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_CURRENT;
    public const int TOSTRING_USE_INNER;
    public const int FULL_CACHE;
    /* Métodos */
    public function __construct(Iterator $iterator, int $flags = CachingIterator::CALL_TOSTRING)
    public function count(): int
    public function current(): mixed
    public function getCache(): array
    public function getFlags(): int
    public function hasNext(): bool
    public function key(): scalar
    public function next(): void
    public function offsetExists(string $key): bool
    public function offsetGet(string $key): mixed
    public function offsetSet(string $key, mixed $value): void
    public function offsetUnset(string $key): void
    public function rewind(): void
    public function setFlags(int $flags): void
    public function __toString(): string
    public function valid(): bool
    /* Métodos herdados */
    public function IteratorIterator::current(): mixed
    public function IteratorIterator::getInnerIterator(): ?Iterator
    public function IteratorIterator::key(): mixed
    public function IteratorIterator::next(): void
    public function IteratorIterator::rewind(): void
    public function IteratorIterator::valid(): bool
    }

    Constantes predefinidas

    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

    Melhore Esta Página

    Aprenda Como Melhorar Esta Página • Envie uma Solicitação de Modificação • Reporte um Problema
    ＋adicionar nota

    Notas de Usuários 4 notes

    up
    10
    ahmad dot mayahi at gmail dot com
    6 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
    9 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
    1
    jerome at chaman dot ca
    6 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
    6 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.
    ＋adicionar nota
    To Top