Pod::Parser(3) Perl Programmers Reference Guide Pod::Parser(3)NAMEPod::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.
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
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. 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 pre_
process_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 appropri
ate state variable to control the operation for each pass.
If your input source can't be reset to start at the begin
ning, 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).
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 the section on "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 possi
ble to use the Pod::Parser::parse_text function to do more
sophisticated tree-based parsing. See the section on
"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 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 para
graphs that are not part of the POD-format documenta
tion 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_para_
graph() 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 para
graph, 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 com_
mand() 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 the section on "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
the Pod::InputObjects manpage 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
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 the
Pod::InputObjects manpage 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
""$pod_para""
a reference to a "Pod::Paragraph" object which contains
further information about the paragraph (see the
Pod::InputObjects manpage for details).
In order to process interior sequences, subclasses imple
mentations of this method will probably want to invoke
either interpolate() or parse_text(), passing it the text
block "$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 encoun
tered. 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 inter_
polate() 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 "$pod_seq" argument is a reference to a "Pod::Interi
orSequence" object which contains further information
about the interior sequence. Please see the Pod::InputOb
jects manpage for details if you need to access this addi
tional information.
Subclass implementations of this method may wish to invoke
the nested() method of "$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-process
ing. 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 sub
classes. 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 con
structor 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 construc
tor is not recommended, but if you insist on being able to
do this, then the subclass will need to override the new()
constructor 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:
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 con
tents of the given hash-table (which may have been empty).
The new() constructor for this class and all of its sub
classes 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. Sub
classes 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" 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
finalization.
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 num
ber 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 per
formed for this line.
Please note that the preprocess_line() method is invoked
before the preprocess_paragraph() method. After all (pos
sibly preprocessed) lines in a paragraph have been assem
bled together and it has been determined that the para
graph is part of the POD documentation from one of the
selected sections, then preprocess_paragraph() is invoked.
The base class implementation of this method returns the
given text.
preprocess_paragraph()
$textblock = $parser->preprocess_paragraph($text, $line_num);
This method should be overridden by subclasses that wish
to perform any kind of preprocessing for each block (para
graph) of POD documentation that appears in the input
stream. The parameter "$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 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 preprocess_paragraph() returns, the current
cutting state (which is returned by "$self->cutting()") is
examined. If it evaluates to true then input text (includ
ing the given "$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 (pos
sibly preprocessed) lines in a paragraph have been assem
bled 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 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 sub
classes may want to invoke them to exploit their function
ality.
parse_text()
$ptree1 = $parser->parse_text($text, $line_num);
$ptree2 = $parser->parse_text({%opts}, $text, $line_num);
$ptree3 = $parser->parse_text(\%opts, $text, $line_num);
This method is useful if you need to perform your own
interpolation of interior sequences and can't rely upon
interpolate to expand them in simple bottom-up order
order.
The parameter "$text" is a string or block of text to be
parsed for interior sequences; and the parameter
"$line_num" is the line number curresponding to the begin
ning of "$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::InteriorSe
quence. The result returned is a parse-tree of type
Pod::ParseTree. Please see the Pod::InputObjects manpage
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 parse_text() will
contain an unexpanded "Pod::InteriorSequence" object
for each interior-sequence encountered. Specifying
-expand_seq tells parse_text() to "expand" every inte
rior-sequence it sees by invoking the referenced func
tion (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 "$sequence" is a reference to the interior-sequence
object. [NOTE: If the interior_sequence() method is
specified, then it is invoked according to the inter
face specified in the section on "inte
rior_sequence()"].
-expand_text => code-ref|method-name
Normally, the parse-tree returned by parse_text() will
contain a text-string for each contiguous sequence of
characters outside of an interior-sequence. Specifying
-expand_text tells parse_text() to "preprocess" every
such text-string it sees by invoking the referenced
function (or named method of the parser object) and
using the return value as the preprocessed (or
"expanded") result. [Note that if the result is an
interior-sequence, then it will not be expanded as
specified by the -expand_seq option; Any such recursive
expansion needs to be handled by the specified callback
routine.]
If a subroutine reference was given, it is invoked as:
&$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
(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 recur
sively 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 parse_text instead.
parse_from_filehandle()
$parser->parse_from_filehandle($in_fh,$out_fh);
This method takes an input filehandle (which is assumed to
already be opened for reading) and reads the entire input
stream looking for blocks (paragraphs) of POD documenta
tion to be processed. If no first argument is given the
default input filehandle "STDIN" is used.
The "$in_fh" parameter may be any object that provides a
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 "$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 file
handle 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 dur
ing processing when in the midst executing of this method
will not affect the input stream used by the current invo
cation of this method.
This method does not usually need to be overridden by sub
classes.
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 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.
This method does not usually need to be overridden by sub
classes.
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, @_ });
Specifies the method or subroutine to use when printing
error messages about POD syntax. The supplied method/sub
routine 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 behav
ior).
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 mes
sages (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 cor
responding 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 the section on "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 = $parser->input_handle();
Returns the current input filehandle object.
PRIVATE METHODS AND DATAPod::Parser makes use of several internal methods and data
fields which clients should not need to see or use. For
the sake of avoiding name collisions for client data and
methods, these methods and fields are briefly discussed
here. Determined hackers may obtain further information
about them by reading the Pod::Parser source code.
Private data fields are stored in the hash-object whose
reference is returned by the new() constructor for this
class. The names of all private methods and data-fields
used by Pod::Parser begin with a prefix of "_" and match
the regular expression "/^_\w+$/".
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 interpo_
late() 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 list of children (each of
which may be a text-string, or a similar tree-like struc
ture).
Pay special attention to the section on "METHODS FOR PARS
ING AND PROCESSING" and to the objects described in the
Pod::InputObjects manpage. The former describes the gory
details and parameters for how to customize and extend the
parsing behavior of Pod::Parser. Pod::InputObjects pro
vides 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 chil
dren, each of which may be a text-string, or an Interi
orSequence 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:
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, alter
natively, 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/sub
class 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 format
ting them if they are text-strings, or by calling their
emit() method if they are objects/references.
SEE ALSO
the Pod::InputObjects manpage, the Pod::Select manpage
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
Brad Appleton <bradapp@enteract.com>
Based on code for Pod::Text written by Tom Christiansen
<tchrist@mox.perl.com>
2001-02-22 perl v5.6.1 Pod::Parser(3)
