<?php

/**
 * Xrange for PHP
 */
class XRange implements Iterator
{
    /**
     * initial value for iteration
     * @var int
     * */
    protected $value;

    /**
     * limit for iteration
     * @var int
     * */
    protected $limit;

    /**
     *
    * @var int
    */
    protected $step;

    protected $initial;

    protected $key = 0;

    /**
     * @param int $value
     * @param int $limit
     * @param int $step
     * */
    public function __construct($value, $limit, $step = 1)
    {

        if ($step == 0) {

            throw new UnexpectedValueException('You can\'t set the value of $step to zero.');
        }

        if ($step < 0 && $limit >= $value || $step > 0 && $value >= $limit) {

            throw new RangeException('The definition causes possible infinite loop');
        }

        $this->value = $this->initial = $value;

        $this->limit = $limit;

        $this->step = $step;
    }

    /**
     *
     * Rewind the iteration. This is a implementation of \Iterator
     * @return void
     **/
    public function rewind()
    {
        $this->value = $this->initial;

        $this->key = 0;
    }

    /**
     * Return the current value of iteration. This is a implementation of \Iterator
     * @return int
     * */
    public function current()
    {
        return $this->value;
    }

    /**
     * This is a implementation of \Iterator
     * @return void
     * */
    public function next()
    {
        $this->value += $this->step;

        ++$this->key;
    }

    /**
     * Valid the iteration
     * @return boolean
     * */
    public function valid()
    {
        if ($this->step > 0) {

             return $this->value <= $this->limit;
        }

        return $this->value >= $this->limit;

    }

    /**
     * Return a key for iteration. This is a implementation of \Iterator
     * @return int
     **/
    public function key()
    {
        return $this->key;
    }
}


if (! function_exists('xrange')) {

    function xrange($value, $limit, $step = 1)
    {
        return new XRange($value, $limit, $step);
    }
}


foreach(new XRange(1, 10, -1) as $value) {

    echo $value;
}