Http Routes Tokenizer

Tokenizer.php

<?php

namespace Http;

require './Token.php';

use Iterator;
use RuntimeException;

class Tokenizer implements Iterator {

    protected $file;
    protected $line = null;
    protected $position = 0;
    protected $token = null;
    protected $httpMethods = ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS', 'HEAD', 'PATCH'];

    public function __construct($path) {
        $this->file = fopen($path, 'r');
        
        if (!$this->file)
            throw new RuntimeException('Tokenizer must be provided a readable file.');
            
    }
    
    public function current() {
    
        if ($this->token === NULL) {
            if ($this->position === strlen($this->line)) {
                $this->line = $this->getLine();
                if ($this->line === FALSE) {
                    return new Token('EOF');
                }
                $this->token = new Token('EOL');
                $this->position = 0;
            } else {
                $this->token = $this->getToken();
            }
        }
        
        return $this->token;
        
    }
    public function valid() {
        
        if ($this->line === null) {
            $this->line = $this->getLine();
        }
        
        if ($this->position <= strlen($this->line)) {
            return TRUE;
        }
        
        
        $this->line = $this->getLine();
        $this->position = 0;
        
        
        return $this->line !== FALSE;
        
    }
    
    public function next() {
        $this->token = null;
    }
    
    public function rewind() {
        return rewind($this->file);
    }
    
    public function key() {
        return 'unknown';
    }
    
    protected function getLine() {
        $line = fgets($this->file);
        if ($line === FALSE) {
            return FALSE;
        }
        return trim($line);
    }
    
    protected function getToken() {
    
        $char = $this->line[$this->position];
        $token;
        
        while ($char !== '\n' && ctype_space($char)) {
            $this->position++;
            $char = $this->line[$this->position];
        }
        
        if ($char === ';') {
            $token = $this->comment();
        } else if ($char === '/' || ctype_alpha($char)) {
            $token = $this->identifier();
        } else {
            echo "char:$char {$this->position}\n";
            throw new RuntimeException($this->line);
        }
        
        return $token;
        
    }
    
    protected function identifier() {
        $value = '';
        for (
            $i =& $this->position, $strlen = strlen($this->line); 
            $i < $strlen && $this->line[$i] !== ';' && !ctype_space($this->line[$i]); 
            $i++
        ) {
            $value .= $this->line[$i];
        }
        
        $token = 'string';
        if (in_array($value, $this->httpMethods)) {
            $token = 'httpMethod';
        }
        if ($value[0] === '/') {
            $token = 'pattern';
        }
        
        return new Token($token, $value);
    }
    
    protected function comment() {
        $value = '';
        $strlen = strlen($this->line);
        if ($this->position < $strlen) {
            $value = substr($this->line, $this->position);
        }
        
        $token = new Token('comment', $value);
        
        $this->position = $strlen;
        return $token;
    }
    
}