//---------------------------------------------------------------------------//
//  1100101 |_ mov #0, r4         __                                         //
//     11   |_ <0xb380 %5c4>     / _|_ _____ ___                             //
//     0110 |_ 3.50 -> 3.60     |  _\ \ / _ (_-<                             //
//          |_ base# + offset   |_| /_\_\___/__/                             //
//---------------------------------------------------------------------------//
// fxos/util/Queue: Simple queue that handles recursion
//
// Can be instantiated for any T for which std::set<T> is valid and properly
// checks objects' identity.
//---

#ifndef FXOS_UTIL_QUEUE_H
#define FXOS_UTIL_QUEUE_H

#include <queue>
#include <set>

template<typename T>
struct Queue
{
    Queue(): pending {}, seen {}
    {
    }

    bool empty() const
    {
        return pending.empty();
    }
    T &pop()
    {
        T &object = pending.front();
        pending.pop();
        return object;
    }
    void clear()
    {
        pending.clear();
        seen.clear();
    }

    /* Enqueue an object to visit later (if not already visited) */
    void enqueue(T object)
    {
        if(!seen.count(object)) {
            pending.push(object);
            seen.insert(object);
        }
    }
    /* Enqueue an object even for later update, regardless of loops */
    void update(T object)
    {
        pending.push(object);
        seen.insert(object);
    }

    /* Queue of objects to visit next */
    std::queue<T> pending;
    /* Objects already visited or currently pending */
    std::set<T> seen;
};

#endif /* FXOS_UTIL_QUEUE_H */