[pod-constants.git] / lib / Pod / Constants.pm

package Pod::Constants;

use 5.006002;
use strict;
use warnings;

use base qw(Pod::Parser Exporter);
use Carp;

our $VERSION = 0.17;

# An ugly hack to go from caller() to the relevant parser state
# variable
my %parsers;

sub end_input {
	#my ($parser, $command, $paragraph, $line_num) = (@_);
	my $parser = shift;

	return unless $parser->{active};

	print "Found end of $parser->{active}\n" if $parser->{DEBUG};
	my $whereto = $parser->{wanted_pod_tags}->{$parser->{active}};
	print "\$_ will be set to:\n---\n$parser->{paragraphs}\n---\n" if $parser->{DEBUG};

	$parser->{paragraphs} =~ s/^\s*|\s*$//gs if $parser->{trimmed_tags}->{$parser->{active}};

	if (ref $whereto eq 'CODE') {
		print "calling sub\n" if $parser->{DEBUG};
		local ($_) = $parser->{paragraphs};
		$whereto->();
		print "done\n" if $parser->{DEBUG};
	} elsif (ref $whereto eq 'SCALAR') {
		print "inserting into scalar\n" if $parser->{DEBUG};
		$$whereto = $parser->{paragraphs};
	} elsif (ref $whereto eq 'ARRAY') {
		print "inserting into array\n" if $parser->{DEBUG};
		@$whereto = split /\n/, $parser->{paragraphs};
	} elsif (ref $whereto eq 'HASH') {
		print "inserting into hash\n" if $parser->{DEBUG};
		# Oh, sorry, should I be in LISP101?
		%$whereto = (
			map { map { s/^\s*|\s*$//g; $_ } split /=>/ } grep m/^
					 ( (?:[^=]|=[^>])+ )   # scan up to "=>"
					 =>
					 ( (?:[^=]|=[^>])+ =? )# don't allow more "=>"'s
					 $/x, split /\n/, $parser->{paragraphs},);
	} else { die $whereto }
	$parser->{active} = undef;
}

# Pod::Parser overloaded command
sub command {
	my ($parser, $command, $paragraph, $line_num) = @_;

	$paragraph =~ s/(?:\r\n|\n\r)/\n/g;

	print "Got command =$command, value=$paragraph\n" if $parser->{DEBUG};

	$parser->end_input() if $parser->{active};

	my ($lookup);
	# first check for a catch-all for this command type
	if ( exists $parser->{wanted_pod_tags}->{"*$command"} ) {
		$parser->{paragraphs} = $paragraph;
		$parser->{active} = "*$command";
	} elsif ($command =~ m/^(head\d+|item|(for|begin))$/) {
		if ( $2 ) {
			# if it's a "for" or "begin" section, the title is the
			# first word only
			($lookup, $parser->{paragraphs}) = $paragraph =~ m/^\s*(\S*)\s*(.*)/s;
		} else {
			# otherwise, it's up to the end of the line
			($lookup, $parser->{paragraphs}) = $paragraph =~ m/^\s*(\S[^\n]*?)\s*\n(.*)$/s;
		}

		# Look for a match by name
		if (defined $lookup && exists $parser->{wanted_pod_tags}->{$lookup}) {
			print "Found $lookup\n" if ($parser->{DEBUG});
			$parser->{active} = $lookup;
		} elsif ($parser->{DEBUG}) {
			local $^W = 0;
			print "Ignoring =$command $paragraph (lookup = $lookup)\n"
		}

	} else {
		# nothing
		print "Ignoring =$command (not known)\n" if $parser->{DEBUG};
	}
}

# Pod::Parser overloaded verbatim
sub verbatim {
	my ($parser, $paragraph, $line_num) = @_;
	$paragraph =~ s/(?:\r\n|\n\r)/\n/g;

	my $status = $parser->{active} ? 'using' : 'ignoring';
	print "Got paragraph: $paragraph ($status)\n" if $parser->{DEBUG};

	$parser->{paragraphs} .= $paragraph if defined $parser->{active}
}

# Pod::Parser overloaded textblock
sub textblock { goto \&verbatim }

sub import {
	my $class = shift;

	# if no args, just return
	return unless (@_);

	# try to guess the source file of the caller
	my $source_file;
	if (caller ne 'main') {
		(my $module = caller.'.pm') =~ s|::|/|g;
		$source_file = $INC{$module};
	}
	$source_file ||= $0;

	croak "Cannot find source file (guessed $source_file) for package ".caller unless -f $source_file;

	# nasty tricks with the stack so we don't have to be silly with
	# caller()
	unshift @_, $source_file;
	goto \&import_from_file;
}

sub import_from_file {
	my $filename = shift;

	my $parser = __PACKAGE__->new();

	$parser->{wanted_pod_tags} = {};
	$parser->{trimmed_tags} = {};
	$parser->{trim_next} = 0;
	$parser->{DEBUG} = 0;
	$parser->{active} = undef;
	$parsers{caller()} = $parser;

	$parser->add_hook(@_);

	print "Pod::Parser: DEBUG: Opening $filename for reading\n" if $parser->{DEBUG};
	open my $fh, '<', $filename or croak "cannot open $filename for reading; $!";

	$parser->parse_from_filehandle($fh, \*STDOUT);

	close $fh;
}

sub add_hook {
	my $parser;
	if (eval { $_[0]->isa(__PACKAGE__) }) {
		$parser = shift;
	} else {
		$parser = $parsers{caller()} or croak 'add_hook called, but don\'t know what for - caller = '.caller;
	}
	while (my ($pod_tag, $var) = splice @_, 0, 2) {
		#print "$pod_tag: $var\n";
		if (lc($pod_tag) eq '-trim') {
			$parser->{trim_next} = $var;
		} elsif ( lc($pod_tag) eq '-debug' ) {
			$parser->{DEBUG} = $var;
		} elsif (lc($pod_tag) eq '-usage') {
			# an idea for later - automatic "usage"
			#%wanted_pod_tags{@tags}
		} else {
			if ((ref $var) =~ /^(?:SCALAR|CODE|ARRAY|HASH)$/) {
				print "Will look for $pod_tag.\n" if $parser->{DEBUG};
				$parser->{wanted_pod_tags}->{$pod_tag} = $var;
				$parser->{trimmed_tags}->{$pod_tag} = 1 if $parser->{trim_next};
			} else {
				croak "Sorry - need a reference to import POD sections into, not the scalar value $var"
			}
		}
	}
}

sub delete_hook {
	my $parser;
	if (eval { $_[0]->isa(__PACKAGE__) }) {
		$parser = shift;
	} else {
		$parser = $parsers{caller()} or croak 'delete_hook called, but don\'t know what for - caller = '.caller;
	}
	while ( my $label = shift ) {
		delete $parser->{wanted_pod_tags}->{$label};
		delete $parser->{trimmed_tags}->{$label};
	}
}

1;
__END__

=encoding utf-8

=head1 NAME

Pod::Constants - Include constants from POD

=head1 SYNOPSIS

 our ($myvar, $VERSION, @myarray, $html, %myhash);

 use Pod::Constants -trim => 1,
     'Pod Section Name' => \$myvar,
     'Version' => sub { eval },
     'Some list' => \@myarray,
     html => \$html,
     'Some hash' => \%myhash;

 =head2 Pod Section Name

 This string will be loaded into $myvar

 =head2 Version

 # This is an example of using a closure.  $_ is set to the
 # contents of the paragraph.  In this example, "eval" is
 # used to execute this code at run time.
 $VERSION = 0.17;

 =head2 Some list

 Each line from this section of the file
 will be placed into a separate array element.
 For example, this is $myarray[2].

 =head2 Some hash

 This text will not go into the hash, because
 it doesn't look like a definition list.
     key1 => Some value (this will go into the hash)
     var2 => Some Other value (so will this)
     wtf = This won't make it in.

 =head2 %myhash's value after the above:

    ( key1 => "Some value (this will go into the hash)",
      var2 => "Some Other value (so will this)"          )

 =begin html <p>This text will be in $html</p>

 =cut

=head1 DESCRIPTION

This module allows you to specify those constants that should be
documented in your POD, and pull them out a run time in a fairly
arbitrary fashion.

Pod::Constants uses Pod::Parser to do the parsing of the source file.
It has to open the source file it is called from, and does so directly
either by lookup in %INC or by assuming it is $0 if the caller is
"main" (or it can't find %INC{caller()})

=head2 ARBITARY DECISIONS

I have made this code only allow the "Pod Section Name" to match
`headN', `item', `for' and `begin' POD sections.  If you have a good
reason why you think it should match other POD sections, drop me a
line and if I'm convinced I'll put it in the standard version.

For `for' and `begin' sections, only the first word is counted as
being a part of the specifier, as opposed to `headN' and `item', where
the entire rest of the line counts.

=head1 FUNCTIONS

=head2 import(@args)

This function is called when we are "use"'d.  It determines the source
file by inspecting the value of caller() or $0.

The form of @args is HOOK => $where.

$where may be a scalar reference, in which case the contents of the
POD section called "HOOK" will be loaded into $where.

$where may be an array reference, in which case the contents of the
array will be the contents of the POD section called "HOOK", split
into lines.

$where may be a hash reference, in which case any lines with a "=>"
symbol present will have everything on the left have side of the =>
operator as keys and everything on the right as values.  You do not
need to quote either, nor have trailing commas at the end of the
lines.

$where may be a code reference (sub { }), in which case the sub is
called when the hook is encountered.  $_ is set to the value of the
POD paragraph.

You may also specify the behaviour of whitespace trimming; by default,
no trimming is done except on the HOOK names.  Setting "-trim => 1"
turns on a package "global" (until the next time import is called)
that will trim the $_ sent for processing by the hook processing
function (be it a given function, or the built-in array/hash
splitters) for leading and trailing whitespace.

The name of HOOK is matched against any "=head1", "=head2", "=item",
"=for", "=begin" value.  If you specify the special hooknames "*item",
"*head1", etc, then you will get a function that is run for every 

Note that the supplied functions for array and hash splitting are
exactly equivalent to fairly simple Perl blocks:

Array:

  HOOK => sub { @array = split /\n/, $_ }

Hash:

  HOOK => sub {
  %hash =
      (map { map { s/^\s+|\s+$//g; $_ } split /=>/, $_ }
        (grep m/^
            ( (?:[^=]|=[^>])+ )   # scan up to "=>"
            =>
            ( (?:[^=]|=[^>])+ =? )# don't allow more "=>"'s
            $/x, split /\n/, $_));
  }

Well, they're simple if you can grok map, a regular expression like
that and a functional programming style.  If you can't I'm sure it is
probably voodoo to you.

Here's the procedural equivalent:

  HOOK => sub {
     for my $line (split /\n/, $_) {
         my ($key, $value, $junk) = split /=>/, $line;
         next if $junk;
         $key =~ s/^\s+|\s+$//g
         $value =~ s/^\s+|\s+$//g
         $hash{$key} = $value;
     }
  },

=head2 import_from_file($filename, @args)

Very similar to straight "import", but you specify the source filename
explicitly.

=head2 add_hook(NAME => value)

This function adds another hook, it is useful for dynamic updating of
parsing through the document.

For an example, please see t/01-constants.t in the source
distribution.  More detailed examples will be added in a later
release.

=head2 delete_hook(@list)

Deletes the named hooks.  Companion function to add_hook

=head2 CLOSURES AS DESTINATIONS

If the given value is a ref CODE, then that function is called, with
$_ set to the value of the paragraph.  This can be very useful for
applying your own custom mutations to the POD to change it from human
readable text into something your program can use.

After I added this function, I just kept on thinking of cool uses for
it.  The nice, succinct code you can make with it is one of
Pod::Constant's strongest features.

Below are some examples.

=head1 EXAMPLES

=head2 Module Makefile.PL maintenance

Tired of keeping those module Makefile.PL's up to date?  Note: This
method seems to break dh-make-perl.

=head2 Example Makefile.PL

 eval "use Pod::Constants";
 ($Pod::Constants::VERSION >= 0.11)
     or die <<EOF
 ####
 ####  ERROR: This module requires Pod::Constants 0.11 or
 ####  higher to be installed.
 ####
 EOF

 my ($VERSION, $NAME, $PREREQ_PM, $ABSTRACT, $AUTHOR);
 Pod::Constants::import_from_file 
     (
      'MyTestModule.pm',
      'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+)/ },
      'DEPENDENCIES' => ($PREREQ_PM = { }),
       -trim => 1,
      'NAME' => sub { $ABSTRACT=$_; ($NAME) = m/(\S+)/ },
      'AUTHOR' => \$AUTHOR,
     );

 WriteMakefile
     (
      'NAME'        => $NAME,
      'PREREQ_PM'        => $PREREQ_PM,
      'VERSION'          => $VERSION,
      ($] >= 5.005 ?    ## Add these new keywords supported since 5.005
       (ABSTRACT         => $ABSTRACT,
        AUTHOR           => $AUTHOR) : ()),
     );

=head2 Corresponding Module

 =head1 NAME

 MyTestModule - Demonstrate Pod::Constant's Makefile.PL usefulness

 =head2 MODULE RELEASE

 This is release 1.05 of this module.

 =head2 DEPENDENCIES

 The following modules are required to make this module:

    Some::Module => 0.02

 =head2 AUTHOR

 Ima Twat <ima@twat.name>

 =cut

 our $VERSION;
 use Pod::Constants -trim => 1,
     'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+) or die };

=head1 AUTHOR

Sam Vilain, <samv@cpan.org>

Maintained by Marius Gavrilescu, <marius@ieval.ro> since July 2015

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2001, 2002, 2007 Sam Vilain. All Rights Reserved.
Copyright (C) 2015 by Marius Gavrilescu <marius@ieval.ro>

This module is free software. It may be used, redistributed and/or
modified under the terms of the Perl Artistic License, version 2

=head1 BUGS/TODO

I keep thinking it would be nice to be able to import an =item list
into an array or something, eg for a program argument list.  But I'm
not too sure how it would be all that useful in practice; you'd end up
putting the function names for callbacks in the pod or something
(perhaps not all that bad).

Would this be useful?

 Pod::Constants::import(Foo::SECTION => \$myvar);

Debug output is not very readable


=cut
Commit	Line	Data
f46dd377 MG	1	package Pod::Constants;
f46dd377 MG	2
222de36b	3	use 5.006002;
f46dd377	4	use strict;
222de36b	5	use warnings;
f46dd377 MG	6
f46dd377 MG	7	use base qw(Pod::Parser Exporter);
f46dd377 MG	8	use Carp;
f46dd377 MG	9
222de36b	10	our $VERSION = 0.17;
f46dd377 MG	11
	12	# An ugly hack to go from caller() to the relevant parser state
	13	# variable
	14	my %parsers;
	15
	16	sub end_input {
db966dd0 MG	17	#my ($parser, $command, $paragraph, $line_num) = (@_);
	18	my $parser = shift;
	19
	20	return unless $parser->{active};
	21
612aada2	22	print "Found end of $parser->{active}\n" if $parser->{DEBUG};
db966dd0	23	my $whereto = $parser->{wanted_pod_tags}->{$parser->{active}};
612aada2	24	print "\$_ will be set to:\n---\n$parser->{paragraphs}\n---\n" if $parser->{DEBUG};
db966dd0	25
612aada2	26	$parser->{paragraphs} =~ s/^\s\|\s$//gs if $parser->{trimmed_tags}->{$parser->{active}};
db966dd0	27
fa6e78f4	28	if (ref $whereto eq 'CODE') {
db966dd0 MG	29	print "calling sub\n" if $parser->{DEBUG};
	30	local ($_) = $parser->{paragraphs};
	31	$whereto->();
	32	print "done\n" if $parser->{DEBUG};
fa6e78f4	33	} elsif (ref $whereto eq 'SCALAR') {
db966dd0 MG	34	print "inserting into scalar\n" if $parser->{DEBUG};
db966dd0 MG	35	$$whereto = $parser->{paragraphs};
fa6e78f4	36	} elsif (ref $whereto eq 'ARRAY') {
db966dd0 MG	37	print "inserting into array\n" if $parser->{DEBUG};
db966dd0 MG	38	@$whereto = split /\n/, $parser->{paragraphs};
fa6e78f4	39	} elsif (ref $whereto eq 'HASH') {
db966dd0 MG	40	print "inserting into hash\n" if $parser->{DEBUG};
db966dd0 MG	41	# Oh, sorry, should I be in LISP101?
612aada2	42	%$whereto = (
fa6e78f4	43	map { map { s/^\s\|\s$//g; $_ } split /=>/ } grep m/^
612aada2 MG	44	( (?:[^=]\|=[^>])+ ) # scan up to "=>"
	45	=>
	46	( (?:[^=]\|=[^>])+ =? )# don't allow more "=>"'s
fa6e78f4	47	$/x, split /\n/, $parser->{paragraphs},);
db966dd0 MG	48	} else { die $whereto }
db966dd0 MG	49	$parser->{active} = undef;
f46dd377 MG	50	}
	51
	52	# Pod::Parser overloaded command
	53	sub command {
db966dd0 MG	54	my ($parser, $command, $paragraph, $line_num) = @_;
	55
	56	$paragraph =~ s/(?:\r\n\|\n\r)/\n/g;
	57
612aada2	58	print "Got command =$command, value=$paragraph\n" if $parser->{DEBUG};
db966dd0 MG	59
	60	$parser->end_input() if $parser->{active};
	61
db966dd0 MG	62	my ($lookup);
	63	# first check for a catch-all for this command type
	64	if ( exists $parser->{wanted_pod_tags}->{"*$command"} ) {
	65	$parser->{paragraphs} = $paragraph;
	66	$parser->{active} = "*$command";
db966dd0 MG	67	} elsif ($command =~ m/^(head\d+\|item\|(for\|begin))$/) {
	68	if ( $2 ) {
	69	# if it's a "for" or "begin" section, the title is the
	70	# first word only
612aada2	71	($lookup, $parser->{paragraphs}) = $paragraph =~ m/^\s(\S)\s(.)/s;
db966dd0 MG	72	} else {
db966dd0 MG	73	# otherwise, it's up to the end of the line
612aada2	74	($lookup, $parser->{paragraphs}) = $paragraph =~ m/^\s(\S[^\n]?)\s\n(.)$/s;
db966dd0 MG	75	}
	76
	77	# Look for a match by name
612aada2	78	if (defined $lookup && exists $parser->{wanted_pod_tags}->{$lookup}) {
db966dd0 MG	79	print "Found $lookup\n" if ($parser->{DEBUG});
db966dd0 MG	80	$parser->{active} = $lookup;
612aada2 MG	81	} elsif ($parser->{DEBUG}) {
	82	local $^W = 0;
	83	print "Ignoring =$command $paragraph (lookup = $lookup)\n"
db966dd0	84	}
f46dd377	85
f46dd377	86	} else {
db966dd0 MG	87	# nothing
db966dd0 MG	88	print "Ignoring =$command (not known)\n" if $parser->{DEBUG};
f46dd377	89	}
f46dd377 MG	90	}
	91
	92	# Pod::Parser overloaded verbatim
	93	sub verbatim {
db966dd0 MG	94	my ($parser, $paragraph, $line_num) = @_;
db966dd0 MG	95	$paragraph =~ s/(?:\r\n\|\n\r)/\n/g;
f46dd377	96
fa6e78f4	97	my $status = $parser->{active} ? 'using' : 'ignoring';
612aada2	98	print "Got paragraph: $paragraph ($status)\n" if $parser->{DEBUG};
f46dd377	99
612aada2	100	$parser->{paragraphs} .= $paragraph if defined $parser->{active}
f46dd377 MG	101	}
	102
	103	# Pod::Parser overloaded textblock
	104	sub textblock { goto \&verbatim }
	105
f46dd377	106	sub import {
db966dd0 MG	107	my $class = shift;
	108
	109	# if no args, just return
	110	return unless (@_);
	111
	112	# try to guess the source file of the caller
	113	my $source_file;
fa6e78f4 MG	114	if (caller ne 'main') {
fa6e78f4 MG	115	(my $module = caller.'.pm') =~ s\|::\|/\|g;
db966dd0 MG	116	$source_file = $INC{$module};
	117	}
	118	$source_file \|\|= $0;
	119
612aada2	120	croak "Cannot find source file (guessed $source_file) for package ".caller unless -f $source_file;
db966dd0 MG	121
	122	# nasty tricks with the stack so we don't have to be silly with
	123	# caller()
	124	unshift @_, $source_file;
	125	goto \&import_from_file;
f46dd377 MG	126	}
f46dd377 MG	127
f46dd377	128	sub import_from_file {
db966dd0	129	my $filename = shift;
f46dd377	130
db966dd0	131	my $parser = __PACKAGE__->new();
f46dd377	132
db966dd0 MG	133	$parser->{wanted_pod_tags} = {};
	134	$parser->{trimmed_tags} = {};
	135	$parser->{trim_next} = 0;
	136	$parser->{DEBUG} = 0;
	137	$parser->{active} = undef;
	138	$parsers{caller()} = $parser;
f46dd377	139
db966dd0	140	$parser->add_hook(@_);
f46dd377	141
612aada2	142	print "Pod::Parser: DEBUG: Opening $filename for reading\n" if $parser->{DEBUG};
fa6e78f4	143	open my $fh, '<', $filename or croak "cannot open $filename for reading; $!";
f46dd377	144
db966dd0	145	$parser->parse_from_filehandle($fh, \*STDOUT);
f46dd377	146
db966dd0	147	close $fh;
f46dd377 MG	148	}
f46dd377 MG	149
f46dd377	150	sub add_hook {
db966dd0	151	my $parser;
fa6e78f4	152	if (eval { $_[0]->isa(__PACKAGE__) }) {
db966dd0	153	$parser = shift;
f46dd377	154	} else {
fa6e78f4	155	$parser = $parsers{caller()} or croak 'add_hook called, but don\'t know what for - caller = '.caller;
db966dd0 MG	156	}
	157	while (my ($pod_tag, $var) = splice @_, 0, 2) {
	158	#print "$pod_tag: $var\n";
fa6e78f4	159	if (lc($pod_tag) eq '-trim') {
db966dd0	160	$parser->{trim_next} = $var;
fa6e78f4	161	} elsif ( lc($pod_tag) eq '-debug' ) {
db966dd0	162	$parser->{DEBUG} = $var;
fa6e78f4	163	} elsif (lc($pod_tag) eq '-usage') {
db966dd0 MG	164	# an idea for later - automatic "usage"
	165	#%wanted_pod_tags{@tags}
	166	} else {
	167	if ((ref $var) =~ /^(?:SCALAR\|CODE\|ARRAY\|HASH)$/) {
612aada2	168	print "Will look for $pod_tag.\n" if $parser->{DEBUG};
db966dd0	169	$parser->{wanted_pod_tags}->{$pod_tag} = $var;
612aada2	170	$parser->{trimmed_tags}->{$pod_tag} = 1 if $parser->{trim_next};
db966dd0	171	} else {
fa6e78f4	172	croak "Sorry - need a reference to import POD sections into, not the scalar value $var"
db966dd0 MG	173	}
db966dd0 MG	174	}
f46dd377	175	}
f46dd377 MG	176	}
f46dd377 MG	177
f46dd377	178	sub delete_hook {
db966dd0	179	my $parser;
fa6e78f4	180	if (eval { $_[0]->isa(__PACKAGE__) }) {
db966dd0 MG	181	$parser = shift;
db966dd0 MG	182	} else {
fa6e78f4	183	$parser = $parsers{caller()} or croak 'delete_hook called, but don\'t know what for - caller = '.caller;
db966dd0 MG	184	}
	185	while ( my $label = shift ) {
	186	delete $parser->{wanted_pod_tags}->{$label};
	187	delete $parser->{trimmed_tags}->{$label};
	188	}
f46dd377 MG	189	}
f46dd377 MG	190
fa6e78f4	191	1;
49655cb6 MG	192	__END__
	193
	194	=encoding utf-8
	195
	196	=head1 NAME
	197
	198	Pod::Constants - Include constants from POD
	199
	200	=head1 SYNOPSIS
	201
612aada2	202	our ($myvar, $VERSION, @myarray, $html, %myhash);
49655cb6 MG	203
	204	use Pod::Constants -trim => 1,
	205	'Pod Section Name' => \$myvar,
	206	'Version' => sub { eval },
	207	'Some list' => \@myarray,
	208	html => \$html,
	209	'Some hash' => \%myhash;
	210
	211	=head2 Pod Section Name
	212
	213	This string will be loaded into $myvar
	214
	215	=head2 Version
	216
	217	# This is an example of using a closure. $_ is set to the
	218	# contents of the paragraph. In this example, "eval" is
	219	# used to execute this code at run time.
	220	$VERSION = 0.17;
	221
	222	=head2 Some list
	223
	224	Each line from this section of the file
	225	will be placed into a separate array element.
	226	For example, this is $myarray[2].
	227
	228	=head2 Some hash
	229
	230	This text will not go into the hash, because
	231	it doesn't look like a definition list.
	232	key1 => Some value (this will go into the hash)
	233	var2 => Some Other value (so will this)
	234	wtf = This won't make it in.
	235
	236	=head2 %myhash's value after the above:
	237
	238	( key1 => "Some value (this will go into the hash)",
	239	var2 => "Some Other value (so will this)" )
	240
	241	=begin html <p>This text will be in $html</p>
	242
	243	=cut
	244
	245	=head1 DESCRIPTION
	246
	247	This module allows you to specify those constants that should be
	248	documented in your POD, and pull them out a run time in a fairly
	249	arbitrary fashion.
	250
	251	Pod::Constants uses Pod::Parser to do the parsing of the source file.
	252	It has to open the source file it is called from, and does so directly
	253	either by lookup in %INC or by assuming it is $0 if the caller is
	254	"main" (or it can't find %INC{caller()})
	255
	256	=head2 ARBITARY DECISIONS
	257
	258	I have made this code only allow the "Pod Section Name" to match
	259	`headN', `item', `for' and `begin' POD sections. If you have a good
	260	reason why you think it should match other POD sections, drop me a
	261	line and if I'm convinced I'll put it in the standard version.
	262
	263	For `for' and `begin' sections, only the first word is counted as
	264	being a part of the specifier, as opposed to `headN' and `item', where
	265	the entire rest of the line counts.
	266
267	=head1 FUNCTIONS
268
269	=head2 import(@args)
270
271	This function is called when we are "use"'d. It determines the source
272	file by inspecting the value of caller() or $0.
273
274	The form of @args is HOOK => $where.
275
276	$where may be a scalar reference, in which case the contents of the
277	POD section called "HOOK" will be loaded into $where.
278
279	$where may be an array reference, in which case the contents of the
280	array will be the contents of the POD section called "HOOK", split
281	into lines.
282
283	$where may be a hash reference, in which case any lines with a "=>"
284	symbol present will have everything on the left have side of the =>
285	operator as keys and everything on the right as values. You do not
286	need to quote either, nor have trailing commas at the end of the
287	lines.
288
289	$where may be a code reference (sub { }), in which case the sub is
290	called when the hook is encountered. $_ is set to the value of the
291	POD paragraph.
292
293	You may also specify the behaviour of whitespace trimming; by default,
294	no trimming is done except on the HOOK names. Setting "-trim => 1"
295	turns on a package "global" (until the next time import is called)
296	that will trim the $_ sent for processing by the hook processing
297	function (be it a given function, or the built-in array/hash
298	splitters) for leading and trailing whitespace.
299
300	The name of HOOK is matched against any "=head1", "=head2", "=item",
301	"=for", "=begin" value. If you specify the special hooknames "*item",
302	"*head1", etc, then you will get a function that is run for every
303
304	Note that the supplied functions for array and hash splitting are
305	exactly equivalent to fairly simple Perl blocks:
306
307	Array:
308
309	HOOK => sub { @array = split /\n/, $_ }
310
311	Hash:
312
313	HOOK => sub {
314	%hash =
315	(map { map { s/^\s+\|\s+$//g; $_ } split /=>/, $_ }
316	(grep m/^
317	( (?:[^=]\|=[^>])+ ) # scan up to "=>"
318	=>
319	( (?:[^=]\|=[^>])+ =? )# don't allow more "=>"'s
320	$/x, split /\n/, $_));
321	}
322
323	Well, they're simple if you can grok map, a regular expression like
324	that and a functional programming style. If you can't I'm sure it is
325	probably voodoo to you.
326
327	Here's the procedural equivalent:
328
329	HOOK => sub {
330	for my $line (split /\n/, $_) {
331	my ($key, $value, $junk) = split /=>/, $line;
332	next if $junk;
333	$key =~ s/^\s+\|\s+$//g
334	$value =~ s/^\s+\|\s+$//g
335	$hash{$key} = $value;
336	}
337	},
338
339	=head2 import_from_file($filename, @args)
340
341	Very similar to straight "import", but you specify the source filename
342	explicitly.
343
344	=head2 add_hook(NAME => value)
345
346	This function adds another hook, it is useful for dynamic updating of
347	parsing through the document.
348
349	For an example, please see t/01-constants.t in the source
350	distribution. More detailed examples will be added in a later
351	release.
352
353	=head2 delete_hook(@list)
354
355	Deletes the named hooks. Companion function to add_hook
356
f46dd377 MG	357	=head2 CLOSURES AS DESTINATIONS
	358
	359	If the given value is a ref CODE, then that function is called, with
	360	$_ set to the value of the paragraph. This can be very useful for
	361	applying your own custom mutations to the POD to change it from human
	362	readable text into something your program can use.
	363
	364	After I added this function, I just kept on thinking of cool uses for
	365	it. The nice, succinct code you can make with it is one of
	366	Pod::Constant's strongest features.
	367
	368	Below are some examples.
	369
	370	=head1 EXAMPLES
	371
	372	=head2 Module Makefile.PL maintenance
	373
	374	Tired of keeping those module Makefile.PL's up to date? Note: This
	375	method seems to break dh-make-perl.
	376
	377	=head2 Example Makefile.PL
	378
	379	eval "use Pod::Constants";
	380	($Pod::Constants::VERSION >= 0.11)
	381	or die <<EOF
	382	####
	383	#### ERROR: This module requires Pod::Constants 0.11 or
	384	#### higher to be installed.
	385	####
	386	EOF
	387
	388	my ($VERSION, $NAME, $PREREQ_PM, $ABSTRACT, $AUTHOR);
	389	Pod::Constants::import_from_file
	390	(
	391	'MyTestModule.pm',
	392	'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+)/ },
e18addae	393	'DEPENDENCIES' => ($PREREQ_PM = { }),
f46dd377 MG	394	-trim => 1,
	395	'NAME' => sub { $ABSTRACT=$_; ($NAME) = m/(\S+)/ },
	396	'AUTHOR' => \$AUTHOR,
	397	);
	398
	399	WriteMakefile
	400	(
db966dd0	401	'NAME' => $NAME,
f46dd377 MG	402	'PREREQ_PM' => $PREREQ_PM,
	403	'VERSION' => $VERSION,
	404	($] >= 5.005 ? ## Add these new keywords supported since 5.005
	405	(ABSTRACT => $ABSTRACT,
	406	AUTHOR => $AUTHOR) : ()),
	407	);
	408
	409	=head2 Corresponding Module
	410
	411	=head1 NAME
	412
	413	MyTestModule - Demonstrate Pod::Constant's Makefile.PL usefulness
	414
	415	=head2 MODULE RELEASE
	416
	417	This is release 1.05 of this module.
	418
e18addae	419	=head2 DEPENDENCIES
f46dd377 MG	420
	421	The following modules are required to make this module:
	422
	423	Some::Module => 0.02
	424
	425	=head2 AUTHOR
	426
	427	Ima Twat <ima@twat.name>
	428
	429	=cut
	430
222de36b	431	our $VERSION;
f46dd377 MG	432	use Pod::Constants -trim => 1,
	433	'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+) or die };
	434
	435	=head1 AUTHOR
	436
	437	Sam Vilain, <samv@cpan.org>
	438
70413288 MG	439	Maintained by Marius Gavrilescu, <marius@ieval.ro> since July 2015
	440
	441	=head1 COPYRIGHT AND LICENSE
	442
	443	Copyright (C) 2001, 2002, 2007 Sam Vilain. All Rights Reserved.
	444	Copyright (C) 2015 by Marius Gavrilescu <marius@ieval.ro>
	445
	446	This module is free software. It may be used, redistributed and/or
	447	modified under the terms of the Perl Artistic License, version 2
	448
f46dd377 MG	449	=head1 BUGS/TODO
	450
	451	I keep thinking it would be nice to be able to import an =item list
	452	into an array or something, eg for a program argument list. But I'm
	453	not too sure how it would be all that useful in practice; you'd end up
	454	putting the function names for callbacks in the pod or something
	455	(perhaps not all that bad).
	456
	457	Would this be useful?
	458
	459	Pod::Constants::import(Foo::SECTION => \$myvar);
	460
	461	Debug output is not very readable
	462
f46dd377	463
49655cb6	464	=cut