162 lines
3.7 KiB
C++
162 lines
3.7 KiB
C++
/**
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* @file llindexedqueue.h
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* @brief An indexed FIFO queue, where only one element with each key
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* can be in the queue.
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*
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* $LicenseInfo:firstyear=2003&license=viewergpl$
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*
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* Copyright (c) 2003-2009, Linden Research, Inc.
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*
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* Second Life Viewer Source Code
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* The source code in this file ("Source Code") is provided by Linden Lab
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* to you under the terms of the GNU General Public License, version 2.0
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* ("GPL"), unless you have obtained a separate licensing agreement
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* ("Other License"), formally executed by you and Linden Lab. Terms of
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* the GPL can be found in doc/GPL-license.txt in this distribution, or
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* online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
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*
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* There are special exceptions to the terms and conditions of the GPL as
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* it is applied to this Source Code. View the full text of the exception
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* in the file doc/FLOSS-exception.txt in this software distribution, or
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* online at
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* http://secondlifegrid.net/programs/open_source/licensing/flossexception
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*
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* By copying, modifying or distributing this software, you acknowledge
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* that you have read and understood your obligations described above,
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* and agree to abide by those obligations.
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*
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* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
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* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
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* COMPLETENESS OR PERFORMANCE.
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* $/LicenseInfo$
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*/
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#ifndef LL_LLINDEXEDQUEUE_H
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#define LL_LLINDEXEDQUEUE_H
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// An indexed FIFO queue, where only one element with each key can be in the queue.
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// This is ONLY used in the interest list, you'll probably want to review this code
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// carefully if you want to use it elsewhere - Doug
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template <typename Type>
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class LLIndexedQueue
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{
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protected:
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typedef std::deque<Type> type_deque;
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type_deque mQueue;
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std::set<Type> mKeySet;
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public:
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LLIndexedQueue() {}
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// move_if_there is an O(n) operation
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bool push_back(const Type &value, bool move_if_there = false)
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{
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if (mKeySet.find(value) != mKeySet.end())
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{
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// Already on the queue
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if (move_if_there)
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{
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// Remove the existing entry.
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typename type_deque::iterator it;
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for (it = mQueue.begin(); it != mQueue.end(); ++it)
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{
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if (*it == value)
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{
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break;
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}
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}
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// This HAS to succeed, otherwise there's a serious bug in the keyset implementation
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// (although this isn't thread safe, at all)
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mQueue.erase(it);
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}
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else
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{
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// We're not moving it, leave it alone
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return false;
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}
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}
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else
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{
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// Doesn't exist, add it to the key set
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mKeySet.insert(value);
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}
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mQueue.push_back(value);
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// We succeeded in adding the new element.
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return true;
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}
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bool push_front(const Type &value, bool move_if_there = false)
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{
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if (mKeySet.find(value) != mKeySet.end())
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{
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// Already on the queue
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if (move_if_there)
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{
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// Remove the existing entry.
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typename type_deque::iterator it;
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for (it = mQueue.begin(); it != mQueue.end(); ++it)
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{
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if (*it == value)
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{
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break;
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}
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}
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// This HAS to succeed, otherwise there's a serious bug in the keyset implementation
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// (although this isn't thread safe, at all)
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mQueue.erase(it);
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}
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else
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{
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// We're not moving it, leave it alone
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return false;
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}
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}
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else
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{
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// Doesn't exist, add it to the key set
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mKeySet.insert(value);
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}
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mQueue.push_front(value);
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return true;
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}
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void pop()
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{
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Type value = mQueue.front();
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mKeySet.erase(value);
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mQueue.pop_front();
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}
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Type &front()
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{
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return mQueue.front();
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}
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S32 size() const
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{
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return mQueue.size();
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}
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bool empty() const
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{
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return mQueue.empty();
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}
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void clear()
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{
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// Clear out all elements on the queue
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mQueue.clear();
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mKeySet.clear();
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}
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};
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#endif // LL_LLINDEXEDQUEUE_H
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