Copy the KDE 3.5 branch to branches/trinity for new KDE 3.5 features.

BUG:215923


git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdegraphics@1054174 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

1 files changed, 169 insertions, 0 deletions

diff --git a/ksvg/impl/LRUCache.h b/ksvg/impl/LRUCache.h
new file mode 100644
index 00000000..879f1856
--- /dev/null
+++ b/ksvg/impl/LRUCache.h
@@ -0,0 +1,169 @@
+/*
+    Copyright (C) 2003 KSVG Team
+    This file is part of the KDE project
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    aint with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA 02110-1301, USA.
+*/
+
+#ifndef LRUCACHE_H
+#define LRUCACHE_H
+
+#include <qvaluelist.h>
+
+namespace KSVG
+{
+
+// A value-based LRU cache with a maximum total cost constraint, but with the exception that the
+// most recently added item is kept in the cache even if its cost exceeds the maximum total cost.
+template<class keyType, class valueType>
+class MinOneLRUCache
+{
+public:
+	MinOneLRUCache(int maxTotalCost = 0) : m_maxTotalCost(maxTotalCost), m_totalCost(0) {}
+	virtual ~MinOneLRUCache() {}
+
+	void insert(const keyType& key, const valueType& value, int cost);
+	bool find(const keyType& key, valueType& result);
+
+	void setMaxTotalCost(int maxTotalCost);
+	int maxTotalCost() const { return m_maxTotalCost; }
+	int totalCost() const { return m_totalCost; }
+
+	void clear();
+
+protected:
+	class CacheItem
+	{
+	public:
+		CacheItem() : m_cost(0) {}
+		CacheItem(const keyType& key, const valueType& value, int cost) : m_key(key), m_value(value), m_cost(cost) {}
+
+		const keyType& key() const { return m_key; }
+		const valueType& value() const { return m_value; }
+		int cost() const { return m_cost; }
+
+	private:
+		keyType m_key;
+		valueType m_value;
+		int m_cost;
+	};
+
+	typedef QValueList<CacheItem> CacheItemList;
+
+	typename CacheItemList::iterator find(const keyType& key);
+	void enforceCostConstraint();
+
+	CacheItemList m_items;
+	int m_maxTotalCost;
+	int m_totalCost;
+};
+
+template<class keyType, class valueType>
+void MinOneLRUCache<keyType, valueType>::insert(const keyType& key, const valueType& value, int cost)
+{
+	typename CacheItemList::iterator it = find(key);
+
+	if(it != m_items.end())
+	{
+		// Replace the existing item.
+		m_totalCost -= (*it).cost();
+		m_items.erase(it);
+	}
+
+	// We always hold the most recently added item in the cache, even if it exceeds
+	// the maximum total cost.
+	m_items.push_front(CacheItem(key, value, cost));
+	m_totalCost += cost;
+	enforceCostConstraint();
+}
+
+template<class keyType, class valueType>
+bool MinOneLRUCache<keyType, valueType>::find(const keyType& key, valueType& result)
+{
+	bool foundKey = false;
+	typename CacheItemList::iterator it = find(key);
+
+	if(it != m_items.end())
+	{
+		CacheItem item = *it;
+		result = item.value();
+
+		if(it != m_items.begin())
+		{
+			// This is now the most recently used item.
+			m_items.erase(it);
+			m_items.push_front(item);
+		}
+
+		foundKey = true;
+	}
+
+	return foundKey;
+}
+
+template<class keyType, class valueType>
+typename MinOneLRUCache<keyType, valueType>::CacheItemList::iterator MinOneLRUCache<keyType, valueType>::find(const keyType& key)
+{
+	typename CacheItemList::iterator it;
+
+	for(it = m_items.begin(); it != m_items.end(); it++)
+	{
+		if((*it).key() == key)
+			break;
+	}
+
+	return it;
+}
+
+template<class keyType, class valueType>
+void MinOneLRUCache<keyType, valueType>::enforceCostConstraint()
+{
+	if(m_totalCost > m_maxTotalCost && m_items.size() > 1)
+	{
+		typename CacheItemList::iterator it = m_items.begin();
+		m_totalCost = (*it).cost();
+		++it;
+
+		while(it != m_items.end() && m_totalCost + (*it).cost() <= m_maxTotalCost)
+		{
+			m_totalCost += (*it).cost();
+			++it;
+		}
+
+		// Remove the remainder
+		while(it != m_items.end())
+			it = m_items.erase(it);
+	}
+}
+
+template<class keyType, class valueType>
+void MinOneLRUCache<keyType, valueType>::setMaxTotalCost(int maxTotalCost)
+{
+	m_maxTotalCost = maxTotalCost;
+	enforceCostConstraint();
+}
+
+template<class keyType, class valueType>
+void MinOneLRUCache<keyType, valueType>::clear()
+{
+	m_items.clear();
+	m_totalCost = 0;
+}
+
+}
+
+#endif
+