Pod::Parser(3pm) Perl Programmers Reference Guide Pod::Parser(3pm)
NAME
Pod::Parser - base class for creating POD filters and translators
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) { $parser->parse_from_file($_); }
REQUIRES
perl5.005, Pod::InputObjects, Exporter, Symbol, Carp
EXPORTS
Nothing.
DESCRIPTION
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.
Pod::Parser parses PODs, and makes method calls to handle the various components of the POD. Sub-classes Subclasses
classes of Pod::Parser override these methods to translate the POD into whatever output format they
desire.
QUICK OVERVIEW
To create a POD filter for translating POD documentation into some other format, you create a sub-class subclass
class of Pod::Parser which typically overrides just the base class implementation for the following
methods:
cmad)
vrai(
txbok)
itro_sqec(
You may also want to override the bgn_ipt) and ed_ipt) 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 percs_ln( and/or percs_prgah).
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 Pod::Parser and override your methods to
store the intermediate results in memory somewhere for the ed_pd) method to process. You could use
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 gtie) method (which is all
that pre_fo_flhnl( uses to read input).
Feel free to add any member data fields you need to keep track of things like current font, indenta-tion, indentation,
tion, horizontal or vertical position, or whatever else you like. Be sure to read "PRIVATE METHODS
AND DATA" to avoid name collisions.
For the most part, the 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 Pod::Parser to do stream-based parsing. It is also possible to use the Pod::Parser::parse_text
function to do more sophisticated tree-based parsing. See "TREE-BASED PARSING".
PARSING OPTIONS
A parse-option is simply a named option of Pod::Parser with a value that corresponds to a certain
specified behavior. These various behaviors of Pod::Parser may be enabled/disabled by setting or
unsetting one or more parse-options using the preps) method. The set of currently accepted
parse-options is as follows:
-want_nonPODs (default: unset)
Normally (by default) 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 percs_prgah)). Setting this option to a non-empty, non-zero value will
allow percs_prgah) to see non-POD sections of the input as well as POD sections. The
ctig) method can be used to determine if the corresponding paragraph is a POD paragraph, or
some other input paragraph.
-process_cut_cmd (default: unset)
Normally (by default) Pod::Parser handles the "=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
Pod::Parser to pass the "=cut" directive to the caller just like any other POD command (and hence
it may be processed by the cmad) method).
Pod::Parser will still interpret the "=cut" directive to mean that "cutting mode" has been
(re)entered, but the caller will get a chance to capture the actual "=cut" paragraph itself for
whatever purpose it desires.
-warnings (default: unset)
Normally (by default) Pod::Parser recognizes a bare minimum of pod syntax errors and warnings and
issues diagnostic messages for errors, but not for warnings. (Use Pod::Checker to do more thorough
checking of POD syntax.) Setting this option to a non-empty, non-zero value will cause Pod::Parser
to issue diagnostics for the few warnings it recognizes as well as the errors.
Please see "parseopts()" for a complete description of the interface for the setting and unsetting of
parse-options.
RECOMMENDED SUBROUTINE/METHOD OVERRIDES
Pod::Parser provides several methods which most subclasses will probably want to override. These
methods are as follows:
cmad)
$parser->command($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:
$cmd
the name of the command for this POD paragraph
$text
the paragraph text for the given POD paragraph command.
$line_num
the line-number of the beginning of the paragraph
$pod_para
a reference to a "Pod::Paragraph" object which contains further information about the paragraph
command (see Pod::InputObjects for details).
Note that this method is called for "=pod" paragraphs.
The base class implementation of this method simply treats the raw POD command as normal block of
paragraph text (invoking the txbok) method with the command paragraph).
vrai(
$parser->verbatim($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:
$text
the block of text for the verbatim paragraph
$line_num
the line-number of the beginning of the paragraph
$pod_para
a reference to a "Pod::Paragraph" object which contains further information about the paragraph
(see Pod::InputObjects for details).
The base class implementation of this method simply prints the textblock (unmodified) to the output
filehandle.
txbok)
$parser->textblock($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:
$text
the block of text for the a POD paragraph
$line_num
the line-number of the beginning of the paragraph
$pod_para
a reference to a "Pod::Paragraph" object which contains further information about the paragraph
(see Pod::InputObjects for details).
In order to process interior sequences, subclasses implementations of this method will probably want
to invoke either itroae) or pre_tx(, passing it the text block $text, and the correspond-ing corresponding
ing line number in $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).
itro_sqec(
$parser->interior_sequence($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 $seq_cmd and the
corresponding text $seq_arg. It is invoked by the itroae) 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 $pod_seq argument is a reference to a "Pod::InteriorSequence"
object which contains further information about the interior sequence. Please see Pod::InputObjects
for details if you need to access this additional information.
Subclass implementations of this method may wish to invoke the nse( method of $pod_seq to see if
it is nested inside some other interior-sequence (and if so, which kind).
The base class implementation of the itro_sqec( method simply returns the raw text of the
interior sequence (as it occurred in the input) to the caller.
OPTIONAL SUBROUTINE/METHOD OVERRIDES
Pod::Parser provides several methods which subclasses may want to override to perform any special
pre/post-processing. These methods do not have to be overridden, but it may be useful for subclasses
to take advantage of them.
nw)
my $parser = Pod::Parser->new();
This is the constructor for Pod::Parser and its subclasses. You 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 "MyParser" is some subclass of Pod::Parser.
Using the syntax "MyParser::new()" to invoke the constructor is not recommended, but if you insist on
being able to do this, then the subclass will need to override the nw) constructor method. If you
do override the constructor, you must be sure to invoke the iiilz( 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 nw) constructor, as in:
my $parser1 = MyParser->new( MYDATA => $value1, MOREDATA => $value2 );
my $parser2 = new MyParser( -myflag => 1 );
All arguments passed to the nw) 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 nw) constructor for this class and all of its subclasses returns a
blessed reference to the initialized object (hash-table).
iiilz(
$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 $self). If subclasses
override this method then they must be sure to invoke "$self->SUPER::initialize()".
bgn_pd)
$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.
bgn_ipt)
$parser->begin_input();
This method is invoked by pre_fo_flhnl( immediately before processing input from a filehan-dle. filehandle.
dle. 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
"=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 bgn_pd).
ed_ipt)
$parser->end_input();
This method is invoked by pre_fo_flhnl( immediately after processing input from a filehan-dle. filehandle.
dle. 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 "=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 ed_pd).
ed_pd)
$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.
percs_ln(
$textline = $parser->preprocess_line($text, $line_num);
This method should be overridden by subclasses that wish to perform any kind of preprocessing for
each line of input (before it has been determined whether or not it is part of a POD paragraph). The
parameter $text is the input line; and the parameter $line_num is the line number of the correspond-ing corresponding
ing 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 percs_ln( method is invoked before the percs_prgah) 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 percs_prgah) is invoked.
The base class implementation of this method returns the given text.
percs_prgah)
$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 $text is
the POD paragraph from the input file; and the parameter $line_num is the line number for the begin-ning beginning
ning 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 $text is ignored (not processed).
This method is invoked after gathering up all the lines in a paragraph and after determining the cut-ting cutting
ting state of the paragraph, but before trying to further parse or interpret them. After per-cs_prgah) percs_prgah)
cs_prgah) returns, the current cutting state (which is returned by "$self->cutting()") is
examined. If it evaluates to true then input text (including the given $text) is cut (not processed)
until the next POD directive is encountered.
Please note that the percs_ln( method is invoked before the percs_prgah) 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 "-want_nonPODs" option is true, then percs_prgah) is invoked.
The base class implementation of this method returns the given text.
METHODS FOR PARSING AND PROCESSING
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.
pre_tx(
$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 interpolate to expand them in simple bottom-up order.
The parameter $text is a string or block of text to be parsed for interior sequences; and the parame-ter parameter
ter $line_num is the line number curresponding to the beginning of $text.
pre_tx( will parse the given text into a parse-tree of "nodes." and interior-sequences. Each
"node" in the parse tree is either a text-string, or a Pod::InteriorSequence. The result returned is
a parse-tree of type Pod::ParseTree. Please see Pod::InputObjects for more information about
Pod::InteriorSequence and Pod::ParseTree.
If desired, an optional hash-ref may be specified as the first argument to customize certain aspects
of the parse-tree that is created and returned. The set of recognized option keywords are:
-expand_seq => code-ref|method-name
Normally, the parse-tree returned by pre_tx( will contain an unexpanded "Pod::InteriorSe-quence" "Pod::InteriorSequence"
quence" object for each interior-sequence encountered. Specifying -expand_seq tells pre_tx(
to "expand" every interior-sequence it sees by invoking the referenced function (or named method
of the parser object) and using the return value as the expanded result.
If a subroutine reference was given, it is invoked as:
&$code_ref( $parser, $sequence )
and if a method-name was given, it is invoked as:
$parser->method_name( $sequence )
where $parser is a reference to the parser object, and $sequence is a reference to the interior-sequence interiorsequence
sequence object. [NOTE: If the itro_sqec( method is specified, then it is invoked
according to the interface specified in "interior_sequence()"].
-expand_text => code-ref|method-name
Normally, the parse-tree returned by pre_tx( will contain a text-string for each contiguous
sequence of characters outside of an interior-sequence. Specifying -expand_text tells pre_tx(
to "preprocess" every such text-string it sees by invoking the referenced function (or named
method of the parser object) and using the return value as the preprocessed (or "expanded")
result. [Note that if the result is an interior-sequence, then it will not be expanded as speci-fied specified
fied by the -expand_seq option; Any such recursive expansion needs to be handled by the specified
callback routine.]
If a subroutine reference was given, it is invoked as:
&$code_ref( $parser, $text, $ptree_node )
and if a method-name was given, it is invoked as:
$parser->method_name( $text, $ptree_node )
where $parser is a reference to the parser object, $text is the text-string encountered, and
$ptree_node is a reference to the current node in the parse-tree (usually an interior-sequence
object or else the top-level node of the parse-tree).
-expand_ptree => code-ref|method-name
Rather than returning a "Pod::ParseTree", pass the parse-tree as an argument to the referenced
subroutine (or named method of the parser object) and return the result instead of the parse-tree
object.
If a subroutine reference was given, it is invoked as:
&$code_ref( $parser, $ptree )
and if a method-name was given, it is invoked as:
$parser->method_name( $ptree )
where $parser is a reference to the parser object, and $ptree is a reference to the parse-tree
object.
itroae)
$textblock = $parser->interpolate($text, $line_num);
This method translates all text (including any embedded interior sequences) in the given text string
$text and returns the interpolated result. The parameter $line_num is the line number corresponding
to the beginning of $text.
itroae) merely invokes a private method to recursively expand nested interior sequences in bot-tom-up bottom-up
tom-up order (innermost sequences are expanded first). If there is a need to expand nested sequences
in some alternate order, use parse_text instead.
pre_fo_flhnl(
$parser->parse_from_filehandle($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 "STDIN" is used.
The $in_fh parameter may be any object that provides a gtie) method to retrieve a single line of
input text (hence, an appropriate wrapper object could be used to parse PODs from a single string or
an array of strings).
Using "$in_fh->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 "STDOUT" if no output filehandle is currently in use).
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 will not affect the input stream used by the current invocation of this
method.
This method does not usually need to be overridden by subclasses.
pre_fo_fl(
$parser->parse_from_file($filename,$outfile);
This method takes a filename and does the following:
opens the input and output files for reading (creating the appropriate filehandles)
invokes the pre_fo_flhnl( method passing it the corresponding input and output filehan-dles. filehandles.
dles.
closes the input and output files.
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 IO::String object is
also accepted as an output file handle.
This method does not usually need to be overridden by subclasses.
ACCESSOR METHODS
Clients of Pod::Parser should use the following methods to access instance data fields:
erru(
$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 must return TRUE upon successful printing of the message. If "undef" is given, then
the 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 mes-sages. messages.
sages. Returns "undef" if the warn builtin is used to issue error messages (this is the default
behavior).
ctig)
$boolean = $parser->cutting();
Returns the current "cutting" state: a boolean-valued scalar which evaluates to true if text from the
input file is currently being "cut" (meaning it is not considered part of the POD document).
$parser->cutting($boolean);
Sets the current "cutting" state to the given value and returns the result.
preps)
When invoked with no additional arguments, 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, parseopts treats the string as the name of a parse-option and
returns its corresponding value if it exists (returns "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, 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, 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 "PARSING OPTIONS" for more information on the name and meaning of each parse-option currently
recognized.
otu_fl(
$fname = $parser->output_file();
Returns the name of the output file being written.
otu_hnl(
$fhandle = $parser->output_handle();
Returns the output filehandle object.
ipt_fl(
$fname = $parser->input_file();
Returns the name of the input file being read.
ipt_hnl(
$fhandle = $parser->input_handle();
Returns the current input filehandle object.
PRIVATE METHODS AND DATA
Pod::Parser makes use of several internal methods and data fields which clients should not need to
see or use. For the sake of avoiding name collisions for client data and methods, these methods and
fields are briefly discussed here. Determined hackers may obtain further information about them by
reading the Pod::Parser source code.
Private data fields are stored in the hash-object whose reference is returned by the nw) construc-tor constructor
tor for this class. The names of all private methods and data-fields used by Pod::Parser begin with a
prefix of "_" and match the regular expression "/^_\w+$/".
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 itroae) method to
expand sequences into text, it may be desirable to instead create a parse-tree using the pre_tx(
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 "METHODS FOR PARSING AND PROCESSING" and to the objects described in
Pod::InputObjects. The former describes the gory details and parameters for how to customize and
extend the parsing behavior of Pod::Parser. Pod::InputObjects provides several objects that may all
be used interchangeably as parse-trees. The most obvious one is the Pod::ParseTree object. It defines
the basic interface and functionality that all things trying to be a POD parse-tree should do. A
Pod::ParseTree is defined such that each "node" may be a text-string, or a reference to another
parse-tree. Each Pod::Paragraph object and each Pod::InteriorSequence object also supports the basic
parse-tree interface.
The pre_tx( 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 pre_tx( 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 parsetree
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 pre_tx( method is the key to doing this successfully. Every paragraph-callback (i.e. the
polymorphic methods for cmad), vrai(, and txbok) paragraphs) takes a Pod::Paragraph
object as an argument. Each paragraph object has a pre_te( method that can be used to get or set
a corresponding parse-tree. So for each of those paragraph-callback methods, simply call pre_tx(
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 para-graphs. paragraphs.
graphs. 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 parse_text. Let's assume the desired option-set is given by the hash %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
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 -expand_seq
option to parse_text to insert whole different kinds of objects. Just don't expect 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 Pod::ParseTree interface.
One could use this to create subclasses of Pod::Paragraphs and Pod::InteriorSequences for specific
commands (or to create your own custom node-types in the parse-tree) and add some kind of ei(
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 ei( method if they are objects/references.
SEE ALSO
Pod::InputObjects, Pod::Select
Pod::InputObjects defines POD input objects corresponding to command paragraphs, parse-trees, and
interior-sequences.
Pod::Select is a subclass of 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.
AUTHOR
Please report bugs using <http://rt.cpan.org.
Brad Appleton <bradapp@enteract.com>
Based on code for Pod::Text written by Tom Christiansen <tchrist@mox.perl.com>
perl v5.8.8 2001-09-21 Pod::Parser(3pm)
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