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 arrayargs 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

add a note

User Contributed Notes 3 notes

up
3
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)
up
-1
ycgambo at outlook dot com
6 years ago
$args is an array and each of its elements are passed to the callback as separate arguments.

so this is the right way to get args:

<?php
$ai
= new ArrayIterator(range(0, 2));

iterator_apply($ai, function() {
var_dump(func_get_args()); // use this func
return true;
}, array(
1, 2));
?>

output:

array(2) {
[0] =>
int(1)
[1] =>
int(2)
}
array(2) {
[0] =>
int(1)
[1] =>
int(2)
}
array(2) {
[0] =>
int(1)
[1] =>
int(2)
}

--------------------------------------------------
or list each args:

<?php
$ai
= new ArrayIterator(range(0, 2));

iterator_apply($ai, function($arg1, $arg2, $arg3) {
var_dump([$arg1, $arg2, $arg3]);
return
true;
}, array(
1, 2));
?>

same output.
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