用于模拟数组在PHP中无法正常工作的左连接的函数

function leftJoin(array $leftArray, array $rightArray, $leftKey, $rightKey)
{
    $result = [];
    foreach ($leftArray as $leftItem) {
        $matched = false;
        foreach ($rightArray as $rightItem) {
            if ($leftItem[$leftKey] == $rightItem[$rightKey]) {
                $result[] = array_merge($leftItem, $rightItem);
                $matched = true;
            }
        }
        if (!$matched) {
            $result[] = array_merge($leftItem, array_fill_keys(array_keys($rightArray[0]), null));
        }
    }
    return $result;
}