使用Composer的自动加载器和个人代码

I'm building a small project using Composer, but I now have to use some custom code, in the parent folder of vendor folder.

Similar file structure: libraries > companyname > namespace > classfile.php

Is it possible to effectively use the composer autoloader? It seems that it is, but I'm having trouble wrapping my head around it.

Would it be easier to use a second autoloader script?

We're loading in our own code via composer.

Our code is installed in the lib folder under our company name. Our composer file looks like this.

{
    "config": {
        "vendor-dir": "lib"
    },
    "require": {
        "twig/twig": "v1.15.1",
        "symfony/symfony": "2.5.4"
    },
    "autoload": {
        "psr-4": {
            "CompanyName\\": "lib/companyName/src"
        }
    }
}

the autoload psr4 section is the important part. CompanyName will resolve files located in lib/companyName/src.

Inside lib/companyName/src, you'd have a file called ThingDoer.php

<?php

namespace CompanyName;

class ThingDoer {
    public static function doThings() {}
}

And now from anywhere in your codebase, you can call CompanyName\ThingDoer::doThings();