138 lines
2.5 KiB
C++
138 lines
2.5 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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* Copyright (c) 2003-$CurrentYear$, Linden Research, Inc.
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* $License$
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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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