HeaderFactory.php

<?php
 
namespace Guzzle\Http\Message\Header;
 
use Guzzle\Http\Message\Header;
 
class HeaderFactory implements HeaderFactoryInterface
{
    protected $mapping = array(
        'cache-control' => 'Guzzle\Http\Message\Header\CacheControl',
        'link'          => 'Guzzle\Http\Message\Header\Link',
    );
 
    public function createHeader($header, $value = null)
    {
        $lowercase = strtolower($header);
 
        return isset($this->mapping[$lowercase])
            ? new $this->mapping[$lowercase]($header, $value)
            : new Header($header, $value);
    }
}