protected function findClass($file)
    {
        $class = false;
        $namespace = false;
        $tokens = token_get_all(file_get_contents($file));

        if (1 === \count($tokens) && T_INLINE_HTML === $tokens[0][0]) {
            throw new \InvalidArgumentException(sprintf('The file "%s" does not contain PHP code. Did you forgot to add the "<?php" start tag at the beginning of the file?', $file));
        }

        for ($i = 0; isset($tokens[$i]); ++$i) {
            $token = $tokens[$i];

            if (!isset($token[1])) {
                continue;
            }

            if (true === $class && T_STRING === $token[0]) {
                return $namespace.'\\'.$token[1];
            }

            if (true === $namespace && T_STRING === $token[0]) {
                $namespace = $token[1];
                while (isset($tokens[++$i][1]) && \in_array($tokens[$i][0], [T_NS_SEPARATOR, T_STRING])) {
                    $namespace .= $tokens[$i][1];
                }
                $token = $tokens[$i];
            }

            if (T_CLASS === $token[0]) {
                // Skip usage of ::class constant and anonymous classes
                $skipClassToken = false;
                for ($j = $i - 1; $j > 0; --$j) {
                    if (!isset($tokens[$j][1])) {
                        break;
                    }

                    if (T_DOUBLE_COLON === $tokens[$j][0] || T_NEW === $tokens[$j][0]) {
                        $skipClassToken = true;
                        break;
                    } elseif (!\in_array($tokens[$j][0], [T_WHITESPACE, T_DOC_COMMENT, T_COMMENT])) {
                        break;
                    }
                }

                if (!$skipClassToken) {
                    $class = true;
                }
            }

            if (T_NAMESPACE === $token[0]) {
                $namespace = true;
            }
        }

        return false;
    }