PHP NBT Class

<?php
class nbt {
    public $root;

    public $verbose = false;

    const TAG_END = 0;
    const TAG_BYTE = 1;
    const TAG_SHORT = 2;
    const TAG_INT = 3;
    const TAG_LONG = 4;
    const TAG_FLOAT = 5;
    const TAG_DOUBLE = 6;
    const TAG_BYTE_ARRAY = 7;
    const TAG_STRING = 8;
    const TAG_LIST = 9;
    const TAG_COMPOUND = 10;

    public function loadFile($filename) {
        $fp = fopen("compress.zlib://{$filename}", "r");
        $this->root = null;
        $this->traverseTag($fp, &$this->root);
    }

    private function traverseTag($fp, $tree) {
        if(feof($fp)) return false;
        $tagType = $this->readType($fp, self::TAG_BYTE); // Read type byte.
        if($tagType == self::TAG_END) {
            return false;
        } else {
            if($this->verbose) $position = ftell($fp);
            $tagName = $this->readType($fp, self::TAG_STRING);
            $tagData = $this->readType($fp, $tagType);
            if($this->verbose) echo "{$position}; {$tagName}: ".PHP_EOL.var_export($tagData, true).PHP_EOL;
            $tree[] = array("type"=>$tagType, "name"=>$tagName, "value"=>$tagData);
            return true;
        }
    }

    private function readType($fp, $tagType) {
        switch($tagType) {
            case self::TAG_BYTE: // Signed byte (8 bit)
                $unpacked = unpack("c", fread($fp, 1));
                return $unpacked[1];
            case self::TAG_SHORT: // Signed short (16 bit, big endian)
                $unpacked = unpack("n", $binary = fread($fp, 2));
                return $unpacked[1];
            case self::TAG_INT: // Signed integer (32 bit, big endian)
                $unpacked = unpack("i", fread($fp, 4));
                return $unpacked[1];
            case self::TAG_LONG: // Signed long (64 bit, big endian)
                $unpacked = unpack("l", fread($fp, 8));
                return $unpacked[1];
            case self::TAG_FLOAT: // Floating point value (32 bit, big endian, IEEE 754-2008)
                $unpacked = unpack("f", fread($fp, 4));
                return $unpacked[1];
            case self::TAG_DOUBLE: // Double value (64 bit, big endian, IEEE 754-2008)
                $unpacked = unpack("d", fread($fp, 8));
                return $unpacked[1];
            case self::TAG_BYTE_ARRAY: // Byte array
                $arrayLength = fread($fp, $this->readType($fp, self::TAG_INT));
                $array = array();
                for($i = 0; $i < $arrayLength; $i++) $array[] = fread($fp, 1);
                return $array;
            case self::TAG_STRING: // String
                if(!$stringLength = $this->readType($fp, self::TAG_SHORT)) return "";
                var_dump($stringLength);
                $string = utf8_decode(fread($fp, $stringLength)); // Read in number of bytes specified by string length, and decode from utf8.
                return $string;
            case self::TAG_LIST: // List
                $tagID = $this->readType($fp, self::TAG_BYTE);
                $listLength = $this->readType($fp, self::TAG_INT);
                $list = array();
                for($i = 0; $i < $listLength; $i++) {
                    if(feof($fp)) break;
                    $array[] = $this->readType($fp, $tagID);
                }
                return $list;
            case self::TAG_COMPOUND: // Compound
                $tree = array();
                while($this->traverseTag($fp, &$tree));
                return $tree;
        }
    }
}
?>