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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QCACHE_H
#define QCACHE_H
#include <QtCore/qhash.h>
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
QT_MODULE(Core)
template <class Key, class T>
class QCache
{
struct Node {
inline Node() : keyPtr(0) {}
inline Node(T *data, int cost)
: keyPtr(0), t(data), c(cost), p(0), n(0) {}
const Key *keyPtr; T *t; int c; Node *p,*n;
};
Node *f, *l;
QHash<Key, Node> hash;
void *unused;
int mx, total;
inline void unlink(Node &n) {
if (n.p) n.p->n = n.n;
if (n.n) n.n->p = n.p;
if (l == &n) l = n.p;
if (f == &n) f = n.n;
total -= n.c;
T *obj = n.t;
hash.remove(*n.keyPtr);
delete obj;
}
inline T *relink(const Key &key) {
typename QHash<Key, Node>::iterator i = hash.find(key);
if (typename QHash<Key, Node>::const_iterator(i) == hash.constEnd())
return 0;
Node &n = *i;
if (f != &n) {
if (n.p) n.p->n = n.n;
if (n.n) n.n->p = n.p;
if (l == &n) l = n.p;
n.p = 0;
n.n = f;
f->p = &n;
f = &n;
}
return n.t;
}
Q_DISABLE_COPY(QCache)
public:
inline explicit QCache(int maxCost = 100);
#ifdef QT3_SUPPORT
inline QT3_SUPPORT_CONSTRUCTOR QCache(int maxCost, int /* dummy */)
: f(0), l(0), mx(maxCost), total(0) {}
#endif
inline ~QCache() { clear(); }
inline int maxCost() const { return mx; }
void setMaxCost(int m);
inline int totalCost() const { return total; }
inline int size() const { return hash.size(); }
inline int count() const { return hash.size(); }
inline bool isEmpty() const { return hash.isEmpty(); }
inline QList<Key> keys() const { return hash.keys(); }
void clear();
bool insert(const Key &key, T *object, int cost = 1);
T *object(const Key &key) const;
inline bool contains(const Key &key) const { return hash.contains(key); }
T *operator[](const Key &key) const;
bool remove(const Key &key);
T *take(const Key &key);
private:
void trim(int m);
#ifdef QT3_SUPPORT
inline QT3_SUPPORT T *find(const Key &key) const { return object(key); }
#endif
};
template <class Key, class T>
inline QCache<Key, T>::QCache(int amaxCost)
: f(0), l(0), unused(0), mx(amaxCost), total(0) {}
template <class Key, class T>
inline void QCache<Key,T>::clear()
{ while (f) { delete f->t; f = f->n; }
hash.clear(); l = 0; total = 0; }
template <class Key, class T>
inline void QCache<Key,T>::setMaxCost(int m)
{ mx = m; trim(mx); }
template <class Key, class T>
inline T *QCache<Key,T>::object(const Key &key) const
{ return const_cast<QCache<Key,T>*>(this)->relink(key); }
template <class Key, class T>
inline T *QCache<Key,T>::operator[](const Key &key) const
{ return object(key); }
template <class Key, class T>
inline bool QCache<Key,T>::remove(const Key &key)
{
typename QHash<Key, Node>::iterator i = hash.find(key);
if (typename QHash<Key, Node>::const_iterator(i) == hash.constEnd()) {
return false;
} else {
unlink(*i);
return true;
}
}
template <class Key, class T>
inline T *QCache<Key,T>::take(const Key &key)
{
typename QHash<Key, Node>::iterator i = hash.find(key);
if (i == hash.end())
return 0;
Node &n = *i;
T *t = n.t;
n.t = 0;
unlink(n);
return t;
}
template <class Key, class T>
bool QCache<Key,T>::insert(const Key &akey, T *aobject, int acost)
{
remove(akey);
if (acost > mx) {
delete aobject;
return false;
}
trim(mx - acost);
Node sn(aobject, acost);
typename QHash<Key, Node>::iterator i = hash.insert(akey, sn);
total += acost;
Node *n = &i.value();
n->keyPtr = &i.key();
if (f) f->p = n;
n->n = f;
f = n;
if (!l) l = f;
return true;
}
template <class Key, class T>
void QCache<Key,T>::trim(int m)
{
Node *n = l;
while (n && total > m) {
Node *u = n;
n = n->p;
if (qIsDetached(*u->t))
unlink(*u);
}
}
QT_END_NAMESPACE
QT_END_HEADER
#endif // QCACHE_H
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