L'interface SeekableIterator

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

Introduction

L'itérateur SeekableIterator.

Sommaire de l'Interface

interface SeekableIterator extends Iterator {
/* Méthodes */
public seek(int $offset): void
/* Méthodes héritées */
}

Exemples

Exemple #1 Utilisation simple

Cet exemple montre comment crée une classe SeekableIterator personnalisée, qui gère une position invalide.

<?php
class MySeekableIterator implements SeekableIterator {

private
$position;

private
$array = array(
"premier élément",
"second élément",
"troisième élément",
"quatriéme élément"
);

/* Méthode requis pour l'interface SeekableIterator */

public function seek($position) {
if (!isset(
$this->array[$position])) {
throw new
OutOfBoundsException("position invalide ($position)");
}

$this->position = $position;
}

/* Méthodes requises par l'interface Iterator */

public function rewind() {
$this->position = 0;
}

public function
current() {
return
$this->array[$this->position];
}

public function
key() {
return
$this->position;
}

public function
next() {
++
$this->position;
}

public function
valid() {
return isset(
$this->array[$this->position]);
}
}

try {

$it = new MySeekableIterator;
echo
$it->current(), "\n";

$it->seek(2);
echo
$it->current(), "\n";

$it->seek(1);
echo
$it->current(), "\n";

$it->seek(10);

} catch (
OutOfBoundsException $e) {
echo
$e->getMessage();
}
?>

Résultat de l'exemple ci-dessus est similaire à :

premier élément
troisième élément
second élément
position invalide (10)

Sommaire

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User Contributed Notes 4 notes

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8
svenr at selfhtml dot org
13 years ago
Best method:<?phpif ($object instanceof SeekableIterator) {  echo "\$object has method seek()";}?>Please, make use of checking if a particular interface has been implemented to assure that the object you are dealing with definately has the methods you are about to use.This also works as typehinting:<?phpclass foo {  public function doSomeSeeking(SeekableIterator $seekMe) {    $seekMe->seek(10); // will work, otherwise Typehint triggers complaints  }}?>
up
1
info at ensostudio dot ru
3 years ago
Note: $offset parameter of SeekableIterator::seek()  is position in list, not array key.<?php$iterator = new ArrayIterator([1 => "apple", 2 => "banana", 3 => "cherry"]);echo $iterator->offsetGet(2); // banana$iterator->seek(2);echo $iterator->current(); // cherry?>
up
-1
info at ensostudio dot ru
4 years ago
Note: use array_key_exists instead isset!<?phppublic function seek($position){    $position = (int) $position;    if (! array_key_exists($position, array_values($this->array))) {        throw new OutOfBoundsException('Invalid position to seek: ' . $position);    }    $this->position = $position;}?>
up
-2
Anonymous
11 years ago
The code above is missing a closing parenthesis.<?phpif (!isset($this->array[$position]) {          throw new OutOfBoundsException("invalid seek position ($position)");}?>should be<?phpif (!isset($this->array[$position])) { // close here          throw new OutOfBoundsException("invalid seek position ($position)");}?>
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