=pod

=for vim
   vim: tw=72 ts=3 sts=3 sw=3 et ai :

=encoding utf8

=head1 NAME

Data::Resolver::FromDir - resolver for directories in the filesystem

=head1 SYNOPSIS

   use Data::Resolver::FromDir;
   my $resolver = Data::Resolver::FromDir->new(root => $path);

   my @list_of_asset_keys = $resolver->list_asset_keys;
   say 'have it' if $resolver->has_asset($key);
   my $asset = $resolver->get($key);

   my @list_of_sub_resolver_keys = $resolver->list_sub_resolver_keys;
   say 'have it' if $resolver->has_sub_resolver($srkey);
   my $sub_resolver = $resolver->get_sub_resolver($srkey);


=head1 DESCRIPTION

This class implements a resolver that is fed from a directory in the
filesystem. It inherits from L<Data::Resolver::Base> and implements the
corresponding methods according to the expected semantics.

The class is provided a path to a directory in the filesystem; files in
the directory will be considered valid assets, while sub-directories
will be considered valid starting positions for generating
sub-resolvers. So, as an example, if there is the following tree of
directories/files:

   <root-dir>
   ├── ciao.txt
   └── foo
      ├── bar.txt
      └── galook
         └── final.txt

the corresponding resolver will expose one key for assets (C<ciao.txt>)
and one for sub-resolvers (C<foo>). Getting the sub-resolver for C<foo>,
it will expose one key for assets (C<bar.txt>) and one for sub-resolvers
(C<galook>), and so on.


=head1 INTERFACE

This class inherits from L<Data::Resolver::Base>, inheriting all of its
methods and overloading the abstract ones, while keeping the expected
semantics.

=head2 METHODS

=head3 B<< get_asset >>

   sub get_asset              ($self, $key) { ... }

retrieve the file associated to C<$key>, as a L<Data::Resolver::Asset>.

=head3 B<< get_sub_resolver >>

   sub get_sub_resolver       ($self, $key) { ... }

retrieve the sub-resolver associated to sub-directory C<$key>, as a new
object of class L<Data::Resolver::FromDir>.

=head3 B<< has_asset >>

   sub has_asset              ($self, $key) { ... }

test existence of asset (file) for C<$key>.

=head3 B<< has_sub_resolver >>

   sub has_sub_resolver       ($self, $key) { ... }

test existence of sub-resolver for sub-directory C<$key>.

=head3 B<< list_asset_keys >>

   sub list_asset_keys        ($self)       { ... }

return a list of file names available from the resolver.

=head3 B<< list_sub_resolver_keys >>

   sub list_sub_resolver_keys ($self)       { ... }

return a list of directory names available as sub-resolvers.

=head3 B<< root >>

   my $dirpath = $obj->root;

The path to the root directory used for the resolver.


=head1 AUTHOR

Flavio Poletti <flavio@polettix.it>

=head1 COPYRIGHT AND LICENSE

Copyright 2023 by Flavio Poletti <flavio@polettix.it>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.


=cut
