
182under the same terms as Perl itself.
183
184=cut
185