How does \Magento\Framework\Module\ModuleList\Loader::sortBySequence() work?

dmitrii_fediuk (Dmitrii Fediuk) April 9, 2016, 1:44am 1

Contexts:

github.com

magento/magento2/blob/ec436ce/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L124-L131


/**
 * Sort the list of modules using "sequence" key in meta-information
 *
 * @param array $origList
 * @return array
 * @SuppressWarnings(PHPMD.UnusedLocalVariable)
 */
private function sortBySequence($origList)

github.com

magento/magento2/blob/ec436ce/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L133-L140


ksort($origList);
$expanded = [];
foreach ($origList as $moduleName => $value) {
    $expanded[] = [
        'name' => $moduleName,
        'sequence' => $this->expandSequence($origList, $moduleName),
    ];
}

github.com

magento/magento2/blob/ec436ce/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L162-L174


/**
 * Accumulate information about all transitive "sequence" references
 *
 * @param array $list
 * @param string $name
 * @param array $accumulated
 * @return array
 * @throws \Exception
 */
private function expandSequence($list, $name, $accumulated = [])
{
    $accumulated[] = $name;
    $result = $list[$name]['sequence'];

github.com

magento/magento2/blob/ec436ce/app/code/Magento/Customer/etc/module.xml#L9-L14


<module name="Magento_Customer" setup_version="2.0.7">
    <sequence>
        <module name="Magento_Eav"/>
        <module name="Magento_Directory"/>
    </sequence>
</module>

github.com

magento/magento2/blob/ec436ce/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L175-L186


    foreach ($result as $relatedName) {
        if (in_array($relatedName, $accumulated)) {
            throw new \Exception("Circular sequence reference from '{$name}' to '{$relatedName}'.");
        }
        if (!isset($list[$relatedName])) {
            continue;
        }
        $relatedResult = $this->expandSequence($list, $relatedName, $accumulated);
        $result = array_unique(array_merge($result, $relatedResult));
    }
    return $result;
}

github.com

magento/magento2/blob/ec436ce/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L142-L143


// Use "bubble sorting" because usort does not check each pair of elements and in this case it is important
$total = count($expanded);

github.com

magento/magento2/blob/ec436ce/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L144-L159


for ($i = 0; $i < $total - 1; $i++) {
    for ($j = $i; $j < $total; $j++) {
        if (in_array($expanded[$j]['name'], $expanded[$i]['sequence'])) {
            $temp = $expanded[$i];
            $expanded[$i] = $expanded[$j];
            $expanded[$j] = $temp;
        }
    }
}


$result = [];
foreach ($expanded as $pair) {
    $result[$pair['name']] = $origList[$pair['name']];
}


return $result;