package Pod::Elemental::Transformer::Nester;
# ABSTRACT: group the document into sections
$Pod::Elemental::Transformer::Nester::VERSION = '0.103005';
use Moose;
with 'Pod::Elemental::Transformer';
#pod =head1 OVERVIEW
#pod
#pod The Nester transformer is meant to find potential container elements and make
#pod them into actual containers. It works by being told what elements may be made
#pod into containers and what subsequent elements they should allow to be stuffed
#pod into them.
#pod
#pod For example, given the following nester:
#pod
#pod use Pod::Elemental::Selectors qw(s_command s_flat);
#pod
#pod my $nester = Pod::Elemental::Transformer::Nester->new({
#pod top_selector => s_command('head1'),
#pod content_selectors => [
#pod s_command([ qw(head2 head3 head4) ]),
#pod s_flat,
#pod ],
#pod });
#pod
#pod ..then when we apply the transformation:
#pod
#pod $nester->transform_node($document);
#pod
#pod ...the nester will find all C<=head1> elements in the top-level of the
#pod document. It will ensure that they are represented by objects that perform the
#pod Pod::Elemental::Node role, and then it will move all subsequent elements
#pod matching the C<content_selectors> into the container.
#pod
#pod So, if we start with this input:
#pod
#pod =head1 Header
#pod =head2 Subheader
#pod Pod5::Ordinary <some content>
#pod =head1 New Header
#pod
#pod The nester will convert its structure to look like this:
#pod
#pod =head1 Header
#pod =head2 Subheader
#pod Pod5::Ordinary <some content>
#pod =head1 New Header
#pod
#pod Once an element is reached that does not pass the content selectors, the
#pod nesting ceases until the next potential container.
#pod
#pod =cut
use MooseX::Types::Moose qw(ArrayRef CodeRef);
use Pod::Elemental::Element::Nested;
use Pod::Elemental::Selectors -all;
use namespace::autoclean;
#pod =attr top_selector
#pod
#pod This attribute must be a coderef (presumably made from
#pod Pod::Elemental::Selectors) that will test elements in the transformed node and
#pod return true if the element is a potential new container.
#pod
#pod =cut
has top_selector => (
is => 'ro',
isa => CodeRef,
required => 1,
);
#pod =attr content_selectors
#pod
#pod This attribute must be an arrayref of coderefs (again presumably made from
#pod Pod::Elemental::Selectors) that will test whether paragraphs subsequent to the
#pod top-level container may be moved under the container.
#pod
#pod =cut
has content_selectors => (
is => 'ro',
isa => ArrayRef[ CodeRef ],
required => 1,
);
sub _is_containable {
my ($self, $para) = @_;
for my $sel (@{ $self->content_selectors }) {
return 1 if $sel->($para);
}
return;
}
sub transform_node {
my ($self, $node) = @_;
# We used to say (length -2) because "if we're already at the last element,
# we can't nest anything -- there's nothing subsequent to the potential
# top-level element to nest!" -- my (rjbs's) reasoning in 2009.
#
# This was an unneeded optimization, and therefore stupid. Worse, it was a
# bug. It meant that a nestable element that was the last element in a
# sequence wouldn't be upgraded to a Nested element, so later munging could
# barf. In fact, that's what happened in [rt.cpan.org #69189]
# -- rjbs, 2012-05-04
PASS: for my $i (0 .. @{ $node->children }- 1) {
last PASS if $i >= @{ $node->children };
my $para = $node->children->[ $i ];
next unless $self->top_selector->($para);
if (s_command(undef, $para) and not s_node($para)) {
$para = $node->children->[ $i ] = Pod::Elemental::Element::Nested->new({
command => $para->command,
content => $para->content,
});
}
if (! s_node($para) or @{ $para->children }) {
confess "can't use $para as the top of a nesting";
}
my @to_nest;
NEST: for my $j ($i+1 .. @{ $node->children } - 1) {
last unless $self->_is_containable($node->children->[ $j ]);
push @to_nest, $j;
}
if (@to_nest) {
my @to_nest_elem =
splice @{ $node->children }, $to_nest[0], scalar(@to_nest);
push @{ $para->children }, @to_nest_elem;
next PASS;
}
}
return $node;
}
__PACKAGE__->meta->make_immutable;
1;
__END__
=pod
=encoding UTF-8
=head1 NAME
Pod::Elemental::Transformer::Nester - group the document into sections
=head1 VERSION
version 0.103005
=head1 OVERVIEW
The Nester transformer is meant to find potential container elements and make
them into actual containers. It works by being told what elements may be made
into containers and what subsequent elements they should allow to be stuffed
into them.
For example, given the following nester:
use Pod::Elemental::Selectors qw(s_command s_flat);
my $nester = Pod::Elemental::Transformer::Nester->new({
top_selector => s_command('head1'),
content_selectors => [
s_command([ qw(head2 head3 head4) ]),
s_flat,
],
});
..then when we apply the transformation:
$nester->transform_node($document);
...the nester will find all C<=head1> elements in the top-level of the
document. It will ensure that they are represented by objects that perform the
Pod::Elemental::Node role, and then it will move all subsequent elements
matching the C<content_selectors> into the container.
So, if we start with this input:
=head1 Header
=head2 Subheader
Pod5::Ordinary <some content>
=head1 New Header
The nester will convert its structure to look like this:
=head1 Header
=head2 Subheader
Pod5::Ordinary <some content>
=head1 New Header
Once an element is reached that does not pass the content selectors, the
nesting ceases until the next potential container.
=head1 ATTRIBUTES
=head2 top_selector
This attribute must be a coderef (presumably made from
Pod::Elemental::Selectors) that will test elements in the transformed node and
return true if the element is a potential new container.
=head2 content_selectors
This attribute must be an arrayref of coderefs (again presumably made from
Pod::Elemental::Selectors) that will test whether paragraphs subsequent to the
top-level container may be moved under the container.
=head1 AUTHOR
Ricardo SIGNES <rjbs@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2020 by Ricardo SIGNES.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut