Pod::Simple - framework for parsing Pod
Pod::Simple is a Perl library for parsing text in the Pod
("plain old documentation") markup language that is typically used
for writing documentation for Perl and for Perl modules. The Pod format is
explained in perlpod; the most common formatter is called
"perldoc".
Be sure to read "ENCODING" if your Pod contains
non-ASCII characters.
Pod formatters can use Pod::Simple to parse Pod documents and
render them into plain text, HTML, or any number of other formats.
Typically, such formatters will be subclasses of Pod::Simple, and so they
will inherit its methods, like
"parse_file". But note that Pod::Simple
doesn't understand and properly parse Perl itself, so if you have a file
which contains a Perl program that has a multi-line quoted string which has
lines that look like pod, Pod::Simple will treat them as pod. This can be
avoided if the file makes these into indented here documents instead.
If you're reading this document just because you have a
Pod-processing subclass that you want to use, this document (plus the
documentation for the subclass) is probably all you need to read.
If you're reading this document because you want to write a
formatter subclass, continue reading it and then read
Pod::Simple::Subclassing, and then possibly even read perlpodspec (some of
which is for parser-writers, but much of which is notes to
formatter-writers).
- "$parser = SomeClass->new();"
- This returns a new parser object, where
"SomeClass" is a
subclass of Pod::Simple.
- "$parser->output_fh( *OUT );"
- This sets the filehandle that $parser's output
will be written to. You can pass *STDOUT or
*STDERR, otherwise you should probably do
something like this:
my $outfile = "output.txt";
open TXTOUT, ">$outfile" or die "Can't write to $outfile: $!";
$parser->output_fh(*TXTOUT);
...before you call one of the
"$parser->parse_whatever"
methods.
- "$parser->output_string( \$somestring );"
- This sets the string that $parser's output will be
sent to, instead of any filehandle.
- "$parser->parse_file( $some_filename );"
- "$parser->parse_file( *INPUT_FH );"
- This reads the Pod content of the file (or filehandle) that you specify,
and processes it with that $parser object,
according to however $parser's class works, and
according to whatever parser options you have set up for this
$parser object.
- "$parser->parse_string_document( $all_content );"
- This works just like "parse_file" except
that it reads the Pod content not from a file, but from a string that you
have already in memory.
- "$parser->parse_lines( ...@lines..., undef );"
- This processes the lines in @lines (where each
list item must be a defined value, and must contain exactly one line of
content -- so no items like "foo\nbar"
are allowed). The final "undef" is used
to indicate the end of document being parsed.
The other
"parser_whatever"
methods are meant to be called only once per
$parser object; but
"parse_lines" can be called as many
times per $parser object as you want, as long as
the last call (and only the last call) ends with an
"undef" value.
- "$parser->content_seen"
- This returns true only if there has been any real content seen for this
document. Returns false in cases where the document contains content, but
does not make use of any Pod markup.
- "SomeClass->filter( $filename );"
- "SomeClass->filter( *INPUT_FH );"
- "SomeClass->filter( \$document_content );"
- This is a shortcut method for creating a new parser object, setting the
output handle to STDOUT, and then processing the specified file (or
filehandle, or in-memory document). This is handy for one-liners like
this:
perl -MPod::Simple::Text -e "Pod::Simple::Text->filter('thingy.pod')"
Some of these methods might be of interest to general users, as
well as of interest to formatter-writers.
Note that the general pattern here is that the accessor-methods
read the attribute's value with "$value =
$parser->attribute"
and set the attribute's value with
"$parser->attribute(newvalue)".
For each accessor, I typically only mention one syntax or another, based on
which I think you are actually most likely to use.
- "$parser->parse_characters( SOMEVALUE )"
- The Pod parser normally expects to read octets and to convert those octets
to characters based on the "=encoding"
declaration in the Pod source. Set this option to a true value to indicate
that the Pod source is already a Perl character stream. This tells the
parser to ignore any "=encoding" command
and to skip all the code paths involving decoding octets.
- "$parser->no_whining( SOMEVALUE )"
- If you set this attribute to a true value, you will suppress the parser's
complaints about irregularities in the Pod coding. By default, this
attribute's value is false, meaning that irregularities will be reported.
Note that turning this attribute to true won't suppress one or
two kinds of complaints about rarely occurring unrecoverable errors.
- "$parser->no_errata_section( SOMEVALUE )"
- If you set this attribute to a true value, you will stop the parser from
generating a "POD ERRORS" section at the end of the document. By
default, this attribute's value is false, meaning that an errata section
will be generated, as necessary.
- "$parser->complain_stderr( SOMEVALUE )"
- If you set this attribute to a true value, it will send reports of parsing
errors to STDERR. By default, this attribute's value is false, meaning
that no output is sent to STDERR.
Setting "complain_stderr"
also sets "no_errata_section".
- "$parser->source_filename"
- This returns the filename that this parser object was set to read
from.
- "$parser->doc_has_started"
- This returns true if $parser has read from a
source, and has seen Pod content in it.
- "$parser->source_dead"
- This returns true if $parser has read from a
source, and come to the end of that source.
- "$parser->strip_verbatim_indent( SOMEVALUE )"
- The perlpod spec for a Verbatim paragraph is "It should be reproduced
exactly...", which means that the whitespace you've used to indent
your verbatim blocks will be preserved in the output. This can be annoying
for outputs such as HTML, where that whitespace will remain in front of
every line. It's an unfortunate case where syntax is turned into
semantics.
If the POD you're parsing adheres to a consistent indentation
policy, you can have such indentation stripped from the beginning of
every line of your verbatim blocks. This method tells Pod::Simple what
to strip. For two-space indents, you'd use:
$parser->strip_verbatim_indent(' ');
For tab indents, you'd use a tab character:
$parser->strip_verbatim_indent("\t");
If the POD is inconsistent about the indentation of verbatim
blocks, but you have figured out a heuristic to determine how much a
particular verbatim block is indented, you can pass a code reference
instead. The code reference will be executed with one argument, an array
reference of all the lines in the verbatim block, and should return the
value to be stripped from each line. For example, if you decide that
you're fine to use the first line of the verbatim block to set the
standard for indentation of the rest of the block, you can look at the
first line and return the appropriate value, like so:
$new->strip_verbatim_indent(sub {
my $lines = shift;
(my $indent = $lines->[0]) =~ s/\S.*//;
return $indent;
});
If you'd rather treat each line individually, you can do that,
too, by just transforming them in-place in the code reference and
returning "undef". Say that you don't
want any lines indented. You can do something like this:
$new->strip_verbatim_indent(sub {
my $lines = shift;
sub { s/^\s+// for @{ $lines },
return undef;
});
- "$parser->expand_verbatim_tabs( n )"
- Default: 8
If after any stripping of indentation in verbatim blocks,
there remain tabs, this method call indicates what to do with them.
0 means leave them as tabs, any other number
indicates that each tab is to be translated so as to have tab stops
every "n" columns.
This is independent of other methods (except that it operates
after any verbatim input stripping is done).
Like the other methods, the input parameter is not checked for
validity. "undef" or containing
non-digits has the same effect as 8.
- "$parser->abandon_output_fh()"
- Cancel output to the file handle. Any POD read by the
$parser is not effected.
- "$parser->abandon_output_string()"
- Cancel output to the output string. Any POD read by the
$parser is not effected.
- "$parser->accept_code( @codes )"
- Alias for accept_codes.
- "$parser->accept_codes( @codes )"
- Allows $parser to accept a list of
"Formatting Codes" in perlpod. This can be used to implement
user-defined codes.
- "$parser->accept_directive_as_data( @directives )"
- Allows $parser to accept a list of directives for
data paragraphs. A directive is the label of a "Command
Paragraph" in perlpod. A data paragraph is one delimited by
"=begin/=for/=end" directives. This can
be used to implement user-defined directives.
- "$parser->accept_directive_as_processed( @directives )"
- Allows $parser to accept a list of directives for
processed paragraphs. A directive is the label of a "Command
Paragraph" in perlpod. A processed paragraph is also known as
"Ordinary Paragraph" in perlpod. This can be used to implement
user-defined directives.
- "$parser->accept_directive_as_verbatim( @directives )"
- Allows $parser to accept a list of directives for
"Verbatim Paragraph" in perlpod. A directive is the label of a
"Command Paragraph" in perlpod. This can be used to implement
user-defined directives.
- "$parser->accept_target( @targets )"
- Alias for accept_targets.
- "$parser->accept_target_as_text( @targets )"
- Alias for accept_targets_as_text.
- "$parser->accept_targets( @targets )"
- Accepts targets for "=begin/=for/=end"
sections of the POD.
- "$parser->accept_targets_as_text( @targets )"
- Accepts targets for "=begin/=for/=end"
sections that should be parsed as POD. For details, see "About Data
Paragraphs" in perlpodspec.
- "$parser->any_errata_seen()"
- Used to check if any errata was seen.
Example:
die "too many errors\n" if $parser->any_errata_seen();
- "$parser->errata_seen()"
- Returns a hash reference of all errata seen, both whines and screams. The
hash reference's keys are the line number and the value is an array
reference of the errors for that line.
Example:
if ( $parser->any_errata_seen() ) {
$logger->log( $parser->errata_seen() );
}
- "$parser->detected_encoding()"
- Return the encoding corresponding to
"=encoding", but only if the encoding
was recognized and handled.
- "$parser->encoding()"
- Return encoding of the document, even if the encoding is not correctly
handled.
- "$parser->parse_from_file( $source, $to )"
- Parses from $source file to
$to file. Similar to "parse_from_file"
in Pod::Parser.
- "$parser->scream( @error_messages )"
- Log an error that can't be ignored.
- "$parser->unaccept_code( @codes )"
- Alias for unaccept_codes.
- "$parser->unaccept_codes( @codes )"
- Removes @codes as valid codes for the parse.
- "$parser->unaccept_directive( @directives )"
- Alias for unaccept_directives.
- "$parser->unaccept_directives( @directives )"
- Removes @directives as valid directives for the
parse.
- "$parser->unaccept_target( @targets )"
- Alias for unaccept_targets.
- "$parser->unaccept_targets( @targets )"
- Removes @targets as valid targets for the
parse.
- "$parser->version_report()"
- Returns a string describing the version.
- "$parser->whine( @error_messages )"
- Log an error unless "$parser->no_whining( TRUE
);".
The Pod::Simple parser expects to read octets. The parser
will decode the octets into Perl's internal character string representation
using the value of the "=encoding"
declaration in the POD source.
If the POD source does not include an
"=encoding" declaration, the parser will
attempt to guess the encoding (selecting one of UTF-8 or CP 1252) by
examining the first non-ASCII bytes and applying the heuristic described in
perlpodspec. (If the POD source contains only ASCII bytes, the encoding is
assumed to be ASCII.)
If you set the
"parse_characters" option to a true value
the parser will expect characters rather than octets; will ignore any
"=encoding"; and will make no attempt to
decode the input.
Pod::Simple::Subclassing
perlpod
perlpodspec
Pod::Escapes
perldoc
Questions or discussion about POD and Pod::Simple should be sent
to the pod-people@perl.org mail list. Send an empty email to
pod-people-subscribe@perl.org to subscribe.
This module is managed in an open GitHub repository,
<https://github.com/perl-pod/pod-simple/>. Feel free to fork and
contribute, or to clone <git://github.com/perl-pod/pod-simple.git> and
send patches!
Please use
<https://github.com/perl-pod/pod-simple/issues/new> to file a bug
report.
Copyright (c) 2002 Sean M. Burke.
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
This program is distributed in the hope that it will be useful,
but without any warranty; without even the implied warranty of
merchantability or fitness for a particular purpose.
Pod::Simple was created by Sean M. Burke <sburke@cpan.org>.
But don't bother him, he's retired.
Pod::Simple is maintained by:
- Allison Randal "allison@perl.org"
- Hans Dieter Pearcey "hdp@cpan.org"
- David E. Wheeler
"dwheeler@cpan.org"
- Karl Williamson "khw@cpan.org"
Documentation has been contributed by:
- Gabor Szabo "szabgab@gmail.com"
- Shawn H Corey "SHCOREY at cpan.org"