DPC2020 - Workshop day

NoRewindIterator クラス

(PHP 5 >= 5.1.0, PHP 7)

はじめに

このイテレータは巻き戻しの操作を無視します。 これにより、一部のみを走査する 複数の foreach ループでイテレータを処理することが可能になります。

クラス概要

NoRewindIterator extends IteratorIterator {
/* メソッド */
public __construct ( Iterator $iterator )
public current ( void ) : mixed
public getInnerIterator ( void ) : iterator
public key ( void ) : mixed
public next ( void ) : void
public rewind ( void ) : void
public valid ( void ) : bool
/* 継承したメソッド */
public IteratorIterator::current ( void ) : mixed
public IteratorIterator::key ( void ) : mixed
public IteratorIterator::next ( void ) : void
public IteratorIterator::rewind ( void ) : void
public IteratorIterator::valid ( void ) : bool
}

目次

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User Contributed Notes 1 note

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Anonymous
1 month ago
As its name implies, NoRewindIterator doesn't invoke the "rewind" method when It reaches the end of the iterator.

Let's demonstrate it by two examles.

In this example the "rewind" method will be invoked after when the "foreache" reaches its end, so, we can repeat printing the same values as many times as we want:

<?PHP
$iterator
= new ArrayIterator(['PHP', 'Python', 'Go']);

foreach (
$iterator as $item) {
    echo
$item.PHP_EOL;
}

foreach (
$iterator as $item) {
    echo
$item.PHP_EOL;
}
?>

By using the NoRewindIterator, the "rewind" won't be invoked, so, we can't do as we did in previous example:

<?PHP
$iterator
= new ArrayIterator(['PHP', 'Python', 'Go']);
$iterator = new NoRewindIterator($iterator);

foreach (
$iterator as $item) {
    echo
$item.PHP_EOL;
}

// doesn't do anything
foreach ($iterator as $item) {
    echo
$item.PHP_EOL;
}

?>
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