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iterator_apply

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

iterator_apply — Chama uma função para cada elemento em um iterador

Descrição

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

Chama uma função para cada elemento em um iterador.

Parâmetros

iterator

O objeto iterador sobre o qual iterar.

callback

A função callback para chamar em cada elemento. Esta função recebe apenas os args dados, então é nulária por padrão. Se count($args) === 3, por exemplo, a função callback é ternária.

Nota: A função deve retornar true para continuar iterando sobre o iterator.

args

Um array de argumentos; cada elemento de args é passado para a função callback callback como um argumento separado.

Valor Retornado

Retorna a contagem de iteração.

Exemplos

Exemplo #1 Exemplo de iterator_apply()

<?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));
?>

O exemplo acima produzirá:

APPLES
BANANAS
CHERRIES

Veja Também

array_walk() - Aplica uma determinada função em cada elemento de um array

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User Contributed Notes 3 notes

down

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

down

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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-2

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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