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    iterator_apply

    (PHP 5 >= 5.1.0, PHP 7, PHP 8)

    iterator_apply — ユーザー関数をイテレータのすべての要素でコールする

    説明

    iterator_apply(Traversable $iterator, callable $callback, ?array $args = null): int

    イテレータ内のすべての要素に対して関数をコールします。

    パラメータ

    iterator

    順次処理したいイテレータオブジェクト

    callback

    すべての要素に対してコールしたいコールバック関数。 この関数は args のみを受け取ります。 デフォルトでは引数を渡されません。 たとえば count($args) === 3 の場合、 コールバック関数は3変数関数です。

    注意: iterator での処理を続けるために、 この関数は true を返さなければなりません。

    args

    コールバック関数に渡す引数。 引数の array。 args の個々の要素が コールバック callback に別々の引数として渡されます。

    戻り値

    イテレータの要素数を返します。

    例

    例1 iterator_apply() の例

    <?php
    function print_caps(Iterator $iterator) {
    echo     strtoupper($iterator->current()) . "\n";
    return     TRUE;
    }

    $it = new ArrayIterator(array("Apples", "Bananas", "Cherries"));
    iterator_apply($it, "print_caps", array($it));
    ?>

    上の例の出力は以下となります。

    APPLES
BANANAS
CHERRIES

    参考

    • array_walk() - 配列の全ての要素にユーザー定義の関数を適用する

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    User Contributed Notes 2 notes

    up
    2
    tezcatl at fedoraproject dot org
    6 years ago
    Each of the arguments required by the function, must be in the array supplied in the third argument to iterator_apply. You can use references too. Example:

    <?php

    function translate_to(string $target_language, Iterator $words, array $dictionaries) {

    $language = ucfirst($target_language);
    $dictionary = $dictionaries[$target_language] ?? 'not found';

    if (    $dictionary === 'not found') {
    echo     "Not found dictionary for {$language}\n";
    return;
    }

    echo     "English words translated to {$language}\n";

    $not_found = [];

    iterator_apply($words, function($words, $dictionary, &$not_found){

    $english_word = $words->current();

    $translated_word = $dictionary[$english_word] ?? '';

    if (    $translated_word !== '') {
    echo     "{$english_word} translates to {$translated_word}\n";
    } else {
    $not_found[] = $english_word;
    }

    return     true;

    }, array(    $words, $dictionary, &$not_found));

    echo     "\nNot found words:\n" . implode("\n", $not_found) . "\n";
    }

    $dictionaries = [
    'nahuatl' => [
    'one' => 'Ze',
    'two' => 'Ome',
    'three' => 'Yei',
    'four' => 'Nahui',
    ],
    ];

    $iterator = new \ArrayIterator(array('one', 'two', 'three', 'four', 'gasoil'));

    translate_to('nahuatl', $iterator, $dictionaries);
    ?>

    English words translated to Nahuatl
    one translates to Ze
    two translates to Ome
    three translates to Yei
    four translates to Nahui

    Not found words:
    gasoil
    up
    2
    tezcatl at fedoraproject dot org
    6 years ago
    Be aware of the proper methods to iterate the specific Iterator you are consuming, as the implementation of the method could vary its behaviour.

    For example, unlike the ArrayIterator, you can't iterate on a SplDoubleLinkedList with current() without using next() on every iteration (and then, only would iterate if you return true at the end of the callable. It is far easier then with LinkedLists use a while($it->valid()) { $it->current(); $it->next(); }

    Let's see:

    <?php

    $ll     = new \SplDoublyLinkedList();

    $ll->push('ze');
    $ll->push('ome');
    $ll->push('yei');
    $ll->push('nahui');

    $ll->rewind();

    $iterations_done = iterator_apply($ll, function(Iterator $it) {

    echo     implode("\t=>", [
    $it->key(),
    $it->current(),
    ucfirst($it->current())
    ]),    "\n";

    return     true;

    }, array(    $ll));

    echo     "Did iterate {$iterations_done} times \n";

    $ll->rewind();

    $iterations_done = iterator_apply($ll, function(Iterator $it) {

    echo     implode("\t=>", [
    $it->key(),
    $it->current(),
    ucfirst($it->current())
    ]),    "\n";

    $it->next();

    return     true;

    }, array(    $ll));

    echo     "Did iterate {$iterations_done} times \n";

    $ll->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO | SplDoublyLinkedList::IT_MODE_DELETE);

    var_dump($ll->count());

    foreach(    $ll as $key => $val) {
    echo     "{$key}\t",ucfirst($val),"\n";
    }

    var_dump($ll->count());
    ?>

    Output:

    0 =>ze =>Ze
    0 =>ze =>Ze
    0 =>ze =>Ze
    0 =>ze =>Ze
    Did iterate 4 times
    0 =>ze =>Ze
    1 =>ome =>Ome
    2 =>yei =>Yei
    3 =>nahui =>Nahui
    Did iterate 4 times
    int(4)
    0 Ze
    0 Ome
    0 Yei
    0 Nahui
    int(0)
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