1Pod::Abstract(3) User Contributed Perl Documentation Pod::Abstract(3)
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6 Pod::Abstract - Abstract document tree for Perl POD documents
7
9 use Pod::Abstract;
10 use Pod::Abstract::BuildNode qw(node);
11 # Get all the first level headings, and put them in a verbatim block
13 # at the start of the document
14 my $pa = Pod::Abstract->load_filehandle(\*STDIN);
15 my @headings = $pa->select('/head1@heading');
16 my @headings_text = map { $_->pod } @headings;
17 my $headings_node = node->verbatim(join "\n",@headings_text);
18 $pa->unshift( node->cut );
20 $pa->unshift( $headings_node );
21 $pa->unshift( node->pod );
22 print $pa->pod;
24
26 POD::Abstract provides a means to load a POD (or POD compatible)
27 document without direct reference to it's syntax, and perform
28 manipulations on the abstract syntax tree.
29 This can be used to support additional features for POD, to format
31 output, to compile into alternative formats, etc.
32 WHY?
34 If you've ever asked yourself "What does Pod do for me?", this module
35 is intended to answer that question.
36 While Pod looks like a simple format, the specification calls for a
38 number of special cases to be handled, and that makes any software that
39 works on Pod as text more complex than it needs to be.
40 In addition to this, Pod does not lend itself to a natural structured
42 model. This makes it difficult to manipulate without damaging the
43 validity of the document.
44 Pod::Abstract solves these problems by loading the document into a
46 structured tree, and providing consistent traversal, searching,
47 manpulation and re-serialisation. Pod related utilities are easy to
48 write using Pod::Abstract.
49 The design goal of Pod::Abstract is to do the hard work for the
51 programmer - the library should work for you, and as such it should be
52 significantly easier than string mashing what you want out of a Pod
53 document.
54 PROCESSING MODEL
56 The intent with POD::Abstract is to provide a means to decorate a parse
57 tree, rather than manipulate text, to allow other software to add
58 features and functionality to POD based documenation systems.
59 If you wish to write modules that interact nicely with other
61 POD::Abstract modules, then you should provide a POD::Abstract ->
62 POD::Abstract translation. Leave any document element that your program
63 is not interested in directly untouched in the parse tree, and if you
64 have data that could be useful to other packages, decorate the parse
65 tree with that data even if you don't see any direct way to use it in
66 the output.
67 In this way, when you want one more feature for POD, rather than write
69 or fork a whole translator, a single inline "decorator" can be added.
70 The "paf" utility provides a good starting point, which also allows you
72 to hook in to an existing filter/transform library. Simply add a
73 "Pod::Abstract::Filter" class to the namespace and it should start
74 working as a "paf" command.
75 EXAMPLE
77 Suppose you are frustrated by the verbose list syntax used by regular
78 POD. You might reasonably want to define a simplified list format for
79 your own use, except POD formatters won't support it.
80 With Pod::Abstract you can write an inline filter to convert:
82 * item 1
84 * item 2
85 * item 3
86 into:
88 =over
90 =item *
92 item 1
94 =item *
96 item 2
98 =item *
100 item 3
102 =back
104 This transformation can be simply performed on the document tree. If
106 your formatter does not use Pod::Abstract, you can simply pipe out POD
107 and use a regular formatter. If your formatter supports Pod::Abstract
108 though, then you can feed in the syntax tree directly without having to
109 re-serialise and parse the document.
110 In addition to this, because the source document is still valid Pod,
112 you aren't breaking compatibility with regular perldoc just by making
113 Pod::Abstract transformations.
114 POD SUPPORT
116 Pod::Abstract aims to support all POD rules defined in perlpodspec
117 (even the ones I don't like), except for those directly related to
118 formatting output, or which cannot be implemented generically.
119
121 Pod::Abstract is comprised of:
122 • The parser, which loads a document tree for you.
124 You should access this through "Pod::Abstract", not directly
126 • The document tree, which is the root node you are given by the
128 parser. Calling pod on the root node should always give you back
129 your original document.
130 See Pod::Abstract::Node
132 • Pod::Abstract::Path, the node selection expression language. This
134 is generally called by doing "$node->select(PATH_EXP)".
135 Pod::Abstract::Path is the most complex and powerful component of
136 this module, and if you're not using it you should be. ;)
137 This allows you to ask questions like:
139 "In the first head1 that starts with "A", find me the head2
141 matching 'foo' with bold text somewhere in the preceding paragraph
142 or heading"
143 /head1[@heading=~{^A}](0)/head2[@heading=~{foo}i]<<head2 :paragraph[//:B]
145 You probably don't need anything that complex, but it's there if
147 you do.
148 • The node builder, Pod::Abstract::BuildNode
150
152 load_file
153 my $pa = Pod::Abstract->load_file( FILENAME );
154 Read the POD document in the named file. Returns the root node of the
156 document.
157 load_filehandle
159 my $pa = Pod::Abstract->load_file( FH );
160 Load a POD document from the provided filehandle reference. Returns the
162 root node of the document.
163 load_string
165 my $pa = Pod::Abstract->load_string( STRING );
166 Loads a POD document from a scalar string value. Returns the root node
168 of the document.
169
171 Ben Lilburne <bnej@mac.com>
172
174 Copyright (C) 2009 Ben Lilburne
175 This program is free software; you can redistribute it and/or modify it
177 under the same terms as Perl itself.
178perl v5.32.1 2021-01-27 Pod::Abstract(3)