iterator_apply
(PHP 5 >= 5.1.0)
iterator_apply — Вызывает функцию для каждого элемента в итераторе
Описание
Вызывает функцию для каждого элемента в итераторе.
Список параметров
-
iterator -
Класс для перебора.
-
function -
Функция обратного вызова, которая применяется к каждому элементу.
Замечание: Функция должна возвращать
TRUEдля того, чтобы продолжать процесс итерации надiterator. -
args -
Аргументы для передачи в функцию обратного вызова.
Возвращаемые значения
Returns the iteration count.
Примеры
Пример #1 Пример использования 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));
?>
Результат выполнения данного примера:
APPLES BANANAS CHERRIES
Коментарии
$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, $arg3]);
return true;
}, array(1, 2));
?>
same output.
Be aware of the proper methods to iterate the specific Iterator you are consuming, as the implementation of the method could vary its behaviour.
For example, unlike the ArrayIterator, you can't iterate on a SplDoubleLinkedList with current() without using next() on every iteration (and then, only would iterate if you return true at the end of the callable. It is far easier then with LinkedLists use a while($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)
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