PHP 8.4.0 Alpha 2 available for testing

A classe CachingIterator

(PHP 5, PHP 7, PHP 8)

Introdução

Este objeto suporta iteração em cache sobre outro iterador.

Resumo da classe

class CachingIterator extends IteratorIterator implements ArrayAccess, Countable, Stringable {
/* Constantes */
public const int CALL_TOSTRING;
public const int CATCH_GET_CHILD;
public const int TOSTRING_USE_KEY;
public const int TOSTRING_USE_INNER;
public const int FULL_CACHE;
/* Métodos */
public __construct(Iterator $iterator, int $flags = CachingIterator::CALL_TOSTRING)
public count(): int
public current(): mixed
public getCache(): array
public getFlags(): int
public hasNext(): bool
public key(): scalar
public next(): void
public offsetExists(string $key): bool
public offsetGet(string $key): mixed
public offsetSet(string $key, mixed $value): void
public offsetUnset(string $key): void
public rewind(): void
public setFlags(int $flags): void
public __toString(): string
public valid(): bool
/* Métodos herdados */
}

Constantes pré-definidas

CachingIterator::CALL_TOSTRING

Converte cada elemento para string.

CachingIterator::CATCH_GET_CHILD

Não lançar exceção ao acessar filhos.

CachingIterator::TOSTRING_USE_KEY

Usar key para conversão para string.

CachingIterator::TOSTRING_USE_CURRENT

Usar current para conversão para string.

CachingIterator::TOSTRING_USE_INNER

Usar inner para conversão para string.

CachingIterator::FULL_CACHE

Cache de todos os dados lidos.

Registro de Alterações

Versão Descrição
8.0.0 CachingIterator implementa Stringable agora.

Índice

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User Contributed Notes 4 notes

up
14
ahmad dot mayahi at gmail dot com
4 years ago
The only difference between CachingIterator and other Iterators such as ArrayIterator is the hasNext() method.

Since the data will be loaded into the memory, the CachingIterator is able to check whether the given iterator has a next element.

Let's demonstrate this by an example:

<?php
$iterator
= new CachingIterator(new ArrayIterator(['C', 'C++', 'C#', 'PHP', 'Python', 'Go', 'Ruby']));

foreach (
$iterator as $item) {
if (
$iterator->hasNext()) {
echo
$item.', ';
} else {
echo
'and '.$item;
}
}

// C, C++, C#, PHP, Python, Go, and Ruby
?>

In this example I check whether the iterator has a next value, if so, I append a comma otherwise "and" will be appended to the last element.
up
9
ahmad dot mayahi at gmail dot com
7 years ago
<?php
//This snippet will print out all the cached elements (foreach) .

$cache = new CachingIterator(new ArrayIterator(range(1,100)), CachingIterator::FULL_CACHE);

foreach (
$cache as $c) {

}

print_r($cache->getCache());
?>
up
4
jerome at chaman dot ca
4 years ago
"cached iteration over another iterator" means this iterator is always one step behind the inner iterator. In other words, the "first" iteration will yield null:

<?php

$cit
= new CachingIterator( new ArrayIterator( [ 'a', 'b', 'c'] ) );

echo
$cit->current() ); // null
echo $cit->getInnerIterator()->current() ); // "a"

while($cit->hasNext()){

// we start with a "next" since the "first" item is null
$cit->next();
echo
$cit->current(), '<br>';

}
?>

iterating this way gives us an access, ahead, to the future item (aka current item of the inner iterator)
up
0
xedin dot unknown at gmail dot com
4 years ago
Apparently, the `FULL_CACHE` flag automatically cancels the default flag `CALL_TOSTRING`. This is evident when one of the values cannot be converted to string: with the default `CALL_TOSTRING` flag, it would throw an error; without that flag, or with the `FULL_CACHE` flag, it does not.
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