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package KinoSearch1::Search::Query;
use strict;
use warnings;
use KinoSearch1::Util::ToolSet;
use base qw( KinoSearch1::Util::Class );

BEGIN {
    __PACKAGE__->init_instance_vars(
        # constructor params / members
        boost => 1,
    );
    __PACKAGE__->ready_get_set(qw( boost ));
}

=begin comment

    my $string = $query->to_string( $field_name );

Return a string representation of the query.  $field_name is a default field,
and affects how the string is generated -- for instance, if a TermQuery's
field matches $field_name, the field will be omitted, while if it doesn't
match, the field will be included in the string.

=end comment
=cut

sub to_string { shift->abstract_death }

=begin comment

    my $weight = $query->create_weight($searcher);

Only low-level Queries which rewrite themselves implement this method.

=end comment
=cut

sub create_weight { shift->abstract_death }

# Derive a weight for a high-level query.
sub to_weight {    # in Lucene, this method is simply "weight"
    my ( $self, $searcher ) = @_;
    my $rewritten_self = $searcher->rewrite($self);
    my $weight         = $rewritten_self->create_weight($searcher);
    my $sum            = $weight->sum_of_squared_weights;
    my $sim            = $self->get_similarity($searcher);
    my $norm           = $sim->query_norm($sum);
    $weight->normalize($norm);
    return $weight;
}

=begin comment

    my $rewritten_query = $query->rewrite( $index_reader );

Called by high-level Queries that wish to reformulate themselves as
agglomerations of low-level queries.

=end comment
=cut

sub rewrite { return shift }

=begin comment

my @terms = $query->extract_terms;

Return all the Terms within this query.

=end comment
=cut

sub extract_terms { shift->abstract_death }

# These will be needed by MultiSearcher if we add queries which rewrite
# themselves.
sub combine               { shift->todo_death }
sub merge_boolean_queries { shift->todo_death }

# return the Similarity implementation used by the Query.
sub get_similarity {
    my ( $self, $searcher, $field_name ) = @_;
    # This can be overriden in subclasses, allowing alternative Sims.
    return defined $field_name
        ? $searcher->get_similarity($field_name)
        : $searcher->get_similarity;
}

sub clone { shift->todo_death }

1;

__END__

=head1 NAME

KinoSearch1::Search::Query - base class for search queries

=head1 SYNOPSIS

    # abstract base class

=head1 DESCRIPTION

Base class for queries to be performed against an invindex.
L<TermQuery|KinoSearch1::Search::TermQuery> is one example.

=head1 METHODS

=head2 set_boost get_boost

    $term_query_a->set_boost(2);
    $boolean_query->add_clause( query => $term_query_a, occur => 'SHOULD' );
    $boolean_query->add_clause( query => $term_query_b, occur => 'SHOULD' );

The boost of any Query is 1.0 by default. Setting boost to a number greater