/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-

 * vim: set ts=8 sts=4 et sw=4 tw=99:

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef js_TraceableFifo_h

#define js_TraceableFifo_h

#include "ds/Fifo.h"

#include "js/RootingAPI.h"

#include "js/TracingAPI.h"

namespace js {

// A TraceableFifo is a Fifo with an additional trace method that knows how to

// visit all of the items stored in the Fifo. For Fifos that contain GC things,

// this is usually more convenient than manually iterating and marking the

// contents.

//

// Most types of GC pointers as keys and values can be traced with no extra

// infrastructure. For structs and non-gc-pointer members, ensure that there is

// a specialization of GCPolicy<T> with an appropriate trace method available

// to handle the custom type. Generic helpers can be found in

// js/public/TracingAPI.h. Generic helpers can be found in

// js/public/TracingAPI.h.

//

// Note that although this Fifo's trace will deal correctly with moved items, it

// does not itself know when to barrier or trace items. To function properly it

// must either be used with Rooted, or barriered and traced manually.

template <typename T,

          size_t MinInlineCapacity = 0,

          typename AllocPolicy = TempAllocPolicy>

class TraceableFifo : public js::Fifo<T, MinInlineCapacity, AllocPolicy>

{

    using Base = js::Fifo<T, MinInlineCapacity, AllocPolicy>;

  public:

    explicit TraceableFifo(AllocPolicy alloc = AllocPolicy()) : Base(alloc) {}

    TraceableFifo(TraceableFifo&& rhs) : Base(std::move(rhs)) { }

    TraceableFifo& operator=(TraceableFifo&& rhs) { return Base::operator=(std::move(rhs)); }

    TraceableFifo(const TraceableFifo&) = delete;

    TraceableFifo& operator=(const TraceableFifo&) = delete;

    void trace(JSTracer* trc) {

        for (size_t i = 0; i < this->front_.length(); ++i)

            JS::GCPolicy<T>::trace(trc, &this->front_[i], "fifo element");

        for (size_t i = 0; i < this->rear_.length(); ++i)

            JS::GCPolicy<T>::trace(trc, &this->rear_[i], "fifo element");

    }

};

template <typename Wrapper, typename T, size_t Capacity, typename AllocPolicy>

class WrappedPtrOperations<TraceableFifo<T, Capacity, AllocPolicy>, Wrapper>

{

    using TF = TraceableFifo<T, Capacity, AllocPolicy>;

    const TF& fifo() const { return static_cast<const Wrapper*>(this)->get(); }

  public:

    size_t length() const { return fifo().length(); }

    bool empty() const { return fifo().empty(); }

    const T& front() const { return fifo().front(); }

};

template <typename Wrapper, typename T, size_t Capacity, typename AllocPolicy>

class MutableWrappedPtrOperations<TraceableFifo<T, Capacity, AllocPolicy>, Wrapper>

  : public WrappedPtrOperations<TraceableFifo<T, Capacity, AllocPolicy>, Wrapper>

{

    using TF = TraceableFifo<T, Capacity, AllocPolicy>;

    TF& fifo() { return static_cast<Wrapper*>(this)->get(); }

  public:

    T& front() { return fifo().front(); }

    template<typename U> bool pushBack(U&& u) { return fifo().pushBack(std::forward<U>(u)); }

    template<typename... Args> bool emplaceBack(Args&&... args) {

        return fifo().emplaceBack(std::forward<Args...>(args...));

    }

    void popFront() { fifo().popFront(); }

    void clear() { fifo().clear(); }

};

} // namespace js

#endif // js_TraceableFifo_h