PHP版無限リスト

Stream.php

<?php

class Stream implements \Iterator
{
    /**
     * @var int
     */
    private $position;

    /**
     * @var int
     */
    private $offset;

    /**
     * @var int
     */
    private $limit;

    /**
     * @param int $offset
     * @param int $limit
     */
    public function __construct($offset, $limit = null)
    {
        $this->position = $offset;
        $this->offset   = $offset;
        $this->limit    = $limit;
    }

    /**
     * {@inheritDoc}
     */
    public function current()
    {
        return $this->position;
    }

    /**
     * {@inheritDoc}
     */
    public function next()
    {
        $this->position++;
    }

    /**
     * {@inheritDoc}
     */
    public function valid()
    {
        if ($this->limit && $this->position > $this->limit) {
            return false;
        }

        return true;
    }

    /**
     * {@inheritDoc}
     */
    public function key()
    {
        return $this->position;
    }

    /**
     * {@inheritDoc}
     */
    public function rewind()
    {
        $this->position = $this->offset;
    }

    public function take($n)
    {
        return new \LimitIterator($this, 0, $n);
    }
}

StreamExample.php

<?php

/**
 * 無限ループ
 */
$stream1 = new Stream(0);
foreach ($stream1 as $i) {
    echo $i . "\n";   
}

/**
 * 範囲指定
 */
$stream2 = new Stream(50, 200);
foreach ($stream2 as $i) {
    echo $i . "\n";
}

/**
 * 10件のみ取得
 */
$stream3 = new Stream(0);
foreach ($stream3->take(10) as $i) {
    echo $i . "\n";
}