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package App::Ack::Filter;
use strict;
use warnings;
use App::Ack ();
use App::Ack::Filter::Inverse ();
my %filter_types;
=head1 NAME
App::Ack::Filter - Filter objects to filter files
=head1 DESCRIPTION
An abstract superclass that represents objects that can filter
C<App::Ack::File> objects. App::Ack::Filter implementations are
responsible for filtering filenames to be searched.
=head1 SYNOPSIS
# filter implementation
package MyFilter;
use strict;
use warnings;
use parent 'App::Ack::Filter';
sub filter {
my ( $self, $file ) = @_;
}
BEGIN {
App::Ack::Filter->register_filter('mine' => __PACKAGE__);
}
1;
# users
App::Ack::Filter->create_filter('mine', @args);
=head1 METHODS
=head2 App::Ack::Filter->create_filter($type, @args)
Creates a filter implementation, registered as C<$type>. C<@args>
are provided as additional arguments to the implementation's constructor.
=cut
sub create_filter {
my ( undef, $type, @args ) = @_;
if ( my $package = $filter_types{$type} ) {
return $package->new(@args);
}
my $allowed_types = join( ', ', sort keys %filter_types );
App::Ack::die( "Unknown filter type '$type'. Type must be one of: $allowed_types." );
}
=head2 App::Ack::Filter->register_filter($type, $package)
Registers a filter implementation package C<$package> under
the name C<$type>.
=cut
sub register_filter {
my ( undef, $type, $package ) = @_;
$filter_types{$type} = $package;
return;
}
=head2 $filter->filter( $file )
Must be implemented by filter implementations. Returns
true if the filter passes, false otherwise. This method
must B<not> alter the passed-in C<$file> object.
=head2 $filter->invert()
Returns a filter whose L</filter> method returns the opposite of this filter.
=cut
sub invert {
my ( $self ) = @_;
return App::Ack::Filter::Inverse->new( $self );
}
=head2 $filter->is_inverted()
Returns true if this filter is an inverted filter; false otherwise.
=cut
sub is_inverted {
return 0;
}
=head2 $filter->to_string
Converts the filter to a string. This method is also
called implicitly by stringification.
=cut
sub to_string {
return '(unimplemented to_string)';
}
=head2 $filter->inspect
Prints a human-readable debugging string for this filter. Useful for,
you guessed it, debugging.
=cut
sub inspect {
my ( $self ) = @_;
return ref($self);
}
1;
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