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+#############################################################################
+# Pod/Parser.pm -- package which defines a base class for parsing POD docs.
+#
+# Copyright (C) 1996-2000 by Bradford Appleton. All rights reserved.
+# This file is part of "PodParser". PodParser is free software;
+# you can redistribute it and/or modify it under the same terms
+# as Perl itself.
+#############################################################################
+
+package Pod::Parser;
+
+use vars qw($VERSION);
+$VERSION = 1.32; ## Current version of this package
+require 5.005; ## requires this Perl version or later
+
+#############################################################################
+
+=head1 NAME
+
+Pod::Parser - base class for creating POD filters and translators
+
+=head1 SYNOPSIS
+
+ use Pod::Parser;
+
+ package MyParser;
+ @ISA = qw(Pod::Parser);
+
+ sub command {
+ my ($parser, $command, $paragraph, $line_num) = @_;
+ ## Interpret the command and its text; sample actions might be:
+ if ($command eq 'head1') { ... }
+ elsif ($command eq 'head2') { ... }
+ ## ... other commands and their actions
+ my $out_fh = $parser->output_handle();
+ my $expansion = $parser->interpolate($paragraph, $line_num);
+ print $out_fh $expansion;
+ }
+
+ sub verbatim {
+ my ($parser, $paragraph, $line_num) = @_;
+ ## Format verbatim paragraph; sample actions might be:
+ my $out_fh = $parser->output_handle();
+ print $out_fh $paragraph;
+ }
+
+ sub textblock {
+ my ($parser, $paragraph, $line_num) = @_;
+ ## Translate/Format this block of text; sample actions might be:
+ my $out_fh = $parser->output_handle();
+ my $expansion = $parser->interpolate($paragraph, $line_num);
+ print $out_fh $expansion;
+ }
+
+ sub interior_sequence {
+ my ($parser, $seq_command, $seq_argument) = @_;
+ ## Expand an interior sequence; sample actions might be:
+ return "*$seq_argument*" if ($seq_command eq 'B');
+ return "`$seq_argument'" if ($seq_command eq 'C');
+ return "_${seq_argument}_'" if ($seq_command eq 'I');
+ ## ... other sequence commands and their resulting text
+ }
+
+ package main;
+
+ ## Create a parser object and have it parse file whose name was
+ ## given on the command-line (use STDIN if no files were given).
+ $parser = new MyParser();
+ $parser->parse_from_filehandle(\*STDIN) if (@ARGV == 0);
+ for (@ARGV) { $parser->parse_from_file($_); }
+
+=head1 REQUIRES
+
+perl5.005, Pod::InputObjects, Exporter, Symbol, Carp
+
+=head1 EXPORTS
+
+Nothing.
+
+=head1 DESCRIPTION
+
+B<Pod::Parser> is a base class for creating POD filters and translators.
+It handles most of the effort involved with parsing the POD sections
+from an input stream, leaving subclasses free to be concerned only with
+performing the actual translation of text.
+
+B<Pod::Parser> parses PODs, and makes method calls to handle the various
+components of the POD. Subclasses of B<Pod::Parser> override these methods
+to translate the POD into whatever output format they desire.
+
+=head1 QUICK OVERVIEW
+
+To create a POD filter for translating POD documentation into some other
+format, you create a subclass of B<Pod::Parser> which typically overrides
+just the base class implementation for the following methods:
+
+=over 2
+
+=item *
+
+B<command()>
+
+=item *
+
+B<verbatim()>
+
+=item *
+
+B<textblock()>
+
+=item *
+
+B<interior_sequence()>
+
+=back
+
+You may also want to override the B<begin_input()> and B<end_input()>
+methods for your subclass (to perform any needed per-file and/or
+per-document initialization or cleanup).
+
+If you need to perform any preprocesssing of input before it is parsed
+you may want to override one or more of B<preprocess_line()> and/or
+B<preprocess_paragraph()>.
+
+Sometimes it may be necessary to make more than one pass over the input
+files. If this is the case you have several options. You can make the
+first pass using B<Pod::Parser> and override your methods to store the
+intermediate results in memory somewhere for the B<end_pod()> method to
+process. You could use B<Pod::Parser> for several passes with an
+appropriate state variable to control the operation for each pass. If
+your input source can't be reset to start at the beginning, you can
+store it in some other structure as a string or an array and have that
+structure implement a B<getline()> method (which is all that
+B<parse_from_filehandle()> uses to read input).
+
+Feel free to add any member data fields you need to keep track of things
+like current font, indentation, horizontal or vertical position, or
+whatever else you like. Be sure to read L<"PRIVATE METHODS AND DATA">
+to avoid name collisions.
+
+For the most part, the B<Pod::Parser> base class should be able to
+do most of the input parsing for you and leave you free to worry about
+how to intepret the commands and translate the result.
+
+Note that all we have described here in this quick overview is the
+simplest most straightforward use of B<Pod::Parser> to do stream-based
+parsing. It is also possible to use the B<Pod::Parser::parse_text> function
+to do more sophisticated tree-based parsing. See L<"TREE-BASED PARSING">.
+
+=head1 PARSING OPTIONS
+
+A I<parse-option> is simply a named option of B<Pod::Parser> with a
+value that corresponds to a certain specified behavior. These various
+behaviors of B<Pod::Parser> may be enabled/disabled by setting
+or unsetting one or more I<parse-options> using the B<parseopts()> method.
+The set of currently accepted parse-options is as follows:
+
+=over 3
+
+=item B<-want_nonPODs> (default: unset)
+
+Normally (by default) B<Pod::Parser> will only provide access to
+the POD sections of the input. Input paragraphs that are not part
+of the POD-format documentation are not made available to the caller
+(not even using B<preprocess_paragraph()>). Setting this option to a
+non-empty, non-zero value will allow B<preprocess_paragraph()> to see
+non-POD sections of the input as well as POD sections. The B<cutting()>
+method can be used to determine if the corresponding paragraph is a POD
+paragraph, or some other input paragraph.
+
+=item B<-process_cut_cmd> (default: unset)
+
+Normally (by default) B<Pod::Parser> handles the C<=cut> POD directive
+by itself and does not pass it on to the caller for processing. Setting
+this option to a non-empty, non-zero value will cause B<Pod::Parser> to
+pass the C<=cut> directive to the caller just like any other POD command
+(and hence it may be processed by the B<command()> method).
+
+B<Pod::Parser> will still interpret the C<=cut> directive to mean that
+"cutting mode" has been (re)entered, but the caller will get a chance
+to capture the actual C<=cut> paragraph itself for whatever purpose
+it desires.
+
+=item B<-warnings> (default: unset)
+
+Normally (by default) B<Pod::Parser> recognizes a bare minimum of
+pod syntax errors and warnings and issues diagnostic messages
+for errors, but not for warnings. (Use B<Pod::Checker> to do more
+thorough checking of POD syntax.) Setting this option to a non-empty,
+non-zero value will cause B<Pod::Parser> to issue diagnostics for
+the few warnings it recognizes as well as the errors.
+
+=back
+
+Please see L<"parseopts()"> for a complete description of the interface
+for the setting and unsetting of parse-options.
+
+=cut
+
+#############################################################################
+
+use vars qw(@ISA);
+use strict;
+#use diagnostics;
+use Pod::InputObjects;
+use Carp;
+use Exporter;
+BEGIN {
+ if ($] < 5.6) {
+ require Symbol;
+ import Symbol;
+ }
+}
+@ISA = qw(Exporter);
+
+## These "variables" are used as local "glob aliases" for performance
+use vars qw(%myData %myOpts @input_stack);
+
+#############################################################################
+
+=head1 RECOMMENDED SUBROUTINE/METHOD OVERRIDES
+
+B<Pod::Parser> provides several methods which most subclasses will probably
+want to override. These methods are as follows:
+
+=cut
+
+##---------------------------------------------------------------------------
+
+=head1 B<command()>
+
+ $parser->command($cmd,$text,$line_num,$pod_para);
+
+This method should be overridden by subclasses to take the appropriate
+action when a POD command paragraph (denoted by a line beginning with
+"=") is encountered. When such a POD directive is seen in the input,
+this method is called and is passed:
+
+=over 3
+
+=item C<$cmd>
+
+the name of the command for this POD paragraph
+
+=item C<$text>
+
+the paragraph text for the given POD paragraph command.
+
+=item C<$line_num>
+
+the line-number of the beginning of the paragraph
+
+=item C<$pod_para>
+
+a reference to a C<Pod::Paragraph> object which contains further
+information about the paragraph command (see L<Pod::InputObjects>
+for details).
+
+=back
+
+B<Note> that this method I<is> called for C<=pod> paragraphs.
+
+The base class implementation of this method simply treats the raw POD
+command as normal block of paragraph text (invoking the B<textblock()>
+method with the command paragraph).
+
+=cut
+
+sub command {
+ my ($self, $cmd, $text, $line_num, $pod_para) = @_;
+ ## Just treat this like a textblock
+ $self->textblock($pod_para->raw_text(), $line_num, $pod_para);
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<verbatim()>
+
+ $parser->verbatim($text,$line_num,$pod_para);
+
+This method may be overridden by subclasses to take the appropriate
+action when a block of verbatim text is encountered. It is passed the
+following parameters:
+
+=over 3
+
+=item C<$text>
+
+the block of text for the verbatim paragraph
+
+=item C<$line_num>
+
+the line-number of the beginning of the paragraph
+
+=item C<$pod_para>
+
+a reference to a C<Pod::Paragraph> object which contains further
+information about the paragraph (see L<Pod::InputObjects>
+for details).
+
+=back
+
+The base class implementation of this method simply prints the textblock
+(unmodified) to the output filehandle.
+
+=cut
+
+sub verbatim {
+ my ($self, $text, $line_num, $pod_para) = @_;
+ my $out_fh = $self->{_OUTPUT};
+ print $out_fh $text;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<textblock()>
+
+ $parser->textblock($text,$line_num,$pod_para);
+
+This method may be overridden by subclasses to take the appropriate
+action when a normal block of POD text is encountered (although the base
+class method will usually do what you want). It is passed the following
+parameters:
+
+=over 3
+
+=item C<$text>
+
+the block of text for the a POD paragraph
+
+=item C<$line_num>
+
+the line-number of the beginning of the paragraph
+
+=item C<$pod_para>
+
+a reference to a C<Pod::Paragraph> object which contains further
+information about the paragraph (see L<Pod::InputObjects>
+for details).
+
+=back
+
+In order to process interior sequences, subclasses implementations of
+this method will probably want to invoke either B<interpolate()> or
+B<parse_text()>, passing it the text block C<$text>, and the corresponding
+line number in C<$line_num>, and then perform any desired processing upon
+the returned result.
+
+The base class implementation of this method simply prints the text block
+as it occurred in the input stream).
+
+=cut
+
+sub textblock {
+ my ($self, $text, $line_num, $pod_para) = @_;
+ my $out_fh = $self->{_OUTPUT};
+ print $out_fh $self->interpolate($text, $line_num);
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<interior_sequence()>
+
+ $parser->interior_sequence($seq_cmd,$seq_arg,$pod_seq);
+
+This method should be overridden by subclasses to take the appropriate
+action when an interior sequence is encountered. An interior sequence is
+an embedded command within a block of text which appears as a command
+name (usually a single uppercase character) followed immediately by a
+string of text which is enclosed in angle brackets. This method is
+passed the sequence command C<$seq_cmd> and the corresponding text
+C<$seq_arg>. It is invoked by the B<interpolate()> method for each interior
+sequence that occurs in the string that it is passed. It should return
+the desired text string to be used in place of the interior sequence.
+The C<$pod_seq> argument is a reference to a C<Pod::InteriorSequence>
+object which contains further information about the interior sequence.
+Please see L<Pod::InputObjects> for details if you need to access this
+additional information.
+
+Subclass implementations of this method may wish to invoke the
+B<nested()> method of C<$pod_seq> to see if it is nested inside
+some other interior-sequence (and if so, which kind).
+
+The base class implementation of the B<interior_sequence()> method
+simply returns the raw text of the interior sequence (as it occurred
+in the input) to the caller.
+
+=cut
+
+sub interior_sequence {
+ my ($self, $seq_cmd, $seq_arg, $pod_seq) = @_;
+ ## Just return the raw text of the interior sequence
+ return $pod_seq->raw_text();
+}
+
+#############################################################################
+
+=head1 OPTIONAL SUBROUTINE/METHOD OVERRIDES
+
+B<Pod::Parser> provides several methods which subclasses may want to override
+to perform any special pre/post-processing. These methods do I<not> have to
+be overridden, but it may be useful for subclasses to take advantage of them.
+
+=cut
+
+##---------------------------------------------------------------------------
+
+=head1 B<new()>
+
+ my $parser = Pod::Parser->new();
+
+This is the constructor for B<Pod::Parser> and its subclasses. You
+I<do not> need to override this method! It is capable of constructing
+subclass objects as well as base class objects, provided you use
+any of the following constructor invocation styles:
+
+ my $parser1 = MyParser->new();
+ my $parser2 = new MyParser();
+ my $parser3 = $parser2->new();
+
+where C<MyParser> is some subclass of B<Pod::Parser>.
+
+Using the syntax C<MyParser::new()> to invoke the constructor is I<not>
+recommended, but if you insist on being able to do this, then the
+subclass I<will> need to override the B<new()> constructor method. If
+you do override the constructor, you I<must> be sure to invoke the
+B<initialize()> method of the newly blessed object.
+
+Using any of the above invocations, the first argument to the
+constructor is always the corresponding package name (or object
+reference). No other arguments are required, but if desired, an
+associative array (or hash-table) my be passed to the B<new()>
+constructor, as in:
+
+ my $parser1 = MyParser->new( MYDATA => $value1, MOREDATA => $value2 );
+ my $parser2 = new MyParser( -myflag => 1 );
+
+All arguments passed to the B<new()> constructor will be treated as
+key/value pairs in a hash-table. The newly constructed object will be
+initialized by copying the contents of the given hash-table (which may
+have been empty). The B<new()> constructor for this class and all of its
+subclasses returns a blessed reference to the initialized object (hash-table).
+
+=cut
+
+sub new {
+ ## Determine if we were called via an object-ref or a classname
+ my $this = shift;
+ my $class = ref($this) || $this;
+ ## Any remaining arguments are treated as initial values for the
+ ## hash that is used to represent this object.
+ my %params = @_;
+ my $self = { %params };
+ ## Bless ourselves into the desired class and perform any initialization
+ bless $self, $class;
+ $self->initialize();
+ return $self;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<initialize()>
+
+ $parser->initialize();
+
+This method performs any necessary object initialization. It takes no
+arguments (other than the object instance of course, which is typically
+copied to a local variable named C<$self>). If subclasses override this
+method then they I<must> be sure to invoke C<$self-E<gt>SUPER::initialize()>.
+
+=cut
+
+sub initialize {
+ #my $self = shift;
+ #return;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<begin_pod()>
+
+ $parser->begin_pod();
+
+This method is invoked at the beginning of processing for each POD
+document that is encountered in the input. Subclasses should override
+this method to perform any per-document initialization.
+
+=cut
+
+sub begin_pod {
+ #my $self = shift;
+ #return;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<begin_input()>
+
+ $parser->begin_input();
+
+This method is invoked by B<parse_from_filehandle()> immediately I<before>
+processing input from a filehandle. The base class implementation does
+nothing, however, subclasses may override it to perform any per-file
+initializations.
+
+Note that if multiple files are parsed for a single POD document
+(perhaps the result of some future C<=include> directive) this method
+is invoked for every file that is parsed. If you wish to perform certain
+initializations once per document, then you should use B<begin_pod()>.
+
+=cut
+
+sub begin_input {
+ #my $self = shift;
+ #return;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<end_input()>
+
+ $parser->end_input();
+
+This method is invoked by B<parse_from_filehandle()> immediately I<after>
+processing input from a filehandle. The base class implementation does
+nothing, however, subclasses may override it to perform any per-file
+cleanup actions.
+
+Please note that if multiple files are parsed for a single POD document
+(perhaps the result of some kind of C<=include> directive) this method
+is invoked for every file that is parsed. If you wish to perform certain
+cleanup actions once per document, then you should use B<end_pod()>.
+
+=cut
+
+sub end_input {
+ #my $self = shift;
+ #return;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<end_pod()>
+
+ $parser->end_pod();
+
+This method is invoked at the end of processing for each POD document
+that is encountered in the input. Subclasses should override this method
+to perform any per-document finalization.
+
+=cut
+
+sub end_pod {
+ #my $self = shift;
+ #return;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<preprocess_line()>
+
+ $textline = $parser->preprocess_line($text, $line_num);
+
+This method should be overridden by subclasses that wish to perform
+any kind of preprocessing for each I<line> of input (I<before> it has
+been determined whether or not it is part of a POD paragraph). The
+parameter C<$text> is the input line; and the parameter C<$line_num> is
+the line number of the corresponding text line.
+
+The value returned should correspond to the new text to use in its
+place. If the empty string or an undefined value is returned then no
+further processing will be performed for this line.
+
+Please note that the B<preprocess_line()> method is invoked I<before>
+the B<preprocess_paragraph()> method. After all (possibly preprocessed)
+lines in a paragraph have been assembled together and it has been
+determined that the paragraph is part of the POD documentation from one
+of the selected sections, then B<preprocess_paragraph()> is invoked.
+
+The base class implementation of this method returns the given text.
+
+=cut
+
+sub preprocess_line {
+ my ($self, $text, $line_num) = @_;
+ return $text;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<preprocess_paragraph()>
+
+ $textblock = $parser->preprocess_paragraph($text, $line_num);
+
+This method should be overridden by subclasses that wish to perform any
+kind of preprocessing for each block (paragraph) of POD documentation
+that appears in the input stream. The parameter C<$text> is the POD
+paragraph from the input file; and the parameter C<$line_num> is the
+line number for the beginning of the corresponding paragraph.
+
+The value returned should correspond to the new text to use in its
+place If the empty string is returned or an undefined value is
+returned, then the given C<$text> is ignored (not processed).
+
+This method is invoked after gathering up all the lines in a paragraph
+and after determining the cutting state of the paragraph,
+but before trying to further parse or interpret them. After
+B<preprocess_paragraph()> returns, the current cutting state (which
+is returned by C<$self-E<gt>cutting()>) is examined. If it evaluates
+to true then input text (including the given C<$text>) is cut (not
+processed) until the next POD directive is encountered.
+
+Please note that the B<preprocess_line()> method is invoked I<before>
+the B<preprocess_paragraph()> method. After all (possibly preprocessed)
+lines in a paragraph have been assembled together and either it has been
+determined that the paragraph is part of the POD documentation from one
+of the selected sections or the C<-want_nonPODs> option is true,
+then B<preprocess_paragraph()> is invoked.
+
+The base class implementation of this method returns the given text.
+
+=cut
+
+sub preprocess_paragraph {
+ my ($self, $text, $line_num) = @_;
+ return $text;
+}
+
+#############################################################################
+
+=head1 METHODS FOR PARSING AND PROCESSING
+
+B<Pod::Parser> provides several methods to process input text. These
+methods typically won't need to be overridden (and in some cases they
+can't be overridden), but subclasses may want to invoke them to exploit
+their functionality.
+
+=cut
+
+##---------------------------------------------------------------------------
+
+=head1 B<parse_text()>
+
+ $ptree1 = $parser->parse_text($text, $line_num);
+ $ptree2 = $parser->parse_text({%opts}, $text, $line_num);
+ $ptree3 = $parser->parse_text(\%opts, $text, $line_num);
+
+This method is useful if you need to perform your own interpolation
+of interior sequences and can't rely upon B<interpolate> to expand
+them in simple bottom-up order.
+
+The parameter C<$text> is a string or block of text to be parsed
+for interior sequences; and the parameter C<$line_num> is the
+line number curresponding to the beginning of C<$text>.
+
+B<parse_text()> will parse the given text into a parse-tree of "nodes."
+and interior-sequences. Each "node" in the parse tree is either a
+text-string, or a B<Pod::InteriorSequence>. The result returned is a
+parse-tree of type B<Pod::ParseTree>. Please see L<Pod::InputObjects>
+for more information about B<Pod::InteriorSequence> and B<Pod::ParseTree>.
+
+If desired, an optional hash-ref may be specified as the first argument
+to customize certain aspects of the parse-tree that is created and
+returned. The set of recognized option keywords are:
+
+=over 3
+
+=item B<-expand_seq> =E<gt> I<code-ref>|I<method-name>
+
+Normally, the parse-tree returned by B<parse_text()> will contain an
+unexpanded C<Pod::InteriorSequence> object for each interior-sequence
+encountered. Specifying B<-expand_seq> tells B<parse_text()> to "expand"
+every interior-sequence it sees by invoking the referenced function
+(or named method of the parser object) and using the return value as the
+expanded result.
+
+If a subroutine reference was given, it is invoked as:
+
+ &$code_ref( $parser, $sequence )
+
+and if a method-name was given, it is invoked as:
+
+ $parser->method_name( $sequence )
+
+where C<$parser> is a reference to the parser object, and C<$sequence>
+is a reference to the interior-sequence object.
+[I<NOTE>: If the B<interior_sequence()> method is specified, then it is
+invoked according to the interface specified in L<"interior_sequence()">].
+
+=item B<-expand_text> =E<gt> I<code-ref>|I<method-name>
+
+Normally, the parse-tree returned by B<parse_text()> will contain a
+text-string for each contiguous sequence of characters outside of an
+interior-sequence. Specifying B<-expand_text> tells B<parse_text()> to
+"preprocess" every such text-string it sees by invoking the referenced
+function (or named method of the parser object) and using the return value
+as the preprocessed (or "expanded") result. [Note that if the result is
+an interior-sequence, then it will I<not> be expanded as specified by the
+B<-expand_seq> option; Any such recursive expansion needs to be handled by
+the specified callback routine.]
+
+If a subroutine reference was given, it is invoked as:
+
+ &$code_ref( $parser, $text, $ptree_node )
+
+and if a method-name was given, it is invoked as:
+
+ $parser->method_name( $text, $ptree_node )
+
+where C<$parser> is a reference to the parser object, C<$text> is the
+text-string encountered, and C<$ptree_node> is a reference to the current
+node in the parse-tree (usually an interior-sequence object or else the
+top-level node of the parse-tree).
+
+=item B<-expand_ptree> =E<gt> I<code-ref>|I<method-name>
+
+Rather than returning a C<Pod::ParseTree>, pass the parse-tree as an
+argument to the referenced subroutine (or named method of the parser
+object) and return the result instead of the parse-tree object.
+
+If a subroutine reference was given, it is invoked as:
+
+ &$code_ref( $parser, $ptree )
+
+and if a method-name was given, it is invoked as:
+
+ $parser->method_name( $ptree )
+
+where C<$parser> is a reference to the parser object, and C<$ptree>
+is a reference to the parse-tree object.
+
+=back
+
+=cut
+
+sub parse_text {
+ my $self = shift;
+ local $_ = '';
+
+ ## Get options and set any defaults
+ my %opts = (ref $_[0]) ? %{ shift() } : ();
+ my $expand_seq = $opts{'-expand_seq'} || undef;
+ my $expand_text = $opts{'-expand_text'} || undef;
+ my $expand_ptree = $opts{'-expand_ptree'} || undef;
+
+ my $text = shift;
+ my $line = shift;
+ my $file = $self->input_file();
+ my $cmd = "";
+
+ ## Convert method calls into closures, for our convenience
+ my $xseq_sub = $expand_seq;
+ my $xtext_sub = $expand_text;
+ my $xptree_sub = $expand_ptree;
+ if (defined $expand_seq and $expand_seq eq 'interior_sequence') {
+ ## If 'interior_sequence' is the method to use, we have to pass
+ ## more than just the sequence object, we also need to pass the
+ ## sequence name and text.
+ $xseq_sub = sub {
+ my ($self, $iseq) = @_;
+ my $args = join("", $iseq->parse_tree->children);
+ return $self->interior_sequence($iseq->name, $args, $iseq);
+ };
+ }
+ ref $xseq_sub or $xseq_sub = sub { shift()->$expand_seq(@_) };
+ ref $xtext_sub or $xtext_sub = sub { shift()->$expand_text(@_) };
+ ref $xptree_sub or $xptree_sub = sub { shift()->$expand_ptree(@_) };
+
+ ## Keep track of the "current" interior sequence, and maintain a stack
+ ## of "in progress" sequences.
+ ##
+ ## NOTE that we push our own "accumulator" at the very beginning of the
+ ## stack. It's really a parse-tree, not a sequence; but it implements
+ ## the methods we need so we can use it to gather-up all the sequences
+ ## and strings we parse. Thus, by the end of our parsing, it should be
+ ## the only thing left on our stack and all we have to do is return it!
+ ##
+ my $seq = Pod::ParseTree->new();
+ my @seq_stack = ($seq);
+ my ($ldelim, $rdelim) = ('', '');
+
+ ## Iterate over all sequence starts text (NOTE: split with
+ ## capturing parens keeps the delimiters)
+ $_ = $text;
+ my @tokens = split /([A-Z]<(?:<+\s)?)/;
+ while ( @tokens ) {
+ $_ = shift @tokens;
+ ## Look for the beginning of a sequence
+ if ( /^([A-Z])(<(?:<+\s)?)$/ ) {
+ ## Push a new sequence onto the stack of those "in-progress"
+ my $ldelim_orig;
+ ($cmd, $ldelim_orig) = ($1, $2);
+ ($ldelim = $ldelim_orig) =~ s/\s+$//;
+ ($rdelim = $ldelim) =~ tr/</>/;
+ $seq = Pod::InteriorSequence->new(
+ -name => $cmd,
+ -ldelim => $ldelim_orig, -rdelim => $rdelim,
+ -file => $file, -line => $line
+ );
+ (@seq_stack > 1) and $seq->nested($seq_stack[-1]);
+ push @seq_stack, $seq;
+ }
+ ## Look for sequence ending
+ elsif ( @seq_stack > 1 ) {
+ ## Make sure we match the right kind of closing delimiter
+ my ($seq_end, $post_seq) = ("", "");
+ if ( ($ldelim eq '<' and /\A(.*?)(>)/s)
+ or /\A(.*?)(\s+$rdelim)/s )
+ {
+ ## Found end-of-sequence, capture the interior and the
+ ## closing the delimiter, and put the rest back on the
+ ## token-list
+ $post_seq = substr($_, length($1) + length($2));
+ ($_, $seq_end) = ($1, $2);
+ (length $post_seq) and unshift @tokens, $post_seq;
+ }
+ if (length) {
+ ## In the middle of a sequence, append this text to it, and
+ ## dont forget to "expand" it if that's what the caller wanted
+ $seq->append($expand_text ? &$xtext_sub($self,$_,$seq) : $_);
+ $_ .= $seq_end;
+ }
+ if (length $seq_end) {
+ ## End of current sequence, record terminating delimiter
+ $seq->rdelim($seq_end);
+ ## Pop it off the stack of "in progress" sequences
+ pop @seq_stack;
+ ## Append result to its parent in current parse tree
+ $seq_stack[-1]->append($expand_seq ? &$xseq_sub($self,$seq)
+ : $seq);
+ ## Remember the current cmd-name and left-delimiter
+ if(@seq_stack > 1) {
+ $cmd = $seq_stack[-1]->name;
+ $ldelim = $seq_stack[-1]->ldelim;
+ $rdelim = $seq_stack[-1]->rdelim;
+ } else {
+ $cmd = $ldelim = $rdelim = '';
+ }
+ }
+ }
+ elsif (length) {
+ ## In the middle of a sequence, append this text to it, and
+ ## dont forget to "expand" it if that's what the caller wanted
+ $seq->append($expand_text ? &$xtext_sub($self,$_,$seq) : $_);
+ }
+ ## Keep track of line count
+ $line += tr/\n//;
+ ## Remember the "current" sequence
+ $seq = $seq_stack[-1];
+ }
+
+ ## Handle unterminated sequences
+ my $errorsub = (@seq_stack > 1) ? $self->errorsub() : undef;
+ while (@seq_stack > 1) {
+ ($cmd, $file, $line) = ($seq->name, $seq->file_line);
+ $ldelim = $seq->ldelim;
+ ($rdelim = $ldelim) =~ tr/</>/;
+ $rdelim =~ s/^(\S+)(\s*)$/$2$1/;
+ pop @seq_stack;
+ my $errmsg = "*** ERROR: unterminated ${cmd}${ldelim}...${rdelim}".
+ " at line $line in file $file\n";
+ (ref $errorsub) and &{$errorsub}($errmsg)
+ or (defined $errorsub) and $self->$errorsub($errmsg)
+ or warn($errmsg);
+ $seq_stack[-1]->append($expand_seq ? &$xseq_sub($self,$seq) : $seq);
+ $seq = $seq_stack[-1];
+ }
+
+ ## Return the resulting parse-tree
+ my $ptree = (pop @seq_stack)->parse_tree;
+ return $expand_ptree ? &$xptree_sub($self, $ptree) : $ptree;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<interpolate()>
+
+ $textblock = $parser->interpolate($text, $line_num);
+
+This method translates all text (including any embedded interior sequences)
+in the given text string C<$text> and returns the interpolated result. The
+parameter C<$line_num> is the line number corresponding to the beginning
+of C<$text>.
+
+B<interpolate()> merely invokes a private method to recursively expand
+nested interior sequences in bottom-up order (innermost sequences are
+expanded first). If there is a need to expand nested sequences in
+some alternate order, use B<parse_text> instead.
+
+=cut
+
+sub interpolate {
+ my($self, $text, $line_num) = @_;
+ my %parse_opts = ( -expand_seq => 'interior_sequence' );
+ my $ptree = $self->parse_text( \%parse_opts, $text, $line_num );
+ return join "", $ptree->children();
+}
+
+##---------------------------------------------------------------------------
+
+=begin __PRIVATE__
+
+=head1 B<parse_paragraph()>
+
+ $parser->parse_paragraph($text, $line_num);
+
+This method takes the text of a POD paragraph to be processed, along
+with its corresponding line number, and invokes the appropriate method
+(one of B<command()>, B<verbatim()>, or B<textblock()>).
+
+For performance reasons, this method is invoked directly without any
+dynamic lookup; Hence subclasses may I<not> override it!
+
+=end __PRIVATE__
+
+=cut
+
+sub parse_paragraph {
+ my ($self, $text, $line_num) = @_;
+ local *myData = $self; ## alias to avoid deref-ing overhead
+ local *myOpts = ($myData{_PARSEOPTS} ||= {}); ## get parse-options
+ local $_;
+
+ ## See if we want to preprocess nonPOD paragraphs as well as POD ones.
+ my $wantNonPods = $myOpts{'-want_nonPODs'};
+
+ ## Update cutting status
+ $myData{_CUTTING} = 0 if $text =~ /^={1,2}\S/;
+
+ ## Perform any desired preprocessing if we wanted it this early
+ $wantNonPods and $text = $self->preprocess_paragraph($text, $line_num);
+
+ ## Ignore up until next POD directive if we are cutting
+ return if $myData{_CUTTING};
+
+ ## Now we know this is block of text in a POD section!
+
+ ##-----------------------------------------------------------------
+ ## This is a hook (hack ;-) for Pod::Select to do its thing without
+ ## having to override methods, but also without Pod::Parser assuming
+ ## $self is an instance of Pod::Select (if the _SELECTED_SECTIONS
+ ## field exists then we assume there is an is_selected() method for
+ ## us to invoke (calling $self->can('is_selected') could verify this
+ ## but that is more overhead than I want to incur)
+ ##-----------------------------------------------------------------
+
+ ## Ignore this block if it isnt in one of the selected sections
+ if (exists $myData{_SELECTED_SECTIONS}) {
+ $self->is_selected($text) or return ($myData{_CUTTING} = 1);
+ }
+
+ ## If we havent already, perform any desired preprocessing and
+ ## then re-check the "cutting" state
+ unless ($wantNonPods) {
+ $text = $self->preprocess_paragraph($text, $line_num);
+ return 1 unless ((defined $text) and (length $text));
+ return 1 if ($myData{_CUTTING});
+ }
+
+ ## Look for one of the three types of paragraphs
+ my ($pfx, $cmd, $arg, $sep) = ('', '', '', '');
+ my $pod_para = undef;
+ if ($text =~ /^(={1,2})(?=\S)/) {
+ ## Looks like a command paragraph. Capture the command prefix used
+ ## ("=" or "=="), as well as the command-name, its paragraph text,
+ ## and whatever sequence of characters was used to separate them
+ $pfx = $1;
+ $_ = substr($text, length $pfx);
+ ($cmd, $sep, $text) = split /(\s+)/, $_, 2;
+ ## If this is a "cut" directive then we dont need to do anything
+ ## except return to "cutting" mode.
+ if ($cmd eq 'cut') {
+ $myData{_CUTTING} = 1;
+ return unless $myOpts{'-process_cut_cmd'};
+ }
+ }
+ ## Save the attributes indicating how the command was specified.
+ $pod_para = new Pod::Paragraph(
+ -name => $cmd,
+ -text => $text,
+ -prefix => $pfx,
+ -separator => $sep,
+ -file => $myData{_INFILE},
+ -line => $line_num
+ );
+ # ## Invoke appropriate callbacks
+ # if (exists $myData{_CALLBACKS}) {
+ # ## Look through the callback list, invoke callbacks,
+ # ## then see if we need to do the default actions
+ # ## (invoke_callbacks will return true if we do).
+ # return 1 unless $self->invoke_callbacks($cmd, $text, $line_num, $pod_para);
+ # }
+ if (length $cmd) {
+ ## A command paragraph
+ $self->command($cmd, $text, $line_num, $pod_para);
+ }
+ elsif ($text =~ /^\s+/) {
+ ## Indented text - must be a verbatim paragraph
+ $self->verbatim($text, $line_num, $pod_para);
+ }
+ else {
+ ## Looks like an ordinary block of text
+ $self->textblock($text, $line_num, $pod_para);
+ }
+ return 1;
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<parse_from_filehandle()>
+
+ $parser->parse_from_filehandle($in_fh,$out_fh);
+
+This method takes an input filehandle (which is assumed to already be
+opened for reading) and reads the entire input stream looking for blocks
+(paragraphs) of POD documentation to be processed. If no first argument
+is given the default input filehandle C<STDIN> is used.
+
+The C<$in_fh> parameter may be any object that provides a B<getline()>
+method to retrieve a single line of input text (hence, an appropriate
+wrapper object could be used to parse PODs from a single string or an
+array of strings).
+
+Using C<$in_fh-E<gt>getline()>, input is read line-by-line and assembled
+into paragraphs or "blocks" (which are separated by lines containing
+nothing but whitespace). For each block of POD documentation
+encountered it will invoke a method to parse the given paragraph.
+
+If a second argument is given then it should correspond to a filehandle where
+output should be sent (otherwise the default output filehandle is
+C<STDOUT> if no output filehandle is currently in use).
+
+B<NOTE:> For performance reasons, this method caches the input stream at
+the top of the stack in a local variable. Any attempts by clients to
+change the stack contents during processing when in the midst executing
+of this method I<will not affect> the input stream used by the current
+invocation of this method.
+
+This method does I<not> usually need to be overridden by subclasses.
+
+=cut
+
+sub parse_from_filehandle {
+ my $self = shift;
+ my %opts = (ref $_[0] eq 'HASH') ? %{ shift() } : ();
+ my ($in_fh, $out_fh) = @_;
+ $in_fh = \*STDIN unless ($in_fh);
+ local *myData = $self; ## alias to avoid deref-ing overhead
+ local *myOpts = ($myData{_PARSEOPTS} ||= {}); ## get parse-options
+ local $_;
+
+ ## Put this stream at the top of the stack and do beginning-of-input
+ ## processing. NOTE that $in_fh might be reset during this process.
+ my $topstream = $self->_push_input_stream($in_fh, $out_fh);
+ (exists $opts{-cutting}) and $self->cutting( $opts{-cutting} );
+
+ ## Initialize line/paragraph
+ my ($textline, $paragraph) = ('', '');
+ my ($nlines, $plines) = (0, 0);
+
+ ## Use <$fh> instead of $fh->getline where possible (for speed)
+ $_ = ref $in_fh;
+ my $tied_fh = (/^(?:GLOB|FileHandle|IO::\w+)$/ or tied $in_fh);
+
+ ## Read paragraphs line-by-line
+ while (defined ($textline = $tied_fh ? <$in_fh> : $in_fh->getline)) {
+ $textline = $self->preprocess_line($textline, ++$nlines);
+ next unless ((defined $textline) && (length $textline));
+
+ if ((! length $paragraph) && ($textline =~ /^==/)) {
+ ## '==' denotes a one-line command paragraph
+ $paragraph = $textline;
+ $plines = 1;
+ $textline = '';
+ } else {
+ ## Append this line to the current paragraph
+ $paragraph .= $textline;
+ ++$plines;
+ }
+
+ ## See if this line is blank and ends the current paragraph.
+ ## If it isnt, then keep iterating until it is.
+ next unless (($textline =~ /^([^\S\r\n]*)[\r\n]*$/)
+ && (length $paragraph));
+
+ ## Issue a warning about any non-empty blank lines
+ if (length($1) > 0 and $myOpts{'-warnings'} and ! $myData{_CUTTING}) {
+ my $errorsub = $self->errorsub();
+ my $file = $self->input_file();
+ my $errmsg = "*** WARNING: line containing nothing but whitespace".
+ " in paragraph at line $nlines in file $file\n";
+ (ref $errorsub) and &{$errorsub}($errmsg)
+ or (defined $errorsub) and $self->$errorsub($errmsg)
+ or warn($errmsg);
+ }
+
+ ## Now process the paragraph
+ parse_paragraph($self, $paragraph, ($nlines - $plines) + 1);
+ $paragraph = '';
+ $plines = 0;
+ }
+ ## Dont forget about the last paragraph in the file
+ if (length $paragraph) {
+ parse_paragraph($self, $paragraph, ($nlines - $plines) + 1)
+ }
+
+ ## Now pop the input stream off the top of the input stack.
+ $self->_pop_input_stream();
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<parse_from_file()>
+
+ $parser->parse_from_file($filename,$outfile);
+
+This method takes a filename and does the following:
+
+=over 2
+
+=item *
+
+opens the input and output files for reading
+(creating the appropriate filehandles)
+
+=item *
+
+invokes the B<parse_from_filehandle()> method passing it the
+corresponding input and output filehandles.
+
+=item *
+
+closes the input and output files.
+
+=back
+
+If the special input filename "-" or "<&STDIN" is given then the STDIN
+filehandle is used for input (and no open or close is performed). If no
+input filename is specified then "-" is implied.
+
+If a second argument is given then it should be the name of the desired
+output file. If the special output filename "-" or ">&STDOUT" is given
+then the STDOUT filehandle is used for output (and no open or close is
+performed). If the special output filename ">&STDERR" is given then the
+STDERR filehandle is used for output (and no open or close is
+performed). If no output filehandle is currently in use and no output
+filename is specified, then "-" is implied.
+Alternatively, an L<IO::String> object is also accepted as an output
+file handle.
+
+This method does I<not> usually need to be overridden by subclasses.
+
+=cut
+
+sub parse_from_file {
+ my $self = shift;
+ my %opts = (ref $_[0] eq 'HASH') ? %{ shift() } : ();
+ my ($infile, $outfile) = @_;
+ my ($in_fh, $out_fh) = (gensym(), gensym()) if ($] < 5.006);
+ my ($close_input, $close_output) = (0, 0);
+ local *myData = $self;
+ local *_;
+
+ ## Is $infile a filename or a (possibly implied) filehandle
+ if (defined $infile && ref $infile) {
+ if (ref($infile) =~ /^(SCALAR|ARRAY|HASH|CODE|REF)$/) {
+ croak "Input from $1 reference not supported!\n";
+ }
+ ## Must be a filehandle-ref (or else assume its a ref to an object
+ ## that supports the common IO read operations).
+ $myData{_INFILE} = ${$infile};
+ $in_fh = $infile;
+ }
+ elsif (!defined($infile) || !length($infile) || ($infile eq '-')
+ || ($infile =~ /^<&(?:STDIN|0)$/i))
+ {
+ ## Not a filename, just a string implying STDIN
+ $infile ||= '-';
+ $myData{_INFILE} = "<standard input>";
+ $in_fh = \*STDIN;
+ }
+ else {
+ ## We have a filename, open it for reading
+ $myData{_INFILE} = $infile;
+ open($in_fh, "< $infile") or
+ croak "Can't open $infile for reading: $!\n";
+ $close_input = 1;
+ }
+
+ ## NOTE: we need to be *very* careful when "defaulting" the output
+ ## file. We only want to use a default if this is the beginning of
+ ## the entire document (but *not* if this is an included file). We
+ ## determine this by seeing if the input stream stack has been set-up
+ ## already
+
+ ## Is $outfile a filename, a (possibly implied) filehandle, maybe a ref?
+ if (ref $outfile) {
+ ## we need to check for ref() first, as other checks involve reading
+ if (ref($outfile) =~ /^(ARRAY|HASH|CODE)$/) {
+ croak "Output to $1 reference not supported!\n";
+ }
+ elsif (ref($outfile) eq 'SCALAR') {
+# # NOTE: IO::String isn't a part of the perl distribution,
+# # so probably we shouldn't support this case...
+# require IO::String;
+# $myData{_OUTFILE} = "$outfile";
+# $out_fh = IO::String->new($outfile);
+ croak "Output to SCALAR reference not supported!\n";
+ }
+ else {
+ ## Must be a filehandle-ref (or else assume its a ref to an
+ ## object that supports the common IO write operations).
+ $myData{_OUTFILE} = ${$outfile};
+ $out_fh = $outfile;
+ }
+ }
+ elsif (!defined($outfile) || !length($outfile) || ($outfile eq '-')
+ || ($outfile =~ /^>&?(?:STDOUT|1)$/i))
+ {
+ if (defined $myData{_TOP_STREAM}) {
+ $out_fh = $myData{_OUTPUT};
+ }
+ else {
+ ## Not a filename, just a string implying STDOUT
+ $outfile ||= '-';
+ $myData{_OUTFILE} = "<standard output>";
+ $out_fh = \*STDOUT;
+ }
+ }
+ elsif ($outfile =~ /^>&(STDERR|2)$/i) {
+ ## Not a filename, just a string implying STDERR
+ $myData{_OUTFILE} = "<standard error>";
+ $out_fh = \*STDERR;
+ }
+ else {
+ ## We have a filename, open it for writing
+ $myData{_OUTFILE} = $outfile;
+ (-d $outfile) and croak "$outfile is a directory, not POD input!\n";
+ open($out_fh, "> $outfile") or
+ croak "Can't open $outfile for writing: $!\n";
+ $close_output = 1;
+ }
+
+ ## Whew! That was a lot of work to set up reasonably/robust behavior
+ ## in the case of a non-filename for reading and writing. Now we just
+ ## have to parse the input and close the handles when we're finished.
+ $self->parse_from_filehandle(\%opts, $in_fh, $out_fh);
+
+ $close_input and
+ close($in_fh) || croak "Can't close $infile after reading: $!\n";
+ $close_output and
+ close($out_fh) || croak "Can't close $outfile after writing: $!\n";
+}
+
+#############################################################################
+
+=head1 ACCESSOR METHODS
+
+Clients of B<Pod::Parser> should use the following methods to access
+instance data fields:
+
+=cut
+
+##---------------------------------------------------------------------------
+
+=head1 B<errorsub()>
+
+ $parser->errorsub("method_name");
+ $parser->errorsub(\&warn_user);
+ $parser->errorsub(sub { print STDERR, @_ });
+
+Specifies the method or subroutine to use when printing error messages
+about POD syntax. The supplied method/subroutine I<must> return TRUE upon
+successful printing of the message. If C<undef> is given, then the B<warn>
+builtin is used to issue error messages (this is the default behavior).
+
+ my $errorsub = $parser->errorsub()
+ my $errmsg = "This is an error message!\n"
+ (ref $errorsub) and &{$errorsub}($errmsg)
+ or (defined $errorsub) and $parser->$errorsub($errmsg)
+ or warn($errmsg);
+
+Returns a method name, or else a reference to the user-supplied subroutine
+used to print error messages. Returns C<undef> if the B<warn> builtin
+is used to issue error messages (this is the default behavior).
+
+=cut
+
+sub errorsub {
+ return (@_ > 1) ? ($_[0]->{_ERRORSUB} = $_[1]) : $_[0]->{_ERRORSUB};
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<cutting()>
+
+ $boolean = $parser->cutting();
+
+Returns the current C<cutting> state: a boolean-valued scalar which
+evaluates to true if text from the input file is currently being "cut"
+(meaning it is I<not> considered part of the POD document).
+
+ $parser->cutting($boolean);
+
+Sets the current C<cutting> state to the given value and returns the
+result.
+
+=cut
+
+sub cutting {
+ return (@_ > 1) ? ($_[0]->{_CUTTING} = $_[1]) : $_[0]->{_CUTTING};
+}
+
+##---------------------------------------------------------------------------
+
+##---------------------------------------------------------------------------
+
+=head1 B<parseopts()>
+
+When invoked with no additional arguments, B<parseopts> returns a hashtable
+of all the current parsing options.
+
+ ## See if we are parsing non-POD sections as well as POD ones
+ my %opts = $parser->parseopts();
+ $opts{'-want_nonPODs}' and print "-want_nonPODs\n";
+
+When invoked using a single string, B<parseopts> treats the string as the
+name of a parse-option and returns its corresponding value if it exists
+(returns C<undef> if it doesn't).
+
+ ## Did we ask to see '=cut' paragraphs?
+ my $want_cut = $parser->parseopts('-process_cut_cmd');
+ $want_cut and print "-process_cut_cmd\n";
+
+When invoked with multiple arguments, B<parseopts> treats them as
+key/value pairs and the specified parse-option names are set to the
+given values. Any unspecified parse-options are unaffected.
+
+ ## Set them back to the default
+ $parser->parseopts(-warnings => 0);
+
+When passed a single hash-ref, B<parseopts> uses that hash to completely
+reset the existing parse-options, all previous parse-option values
+are lost.
+
+ ## Reset all options to default
+ $parser->parseopts( { } );
+
+See L<"PARSING OPTIONS"> for more information on the name and meaning of each
+parse-option currently recognized.
+
+=cut
+
+sub parseopts {
+ local *myData = shift;
+ local *myOpts = ($myData{_PARSEOPTS} ||= {});
+ return %myOpts if (@_ == 0);
+ if (@_ == 1) {
+ local $_ = shift;
+ return ref($_) ? $myData{_PARSEOPTS} = $_ : $myOpts{$_};
+ }
+ my @newOpts = (%myOpts, @_);
+ $myData{_PARSEOPTS} = { @newOpts };
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<output_file()>
+
+ $fname = $parser->output_file();
+
+Returns the name of the output file being written.
+
+=cut
+
+sub output_file {
+ return $_[0]->{_OUTFILE};
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<output_handle()>
+
+ $fhandle = $parser->output_handle();
+
+Returns the output filehandle object.
+
+=cut
+
+sub output_handle {
+ return $_[0]->{_OUTPUT};
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<input_file()>
+
+ $fname = $parser->input_file();
+
+Returns the name of the input file being read.
+
+=cut
+
+sub input_file {
+ return $_[0]->{_INFILE};
+}
+
+##---------------------------------------------------------------------------
+
+=head1 B<input_handle()>
+
+ $fhandle = $parser->input_handle();
+
+Returns the current input filehandle object.
+
+=cut
+
+sub input_handle {
+ return $_[0]->{_INPUT};
+}
+
+##---------------------------------------------------------------------------
+
+=begin __PRIVATE__
+
+=head1 B<input_streams()>
+
+ $listref = $parser->input_streams();
+
+Returns a reference to an array which corresponds to the stack of all
+the input streams that are currently in the middle of being parsed.
+
+While parsing an input stream, it is possible to invoke
+B<parse_from_file()> or B<parse_from_filehandle()> to parse a new input
+stream and then return to parsing the previous input stream. Each input
+stream to be parsed is pushed onto the end of this input stack
+before any of its input is read. The input stream that is currently
+being parsed is always at the end (or top) of the input stack. When an
+input stream has been exhausted, it is popped off the end of the
+input stack.
+
+Each element on this input stack is a reference to C<Pod::InputSource>
+object. Please see L<Pod::InputObjects> for more details.
+
+This method might be invoked when printing diagnostic messages, for example,
+to obtain the name and line number of the all input files that are currently
+being processed.
+
+=end __PRIVATE__
+
+=cut
+
+sub input_streams {
+ return $_[0]->{_INPUT_STREAMS};
+}
+
+##---------------------------------------------------------------------------
+
+=begin __PRIVATE__
+
+=head1 B<top_stream()>
+
+ $hashref = $parser->top_stream();
+
+Returns a reference to the hash-table that represents the element
+that is currently at the top (end) of the input stream stack
+(see L<"input_streams()">). The return value will be the C<undef>
+if the input stack is empty.
+
+This method might be used when printing diagnostic messages, for example,
+to obtain the name and line number of the current input file.
+
+=end __PRIVATE__
+
+=cut
+
+sub top_stream {
+ return $_[0]->{_TOP_STREAM} || undef;
+}
+
+#############################################################################
+
+=head1 PRIVATE METHODS AND DATA
+
+B<Pod::Parser> makes use of several internal methods and data fields
+which clients should not need to see or use. For the sake of avoiding
+name collisions for client data and methods, these methods and fields
+are briefly discussed here. Determined hackers may obtain further
+information about them by reading the B<Pod::Parser> source code.
+
+Private data fields are stored in the hash-object whose reference is
+returned by the B<new()> constructor for this class. The names of all
+private methods and data-fields used by B<Pod::Parser> begin with a
+prefix of "_" and match the regular expression C</^_\w+$/>.
+
+=cut
+
+##---------------------------------------------------------------------------
+
+=begin _PRIVATE_
+
+=head1 B<_push_input_stream()>
+
+ $hashref = $parser->_push_input_stream($in_fh,$out_fh);
+
+This method will push the given input stream on the input stack and
+perform any necessary beginning-of-document or beginning-of-file
+processing. The argument C<$in_fh> is the input stream filehandle to
+push, and C<$out_fh> is the corresponding output filehandle to use (if
+it is not given or is undefined, then the current output stream is used,
+which defaults to standard output if it doesnt exist yet).
+
+The value returned will be reference to the hash-table that represents
+the new top of the input stream stack. I<Please Note> that it is
+possible for this method to use default values for the input and output
+file handles. If this happens, you will need to look at the C<INPUT>
+and C<OUTPUT> instance data members to determine their new values.
+
+=end _PRIVATE_
+
+=cut
+
+sub _push_input_stream {
+ my ($self, $in_fh, $out_fh) = @_;
+ local *myData = $self;
+
+ ## Initialize stuff for the entire document if this is *not*
+ ## an included file.
+ ##
+ ## NOTE: we need to be *very* careful when "defaulting" the output
+ ## filehandle. We only want to use a default value if this is the
+ ## beginning of the entire document (but *not* if this is an included
+ ## file).
+ unless (defined $myData{_TOP_STREAM}) {
+ $out_fh = \*STDOUT unless (defined $out_fh);
+ $myData{_CUTTING} = 1; ## current "cutting" state
+ $myData{_INPUT_STREAMS} = []; ## stack of all input streams
+ }
+
+ ## Initialize input indicators
+ $myData{_OUTFILE} = '(unknown)' unless (defined $myData{_OUTFILE});
+ $myData{_OUTPUT} = $out_fh if (defined $out_fh);
+ $in_fh = \*STDIN unless (defined $in_fh);
+ $myData{_INFILE} = '(unknown)' unless (defined $myData{_INFILE});
+ $myData{_INPUT} = $in_fh;
+ my $input_top = $myData{_TOP_STREAM}
+ = new Pod::InputSource(
+ -name => $myData{_INFILE},
+ -handle => $in_fh,
+ -was_cutting => $myData{_CUTTING}
+ );
+ local *input_stack = $myData{_INPUT_STREAMS};
+ push(@input_stack, $input_top);
+
+ ## Perform beginning-of-document and/or beginning-of-input processing
+ $self->begin_pod() if (@input_stack == 1);
+ $self->begin_input();
+
+ return $input_top;
+}
+
+##---------------------------------------------------------------------------
+
+=begin _PRIVATE_
+
+=head1 B<_pop_input_stream()>
+
+ $hashref = $parser->_pop_input_stream();
+
+This takes no arguments. It will perform any necessary end-of-file or
+end-of-document processing and then pop the current input stream from
+the top of the input stack.
+
+The value returned will be reference to the hash-table that represents
+the new top of the input stream stack.
+
+=end _PRIVATE_
+
+=cut
+
+sub _pop_input_stream {
+ my ($self) = @_;
+ local *myData = $self;
+ local *input_stack = $myData{_INPUT_STREAMS};
+
+ ## Perform end-of-input and/or end-of-document processing
+ $self->end_input() if (@input_stack > 0);
+ $self->end_pod() if (@input_stack == 1);
+
+ ## Restore cutting state to whatever it was before we started
+ ## parsing this file.
+ my $old_top = pop(@input_stack);
+ $myData{_CUTTING} = $old_top->was_cutting();
+
+ ## Dont forget to reset the input indicators
+ my $input_top = undef;
+ if (@input_stack > 0) {
+ $input_top = $myData{_TOP_STREAM} = $input_stack[-1];
+ $myData{_INFILE} = $input_top->name();
+ $myData{_INPUT} = $input_top->handle();
+ } else {
+ delete $myData{_TOP_STREAM};
+ delete $myData{_INPUT_STREAMS};
+ }
+
+ return $input_top;
+}
+
+#############################################################################
+
+=head1 TREE-BASED PARSING
+
+If straightforward stream-based parsing wont meet your needs (as is
+likely the case for tasks such as translating PODs into structured
+markup languages like HTML and XML) then you may need to take the
+tree-based approach. Rather than doing everything in one pass and
+calling the B<interpolate()> method to expand sequences into text, it
+may be desirable to instead create a parse-tree using the B<parse_text()>
+method to return a tree-like structure which may contain an ordered
+list of children (each of which may be a text-string, or a similar
+tree-like structure).
+
+Pay special attention to L<"METHODS FOR PARSING AND PROCESSING"> and
+to the objects described in L<Pod::InputObjects>. The former describes
+the gory details and parameters for how to customize and extend the
+parsing behavior of B<Pod::Parser>. B<Pod::InputObjects> provides
+several objects that may all be used interchangeably as parse-trees. The
+most obvious one is the B<Pod::ParseTree> object. It defines the basic
+interface and functionality that all things trying to be a POD parse-tree
+should do. A B<Pod::ParseTree> is defined such that each "node" may be a
+text-string, or a reference to another parse-tree. Each B<Pod::Paragraph>
+object and each B<Pod::InteriorSequence> object also supports the basic
+parse-tree interface.
+
+The B<parse_text()> method takes a given paragraph of text, and
+returns a parse-tree that contains one or more children, each of which
+may be a text-string, or an InteriorSequence object. There are also
+callback-options that may be passed to B<parse_text()> to customize
+the way it expands or transforms interior-sequences, as well as the
+returned result. These callbacks can be used to create a parse-tree
+with custom-made objects (which may or may not support the parse-tree
+interface, depending on how you choose to do it).
+
+If you wish to turn an entire POD document into a parse-tree, that process
+is fairly straightforward. The B<parse_text()> method is the key to doing
+this successfully. Every paragraph-callback (i.e. the polymorphic methods
+for B<command()>, B<verbatim()>, and B<textblock()> paragraphs) takes
+a B<Pod::Paragraph> object as an argument. Each paragraph object has a
+B<parse_tree()> method that can be used to get or set a corresponding
+parse-tree. So for each of those paragraph-callback methods, simply call
+B<parse_text()> with the options you desire, and then use the returned
+parse-tree to assign to the given paragraph object.
+
+That gives you a parse-tree for each paragraph - so now all you need is
+an ordered list of paragraphs. You can maintain that yourself as a data
+element in the object/hash. The most straightforward way would be simply
+to use an array-ref, with the desired set of custom "options" for each
+invocation of B<parse_text>. Let's assume the desired option-set is
+given by the hash C<%options>. Then we might do something like the
+following:
+
+ package MyPodParserTree;
+
+ @ISA = qw( Pod::Parser );
+
+ ...
+
+ sub begin_pod {
+ my $self = shift;
+ $self->{'-paragraphs'} = []; ## initialize paragraph list
+ }
+
+ sub command {
+ my ($parser, $command, $paragraph, $line_num, $pod_para) = @_;
+ my $ptree = $parser->parse_text({%options}, $paragraph, ...);
+ $pod_para->parse_tree( $ptree );
+ push @{ $self->{'-paragraphs'} }, $pod_para;
+ }
+
+ sub verbatim {
+ my ($parser, $paragraph, $line_num, $pod_para) = @_;
+ push @{ $self->{'-paragraphs'} }, $pod_para;
+ }
+
+ sub textblock {
+ my ($parser, $paragraph, $line_num, $pod_para) = @_;
+ my $ptree = $parser->parse_text({%options}, $paragraph, ...);
+ $pod_para->parse_tree( $ptree );
+ push @{ $self->{'-paragraphs'} }, $pod_para;
+ }
+
+ ...
+
+ package main;
+ ...
+ my $parser = new MyPodParserTree(...);
+ $parser->parse_from_file(...);
+ my $paragraphs_ref = $parser->{'-paragraphs'};
+
+Of course, in this module-author's humble opinion, I'd be more inclined to
+use the existing B<Pod::ParseTree> object than a simple array. That way
+everything in it, paragraphs and sequences, all respond to the same core
+interface for all parse-tree nodes. The result would look something like:
+
+ package MyPodParserTree2;
+
+ ...
+
+ sub begin_pod {
+ my $self = shift;
+ $self->{'-ptree'} = new Pod::ParseTree; ## initialize parse-tree
+ }
+
+ sub parse_tree {
+ ## convenience method to get/set the parse-tree for the entire POD
+ (@_ > 1) and $_[0]->{'-ptree'} = $_[1];
+ return $_[0]->{'-ptree'};
+ }
+
+ sub command {
+ my ($parser, $command, $paragraph, $line_num, $pod_para) = @_;
+ my $ptree = $parser->parse_text({<<options>>}, $paragraph, ...);
+ $pod_para->parse_tree( $ptree );
+ $parser->parse_tree()->append( $pod_para );
+ }
+
+ sub verbatim {
+ my ($parser, $paragraph, $line_num, $pod_para) = @_;
+ $parser->parse_tree()->append( $pod_para );
+ }
+
+ sub textblock {
+ my ($parser, $paragraph, $line_num, $pod_para) = @_;
+ my $ptree = $parser->parse_text({<<options>>}, $paragraph, ...);
+ $pod_para->parse_tree( $ptree );
+ $parser->parse_tree()->append( $pod_para );
+ }
+
+ ...
+
+ package main;
+ ...
+ my $parser = new MyPodParserTree2(...);
+ $parser->parse_from_file(...);
+ my $ptree = $parser->parse_tree;
+ ...
+
+Now you have the entire POD document as one great big parse-tree. You
+can even use the B<-expand_seq> option to B<parse_text> to insert
+whole different kinds of objects. Just don't expect B<Pod::Parser>
+to know what to do with them after that. That will need to be in your
+code. Or, alternatively, you can insert any object you like so long as
+it conforms to the B<Pod::ParseTree> interface.
+
+One could use this to create subclasses of B<Pod::Paragraphs> and
+B<Pod::InteriorSequences> for specific commands (or to create your own
+custom node-types in the parse-tree) and add some kind of B<emit()>
+method to each custom node/subclass object in the tree. Then all you'd
+need to do is recursively walk the tree in the desired order, processing
+the children (most likely from left to right) by formatting them if
+they are text-strings, or by calling their B<emit()> method if they
+are objects/references.
+
+=head1 SEE ALSO
+
+L<Pod::InputObjects>, L<Pod::Select>
+
+B<Pod::InputObjects> defines POD input objects corresponding to
+command paragraphs, parse-trees, and interior-sequences.
+
+B<Pod::Select> is a subclass of B<Pod::Parser> which provides the ability
+to selectively include and/or exclude sections of a POD document from being
+translated based upon the current heading, subheading, subsubheading, etc.
+
+=for __PRIVATE__
+B<Pod::Callbacks> is a subclass of B<Pod::Parser> which gives its users
+the ability the employ I<callback functions> instead of, or in addition
+to, overriding methods of the base class.
+
+=for __PRIVATE__
+B<Pod::Select> and B<Pod::Callbacks> do not override any
+methods nor do they define any new methods with the same name. Because
+of this, they may I<both> be used (in combination) as a base class of
+the same subclass in order to combine their functionality without
+causing any namespace clashes due to multiple inheritance.
+
+=head1 AUTHOR
+
+Please report bugs using L<http://rt.cpan.org>.
+
+Brad Appleton E<lt>bradapp@enteract.comE<gt>
+
+Based on code for B<Pod::Text> written by
+Tom Christiansen E<lt>tchrist@mox.perl.comE<gt>
+
+=cut
+
+1;
+# vim: ts=4 sw=4 et