Pod::Parser(3p) Perl Programmers Reference Guide Pod::Parser(3p)NAMEPod::Parser - base class for creating POD filters and trans-
lators
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) { $parser->parse_from_file($_); }
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Pod::Parser(3p) Perl Programmers Reference Guide Pod::Parser(3p)REQUIRES
perl5.005, Pod::InputObjects, Exporter, Symbol, Carp
EXPORTS
Nothing.
DESCRIPTIONPod::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 subc-
lasses 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. Subclasses 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 subclass of Pod::Parser
which typically overrides just the base class implementation
for the following methods:
+ command()
+ verbatim()
+ textblock()
+ interior_sequence()
You may also want to override the begin_input() and
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
preprocess_line() and/or 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 Pod::Parser and
override your methods to store the intermediate results in
memory somewhere for the end_pod() 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 getline() method
(which is all that parse_from_filehandle() uses to read
input).
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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 "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 parseopts() 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
preprocess_paragraph()). Setting this option to a
non-empty, non-zero value will allow
preprocess_paragraph() to see non-POD sections of the
input as well as POD sections. The cutting() 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 command() 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
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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 fol-
lows:
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:
$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 textblock() method with the command para-
graph).
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 encoun-
tered. It is passed the following parameters:
$text
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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.
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:
$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 implemen-
tations of this method will probably want to invoke either
interpolate() or parse_text(), passing it the text block
$text, and the corresponding 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).
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 $seq_cmd and the corresponding
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text $seq_arg. It is invoked by the 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 $pod_seq argument is
a reference to a "Pod::InteriorSequence" object which con-
tains 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 nested() 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 interior_sequence()
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.
new()
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 new() con-
structor method. If you do override the constructor, you
must be sure to invoke the 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 new() constructor, as in:
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my $parser1 = MyParser->new( MYDATA => $value1, MOREDATA => $value2 );
my $parser2 = new MyParser( -myflag => 1 );
All arguments passed to the new() constructor will be
treated as key/value pairs in a hash-table. The newly con-
structed object will be initialized by copying the contents
of the given hash-table (which may have been empty). The
new() constructor for this class and all of its subclasses
returns a blessed reference to the initialized object
(hash-table).
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
$self). If subclasses override this method then they must be
sure to invoke "$self->SUPER::initialize()".
begin_pod()
$parser->begin_pod();
This method is invoked at the beginning of processing for
each POD document that is encountered in the input. Subc-
lasses should override this method to perform any per-
document initialization.
begin_input()
$parser->begin_input();
This method is invoked by parse_from_filehandle() immedi-
ately 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 "=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 begin_pod().
end_input()
$parser->end_input();
This method is invoked by parse_from_filehandle() immedi-
ately 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 "=include"
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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 end_pod().
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 finaliza-
tion.
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 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
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 preprocess_line() method is invoked
before the preprocess_paragraph() method. After all (possi-
bly 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 sec-
tions, then preprocess_paragraph() is invoked.
The base class implementation of this method returns the
given text.
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 $text is the POD paragraph from the input file;
and the parameter $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 $text is ignored (not pro-
cessed).
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This method is invoked after gathering up all the lines in a
paragraph and after determining the cutting state of the
paragraph, but before trying to further parse or interpret
them. After preprocess_paragraph() returns, the current cut-
ting state (which is returned by "$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 preprocess_line() method is invoked
before the preprocess_paragraph() method. After all (possi-
bly preprocessed) lines in a paragraph have been assembled
together and either it has been determined that the para-
graph is part of the POD documentation from one of the
selected sections or the "-want_nonPODs" option is true,
then preprocess_paragraph() is invoked.
The base class implementation of this method returns the
given text.
METHODS FOR PARSING AND PROCESSINGPod::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.
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 inter-
polation of interior sequences and can't rely upon interpo-
late 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 parameter $line_num
is the line number curresponding to the beginning of $text.
parse_text() will parse the given text into a parse-tree of
"nodes." and interior-sequences. Each "node" in the parse
tree is either a text-string, or a Pod::InteriorSequence.
The result returned is a parse-tree of type Pod::ParseTree.
Please see Pod::InputObjects for more information about
Pod::InteriorSequence and Pod::ParseTree.
If desired, an optional hash-ref may be specified as the
first argument to customize certain aspects of the parse-
tree that is created and returned. The set of recognized
option keywords are:
-expand_seq => code-ref|method-name
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Normally, the parse-tree returned by parse_text() will
contain an unexpanded "Pod::InteriorSequence" object for
each interior-sequence encountered. Specifying
-expand_seq tells parse_text() to "expand" every
interior-sequence it sees by invoking the referenced
function (or named method of the parser object) and using
the return value as the expanded result.
If a subroutine reference was given, it is invoked as:
&$code_ref( $parser, $sequence )
and if a method-name was given, it is invoked as:
$parser->method_name( $sequence )
where $parser is a reference to the parser object, and
$sequence is a reference to the interior-sequence object.
[NOTE: If the interior_sequence() method is specified,
then it is invoked according to the interface specified
in "interior_sequence()"].
-expand_text => code-ref|method-name
Normally, the parse-tree returned by parse_text() will
contain a text-string for each contiguous sequence of
characters outside of an interior-sequence. Specifying
-expand_text tells parse_text() to "preprocess" every
such text-string it sees by invoking the referenced func-
tion (or named method of the parser object) and using the
return value as the preprocessed (or "expanded") result.
[Note that if the result is an interior-sequence, then it
will not be expanded as specified by the -expand_seq
option; Any such recursive expansion needs to be handled
by the specified callback routine.]
If a subroutine reference was given, it is invoked as:
&$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 $ptree_node is a
reference to the current node in the parse-tree (usually
an interior-sequence object or else the top-level node of
the parse-tree).
-expand_ptree => code-ref|method-name
Rather than returning a "Pod::ParseTree", pass the
parse-tree as an argument to the referenced subroutine
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(or named method of the parser object) and return the
result instead of the parse-tree object.
If a subroutine reference was given, it is invoked as:
&$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.
interpolate()
$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.
interpolate() merely invokes a private method to recursively
expand nested interior sequences in bottom-up order (inner-
most sequences are expanded first). If there is a need to
expand nested sequences in some alternate order, use
parse_text instead.
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 "STDIN" is used.
The $in_fh parameter may be any object that provides a get-
line() method to retrieve a single line of input text
(hence, an appropriate wrapper object could be used to parse
PODs from a single string or an array of strings).
Using "$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 filehan-
dle is currently in use).
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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 pro-
cessing 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 subc-
lasses.
parse_from_file()
$parser->parse_from_file($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 parse_from_filehandle() method passing it the
corresponding input and output filehandles.
+ 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 spe-
cial output filename ">&STDERR" is given then the STDERR
filehandle is used for output (and no open or close is per-
formed). If no output filehandle is currently in use and no
output filename is specified, then "-" is implied. Alterna-
tively, an IO::String object is also accepted as an output
file handle.
This method does not usually need to be overridden by subc-
lasses.
ACCESSOR METHODS
Clients of Pod::Parser should use the following methods to
access instance data fields:
errorsub()
$parser->errorsub("method_name");
$parser->errorsub(\&warn_user);
$parser->errorsub(sub { print STDERR, @_ });
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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 messages. Returns
"undef" if the warn builtin is used to issue error messages
(this is the default behavior).
cutting()
$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.
parseopts()
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.
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## 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.
output_file()
$fname = $parser->output_file();
Returns the name of the output file being written.
output_handle()
$fhandle = $parser->output_handle();
Returns the output filehandle object.
input_file()
$fname = $parser->input_file();
Returns the name of the input file being read.
input_handle()
$fhandle = $parser->input_handle();
Returns the current input filehandle object.
PRIVATE METHODS AND DATAPod::Parser makes use of several internal methods and data
fields which clients should not need to see or use. For the
sake of avoiding name collisions for client data and
methods, these methods and fields are briefly discussed
here. Determined hackers may obtain further information
about them by reading the Pod::Parser source code.
Private data fields are stored in the hash-object whose
reference is returned by the new() constructor for this
class. The names of all private methods and data-fields used
by Pod::Parser begin with a prefix of "_" and match the reg-
ular expression "/^_\w+$/".
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
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everything in one pass and calling the interpolate() method
to expand sequences into text, it may be desirable to
instead create a parse-tree using the 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 "METHODS FOR PARSING AND PROCESS-
ING" 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 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 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
parse_text() method is the key to doing this successfully.
Every paragraph-callback (i.e. the polymorphic methods for
command(), verbatim(), and textblock() paragraphs) takes a
Pod::Paragraph object as an argument. Each paragraph object
has a 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 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 parse_text. Let's assume the desired option-set is given
by the hash %options. Then we might do something like the
following:
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Pod::Parser(3p) Perl Programmers Reference Guide Pod::Parser(3p)
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
}
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Pod::Parser(3p) Perl Programmers Reference Guide Pod::Parser(3p)
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 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 emit() method if they
are objects/references.
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Pod::Parser(3p) Perl Programmers Reference Guide Pod::Parser(3p)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 2005-02-05 18
