limititerator.inc

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<?php

class LimitIterator implements OuterIterator
{
    private $it;
    private $offset;
    private $count;
    private $pos;

    function __construct(Iterator $it, $offset = 0, $count = -1)
    {
        if ($offset < 0) {
            throw new exception('Parameter offset must be > 0');
        }
        if ($count < 0 && $count != -1) {
            throw new exception('Parameter count must either be -1 or a value greater than or equal to 0');
        }
        $this->it     = $it;
        $this->offset = $offset;
        $this->count  = $count;
        $this->pos    = 0;
    }
    
    function seek($position) {
        if ($position < $this->offset) {
            throw new exception('Cannot seek to '.$position.' which is below offset '.$this->offset);
        }
        if ($position > $this->offset + $this->count && $this->count != -1) {
            throw new exception('Cannot seek to '.$position.' which is behind offset '.$this->offset.' plus count '.$this->count);
        }
        if ($this->it instanceof SeekableIterator) {
            $this->it->seek($position);
            $this->pos = $position;
        } else {
            while($this->pos < $position && $this->it->valid()) {
                $this->next();
            }
        }
    }

    function rewind()
    {
        $this->it->rewind();
        $this->pos = 0;
        $this->seek($this->offset);
    }
    
    function valid() {
        return ($this->count == -1 || $this->pos < $this->offset + $this->count)
             && $this->it->valid();
    }
    
    function key() {
        return $this->it->key();
    }

    function current() {
        return $this->it->current();
    }

    function next() {
        $this->it->next();
        $this->pos++;
    }

    function getPosition() {
        return $this->pos;
    }

    function getInnerIterator()
    {
        return $this->it;
    }

    function __call($func, $params)
    {
        return call_user_func_array(array($this->it, $func), $params);
    }
}

?>