Sprockets\File::dependsOnDirective PHP Method

    private function dependsOnDirective($name)
    {
        //allows to depend on a file, even if this one isn't included
        if (strpos($name, '.') === false) {
            $type = $this->type;
        } else {
            //depending on another asset type. In example, //= depends_on image.png
            $name_parts = explode('.', $name);
            $type = $name_parts[1];
            //"style" "css" *filters
        }
        $this->pipeline->addDependency($this->type, $this->locator->getFile($name, $type));
    }