wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Lib\Store;

/**
 * PropertyOrderProvider that uses one of two given providers:
 * It first tries the primary provider and, if that has no data, resorts to
 * the secondary provider.
 *
 * @license GPL-2.0-or-later
 * @author Marius Hoch
 */
class FallbackPropertyOrderProvider implements PropertyOrderProvider {

    /**
     * @var PropertyOrderProvider
     */
    private $primaryProvider;

    /**
     * @var PropertyOrderProvider
     */
    private $secondaryProvider;

    public function __construct(
        PropertyOrderProvider $primaryProvider,
        PropertyOrderProvider $secondaryProvider
    ) {
        $this->primaryProvider = $primaryProvider;
        $this->secondaryProvider = $secondaryProvider;
    }

    /**
     * @see PropertyOrderProvider::getPropertyOrder
     * @return int[]|null
     */
    public function getPropertyOrder() {
        $propertyOrder = $this->primaryProvider->getPropertyOrder();

        if ( $propertyOrder === null ) {
            $propertyOrder = $this->secondaryProvider->getPropertyOrder();
        }

        return $propertyOrder;
    }

}