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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
/**
* MODULE NOTES:
*
* The Deque is a very small, very efficient container object
* than can hold elements of type void*, offering the following features:
* Its interface supports pushing and popping of elements.
* It can iterate (via an interator class) its elements.
* When full, it can efficiently resize dynamically.
*
*
* NOTE: The only bit of trickery here is that this deque is
* built upon a ring-buffer. Like all ring buffers, the first
* element may not be at index[0]. The mOrigin member determines
* where the first child is. This point is quietly hidden from
* customers of this class.
*
*/
#ifndef _NSDEQUE
#define _NSDEQUE
#include "nscore.h"
#include "nsDebug.h"
#include "mozilla/Attributes.h"
#include "mozilla/fallible.h"
#include "mozilla/MemoryReporting.h"
/**
* The nsDequeFunctor class is used when you want to create
* callbacks between the deque and your generic code.
* Use these objects in a call to ForEach();
*
*/
class nsDequeFunctor
{
public:
virtual void* operator()(void* aObject) = 0;
virtual ~nsDequeFunctor() {}
};
/******************************************************
* Here comes the nsDeque class itself...
******************************************************/
/**
* The deque (double-ended queue) class is a common container type,
* whose behavior mimics a line in your favorite checkout stand.
* Classic CS describes the common behavior of a queue as FIFO.
* A deque allows insertion and removal at both ends of
* the container.
*
* The deque stores pointers to items.
*/
class nsDequeIterator;
class nsDeque
{
typedef mozilla::fallible_t fallible_t;
public:
explicit nsDeque(nsDequeFunctor* aDeallocator = nullptr);
~nsDeque();
/**
* Returns the number of elements currently stored in
* this deque.
*
* @return number of elements currently in the deque
*/
inline size_t GetSize() const { return mSize; }
/**
* Appends new member at the end of the deque.
*
* @param item to store in deque
*/
void Push(void* aItem)
{
if (!Push(aItem, mozilla::fallible)) {
NS_ABORT_OOM(mSize * sizeof(void*));
}
}
[[nodiscard]] bool Push(void* aItem, const fallible_t&);
/**
* Inserts new member at the front of the deque.
*
* @param item to store in deque
*/
void PushFront(void* aItem)
{
if (!PushFront(aItem, mozilla::fallible)) {
NS_ABORT_OOM(mSize * sizeof(void*));
}
}
[[nodiscard]] bool PushFront(void* aItem, const fallible_t&);
/**
* Remove and return the last item in the container.
*
* @return the item that was the last item in container
*/
void* Pop();
/**
* Remove and return the first item in the container.
*
* @return the item that was first item in container
*/
void* PopFront();
/**
* Retrieve the bottom item without removing it.
*
* @return the first item in container
*/
void* Peek() const;
/**
* Return topmost item without removing it.
*
* @return the first item in container
*/
void* PeekFront() const;
/**
* Retrieve a member from the deque without removing it.
*
* @param index of desired item
* @return element in list
*/
void* ObjectAt(size_t aIndex) const;
/**
* Remove and delete all items from container.
* Deletes are handled by the deallocator nsDequeFunctor
* which is specified at deque construction.
*/
void Erase();
/**
* Call this method when you want to iterate all the
* members of the container, passing a functor along
* to call your code.
*
* @param aFunctor object to call for each member
*/
void ForEach(nsDequeFunctor& aFunctor) const;
size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
protected:
size_t mSize;
size_t mCapacity;
size_t mOrigin;
nsDequeFunctor* mDeallocator;
void* mBuffer[8];
void** mData;
private:
/**
* Copy constructor (PRIVATE)
*
* @param aOther another deque
*/
nsDeque(const nsDeque& aOther);
/**
* Deque assignment operator (PRIVATE)
*
* @param aOther another deque
* @return *this
*/
nsDeque& operator=(const nsDeque& aOther);
bool GrowCapacity();
void SetDeallocator(nsDequeFunctor* aDeallocator);
/**
* Remove all items from container without destroying them.
*/
void Empty();
};
#endif
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