Method enqueue

deps/CVC4/context/cdtrail_queue.h:61–65

* Enqueues an element in the current context. * Returns its index in the queue. */

   * Returns its index in the queue.
   */
  size_t enqueue(const T& data){
    size_t res = d_list.size();
    d_list.push_back(data);
    return res;
  }

  size_t frontIndex() const{
    return d_iter;