This is a bad example (it was thrown together) of getting a namespace and class names that are in a file. It doesn't support multiple namespaces and it makes assumptions about the src. It would need rewritten to make it flexible (probably looping through token_get_all to construct all of the necessary information).

FileInspector.php

<?php

class FileInspector 
{
    protected $filename;
    protected $namespace;
    protected $contents;

    public function __construct($filename) {
        if ( ! $this->contents = @file_get_contents($filename)) {
            throw new \Exception('File not found');
        }

        $this->filename = $filename;
    }

    public function getNamespace() {
        if (null === $this->namespace) {
            preg_match('/^namespace\s+(.*?);/im', $this->contents, $matches);
            $this->namespace = empty($matches) ? false : $matches[1];
        } 

        return $this->namespace;
    }

    public function getClasses() {
        $tokens  = token_get_all($this->contents);
        $classes = array();
        
        foreach ($tokens as $i => $token) {
            if (T_CLASS === $token[0]) {
                $classes[] = array(
                    'ns' => $this->getNamespace(),
                    'class' => $tokens[$i+2][1],
                );
            }
        }
        
        return $classes;
    }
}

$fi = new FileInspector('test.php');
var_dump($fi->getClasses());

test.php

<?php

namespace Acme\Foo;

class TestClass1 {
  // namespace Bar;
  // namespace Foo;
}

class TestClass2 {
  // namespace Bar;
  // namespace Foo;
}