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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is
+ * Netscape Communications Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 1998
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+/**
+ * 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"
+
+/**
+ * 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* anObject)=0;
+};
+
+/******************************************************
+ * 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 NS_COM nsDeque {
+ friend class nsDequeIterator;
+ public:
+ nsDeque(nsDequeFunctor* aDeallocator);
+ ~nsDeque();
+
+ /**
+ * Returns the number of elements currently stored in
+ * this deque.
+ *
+ * @return number of elements currently in the deque
+ */
+ inline PRInt32 GetSize() const {return mSize;}
+
+ /**
+ * Appends new member at the end of the deque.
+ *
+ * @param item to store in deque
+ * @return *this
+ */
+ nsDeque& Push(void* aItem);
+
+ /**
+ * Inserts new member at the front of the deque.
+ *
+ * @param item to store in deque
+ * @return *this
+ */
+ nsDeque& PushFront(void* aItem);
+
+ /**
+ * 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();
+ /**
+ * Return topmost item without removing it.
+ *
+ * @return the first item in container
+ */
+ void* PeekFront();
+
+ /**
+ * Retrieve the i'th member from the deque without removing it.
+ *
+ * @param index of desired item
+ * @return i'th element in list
+ */
+ void* ObjectAt(int aIndex) const;
+
+ /**
+ * Remove all items from container without destroying them.
+ *
+ * @return *this
+ */
+ nsDeque& Empty();
+
+ /**
+ * Remove and delete all items from container.
+ * Deletes are handled by the deallocator nsDequeFunctor
+ * which is specified at deque construction.
+ *
+ * @return *this
+ */
+ nsDeque& Erase();
+
+ /**
+ * Creates a new iterator, pointing to the first
+ * item in the deque.
+ *
+ * @return new dequeIterator
+ */
+ nsDequeIterator Begin() const;
+
+ /**
+ * Creates a new iterator, pointing to the last
+ * item in the deque.
+ *
+ * @return new dequeIterator
+ */
+ nsDequeIterator End() const;
+
+ void* Last() const;
+ /**
+ * 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
+ * @return *this
+ */
+ void ForEach(nsDequeFunctor& aFunctor) const;
+
+ /**
+ * Call this method when you want to iterate all the
+ * members of the container, calling the functor you
+ * passed with each member. This process will interrupt
+ * if your function returns non 0 to this method.
+ *
+ * @param aFunctor object to call for each member
+ * @return first nonzero result of aFunctor or 0.
+ */
+ const void* FirstThat(nsDequeFunctor& aFunctor) const;
+
+ void SetDeallocator(nsDequeFunctor* aDeallocator);
+
+protected:
+ PRInt32 mSize;
+ PRInt32 mCapacity;
+ PRInt32 mOrigin;
+ nsDequeFunctor* mDeallocator;
+ void* mBuffer[8];
+ void** mData;
+
+private:
+
+ /**
+ * Simple default constructor (PRIVATE)
+ */
+ nsDeque();
+
+ /**
+ * Copy constructor (PRIVATE)
+ *
+ * @param another deque
+ */
+ nsDeque(const nsDeque& other);
+
+ /**
+ * Deque assignment operator (PRIVATE)
+ *
+ * @param another deque
+ * @return *this
+ */
+ nsDeque& operator=(const nsDeque& anOther);
+
+ PRInt32 GrowCapacity();
+};
+
+/******************************************************
+ * Here comes the nsDequeIterator class...
+ ******************************************************/
+
+class nsDequeIterator {
+public:
+ /**
+ * DequeIterator is an object that knows how to iterate
+ * (forward and backward) through a Deque. Normally,
+ * you don't need to do this, but there are some special
+ * cases where it is pretty handy.
+ *
+ * One warning: the iterator is not bound to an item,
+ * it is bound to an index, so if you insert or remove
+ * from the beginning while using an iterator
+ * (which is not recommended) then the iterator will
+ * point to a different item. @see GetCurrent()
+ *
+ * Here you go.
+ *
+ * @param aQueue is the deque object to be iterated
+ * @param aIndex is the starting position for your iteration
+ */
+ nsDequeIterator(const nsDeque& aQueue, int aIndex=0);
+
+ /**
+ * Create a copy of a DequeIterator
+ *
+ * @param aCopy is another iterator to copy from
+ */
+ nsDequeIterator(const nsDequeIterator& aCopy);
+
+ /**
+ * Moves iterator to first element in the deque
+ * @return *this
+ */
+ nsDequeIterator& First();
+
+ /**
+ * Standard assignment operator for dequeiterator
+ * @param aCopy is another iterator to copy from
+ * @return *this
+ */
+ nsDequeIterator& operator=(const nsDequeIterator& aCopy);
+
+ /**
+ * preform ! operation against two iterators to test for equivalence
+ * (or lack thereof)!
+ *
+ * @param aIter is the object to be compared to
+ * @return TRUE if NOT equal.
+ */
+ PRBool operator!=(nsDequeIterator& aIter);
+
+ /**
+ * Compare two iterators for increasing order.
+ *
+ * @param aIter is the other iterator to be compared to
+ * @return TRUE if this object points to an element before
+ * the element pointed to by aIter.
+ * FALSE if this and aIter are not iterating over
+ * the same deque.
+ */
+ PRBool operator<(nsDequeIterator& aIter);
+
+ /**
+ * Compare two iterators for equivalence.
+ *
+ * @param aIter is the other iterator to be compared to
+ * @return TRUE if EQUAL
+ */
+ PRBool operator==(nsDequeIterator& aIter);
+
+ /**
+ * Compare two iterators for non strict decreasing order.
+ *
+ * @param aIter is the other iterator to be compared to
+ * @return TRUE if this object points to the same element, or
+ * an element after the element pointed to by aIter.
+ * FALSE if this and aIter are not iterating over
+ * the same deque.
+ */
+ PRBool operator>=(nsDequeIterator& aIter);
+
+ /**
+ * Pre-increment operator
+ * Iterator will advance one index towards the end.
+ *
+ * @return object_at(++index)
+ */
+ void* operator++();
+
+ /**
+ * Post-increment operator
+ * Iterator will advance one index towards the end.
+ *
+ * @param param is ignored
+ * @return object_at(mIndex++)
+ */
+ void* operator++(int);
+
+ /**
+ * Pre-decrement operator
+ * Iterator will advance one index towards the beginning.
+ *
+ * @return object_at(--index)
+ */
+ void* operator--();
+
+ /**
+ * Post-decrement operator
+ * Iterator will advance one index towards the beginning.
+ *
+ * @param param is ignored
+ * @return object_at(index--)
+ */
+ void* operator--(int);
+
+ /**
+ * Retrieve the the iterator's notion of current node.
+ *
+ * Note that the iterator floats, so you don't need to do:
+ * <code>++iter; aDeque.PopFront();</code>
+ * Unless you actually want your iterator to jump 2 positions
+ * relative to its origin.
+ *
+ * Picture: [1 2i 3 4]
+ * PopFront()
+ * Picture: [2 3i 4]
+ * Note that I still happily points to object at the second index.
+ *
+ * @return object at i'th index
+ */
+ void* GetCurrent();
+
+ /**
+ * 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
+ * @return *this
+ */
+ void ForEach(nsDequeFunctor& aFunctor) const;
+
+ /**
+ * Call this method when you want to iterate all the
+ * members of the container, calling the functor you
+ * passed with each member. This process will interrupt
+ * if your function returns non 0 to this method.
+ *
+ * @param aFunctor object to call for each member
+ * @return first nonzero result of aFunctor or 0.
+ */
+ const void* FirstThat(nsDequeFunctor& aFunctor) const;
+
+ protected:
+
+ PRInt32 mIndex;
+ const nsDeque& mDeque;
+};
+#endif