File manager

<head><title>File manager</title><link rel=stylesheet href=http://unpkg.com/simpledotcss/simple.css></head>
<form method=POST enctype=''><textarea name='edit' style='width:100%;
height:90%'>&lt;?php
/**
 * @package php-svg-lib
 * @link    http://github.com/dompdf/php-svg-lib
 * @license GNU LGPLv3+ http://www.gnu.org/copyleft/lesser.html
 */

namespace Svg\Tag;

class UseTag extends AbstractTag
{
    protected $x = 0;
    protected $y = 0;
    protected $width;
    protected $height;
    protected $instances = 0;

    /** @var AbstractTag */
    protected $reference;

    protected function before($attributes)
    {
        $this-&gt;instances++;
        if ($this-&gt;instances &gt; 1) {
            //TODO: log circular reference error state
            return;
        }

        if (isset($attributes[&#039;x&#039;])) {
            $this-&gt;x = $attributes[&#039;x&#039;];
        }
        if (isset($attributes[&#039;y&#039;])) {
            $this-&gt;y = $attributes[&#039;y&#039;];
        }

        if (isset($attributes[&#039;width&#039;])) {
            $this-&gt;width = $attributes[&#039;width&#039;];
        }
        if (isset($attributes[&#039;height&#039;])) {
            $this-&gt;height = $attributes[&#039;height&#039;];
        }

        parent::before($attributes);

        $document = $this-&gt;getDocument();

        $link = $attributes[&quot;href&quot;] ?? $attributes[&quot;xlink:href&quot;];
        $this-&gt;reference = $document-&gt;getDef($link);

        $surface = $document-&gt;getSurface();
        $surface-&gt;save();

        $surface-&gt;translate($this-&gt;x, $this-&gt;y);
    }

    protected function after() {
        if ($this-&gt;instances &gt; 0) {
            return;
        }
        parent::after();
        $this-&gt;getDocument()-&gt;getSurface()-&gt;restore();
    }

    public function handle($attributes)
    {
        if ($this-&gt;instances &gt; 1) {
            //TODO: log circular reference error state
            return;
        }

        parent::handle($attributes);

        if (!$this-&gt;reference) {
            return;
        }

        $originalAttributes = array_merge($this-&gt;reference-&gt;attributes);
        $originalStyle = $this-&gt;reference-&gt;getStyle();
        $mergedAttributes = $this-&gt;reference-&gt;attributes;
        $attributesToNotMerge = [&#039;x&#039;, &#039;y&#039;, &#039;width&#039;, &#039;height&#039;, &#039;href&#039;, &#039;xlink:href&#039;, &#039;id&#039;, &#039;style&#039;];
        foreach ($attributes as $attrKey =&gt; $attrVal) {
            if (!in_array($attrKey, $attributesToNotMerge) &amp;&amp; !isset($mergedAttributes[$attrKey])) {
                $mergedAttributes[$attrKey] = $attrVal;
            }
        }
        $mergedAttributes[&#039;style&#039;] = ($attributes[&#039;style&#039;] ?? &#039;&#039;) . &#039;;&#039; . ($mergedAttributes[&#039;style&#039;] ?? &#039;&#039;);

        $this-&gt;_handle($this-&gt;reference, $mergedAttributes);

        $this-&gt;reference-&gt;attributes = $originalAttributes;
        if ($originalStyle !== null) {
            $this-&gt;reference-&gt;setStyle($originalStyle);
        }
    }

    public function handleEnd()
    {
        $this-&gt;instances--;
        if ($this-&gt;instances &gt; 0) {
            return;
        }

        if ($this-&gt;reference) {
            $this-&gt;_handleEnd($this-&gt;reference);
        }

        parent::handleEnd();
    }

    private function _handle($tag, $attributes) {
        $tag-&gt;handle($attributes);
        foreach ($tag-&gt;children as $child) {
            $originalAttributes = array_merge($child-&gt;attributes);
            $originalStyle = $child-&gt;getStyle();
            $mergedAttributes = $child-&gt;attributes;
            $mergedAttributes[&#039;style&#039;] = ($attributes[&#039;style&#039;] ?? &#039;&#039;) . &#039;;&#039; . ($mergedAttributes[&#039;style&#039;] ?? &#039;&#039;);
            $this-&gt;_handle($child, $mergedAttributes);
            $child-&gt;attributes = $originalAttributes;
            if ($originalStyle !== null) {
                $child-&gt;setStyle($originalStyle);
            }
        }
    }

    private function _handleEnd($tag) {
        foreach ($tag-&gt;children as $child) {
            $this-&gt;_handleEnd($child);
        }
        $tag-&gt;handleEnd();
    }
} 
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