source: for-distributions/trunk/bin/windows/perl/lib/Pod/Parser.pm@ 14489

Last change on this file since 14489 was 14489, checked in by oranfry, 17 years ago

upgrading to perl 5.8

File size: 62.6 KB
Line 
1#############################################################################
2# Pod/Parser.pm -- package which defines a base class for parsing POD docs.
3#
4# Copyright (C) 1996-2000 by Bradford Appleton. All rights reserved.
5# This file is part of "PodParser". PodParser is free software;
6# you can redistribute it and/or modify it under the same terms
7# as Perl itself.
8#############################################################################
9
10package Pod::Parser;
11
12use vars qw($VERSION);
13$VERSION = 1.32; ## Current version of this package
14require 5.005; ## requires this Perl version or later
15
16#############################################################################
17
18=head1 NAME
19
20Pod::Parser - base class for creating POD filters and translators
21
22=head1 SYNOPSIS
23
24 use Pod::Parser;
25
26 package MyParser;
27 @ISA = qw(Pod::Parser);
28
29 sub command {
30 my ($parser, $command, $paragraph, $line_num) = @_;
31 ## Interpret the command and its text; sample actions might be:
32 if ($command eq 'head1') { ... }
33 elsif ($command eq 'head2') { ... }
34 ## ... other commands and their actions
35 my $out_fh = $parser->output_handle();
36 my $expansion = $parser->interpolate($paragraph, $line_num);
37 print $out_fh $expansion;
38 }
39
40 sub verbatim {
41 my ($parser, $paragraph, $line_num) = @_;
42 ## Format verbatim paragraph; sample actions might be:
43 my $out_fh = $parser->output_handle();
44 print $out_fh $paragraph;
45 }
46
47 sub textblock {
48 my ($parser, $paragraph, $line_num) = @_;
49 ## Translate/Format this block of text; sample actions might be:
50 my $out_fh = $parser->output_handle();
51 my $expansion = $parser->interpolate($paragraph, $line_num);
52 print $out_fh $expansion;
53 }
54
55 sub interior_sequence {
56 my ($parser, $seq_command, $seq_argument) = @_;
57 ## Expand an interior sequence; sample actions might be:
58 return "*$seq_argument*" if ($seq_command eq 'B');
59 return "`$seq_argument'" if ($seq_command eq 'C');
60 return "_${seq_argument}_'" if ($seq_command eq 'I');
61 ## ... other sequence commands and their resulting text
62 }
63
64 package main;
65
66 ## Create a parser object and have it parse file whose name was
67 ## given on the command-line (use STDIN if no files were given).
68 $parser = new MyParser();
69 $parser->parse_from_filehandle(\*STDIN) if (@ARGV == 0);
70 for (@ARGV) { $parser->parse_from_file($_); }
71
72=head1 REQUIRES
73
74perl5.005, Pod::InputObjects, Exporter, Symbol, Carp
75
76=head1 EXPORTS
77
78Nothing.
79
80=head1 DESCRIPTION
81
82B<Pod::Parser> is a base class for creating POD filters and translators.
83It handles most of the effort involved with parsing the POD sections
84from an input stream, leaving subclasses free to be concerned only with
85performing the actual translation of text.
86
87B<Pod::Parser> parses PODs, and makes method calls to handle the various
88components of the POD. Subclasses of B<Pod::Parser> override these methods
89to translate the POD into whatever output format they desire.
90
91=head1 QUICK OVERVIEW
92
93To create a POD filter for translating POD documentation into some other
94format, you create a subclass of B<Pod::Parser> which typically overrides
95just the base class implementation for the following methods:
96
97=over 2
98
99=item *
100
101B<command()>
102
103=item *
104
105B<verbatim()>
106
107=item *
108
109B<textblock()>
110
111=item *
112
113B<interior_sequence()>
114
115=back
116
117You may also want to override the B<begin_input()> and B<end_input()>
118methods for your subclass (to perform any needed per-file and/or
119per-document initialization or cleanup).
120
121If you need to perform any preprocesssing of input before it is parsed
122you may want to override one or more of B<preprocess_line()> and/or
123B<preprocess_paragraph()>.
124
125Sometimes it may be necessary to make more than one pass over the input
126files. If this is the case you have several options. You can make the
127first pass using B<Pod::Parser> and override your methods to store the
128intermediate results in memory somewhere for the B<end_pod()> method to
129process. You could use B<Pod::Parser> for several passes with an
130appropriate state variable to control the operation for each pass. If
131your input source can't be reset to start at the beginning, you can
132store it in some other structure as a string or an array and have that
133structure implement a B<getline()> method (which is all that
134B<parse_from_filehandle()> uses to read input).
135
136Feel free to add any member data fields you need to keep track of things
137like current font, indentation, horizontal or vertical position, or
138whatever else you like. Be sure to read L<"PRIVATE METHODS AND DATA">
139to avoid name collisions.
140
141For the most part, the B<Pod::Parser> base class should be able to
142do most of the input parsing for you and leave you free to worry about
143how to intepret the commands and translate the result.
144
145Note that all we have described here in this quick overview is the
146simplest most straightforward use of B<Pod::Parser> to do stream-based
147parsing. It is also possible to use the B<Pod::Parser::parse_text> function
148to do more sophisticated tree-based parsing. See L<"TREE-BASED PARSING">.
149
150=head1 PARSING OPTIONS
151
152A I<parse-option> is simply a named option of B<Pod::Parser> with a
153value that corresponds to a certain specified behavior. These various
154behaviors of B<Pod::Parser> may be enabled/disabled by setting
155or unsetting one or more I<parse-options> using the B<parseopts()> method.
156The set of currently accepted parse-options is as follows:
157
158=over 3
159
160=item B<-want_nonPODs> (default: unset)
161
162Normally (by default) B<Pod::Parser> will only provide access to
163the POD sections of the input. Input paragraphs that are not part
164of the POD-format documentation are not made available to the caller
165(not even using B<preprocess_paragraph()>). Setting this option to a
166non-empty, non-zero value will allow B<preprocess_paragraph()> to see
167non-POD sections of the input as well as POD sections. The B<cutting()>
168method can be used to determine if the corresponding paragraph is a POD
169paragraph, or some other input paragraph.
170
171=item B<-process_cut_cmd> (default: unset)
172
173Normally (by default) B<Pod::Parser> handles the C<=cut> POD directive
174by itself and does not pass it on to the caller for processing. Setting
175this option to a non-empty, non-zero value will cause B<Pod::Parser> to
176pass the C<=cut> directive to the caller just like any other POD command
177(and hence it may be processed by the B<command()> method).
178
179B<Pod::Parser> will still interpret the C<=cut> directive to mean that
180"cutting mode" has been (re)entered, but the caller will get a chance
181to capture the actual C<=cut> paragraph itself for whatever purpose
182it desires.
183
184=item B<-warnings> (default: unset)
185
186Normally (by default) B<Pod::Parser> recognizes a bare minimum of
187pod syntax errors and warnings and issues diagnostic messages
188for errors, but not for warnings. (Use B<Pod::Checker> to do more
189thorough checking of POD syntax.) Setting this option to a non-empty,
190non-zero value will cause B<Pod::Parser> to issue diagnostics for
191the few warnings it recognizes as well as the errors.
192
193=back
194
195Please see L<"parseopts()"> for a complete description of the interface
196for the setting and unsetting of parse-options.
197
198=cut
199
200#############################################################################
201
202use vars qw(@ISA);
203use strict;
204#use diagnostics;
205use Pod::InputObjects;
206use Carp;
207use Exporter;
208BEGIN {
209 if ($] < 5.6) {
210 require Symbol;
211 import Symbol;
212 }
213}
214@ISA = qw(Exporter);
215
216## These "variables" are used as local "glob aliases" for performance
217use vars qw(%myData %myOpts @input_stack);
218
219#############################################################################
220
221=head1 RECOMMENDED SUBROUTINE/METHOD OVERRIDES
222
223B<Pod::Parser> provides several methods which most subclasses will probably
224want to override. These methods are as follows:
225
226=cut
227
228##---------------------------------------------------------------------------
229
230=head1 B<command()>
231
232 $parser->command($cmd,$text,$line_num,$pod_para);
233
234This method should be overridden by subclasses to take the appropriate
235action when a POD command paragraph (denoted by a line beginning with
236"=") is encountered. When such a POD directive is seen in the input,
237this method is called and is passed:
238
239=over 3
240
241=item C<$cmd>
242
243the name of the command for this POD paragraph
244
245=item C<$text>
246
247the paragraph text for the given POD paragraph command.
248
249=item C<$line_num>
250
251the line-number of the beginning of the paragraph
252
253=item C<$pod_para>
254
255a reference to a C<Pod::Paragraph> object which contains further
256information about the paragraph command (see L<Pod::InputObjects>
257for details).
258
259=back
260
261B<Note> that this method I<is> called for C<=pod> paragraphs.
262
263The base class implementation of this method simply treats the raw POD
264command as normal block of paragraph text (invoking the B<textblock()>
265method with the command paragraph).
266
267=cut
268
269sub command {
270 my ($self, $cmd, $text, $line_num, $pod_para) = @_;
271 ## Just treat this like a textblock
272 $self->textblock($pod_para->raw_text(), $line_num, $pod_para);
273}
274
275##---------------------------------------------------------------------------
276
277=head1 B<verbatim()>
278
279 $parser->verbatim($text,$line_num,$pod_para);
280
281This method may be overridden by subclasses to take the appropriate
282action when a block of verbatim text is encountered. It is passed the
283following parameters:
284
285=over 3
286
287=item C<$text>
288
289the block of text for the verbatim paragraph
290
291=item C<$line_num>
292
293the line-number of the beginning of the paragraph
294
295=item C<$pod_para>
296
297a reference to a C<Pod::Paragraph> object which contains further
298information about the paragraph (see L<Pod::InputObjects>
299for details).
300
301=back
302
303The base class implementation of this method simply prints the textblock
304(unmodified) to the output filehandle.
305
306=cut
307
308sub verbatim {
309 my ($self, $text, $line_num, $pod_para) = @_;
310 my $out_fh = $self->{_OUTPUT};
311 print $out_fh $text;
312}
313
314##---------------------------------------------------------------------------
315
316=head1 B<textblock()>
317
318 $parser->textblock($text,$line_num,$pod_para);
319
320This method may be overridden by subclasses to take the appropriate
321action when a normal block of POD text is encountered (although the base
322class method will usually do what you want). It is passed the following
323parameters:
324
325=over 3
326
327=item C<$text>
328
329the block of text for the a POD paragraph
330
331=item C<$line_num>
332
333the line-number of the beginning of the paragraph
334
335=item C<$pod_para>
336
337a reference to a C<Pod::Paragraph> object which contains further
338information about the paragraph (see L<Pod::InputObjects>
339for details).
340
341=back
342
343In order to process interior sequences, subclasses implementations of
344this method will probably want to invoke either B<interpolate()> or
345B<parse_text()>, passing it the text block C<$text>, and the corresponding
346line number in C<$line_num>, and then perform any desired processing upon
347the returned result.
348
349The base class implementation of this method simply prints the text block
350as it occurred in the input stream).
351
352=cut
353
354sub textblock {
355 my ($self, $text, $line_num, $pod_para) = @_;
356 my $out_fh = $self->{_OUTPUT};
357 print $out_fh $self->interpolate($text, $line_num);
358}
359
360##---------------------------------------------------------------------------
361
362=head1 B<interior_sequence()>
363
364 $parser->interior_sequence($seq_cmd,$seq_arg,$pod_seq);
365
366This method should be overridden by subclasses to take the appropriate
367action when an interior sequence is encountered. An interior sequence is
368an embedded command within a block of text which appears as a command
369name (usually a single uppercase character) followed immediately by a
370string of text which is enclosed in angle brackets. This method is
371passed the sequence command C<$seq_cmd> and the corresponding text
372C<$seq_arg>. It is invoked by the B<interpolate()> method for each interior
373sequence that occurs in the string that it is passed. It should return
374the desired text string to be used in place of the interior sequence.
375The C<$pod_seq> argument is a reference to a C<Pod::InteriorSequence>
376object which contains further information about the interior sequence.
377Please see L<Pod::InputObjects> for details if you need to access this
378additional information.
379
380Subclass implementations of this method may wish to invoke the
381B<nested()> method of C<$pod_seq> to see if it is nested inside
382some other interior-sequence (and if so, which kind).
383
384The base class implementation of the B<interior_sequence()> method
385simply returns the raw text of the interior sequence (as it occurred
386in the input) to the caller.
387
388=cut
389
390sub interior_sequence {
391 my ($self, $seq_cmd, $seq_arg, $pod_seq) = @_;
392 ## Just return the raw text of the interior sequence
393 return $pod_seq->raw_text();
394}
395
396#############################################################################
397
398=head1 OPTIONAL SUBROUTINE/METHOD OVERRIDES
399
400B<Pod::Parser> provides several methods which subclasses may want to override
401to perform any special pre/post-processing. These methods do I<not> have to
402be overridden, but it may be useful for subclasses to take advantage of them.
403
404=cut
405
406##---------------------------------------------------------------------------
407
408=head1 B<new()>
409
410 my $parser = Pod::Parser->new();
411
412This is the constructor for B<Pod::Parser> and its subclasses. You
413I<do not> need to override this method! It is capable of constructing
414subclass objects as well as base class objects, provided you use
415any of the following constructor invocation styles:
416
417 my $parser1 = MyParser->new();
418 my $parser2 = new MyParser();
419 my $parser3 = $parser2->new();
420
421where C<MyParser> is some subclass of B<Pod::Parser>.
422
423Using the syntax C<MyParser::new()> to invoke the constructor is I<not>
424recommended, but if you insist on being able to do this, then the
425subclass I<will> need to override the B<new()> constructor method. If
426you do override the constructor, you I<must> be sure to invoke the
427B<initialize()> method of the newly blessed object.
428
429Using any of the above invocations, the first argument to the
430constructor is always the corresponding package name (or object
431reference). No other arguments are required, but if desired, an
432associative array (or hash-table) my be passed to the B<new()>
433constructor, as in:
434
435 my $parser1 = MyParser->new( MYDATA => $value1, MOREDATA => $value2 );
436 my $parser2 = new MyParser( -myflag => 1 );
437
438All arguments passed to the B<new()> constructor will be treated as
439key/value pairs in a hash-table. The newly constructed object will be
440initialized by copying the contents of the given hash-table (which may
441have been empty). The B<new()> constructor for this class and all of its
442subclasses returns a blessed reference to the initialized object (hash-table).
443
444=cut
445
446sub new {
447 ## Determine if we were called via an object-ref or a classname
448 my $this = shift;
449 my $class = ref($this) || $this;
450 ## Any remaining arguments are treated as initial values for the
451 ## hash that is used to represent this object.
452 my %params = @_;
453 my $self = { %params };
454 ## Bless ourselves into the desired class and perform any initialization
455 bless $self, $class;
456 $self->initialize();
457 return $self;
458}
459
460##---------------------------------------------------------------------------
461
462=head1 B<initialize()>
463
464 $parser->initialize();
465
466This method performs any necessary object initialization. It takes no
467arguments (other than the object instance of course, which is typically
468copied to a local variable named C<$self>). If subclasses override this
469method then they I<must> be sure to invoke C<$self-E<gt>SUPER::initialize()>.
470
471=cut
472
473sub initialize {
474 #my $self = shift;
475 #return;
476}
477
478##---------------------------------------------------------------------------
479
480=head1 B<begin_pod()>
481
482 $parser->begin_pod();
483
484This method is invoked at the beginning of processing for each POD
485document that is encountered in the input. Subclasses should override
486this method to perform any per-document initialization.
487
488=cut
489
490sub begin_pod {
491 #my $self = shift;
492 #return;
493}
494
495##---------------------------------------------------------------------------
496
497=head1 B<begin_input()>
498
499 $parser->begin_input();
500
501This method is invoked by B<parse_from_filehandle()> immediately I<before>
502processing input from a filehandle. The base class implementation does
503nothing, however, subclasses may override it to perform any per-file
504initializations.
505
506Note that if multiple files are parsed for a single POD document
507(perhaps the result of some future C<=include> directive) this method
508is invoked for every file that is parsed. If you wish to perform certain
509initializations once per document, then you should use B<begin_pod()>.
510
511=cut
512
513sub begin_input {
514 #my $self = shift;
515 #return;
516}
517
518##---------------------------------------------------------------------------
519
520=head1 B<end_input()>
521
522 $parser->end_input();
523
524This method is invoked by B<parse_from_filehandle()> immediately I<after>
525processing input from a filehandle. The base class implementation does
526nothing, however, subclasses may override it to perform any per-file
527cleanup actions.
528
529Please note that if multiple files are parsed for a single POD document
530(perhaps the result of some kind of C<=include> directive) this method
531is invoked for every file that is parsed. If you wish to perform certain
532cleanup actions once per document, then you should use B<end_pod()>.
533
534=cut
535
536sub end_input {
537 #my $self = shift;
538 #return;
539}
540
541##---------------------------------------------------------------------------
542
543=head1 B<end_pod()>
544
545 $parser->end_pod();
546
547This method is invoked at the end of processing for each POD document
548that is encountered in the input. Subclasses should override this method
549to perform any per-document finalization.
550
551=cut
552
553sub end_pod {
554 #my $self = shift;
555 #return;
556}
557
558##---------------------------------------------------------------------------
559
560=head1 B<preprocess_line()>
561
562 $textline = $parser->preprocess_line($text, $line_num);
563
564This method should be overridden by subclasses that wish to perform
565any kind of preprocessing for each I<line> of input (I<before> it has
566been determined whether or not it is part of a POD paragraph). The
567parameter C<$text> is the input line; and the parameter C<$line_num> is
568the line number of the corresponding text line.
569
570The value returned should correspond to the new text to use in its
571place. If the empty string or an undefined value is returned then no
572further processing will be performed for this line.
573
574Please note that the B<preprocess_line()> method is invoked I<before>
575the B<preprocess_paragraph()> method. After all (possibly preprocessed)
576lines in a paragraph have been assembled together and it has been
577determined that the paragraph is part of the POD documentation from one
578of the selected sections, then B<preprocess_paragraph()> is invoked.
579
580The base class implementation of this method returns the given text.
581
582=cut
583
584sub preprocess_line {
585 my ($self, $text, $line_num) = @_;
586 return $text;
587}
588
589##---------------------------------------------------------------------------
590
591=head1 B<preprocess_paragraph()>
592
593 $textblock = $parser->preprocess_paragraph($text, $line_num);
594
595This method should be overridden by subclasses that wish to perform any
596kind of preprocessing for each block (paragraph) of POD documentation
597that appears in the input stream. The parameter C<$text> is the POD
598paragraph from the input file; and the parameter C<$line_num> is the
599line number for the beginning of the corresponding paragraph.
600
601The value returned should correspond to the new text to use in its
602place If the empty string is returned or an undefined value is
603returned, then the given C<$text> is ignored (not processed).
604
605This method is invoked after gathering up all the lines in a paragraph
606and after determining the cutting state of the paragraph,
607but before trying to further parse or interpret them. After
608B<preprocess_paragraph()> returns, the current cutting state (which
609is returned by C<$self-E<gt>cutting()>) is examined. If it evaluates
610to true then input text (including the given C<$text>) is cut (not
611processed) until the next POD directive is encountered.
612
613Please note that the B<preprocess_line()> method is invoked I<before>
614the B<preprocess_paragraph()> method. After all (possibly preprocessed)
615lines in a paragraph have been assembled together and either it has been
616determined that the paragraph is part of the POD documentation from one
617of the selected sections or the C<-want_nonPODs> option is true,
618then B<preprocess_paragraph()> is invoked.
619
620The base class implementation of this method returns the given text.
621
622=cut
623
624sub preprocess_paragraph {
625 my ($self, $text, $line_num) = @_;
626 return $text;
627}
628
629#############################################################################
630
631=head1 METHODS FOR PARSING AND PROCESSING
632
633B<Pod::Parser> provides several methods to process input text. These
634methods typically won't need to be overridden (and in some cases they
635can't be overridden), but subclasses may want to invoke them to exploit
636their functionality.
637
638=cut
639
640##---------------------------------------------------------------------------
641
642=head1 B<parse_text()>
643
644 $ptree1 = $parser->parse_text($text, $line_num);
645 $ptree2 = $parser->parse_text({%opts}, $text, $line_num);
646 $ptree3 = $parser->parse_text(\%opts, $text, $line_num);
647
648This method is useful if you need to perform your own interpolation
649of interior sequences and can't rely upon B<interpolate> to expand
650them in simple bottom-up order.
651
652The parameter C<$text> is a string or block of text to be parsed
653for interior sequences; and the parameter C<$line_num> is the
654line number curresponding to the beginning of C<$text>.
655
656B<parse_text()> will parse the given text into a parse-tree of "nodes."
657and interior-sequences. Each "node" in the parse tree is either a
658text-string, or a B<Pod::InteriorSequence>. The result returned is a
659parse-tree of type B<Pod::ParseTree>. Please see L<Pod::InputObjects>
660for more information about B<Pod::InteriorSequence> and B<Pod::ParseTree>.
661
662If desired, an optional hash-ref may be specified as the first argument
663to customize certain aspects of the parse-tree that is created and
664returned. The set of recognized option keywords are:
665
666=over 3
667
668=item B<-expand_seq> =E<gt> I<code-ref>|I<method-name>
669
670Normally, the parse-tree returned by B<parse_text()> will contain an
671unexpanded C<Pod::InteriorSequence> object for each interior-sequence
672encountered. Specifying B<-expand_seq> tells B<parse_text()> to "expand"
673every interior-sequence it sees by invoking the referenced function
674(or named method of the parser object) and using the return value as the
675expanded result.
676
677If a subroutine reference was given, it is invoked as:
678
679 &$code_ref( $parser, $sequence )
680
681and if a method-name was given, it is invoked as:
682
683 $parser->method_name( $sequence )
684
685where C<$parser> is a reference to the parser object, and C<$sequence>
686is a reference to the interior-sequence object.
687[I<NOTE>: If the B<interior_sequence()> method is specified, then it is
688invoked according to the interface specified in L<"interior_sequence()">].
689
690=item B<-expand_text> =E<gt> I<code-ref>|I<method-name>
691
692Normally, the parse-tree returned by B<parse_text()> will contain a
693text-string for each contiguous sequence of characters outside of an
694interior-sequence. Specifying B<-expand_text> tells B<parse_text()> to
695"preprocess" every such text-string it sees by invoking the referenced
696function (or named method of the parser object) and using the return value
697as the preprocessed (or "expanded") result. [Note that if the result is
698an interior-sequence, then it will I<not> be expanded as specified by the
699B<-expand_seq> option; Any such recursive expansion needs to be handled by
700the specified callback routine.]
701
702If a subroutine reference was given, it is invoked as:
703
704 &$code_ref( $parser, $text, $ptree_node )
705
706and if a method-name was given, it is invoked as:
707
708 $parser->method_name( $text, $ptree_node )
709
710where C<$parser> is a reference to the parser object, C<$text> is the
711text-string encountered, and C<$ptree_node> is a reference to the current
712node in the parse-tree (usually an interior-sequence object or else the
713top-level node of the parse-tree).
714
715=item B<-expand_ptree> =E<gt> I<code-ref>|I<method-name>
716
717Rather than returning a C<Pod::ParseTree>, pass the parse-tree as an
718argument to the referenced subroutine (or named method of the parser
719object) and return the result instead of the parse-tree object.
720
721If a subroutine reference was given, it is invoked as:
722
723 &$code_ref( $parser, $ptree )
724
725and if a method-name was given, it is invoked as:
726
727 $parser->method_name( $ptree )
728
729where C<$parser> is a reference to the parser object, and C<$ptree>
730is a reference to the parse-tree object.
731
732=back
733
734=cut
735
736sub parse_text {
737 my $self = shift;
738 local $_ = '';
739
740 ## Get options and set any defaults
741 my %opts = (ref $_[0]) ? %{ shift() } : ();
742 my $expand_seq = $opts{'-expand_seq'} || undef;
743 my $expand_text = $opts{'-expand_text'} || undef;
744 my $expand_ptree = $opts{'-expand_ptree'} || undef;
745
746 my $text = shift;
747 my $line = shift;
748 my $file = $self->input_file();
749 my $cmd = "";
750
751 ## Convert method calls into closures, for our convenience
752 my $xseq_sub = $expand_seq;
753 my $xtext_sub = $expand_text;
754 my $xptree_sub = $expand_ptree;
755 if (defined $expand_seq and $expand_seq eq 'interior_sequence') {
756 ## If 'interior_sequence' is the method to use, we have to pass
757 ## more than just the sequence object, we also need to pass the
758 ## sequence name and text.
759 $xseq_sub = sub {
760 my ($self, $iseq) = @_;
761 my $args = join("", $iseq->parse_tree->children);
762 return $self->interior_sequence($iseq->name, $args, $iseq);
763 };
764 }
765 ref $xseq_sub or $xseq_sub = sub { shift()->$expand_seq(@_) };
766 ref $xtext_sub or $xtext_sub = sub { shift()->$expand_text(@_) };
767 ref $xptree_sub or $xptree_sub = sub { shift()->$expand_ptree(@_) };
768
769 ## Keep track of the "current" interior sequence, and maintain a stack
770 ## of "in progress" sequences.
771 ##
772 ## NOTE that we push our own "accumulator" at the very beginning of the
773 ## stack. It's really a parse-tree, not a sequence; but it implements
774 ## the methods we need so we can use it to gather-up all the sequences
775 ## and strings we parse. Thus, by the end of our parsing, it should be
776 ## the only thing left on our stack and all we have to do is return it!
777 ##
778 my $seq = Pod::ParseTree->new();
779 my @seq_stack = ($seq);
780 my ($ldelim, $rdelim) = ('', '');
781
782 ## Iterate over all sequence starts text (NOTE: split with
783 ## capturing parens keeps the delimiters)
784 $_ = $text;
785 my @tokens = split /([A-Z]<(?:<+\s)?)/;
786 while ( @tokens ) {
787 $_ = shift @tokens;
788 ## Look for the beginning of a sequence
789 if ( /^([A-Z])(<(?:<+\s)?)$/ ) {
790 ## Push a new sequence onto the stack of those "in-progress"
791 my $ldelim_orig;
792 ($cmd, $ldelim_orig) = ($1, $2);
793 ($ldelim = $ldelim_orig) =~ s/\s+$//;
794 ($rdelim = $ldelim) =~ tr/</>/;
795 $seq = Pod::InteriorSequence->new(
796 -name => $cmd,
797 -ldelim => $ldelim_orig, -rdelim => $rdelim,
798 -file => $file, -line => $line
799 );
800 (@seq_stack > 1) and $seq->nested($seq_stack[-1]);
801 push @seq_stack, $seq;
802 }
803 ## Look for sequence ending
804 elsif ( @seq_stack > 1 ) {
805 ## Make sure we match the right kind of closing delimiter
806 my ($seq_end, $post_seq) = ("", "");
807 if ( ($ldelim eq '<' and /\A(.*?)(>)/s)
808 or /\A(.*?)(\s+$rdelim)/s )
809 {
810 ## Found end-of-sequence, capture the interior and the
811 ## closing the delimiter, and put the rest back on the
812 ## token-list
813 $post_seq = substr($_, length($1) + length($2));
814 ($_, $seq_end) = ($1, $2);
815 (length $post_seq) and unshift @tokens, $post_seq;
816 }
817 if (length) {
818 ## In the middle of a sequence, append this text to it, and
819 ## dont forget to "expand" it if that's what the caller wanted
820 $seq->append($expand_text ? &$xtext_sub($self,$_,$seq) : $_);
821 $_ .= $seq_end;
822 }
823 if (length $seq_end) {
824 ## End of current sequence, record terminating delimiter
825 $seq->rdelim($seq_end);
826 ## Pop it off the stack of "in progress" sequences
827 pop @seq_stack;
828 ## Append result to its parent in current parse tree
829 $seq_stack[-1]->append($expand_seq ? &$xseq_sub($self,$seq)
830 : $seq);
831 ## Remember the current cmd-name and left-delimiter
832 if(@seq_stack > 1) {
833 $cmd = $seq_stack[-1]->name;
834 $ldelim = $seq_stack[-1]->ldelim;
835 $rdelim = $seq_stack[-1]->rdelim;
836 } else {
837 $cmd = $ldelim = $rdelim = '';
838 }
839 }
840 }
841 elsif (length) {
842 ## In the middle of a sequence, append this text to it, and
843 ## dont forget to "expand" it if that's what the caller wanted
844 $seq->append($expand_text ? &$xtext_sub($self,$_,$seq) : $_);
845 }
846 ## Keep track of line count
847 $line += tr/\n//;
848 ## Remember the "current" sequence
849 $seq = $seq_stack[-1];
850 }
851
852 ## Handle unterminated sequences
853 my $errorsub = (@seq_stack > 1) ? $self->errorsub() : undef;
854 while (@seq_stack > 1) {
855 ($cmd, $file, $line) = ($seq->name, $seq->file_line);
856 $ldelim = $seq->ldelim;
857 ($rdelim = $ldelim) =~ tr/</>/;
858 $rdelim =~ s/^(\S+)(\s*)$/$2$1/;
859 pop @seq_stack;
860 my $errmsg = "*** ERROR: unterminated ${cmd}${ldelim}...${rdelim}".
861 " at line $line in file $file\n";
862 (ref $errorsub) and &{$errorsub}($errmsg)
863 or (defined $errorsub) and $self->$errorsub($errmsg)
864 or warn($errmsg);
865 $seq_stack[-1]->append($expand_seq ? &$xseq_sub($self,$seq) : $seq);
866 $seq = $seq_stack[-1];
867 }
868
869 ## Return the resulting parse-tree
870 my $ptree = (pop @seq_stack)->parse_tree;
871 return $expand_ptree ? &$xptree_sub($self, $ptree) : $ptree;
872}
873
874##---------------------------------------------------------------------------
875
876=head1 B<interpolate()>
877
878 $textblock = $parser->interpolate($text, $line_num);
879
880This method translates all text (including any embedded interior sequences)
881in the given text string C<$text> and returns the interpolated result. The
882parameter C<$line_num> is the line number corresponding to the beginning
883of C<$text>.
884
885B<interpolate()> merely invokes a private method to recursively expand
886nested interior sequences in bottom-up order (innermost sequences are
887expanded first). If there is a need to expand nested sequences in
888some alternate order, use B<parse_text> instead.
889
890=cut
891
892sub interpolate {
893 my($self, $text, $line_num) = @_;
894 my %parse_opts = ( -expand_seq => 'interior_sequence' );
895 my $ptree = $self->parse_text( \%parse_opts, $text, $line_num );
896 return join "", $ptree->children();
897}
898
899##---------------------------------------------------------------------------
900
901=begin __PRIVATE__
902
903=head1 B<parse_paragraph()>
904
905 $parser->parse_paragraph($text, $line_num);
906
907This method takes the text of a POD paragraph to be processed, along
908with its corresponding line number, and invokes the appropriate method
909(one of B<command()>, B<verbatim()>, or B<textblock()>).
910
911For performance reasons, this method is invoked directly without any
912dynamic lookup; Hence subclasses may I<not> override it!
913
914=end __PRIVATE__
915
916=cut
917
918sub parse_paragraph {
919 my ($self, $text, $line_num) = @_;
920 local *myData = $self; ## alias to avoid deref-ing overhead
921 local *myOpts = ($myData{_PARSEOPTS} ||= {}); ## get parse-options
922 local $_;
923
924 ## See if we want to preprocess nonPOD paragraphs as well as POD ones.
925 my $wantNonPods = $myOpts{'-want_nonPODs'};
926
927 ## Update cutting status
928 $myData{_CUTTING} = 0 if $text =~ /^={1,2}\S/;
929
930 ## Perform any desired preprocessing if we wanted it this early
931 $wantNonPods and $text = $self->preprocess_paragraph($text, $line_num);
932
933 ## Ignore up until next POD directive if we are cutting
934 return if $myData{_CUTTING};
935
936 ## Now we know this is block of text in a POD section!
937
938 ##-----------------------------------------------------------------
939 ## This is a hook (hack ;-) for Pod::Select to do its thing without
940 ## having to override methods, but also without Pod::Parser assuming
941 ## $self is an instance of Pod::Select (if the _SELECTED_SECTIONS
942 ## field exists then we assume there is an is_selected() method for
943 ## us to invoke (calling $self->can('is_selected') could verify this
944 ## but that is more overhead than I want to incur)
945 ##-----------------------------------------------------------------
946
947 ## Ignore this block if it isnt in one of the selected sections
948 if (exists $myData{_SELECTED_SECTIONS}) {
949 $self->is_selected($text) or return ($myData{_CUTTING} = 1);
950 }
951
952 ## If we havent already, perform any desired preprocessing and
953 ## then re-check the "cutting" state
954 unless ($wantNonPods) {
955 $text = $self->preprocess_paragraph($text, $line_num);
956 return 1 unless ((defined $text) and (length $text));
957 return 1 if ($myData{_CUTTING});
958 }
959
960 ## Look for one of the three types of paragraphs
961 my ($pfx, $cmd, $arg, $sep) = ('', '', '', '');
962 my $pod_para = undef;
963 if ($text =~ /^(={1,2})(?=\S)/) {
964 ## Looks like a command paragraph. Capture the command prefix used
965 ## ("=" or "=="), as well as the command-name, its paragraph text,
966 ## and whatever sequence of characters was used to separate them
967 $pfx = $1;
968 $_ = substr($text, length $pfx);
969 ($cmd, $sep, $text) = split /(\s+)/, $_, 2;
970 ## If this is a "cut" directive then we dont need to do anything
971 ## except return to "cutting" mode.
972 if ($cmd eq 'cut') {
973 $myData{_CUTTING} = 1;
974 return unless $myOpts{'-process_cut_cmd'};
975 }
976 }
977 ## Save the attributes indicating how the command was specified.
978 $pod_para = new Pod::Paragraph(
979 -name => $cmd,
980 -text => $text,
981 -prefix => $pfx,
982 -separator => $sep,
983 -file => $myData{_INFILE},
984 -line => $line_num
985 );
986 # ## Invoke appropriate callbacks
987 # if (exists $myData{_CALLBACKS}) {
988 # ## Look through the callback list, invoke callbacks,
989 # ## then see if we need to do the default actions
990 # ## (invoke_callbacks will return true if we do).
991 # return 1 unless $self->invoke_callbacks($cmd, $text, $line_num, $pod_para);
992 # }
993 if (length $cmd) {
994 ## A command paragraph
995 $self->command($cmd, $text, $line_num, $pod_para);
996 }
997 elsif ($text =~ /^\s+/) {
998 ## Indented text - must be a verbatim paragraph
999 $self->verbatim($text, $line_num, $pod_para);
1000 }
1001 else {
1002 ## Looks like an ordinary block of text
1003 $self->textblock($text, $line_num, $pod_para);
1004 }
1005 return 1;
1006}
1007
1008##---------------------------------------------------------------------------
1009
1010=head1 B<parse_from_filehandle()>
1011
1012 $parser->parse_from_filehandle($in_fh,$out_fh);
1013
1014This method takes an input filehandle (which is assumed to already be
1015opened for reading) and reads the entire input stream looking for blocks
1016(paragraphs) of POD documentation to be processed. If no first argument
1017is given the default input filehandle C<STDIN> is used.
1018
1019The C<$in_fh> parameter may be any object that provides a B<getline()>
1020method to retrieve a single line of input text (hence, an appropriate
1021wrapper object could be used to parse PODs from a single string or an
1022array of strings).
1023
1024Using C<$in_fh-E<gt>getline()>, input is read line-by-line and assembled
1025into paragraphs or "blocks" (which are separated by lines containing
1026nothing but whitespace). For each block of POD documentation
1027encountered it will invoke a method to parse the given paragraph.
1028
1029If a second argument is given then it should correspond to a filehandle where
1030output should be sent (otherwise the default output filehandle is
1031C<STDOUT> if no output filehandle is currently in use).
1032
1033B<NOTE:> For performance reasons, this method caches the input stream at
1034the top of the stack in a local variable. Any attempts by clients to
1035change the stack contents during processing when in the midst executing
1036of this method I<will not affect> the input stream used by the current
1037invocation of this method.
1038
1039This method does I<not> usually need to be overridden by subclasses.
1040
1041=cut
1042
1043sub parse_from_filehandle {
1044 my $self = shift;
1045 my %opts = (ref $_[0] eq 'HASH') ? %{ shift() } : ();
1046 my ($in_fh, $out_fh) = @_;
1047 $in_fh = \*STDIN unless ($in_fh);
1048 local *myData = $self; ## alias to avoid deref-ing overhead
1049 local *myOpts = ($myData{_PARSEOPTS} ||= {}); ## get parse-options
1050 local $_;
1051
1052 ## Put this stream at the top of the stack and do beginning-of-input
1053 ## processing. NOTE that $in_fh might be reset during this process.
1054 my $topstream = $self->_push_input_stream($in_fh, $out_fh);
1055 (exists $opts{-cutting}) and $self->cutting( $opts{-cutting} );
1056
1057 ## Initialize line/paragraph
1058 my ($textline, $paragraph) = ('', '');
1059 my ($nlines, $plines) = (0, 0);
1060
1061 ## Use <$fh> instead of $fh->getline where possible (for speed)
1062 $_ = ref $in_fh;
1063 my $tied_fh = (/^(?:GLOB|FileHandle|IO::\w+)$/ or tied $in_fh);
1064
1065 ## Read paragraphs line-by-line
1066 while (defined ($textline = $tied_fh ? <$in_fh> : $in_fh->getline)) {
1067 $textline = $self->preprocess_line($textline, ++$nlines);
1068 next unless ((defined $textline) && (length $textline));
1069
1070 if ((! length $paragraph) && ($textline =~ /^==/)) {
1071 ## '==' denotes a one-line command paragraph
1072 $paragraph = $textline;
1073 $plines = 1;
1074 $textline = '';
1075 } else {
1076 ## Append this line to the current paragraph
1077 $paragraph .= $textline;
1078 ++$plines;
1079 }
1080
1081 ## See if this line is blank and ends the current paragraph.
1082 ## If it isnt, then keep iterating until it is.
1083 next unless (($textline =~ /^([^\S\r\n]*)[\r\n]*$/)
1084 && (length $paragraph));
1085
1086 ## Issue a warning about any non-empty blank lines
1087 if (length($1) > 0 and $myOpts{'-warnings'} and ! $myData{_CUTTING}) {
1088 my $errorsub = $self->errorsub();
1089 my $file = $self->input_file();
1090 my $errmsg = "*** WARNING: line containing nothing but whitespace".
1091 " in paragraph at line $nlines in file $file\n";
1092 (ref $errorsub) and &{$errorsub}($errmsg)
1093 or (defined $errorsub) and $self->$errorsub($errmsg)
1094 or warn($errmsg);
1095 }
1096
1097 ## Now process the paragraph
1098 parse_paragraph($self, $paragraph, ($nlines - $plines) + 1);
1099 $paragraph = '';
1100 $plines = 0;
1101 }
1102 ## Dont forget about the last paragraph in the file
1103 if (length $paragraph) {
1104 parse_paragraph($self, $paragraph, ($nlines - $plines) + 1)
1105 }
1106
1107 ## Now pop the input stream off the top of the input stack.
1108 $self->_pop_input_stream();
1109}
1110
1111##---------------------------------------------------------------------------
1112
1113=head1 B<parse_from_file()>
1114
1115 $parser->parse_from_file($filename,$outfile);
1116
1117This method takes a filename and does the following:
1118
1119=over 2
1120
1121=item *
1122
1123opens the input and output files for reading
1124(creating the appropriate filehandles)
1125
1126=item *
1127
1128invokes the B<parse_from_filehandle()> method passing it the
1129corresponding input and output filehandles.
1130
1131=item *
1132
1133closes the input and output files.
1134
1135=back
1136
1137If the special input filename "-" or "<&STDIN" is given then the STDIN
1138filehandle is used for input (and no open or close is performed). If no
1139input filename is specified then "-" is implied.
1140
1141If a second argument is given then it should be the name of the desired
1142output file. If the special output filename "-" or ">&STDOUT" is given
1143then the STDOUT filehandle is used for output (and no open or close is
1144performed). If the special output filename ">&STDERR" is given then the
1145STDERR filehandle is used for output (and no open or close is
1146performed). If no output filehandle is currently in use and no output
1147filename is specified, then "-" is implied.
1148Alternatively, an L<IO::String> object is also accepted as an output
1149file handle.
1150
1151This method does I<not> usually need to be overridden by subclasses.
1152
1153=cut
1154
1155sub parse_from_file {
1156 my $self = shift;
1157 my %opts = (ref $_[0] eq 'HASH') ? %{ shift() } : ();
1158 my ($infile, $outfile) = @_;
1159 my ($in_fh, $out_fh) = (gensym(), gensym()) if ($] < 5.006);
1160 my ($close_input, $close_output) = (0, 0);
1161 local *myData = $self;
1162 local *_;
1163
1164 ## Is $infile a filename or a (possibly implied) filehandle
1165 if (defined $infile && ref $infile) {
1166 if (ref($infile) =~ /^(SCALAR|ARRAY|HASH|CODE|REF)$/) {
1167 croak "Input from $1 reference not supported!\n";
1168 }
1169 ## Must be a filehandle-ref (or else assume its a ref to an object
1170 ## that supports the common IO read operations).
1171 $myData{_INFILE} = ${$infile};
1172 $in_fh = $infile;
1173 }
1174 elsif (!defined($infile) || !length($infile) || ($infile eq '-')
1175 || ($infile =~ /^<&(?:STDIN|0)$/i))
1176 {
1177 ## Not a filename, just a string implying STDIN
1178 $infile ||= '-';
1179 $myData{_INFILE} = "<standard input>";
1180 $in_fh = \*STDIN;
1181 }
1182 else {
1183 ## We have a filename, open it for reading
1184 $myData{_INFILE} = $infile;
1185 open($in_fh, "< $infile") or
1186 croak "Can't open $infile for reading: $!\n";
1187 $close_input = 1;
1188 }
1189
1190 ## NOTE: we need to be *very* careful when "defaulting" the output
1191 ## file. We only want to use a default if this is the beginning of
1192 ## the entire document (but *not* if this is an included file). We
1193 ## determine this by seeing if the input stream stack has been set-up
1194 ## already
1195
1196 ## Is $outfile a filename, a (possibly implied) filehandle, maybe a ref?
1197 if (ref $outfile) {
1198 ## we need to check for ref() first, as other checks involve reading
1199 if (ref($outfile) =~ /^(ARRAY|HASH|CODE)$/) {
1200 croak "Output to $1 reference not supported!\n";
1201 }
1202 elsif (ref($outfile) eq 'SCALAR') {
1203# # NOTE: IO::String isn't a part of the perl distribution,
1204# # so probably we shouldn't support this case...
1205# require IO::String;
1206# $myData{_OUTFILE} = "$outfile";
1207# $out_fh = IO::String->new($outfile);
1208 croak "Output to SCALAR reference not supported!\n";
1209 }
1210 else {
1211 ## Must be a filehandle-ref (or else assume its a ref to an
1212 ## object that supports the common IO write operations).
1213 $myData{_OUTFILE} = ${$outfile};
1214 $out_fh = $outfile;
1215 }
1216 }
1217 elsif (!defined($outfile) || !length($outfile) || ($outfile eq '-')
1218 || ($outfile =~ /^>&?(?:STDOUT|1)$/i))
1219 {
1220 if (defined $myData{_TOP_STREAM}) {
1221 $out_fh = $myData{_OUTPUT};
1222 }
1223 else {
1224 ## Not a filename, just a string implying STDOUT
1225 $outfile ||= '-';
1226 $myData{_OUTFILE} = "<standard output>";
1227 $out_fh = \*STDOUT;
1228 }
1229 }
1230 elsif ($outfile =~ /^>&(STDERR|2)$/i) {
1231 ## Not a filename, just a string implying STDERR
1232 $myData{_OUTFILE} = "<standard error>";
1233 $out_fh = \*STDERR;
1234 }
1235 else {
1236 ## We have a filename, open it for writing
1237 $myData{_OUTFILE} = $outfile;
1238 (-d $outfile) and croak "$outfile is a directory, not POD input!\n";
1239 open($out_fh, "> $outfile") or
1240 croak "Can't open $outfile for writing: $!\n";
1241 $close_output = 1;
1242 }
1243
1244 ## Whew! That was a lot of work to set up reasonably/robust behavior
1245 ## in the case of a non-filename for reading and writing. Now we just
1246 ## have to parse the input and close the handles when we're finished.
1247 $self->parse_from_filehandle(\%opts, $in_fh, $out_fh);
1248
1249 $close_input and
1250 close($in_fh) || croak "Can't close $infile after reading: $!\n";
1251 $close_output and
1252 close($out_fh) || croak "Can't close $outfile after writing: $!\n";
1253}
1254
1255#############################################################################
1256
1257=head1 ACCESSOR METHODS
1258
1259Clients of B<Pod::Parser> should use the following methods to access
1260instance data fields:
1261
1262=cut
1263
1264##---------------------------------------------------------------------------
1265
1266=head1 B<errorsub()>
1267
1268 $parser->errorsub("method_name");
1269 $parser->errorsub(\&warn_user);
1270 $parser->errorsub(sub { print STDERR, @_ });
1271
1272Specifies the method or subroutine to use when printing error messages
1273about POD syntax. The supplied method/subroutine I<must> return TRUE upon
1274successful printing of the message. If C<undef> is given, then the B<warn>
1275builtin is used to issue error messages (this is the default behavior).
1276
1277 my $errorsub = $parser->errorsub()
1278 my $errmsg = "This is an error message!\n"
1279 (ref $errorsub) and &{$errorsub}($errmsg)
1280 or (defined $errorsub) and $parser->$errorsub($errmsg)
1281 or warn($errmsg);
1282
1283Returns a method name, or else a reference to the user-supplied subroutine
1284used to print error messages. Returns C<undef> if the B<warn> builtin
1285is used to issue error messages (this is the default behavior).
1286
1287=cut
1288
1289sub errorsub {
1290 return (@_ > 1) ? ($_[0]->{_ERRORSUB} = $_[1]) : $_[0]->{_ERRORSUB};
1291}
1292
1293##---------------------------------------------------------------------------
1294
1295=head1 B<cutting()>
1296
1297 $boolean = $parser->cutting();
1298
1299Returns the current C<cutting> state: a boolean-valued scalar which
1300evaluates to true if text from the input file is currently being "cut"
1301(meaning it is I<not> considered part of the POD document).
1302
1303 $parser->cutting($boolean);
1304
1305Sets the current C<cutting> state to the given value and returns the
1306result.
1307
1308=cut
1309
1310sub cutting {
1311 return (@_ > 1) ? ($_[0]->{_CUTTING} = $_[1]) : $_[0]->{_CUTTING};
1312}
1313
1314##---------------------------------------------------------------------------
1315
1316##---------------------------------------------------------------------------
1317
1318=head1 B<parseopts()>
1319
1320When invoked with no additional arguments, B<parseopts> returns a hashtable
1321of all the current parsing options.
1322
1323 ## See if we are parsing non-POD sections as well as POD ones
1324 my %opts = $parser->parseopts();
1325 $opts{'-want_nonPODs}' and print "-want_nonPODs\n";
1326
1327When invoked using a single string, B<parseopts> treats the string as the
1328name of a parse-option and returns its corresponding value if it exists
1329(returns C<undef> if it doesn't).
1330
1331 ## Did we ask to see '=cut' paragraphs?
1332 my $want_cut = $parser->parseopts('-process_cut_cmd');
1333 $want_cut and print "-process_cut_cmd\n";
1334
1335When invoked with multiple arguments, B<parseopts> treats them as
1336key/value pairs and the specified parse-option names are set to the
1337given values. Any unspecified parse-options are unaffected.
1338
1339 ## Set them back to the default
1340 $parser->parseopts(-warnings => 0);
1341
1342When passed a single hash-ref, B<parseopts> uses that hash to completely
1343reset the existing parse-options, all previous parse-option values
1344are lost.
1345
1346 ## Reset all options to default
1347 $parser->parseopts( { } );
1348
1349See L<"PARSING OPTIONS"> for more information on the name and meaning of each
1350parse-option currently recognized.
1351
1352=cut
1353
1354sub parseopts {
1355 local *myData = shift;
1356 local *myOpts = ($myData{_PARSEOPTS} ||= {});
1357 return %myOpts if (@_ == 0);
1358 if (@_ == 1) {
1359 local $_ = shift;
1360 return ref($_) ? $myData{_PARSEOPTS} = $_ : $myOpts{$_};
1361 }
1362 my @newOpts = (%myOpts, @_);
1363 $myData{_PARSEOPTS} = { @newOpts };
1364}
1365
1366##---------------------------------------------------------------------------
1367
1368=head1 B<output_file()>
1369
1370 $fname = $parser->output_file();
1371
1372Returns the name of the output file being written.
1373
1374=cut
1375
1376sub output_file {
1377 return $_[0]->{_OUTFILE};
1378}
1379
1380##---------------------------------------------------------------------------
1381
1382=head1 B<output_handle()>
1383
1384 $fhandle = $parser->output_handle();
1385
1386Returns the output filehandle object.
1387
1388=cut
1389
1390sub output_handle {
1391 return $_[0]->{_OUTPUT};
1392}
1393
1394##---------------------------------------------------------------------------
1395
1396=head1 B<input_file()>
1397
1398 $fname = $parser->input_file();
1399
1400Returns the name of the input file being read.
1401
1402=cut
1403
1404sub input_file {
1405 return $_[0]->{_INFILE};
1406}
1407
1408##---------------------------------------------------------------------------
1409
1410=head1 B<input_handle()>
1411
1412 $fhandle = $parser->input_handle();
1413
1414Returns the current input filehandle object.
1415
1416=cut
1417
1418sub input_handle {
1419 return $_[0]->{_INPUT};
1420}
1421
1422##---------------------------------------------------------------------------
1423
1424=begin __PRIVATE__
1425
1426=head1 B<input_streams()>
1427
1428 $listref = $parser->input_streams();
1429
1430Returns a reference to an array which corresponds to the stack of all
1431the input streams that are currently in the middle of being parsed.
1432
1433While parsing an input stream, it is possible to invoke
1434B<parse_from_file()> or B<parse_from_filehandle()> to parse a new input
1435stream and then return to parsing the previous input stream. Each input
1436stream to be parsed is pushed onto the end of this input stack
1437before any of its input is read. The input stream that is currently
1438being parsed is always at the end (or top) of the input stack. When an
1439input stream has been exhausted, it is popped off the end of the
1440input stack.
1441
1442Each element on this input stack is a reference to C<Pod::InputSource>
1443object. Please see L<Pod::InputObjects> for more details.
1444
1445This method might be invoked when printing diagnostic messages, for example,
1446to obtain the name and line number of the all input files that are currently
1447being processed.
1448
1449=end __PRIVATE__
1450
1451=cut
1452
1453sub input_streams {
1454 return $_[0]->{_INPUT_STREAMS};
1455}
1456
1457##---------------------------------------------------------------------------
1458
1459=begin __PRIVATE__
1460
1461=head1 B<top_stream()>
1462
1463 $hashref = $parser->top_stream();
1464
1465Returns a reference to the hash-table that represents the element
1466that is currently at the top (end) of the input stream stack
1467(see L<"input_streams()">). The return value will be the C<undef>
1468if the input stack is empty.
1469
1470This method might be used when printing diagnostic messages, for example,
1471to obtain the name and line number of the current input file.
1472
1473=end __PRIVATE__
1474
1475=cut
1476
1477sub top_stream {
1478 return $_[0]->{_TOP_STREAM} || undef;
1479}
1480
1481#############################################################################
1482
1483=head1 PRIVATE METHODS AND DATA
1484
1485B<Pod::Parser> makes use of several internal methods and data fields
1486which clients should not need to see or use. For the sake of avoiding
1487name collisions for client data and methods, these methods and fields
1488are briefly discussed here. Determined hackers may obtain further
1489information about them by reading the B<Pod::Parser> source code.
1490
1491Private data fields are stored in the hash-object whose reference is
1492returned by the B<new()> constructor for this class. The names of all
1493private methods and data-fields used by B<Pod::Parser> begin with a
1494prefix of "_" and match the regular expression C</^_\w+$/>.
1495
1496=cut
1497
1498##---------------------------------------------------------------------------
1499
1500=begin _PRIVATE_
1501
1502=head1 B<_push_input_stream()>
1503
1504 $hashref = $parser->_push_input_stream($in_fh,$out_fh);
1505
1506This method will push the given input stream on the input stack and
1507perform any necessary beginning-of-document or beginning-of-file
1508processing. The argument C<$in_fh> is the input stream filehandle to
1509push, and C<$out_fh> is the corresponding output filehandle to use (if
1510it is not given or is undefined, then the current output stream is used,
1511which defaults to standard output if it doesnt exist yet).
1512
1513The value returned will be reference to the hash-table that represents
1514the new top of the input stream stack. I<Please Note> that it is
1515possible for this method to use default values for the input and output
1516file handles. If this happens, you will need to look at the C<INPUT>
1517and C<OUTPUT> instance data members to determine their new values.
1518
1519=end _PRIVATE_
1520
1521=cut
1522
1523sub _push_input_stream {
1524 my ($self, $in_fh, $out_fh) = @_;
1525 local *myData = $self;
1526
1527 ## Initialize stuff for the entire document if this is *not*
1528 ## an included file.
1529 ##
1530 ## NOTE: we need to be *very* careful when "defaulting" the output
1531 ## filehandle. We only want to use a default value if this is the
1532 ## beginning of the entire document (but *not* if this is an included
1533 ## file).
1534 unless (defined $myData{_TOP_STREAM}) {
1535 $out_fh = \*STDOUT unless (defined $out_fh);
1536 $myData{_CUTTING} = 1; ## current "cutting" state
1537 $myData{_INPUT_STREAMS} = []; ## stack of all input streams
1538 }
1539
1540 ## Initialize input indicators
1541 $myData{_OUTFILE} = '(unknown)' unless (defined $myData{_OUTFILE});
1542 $myData{_OUTPUT} = $out_fh if (defined $out_fh);
1543 $in_fh = \*STDIN unless (defined $in_fh);
1544 $myData{_INFILE} = '(unknown)' unless (defined $myData{_INFILE});
1545 $myData{_INPUT} = $in_fh;
1546 my $input_top = $myData{_TOP_STREAM}
1547 = new Pod::InputSource(
1548 -name => $myData{_INFILE},
1549 -handle => $in_fh,
1550 -was_cutting => $myData{_CUTTING}
1551 );
1552 local *input_stack = $myData{_INPUT_STREAMS};
1553 push(@input_stack, $input_top);
1554
1555 ## Perform beginning-of-document and/or beginning-of-input processing
1556 $self->begin_pod() if (@input_stack == 1);
1557 $self->begin_input();
1558
1559 return $input_top;
1560}
1561
1562##---------------------------------------------------------------------------
1563
1564=begin _PRIVATE_
1565
1566=head1 B<_pop_input_stream()>
1567
1568 $hashref = $parser->_pop_input_stream();
1569
1570This takes no arguments. It will perform any necessary end-of-file or
1571end-of-document processing and then pop the current input stream from
1572the top of the input stack.
1573
1574The value returned will be reference to the hash-table that represents
1575the new top of the input stream stack.
1576
1577=end _PRIVATE_
1578
1579=cut
1580
1581sub _pop_input_stream {
1582 my ($self) = @_;
1583 local *myData = $self;
1584 local *input_stack = $myData{_INPUT_STREAMS};
1585
1586 ## Perform end-of-input and/or end-of-document processing
1587 $self->end_input() if (@input_stack > 0);
1588 $self->end_pod() if (@input_stack == 1);
1589
1590 ## Restore cutting state to whatever it was before we started
1591 ## parsing this file.
1592 my $old_top = pop(@input_stack);
1593 $myData{_CUTTING} = $old_top->was_cutting();
1594
1595 ## Dont forget to reset the input indicators
1596 my $input_top = undef;
1597 if (@input_stack > 0) {
1598 $input_top = $myData{_TOP_STREAM} = $input_stack[-1];
1599 $myData{_INFILE} = $input_top->name();
1600 $myData{_INPUT} = $input_top->handle();
1601 } else {
1602 delete $myData{_TOP_STREAM};
1603 delete $myData{_INPUT_STREAMS};
1604 }
1605
1606 return $input_top;
1607}
1608
1609#############################################################################
1610
1611=head1 TREE-BASED PARSING
1612
1613If straightforward stream-based parsing wont meet your needs (as is
1614likely the case for tasks such as translating PODs into structured
1615markup languages like HTML and XML) then you may need to take the
1616tree-based approach. Rather than doing everything in one pass and
1617calling the B<interpolate()> method to expand sequences into text, it
1618may be desirable to instead create a parse-tree using the B<parse_text()>
1619method to return a tree-like structure which may contain an ordered
1620list of children (each of which may be a text-string, or a similar
1621tree-like structure).
1622
1623Pay special attention to L<"METHODS FOR PARSING AND PROCESSING"> and
1624to the objects described in L<Pod::InputObjects>. The former describes
1625the gory details and parameters for how to customize and extend the
1626parsing behavior of B<Pod::Parser>. B<Pod::InputObjects> provides
1627several objects that may all be used interchangeably as parse-trees. The
1628most obvious one is the B<Pod::ParseTree> object. It defines the basic
1629interface and functionality that all things trying to be a POD parse-tree
1630should do. A B<Pod::ParseTree> is defined such that each "node" may be a
1631text-string, or a reference to another parse-tree. Each B<Pod::Paragraph>
1632object and each B<Pod::InteriorSequence> object also supports the basic
1633parse-tree interface.
1634
1635The B<parse_text()> method takes a given paragraph of text, and
1636returns a parse-tree that contains one or more children, each of which
1637may be a text-string, or an InteriorSequence object. There are also
1638callback-options that may be passed to B<parse_text()> to customize
1639the way it expands or transforms interior-sequences, as well as the
1640returned result. These callbacks can be used to create a parse-tree
1641with custom-made objects (which may or may not support the parse-tree
1642interface, depending on how you choose to do it).
1643
1644If you wish to turn an entire POD document into a parse-tree, that process
1645is fairly straightforward. The B<parse_text()> method is the key to doing
1646this successfully. Every paragraph-callback (i.e. the polymorphic methods
1647for B<command()>, B<verbatim()>, and B<textblock()> paragraphs) takes
1648a B<Pod::Paragraph> object as an argument. Each paragraph object has a
1649B<parse_tree()> method that can be used to get or set a corresponding
1650parse-tree. So for each of those paragraph-callback methods, simply call
1651B<parse_text()> with the options you desire, and then use the returned
1652parse-tree to assign to the given paragraph object.
1653
1654That gives you a parse-tree for each paragraph - so now all you need is
1655an ordered list of paragraphs. You can maintain that yourself as a data
1656element in the object/hash. The most straightforward way would be simply
1657to use an array-ref, with the desired set of custom "options" for each
1658invocation of B<parse_text>. Let's assume the desired option-set is
1659given by the hash C<%options>. Then we might do something like the
1660following:
1661
1662 package MyPodParserTree;
1663
1664 @ISA = qw( Pod::Parser );
1665
1666 ...
1667
1668 sub begin_pod {
1669 my $self = shift;
1670 $self->{'-paragraphs'} = []; ## initialize paragraph list
1671 }
1672
1673 sub command {
1674 my ($parser, $command, $paragraph, $line_num, $pod_para) = @_;
1675 my $ptree = $parser->parse_text({%options}, $paragraph, ...);
1676 $pod_para->parse_tree( $ptree );
1677 push @{ $self->{'-paragraphs'} }, $pod_para;
1678 }
1679
1680 sub verbatim {
1681 my ($parser, $paragraph, $line_num, $pod_para) = @_;
1682 push @{ $self->{'-paragraphs'} }, $pod_para;
1683 }
1684
1685 sub textblock {
1686 my ($parser, $paragraph, $line_num, $pod_para) = @_;
1687 my $ptree = $parser->parse_text({%options}, $paragraph, ...);
1688 $pod_para->parse_tree( $ptree );
1689 push @{ $self->{'-paragraphs'} }, $pod_para;
1690 }
1691
1692 ...
1693
1694 package main;
1695 ...
1696 my $parser = new MyPodParserTree(...);
1697 $parser->parse_from_file(...);
1698 my $paragraphs_ref = $parser->{'-paragraphs'};
1699
1700Of course, in this module-author's humble opinion, I'd be more inclined to
1701use the existing B<Pod::ParseTree> object than a simple array. That way
1702everything in it, paragraphs and sequences, all respond to the same core
1703interface for all parse-tree nodes. The result would look something like:
1704
1705 package MyPodParserTree2;
1706
1707 ...
1708
1709 sub begin_pod {
1710 my $self = shift;
1711 $self->{'-ptree'} = new Pod::ParseTree; ## initialize parse-tree
1712 }
1713
1714 sub parse_tree {
1715 ## convenience method to get/set the parse-tree for the entire POD
1716 (@_ > 1) and $_[0]->{'-ptree'} = $_[1];
1717 return $_[0]->{'-ptree'};
1718 }
1719
1720 sub command {
1721 my ($parser, $command, $paragraph, $line_num, $pod_para) = @_;
1722 my $ptree = $parser->parse_text({<<options>>}, $paragraph, ...);
1723 $pod_para->parse_tree( $ptree );
1724 $parser->parse_tree()->append( $pod_para );
1725 }
1726
1727 sub verbatim {
1728 my ($parser, $paragraph, $line_num, $pod_para) = @_;
1729 $parser->parse_tree()->append( $pod_para );
1730 }
1731
1732 sub textblock {
1733 my ($parser, $paragraph, $line_num, $pod_para) = @_;
1734 my $ptree = $parser->parse_text({<<options>>}, $paragraph, ...);
1735 $pod_para->parse_tree( $ptree );
1736 $parser->parse_tree()->append( $pod_para );
1737 }
1738
1739 ...
1740
1741 package main;
1742 ...
1743 my $parser = new MyPodParserTree2(...);
1744 $parser->parse_from_file(...);
1745 my $ptree = $parser->parse_tree;
1746 ...
1747
1748Now you have the entire POD document as one great big parse-tree. You
1749can even use the B<-expand_seq> option to B<parse_text> to insert
1750whole different kinds of objects. Just don't expect B<Pod::Parser>
1751to know what to do with them after that. That will need to be in your
1752code. Or, alternatively, you can insert any object you like so long as
1753it conforms to the B<Pod::ParseTree> interface.
1754
1755One could use this to create subclasses of B<Pod::Paragraphs> and
1756B<Pod::InteriorSequences> for specific commands (or to create your own
1757custom node-types in the parse-tree) and add some kind of B<emit()>
1758method to each custom node/subclass object in the tree. Then all you'd
1759need to do is recursively walk the tree in the desired order, processing
1760the children (most likely from left to right) by formatting them if
1761they are text-strings, or by calling their B<emit()> method if they
1762are objects/references.
1763
1764=head1 SEE ALSO
1765
1766L<Pod::InputObjects>, L<Pod::Select>
1767
1768B<Pod::InputObjects> defines POD input objects corresponding to
1769command paragraphs, parse-trees, and interior-sequences.
1770
1771B<Pod::Select> is a subclass of B<Pod::Parser> which provides the ability
1772to selectively include and/or exclude sections of a POD document from being
1773translated based upon the current heading, subheading, subsubheading, etc.
1774
1775=for __PRIVATE__
1776B<Pod::Callbacks> is a subclass of B<Pod::Parser> which gives its users
1777the ability the employ I<callback functions> instead of, or in addition
1778to, overriding methods of the base class.
1779
1780=for __PRIVATE__
1781B<Pod::Select> and B<Pod::Callbacks> do not override any
1782methods nor do they define any new methods with the same name. Because
1783of this, they may I<both> be used (in combination) as a base class of
1784the same subclass in order to combine their functionality without
1785causing any namespace clashes due to multiple inheritance.
1786
1787=head1 AUTHOR
1788
1789Please report bugs using L<http://rt.cpan.org>.
1790
1791Brad Appleton E<lt>[email protected]<gt>
1792
1793Based on code for B<Pod::Text> written by
1794Tom Christiansen E<lt>[email protected]<gt>
1795
1796=cut
1797
17981;
1799# vim: ts=4 sw=4 et
Note: See TracBrowser for help on using the repository browser.