private function collectUsedNamespace(array $tokens, $stackPointer)
    {
        $namespace = '';
        $next      = 2;
        do
        {
            $type = $tokens[$stackPointer + $next]['type'];
            if ($type === 'T_STRING' || $type === 'T_NS_SEPARATOR')
            {
                $namespace .= $tokens[$stackPointer + $next]['content'];
            }
            $next++;
        } while ($tokens[$stackPointer]['line'] === $tokens[$stackPointer + $next]['line']);

        if ($namespace === '')
        {
            $type  = 'Use without namespace found.';
            $data  = [$tokens[$stackPointer]['content']];
            $error = 'Use without qualified namespace found.';
            $this->file->addWarning($error, $stackPointer, $type, $data);
        }
        else
        {
            $this->usePaths[] = trim($namespace);
        }
    }