PHP - SeekableIterator

php_seekable_iterator.php

<?php
/**
 * Class ObjectPicker
 */
class ObjectPicker implements SeekableIterator{

    protected $data = array();
    protected $position = 0;

    /**
     * CompanySkills constructor.
     * @param array $data
     */
    public function __construct(array $data)
    {
        $this->data = $data;
    }

    /**
     * Return the current element
     * @link http://php.net/manual/en/iterator.current.php
     * @return mixed Can return any type.
     * @since 5.0.0
     */
    public function current()
    {

        return $this->data[$this->position];
    }

    /**
     * Move forward to next element
     * @link http://php.net/manual/en/iterator.next.php
     * @return void Any returned value is ignored.
     * @since 5.0.0
     */
    public function next()
    {
        ++$this->position;
    }

    /**
     * Return the key of the current element
     * @link http://php.net/manual/en/iterator.key.php
     * @return mixed scalar on success, or null on failure.
     * @since 5.0.0
     */
    public function key()
    {

        return $this->position;
    }

    /**
     * Checks if current position is valid
     * @link http://php.net/manual/en/iterator.valid.php
     * @return boolean The return value will be casted to boolean and then evaluated.
     * Returns true on success or false on failure.
     * @since 5.0.0
     */
    public function valid()
    {

        return isset($this->data[$this->position]);
    }

    /**
     * Rewind the Iterator to the first element
     * @link http://php.net/manual/en/iterator.rewind.php
     * @return void Any returned value is ignored.
     * @since 5.0.0
     */
    public function rewind()
    {
        $this->position = 0;
    }

    /**
     * @param int $position
     * @throws RuntimeException§
     */
    public function seek($position)
    {
        if(is_int($position)){
            $this->position = $position;
            if(!$this->valid()){
                throw new \OutOfBoundsException('Required position "'.$position.'" is not available '.__METHOD__);
            }
        }else{
            throw new \RuntimeException('Position "'.$position.'" must to be integer - '.__METHOD__);
        }
    }

}

// Generate fake data
$objects = array();
for($i=1;$i<11;$i++)
{
    $obj = new stdClass();
    $obj->name = 'obj_'.$i;
    $objects[] = $obj;
}

// Normal 
$objectPicker = new ObjectPicker($objects);
foreach($objectPicker as $object){
    print_r($object);
}
/*
 * output:
[
    {
        name: "obj_1"
    },
    {
        name: "obj_2"
    },
    {
        name: "obj_3"
    },
    {
        name: "obj_4"
    },
    {
        name: "obj_5"
    },
    {
        name: "obj_6"
    },
    {
        name: "obj_7"
    },
    {
        name: "obj_8"
    },
    {
        name: "obj_9"
    },
    {
        name: "obj_10"
    }
]
*/

// Seek
$objectPicker->seek(5);
while($objectPicker->valid()){
    print_r($objectPicker->current());
    $objectPicker->next();
}

/*
[
    {
        name: "obj_6"
    },
    {
        name: "obj_7"
    },
    {
        name: "obj_8"
    },
    {
        name: "obj_9"
    },
    {
        name: "obj_10"
    }
]
 */