问题

You can use the following code to unset a value in a filter iterator:

你可以使用以下代码来取消过滤迭代器中的某个值：

$iterator->rewind();
while ($iterator->valid()) {
    if ($iterator->current() === $valueToRemove) {
        $iterator->offsetUnset($iterator->key());
    }
    $iterator->next();
}

请将 $iterator 替换为你实际使用的迭代器变量，将 $valueToRemove 替换为要移除的值。

答案1

得分: 2

The documentation states that the FilterIterator "filters out unwanted values," and the logic behind that is in the accept() method which you must implement.

So you don't unset anything, you just reject (or not accept, technically) values you don't want.

class DoctorFilter extends FilterIterator
{
    public function accept(): bool
    {
        $obj = $this->getInnerIterator()->current();
        
        return is_string($obj) && str_starts_with($obj, 'Dr.');
    }
}

$people = [
    'Dr. Jekyll',
    'Mr. Hyde', // This item will be removed
    'Dr. Frankenstein',
];

foreach (new DoctorFilter(new ArrayIterator($people)) as $item) {
    echo $item.PHP_EOL;
}

/*
Outputs:

Dr. Jekyll
Dr. Frankenstein
*/

Demo: https://3v4l.org/ieTAP#v8.2.6

class DoctorFilter extends FilterIterator
{
    public function accept(): bool
    {
        $obj = $this->getInnerIterator()->current();
        
        return is_string($obj) && str_starts_with($obj, 'Dr.');
    }
}

$people = [
    'Dr. Jekyll',
    'Mr. Hyde', // This item will be removed
    'Dr. Frankenstein',
];

foreach (new DoctorFilter(new ArrayIterator($people)) as $item) {
    echo $item.PHP_EOL;
}

/*
Outputs:

Dr. Jekyll
Dr. Frankenstein
*/