wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\DataModel\Services\Diff;

use Diff\DiffOp\Diff\Diff;
use Diff\DiffOp\DiffOpAdd;
use Diff\DiffOp\DiffOpChange;
use Diff\DiffOp\DiffOpRemove;
use Diff\Patcher\PatcherException;
use Wikibase\DataModel\Statement\Statement;
use Wikibase\DataModel\Statement\StatementList;

/**
 * @since 3.6
 *
 * @license GPL-2.0-or-later
 * @author Jeroen De Dauw < jeroendedauw@gmail.com >
 * @author Thiemo Kreuz
 */
class StatementListPatcher {

    /**
     * @since 3.6
     *
     * @param StatementList $statements
     * @param Diff $patch
     *
     * @throws PatcherException
     */
    public function patchStatementList( StatementList $statements, Diff $patch ) {
        /**
         * @var Statement $statement
         * @var Statement $oldStatement
         * @var Statement $newStatement
         */

        foreach ( $patch as $diffOp ) {
            switch ( true ) {
                case $diffOp instanceof DiffOpAdd:
                    $statement = $diffOp->getNewValue();
                    $guid = $statement->getGuid();
                    if ( $statements->getFirstStatementWithGuid( $guid ) === null ) {
                        $statements->addStatement( $statement );
                    }
                    break;

                case $diffOp instanceof DiffOpChange:
                    $oldStatement = $diffOp->getOldValue();
                    $newStatement = $diffOp->getNewValue();
                    $this->changeStatement( $statements, $oldStatement->getGuid(), $newStatement );
                    break;

                case $diffOp instanceof DiffOpRemove:
                    $statement = $diffOp->getOldValue();
                    $statements->removeStatementsWithGuid( $statement->getGuid() );
                    break;

                default:
                    throw new PatcherException( 'Invalid statement list diff' );
            }
        }
    }

    /**
     * @param StatementList $statements
     * @param string|null $oldGuid
     * @param Statement $newStatement
     */
    private function changeStatement( StatementList $statements, $oldGuid, Statement $newStatement ) {
        foreach ( $statements->toArray() as $index => $statement ) {
            if ( $statement->getGuid() === $oldGuid ) {
                $statements->removeStatementsWithGuid( $oldGuid );
                $statements->addStatement( $newStatement, $index );
                return;
            }
        }
    }

}