wikimedia/mediawiki-extensions-CirrusSearch

<?php

namespace CirrusSearch\Search\Rescore;

use CirrusSearch\SearchConfig;
use Elastica\Query\FunctionScore;

/**
 * simple log(factor*field+2)^impact
 * Useful to control the impact when applied in a multiplication.
 */
class LogMultFunctionScoreBuilder extends FunctionScoreBuilder {
    /** @var float */
    private $impact;
    /** @var float */
    private $factor;
    /** @var string */
    private $field;

    /**
     * @param SearchConfig $config
     * @param float $weight
     * @param array $profile
     * @throws InvalidRescoreProfileException
     */
    public function __construct( SearchConfig $config, $weight, $profile ) {
        parent::__construct( $config, $weight );
        if ( isset( $profile['impact'] ) ) {
            $this->impact = $this->getOverriddenFactor( $profile['impact'] );
            if ( $this->impact <= 0 ) {
                throw new InvalidRescoreProfileException( 'Param impact must be > 0' );
            }
        } else {
            throw new InvalidRescoreProfileException( 'Param impact is mandatory' );
        }

        if ( isset( $profile['factor'] ) ) {
            $this->factor = $this->getOverriddenFactor( $profile['factor'] );
            if ( $this->factor <= 0 ) {
                throw new InvalidRescoreProfileException( 'Param factor must be > 0' );
            }
        } else {
            $this->factor = 1;
        }

        if ( isset( $profile['field'] ) ) {
            $this->field = $profile['field'];
        } else {
            throw new InvalidRescoreProfileException( 'Param field is mandatory' );
        }
    }

    public function append( FunctionScore $functionScore ) {
        $formula = "pow(log10({$this->factor} * doc['{$this->field}'].value + 2), {$this->impact})";
        $functionScore->addScriptScoreFunction( new \Elastica\Script\Script( $formula, null,
            'expression' ), null, $this->weight );
    }
}