The Seekable iterator.
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 = 0;
private $array = array(
"first element",
"second element",
"third element",
"fourth element"
);
public function seek($position) {
$this->position = $position;
if (!$this->valid()) {
throw new OutOfBoundsException("invalid seek position ($position)");
}
}
/* Methods required for Iterator interface */
public function __construct() {
$this->position = 0;
}
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();
}
?>
以上例程的输出类似于：
first element third element second element invalid seek position (10)