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iterator_apply

(PHP 5 >= 5.1.0, PHP 7)

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

int iterator_apply ( Traversable $iterator , callable $function [, array $args ] )

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

順次処理したいクラス。

function

すべての要素に対してコールしたいコールバック関数。

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。

返り値

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

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User Contributed Notes 3 notes

up
0
tezcatl at fedoraproject dot org
3 months 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
0
tezcatl at fedoraproject dot org
3 months 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
1 year 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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