The SeekableIterator interface

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

Introduction

The Seekable iterator.

Interface synopsis

interface SeekableIterator extends Iterator {
/* Methods */
public seek(int $offset): void
/* Inherited methods */
public Iterator::current(): mixed
public Iterator::key(): mixed
public Iterator::next(): void
public Iterator::rewind(): void
public Iterator::valid(): bool
}

Example #1 Basic usage

This example demonstrates creating a custom SeekableIterator, seeking to a position and handling an invalid position.

<?php
class MySeekableIterator implements SeekableIterator {

private $position;

private $array = array(
"first element",
"second element",
"third element",
"fourth element"
);

/* Method required for SeekableIterator interface */

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

$this->position = $position;
}

/* Methods required for Iterator interface */

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();
}
?>

The above example will output something similar to:

first element
third element
second element
invalid seek position (10)

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