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q3gcache.cpp

/****************************************************************************
**
** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
**
** This file is part of the Qt3Support module of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file.  Please review the following information to ensure GNU
** General Public Licensing requirements will be met:
** http://www.trolltech.com/products/qt/opensource.html
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://www.trolltech.com/products/qt/licensing.html or contact the
** sales department at sales@trolltech.com.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "q3gcache.h"
#include "q3ptrlist.h"
#include "q3dict.h"
#include "qstring.h"

/*!
  \class Q3GCache
  \reentrant
  \brief The Q3GCache class is an internal class for implementing Q3Cache
  template classes.

  \internal

  Q3GCache is a strictly internal class that acts as a base class for the
  \link collection.html collection classes\endlink Q3Cache and QIntCache.
*/


/*****************************************************************************
  Q3GCacheItem class (internal cache item)
 *****************************************************************************/

struct Q3CacheItem
{
    Q3CacheItem(void *k, Q3PtrCollection::Item d, int c, short p)
      : priority(p), skipPriority(p), cost(c), key(k), data(d), node(0) {}
    short   priority;
    short   skipPriority;
    int           cost;
    void       *key;
    Q3PtrCollection::Item data;
    Q3LNode     *node;
};


/*****************************************************************************
  Q3CList class (internal list of cache items)
 *****************************************************************************/

class Q3CList : private Q3PtrList<Q3CacheItem>
{
friend class Q3GCacheIterator;
friend class Q3CListIt;
public:
    Q3CList()     {}
   ~Q3CList();

    void    insert(Q3CacheItem *);        // insert according to priority
    void    insert(int, Q3CacheItem *);
    void    take(Q3CacheItem *);
    void    reference(Q3CacheItem *);

    void    setAutoDelete(bool del) { Q3PtrCollection::setAutoDelete(del); }

    bool    removeFirst()     { return Q3PtrList<Q3CacheItem>::removeFirst(); }
    bool    removeLast()      { return Q3PtrList<Q3CacheItem>::removeLast(); }

    Q3CacheItem *first()            { return Q3PtrList<Q3CacheItem>::first(); }
    Q3CacheItem *last()       { return Q3PtrList<Q3CacheItem>::last(); }
    Q3CacheItem *prev()       { return Q3PtrList<Q3CacheItem>::prev(); }
    Q3CacheItem *next()       { return Q3PtrList<Q3CacheItem>::next(); }

#if defined(QT_DEBUG)
    int           inserts;                // variables for statistics
    int           insertCosts;
    int           insertMisses;
    int           finds;
    int           hits;
    int           hitCosts;
    int           dumps;
    int           dumpCosts;
#endif
};


Q3CList::~Q3CList()
{
#if defined(QT_DEBUG)
    Q_ASSERT(count() == 0);
#endif
}


void Q3CList::insert(Q3CacheItem *ci)
{
    Q3CacheItem *item = first();
    while(item && item->skipPriority > ci->priority) {
      item->skipPriority--;
      item = next();
    }
    if (item)
      Q3PtrList<Q3CacheItem>::insert(at(), ci);
    else
      append(ci);
#if defined(QT_DEBUG)
    Q_ASSERT(ci->node == 0);
#endif
    ci->node = currentNode();
}

inline void Q3CList::insert(int i, Q3CacheItem *ci)
{
    Q3PtrList<Q3CacheItem>::insert(i, ci);
#if defined(QT_DEBUG)
    Q_ASSERT(ci->node == 0);
#endif
    ci->node = currentNode();
}


void Q3CList::take(Q3CacheItem *ci)
{
    if (ci) {
#if defined(QT_DEBUG)
      Q_ASSERT(ci->node != 0);
#endif
      takeNode(ci->node);
      ci->node = 0;
    }
}


inline void Q3CList::reference(Q3CacheItem *ci)
{
#if defined(QT_DEBUG)
    Q_ASSERT(ci != 0 && ci->node != 0);
#endif
    ci->skipPriority = ci->priority;
    relinkNode(ci->node);                 // relink as first item
}


class Q3CListIt: public Q3PtrListIterator<Q3CacheItem>
{
public:
    Q3CListIt(const Q3CList *p): Q3PtrListIterator<Q3CacheItem>(*p) {}
    Q3CListIt(const Q3CListIt *p): Q3PtrListIterator<Q3CacheItem>(*p) {}
};


/*****************************************************************************
  Q3CDict class (internal dictionary of cache items)
 *****************************************************************************/

//
// Since we need to decide if the dictionary should use an int or const
// char * key (the "bool trivial" argument in the constructor below)
// we cannot use the macro/template dict, but inherit directly from Q3GDict.
//

class Q3CDict : public Q3GDict
{
public:
    Q3CDict(uint size, uint kt, bool caseSensitive, bool copyKeys)
      : Q3GDict(size, (KeyType)kt, caseSensitive, copyKeys) {}
    ~Q3CDict();

    void clear() { Q3GDict::clear(); }

    Q3CacheItem *find_string(const QString &key) const
      { return (Q3CacheItem*)((Q3CDict*)this)->look_string(key, 0, 0); }
    Q3CacheItem *find_ascii(const char *key) const
      { return (Q3CacheItem*)((Q3CDict*)this)->look_ascii(key, 0, 0); }
    Q3CacheItem *find_int(long key) const
      { return (Q3CacheItem*)((Q3CDict*)this)->look_int(key, 0, 0); }

    Q3CacheItem *take_string(const QString &key)
      { return (Q3CacheItem*)Q3GDict::take_string(key); }
    Q3CacheItem *take_ascii(const char *key)
      { return (Q3CacheItem*)Q3GDict::take_ascii(key); }
    Q3CacheItem *take_int(long key)
      { return (Q3CacheItem*)Q3GDict::take_int(key); }

    bool  insert_string(const QString &key, const Q3CacheItem *ci)
      { return Q3GDict::look_string(key,(Item)ci,1)!=0;}
    bool  insert_ascii(const char *key, const Q3CacheItem *ci)
      { return Q3GDict::look_ascii(key,(Item)ci,1)!=0;}
    bool  insert_int(long key, const Q3CacheItem *ci)
      { return Q3GDict::look_int(key,(Item)ci,1)!=0;}

    bool  remove_string(Q3CacheItem *item)
      { return Q3GDict::remove_string(*((QString*)(item->key)),item); }
    bool  remove_ascii(Q3CacheItem *item)
      { return Q3GDict::remove_ascii((const char *)item->key,item); }
    bool  remove_int(Q3CacheItem *item)
      { return Q3GDict::remove_int((long)item->key,item);}

    void  statistics()              { Q3GDict::statistics(); }

private:
    void deleteItem(void *item)
      { if (del_item) { Q3CacheItem *d = (Q3CacheItem*)item; delete d; } }
};

inline Q3CDict::~Q3CDict()
{
    clear();
}

/*****************************************************************************
  Q3GDict member functions
 *****************************************************************************/

/*!
  Constructs a cache.
  The maximum cost of the cache is given by \a maxCost and the size by \a
  size. The key type is \a kt which may be \c StringKey, \c AsciiKey,
  \c IntKey or \c PtrKey. The case-sensitivity of lookups is set with
  \a caseSensitive. Keys are copied if \a copyKeys is true.
*/

00235 Q3GCache::Q3GCache(int maxCost, uint size, KeyType kt, bool caseSensitive,
              bool copyKeys)
{
    keytype = kt;
    lruList = new Q3CList;
    Q_CHECK_PTR(lruList);
    lruList->setAutoDelete(true);
    copyk   = ((keytype == AsciiKey) && copyKeys);
    dict    = new Q3CDict(size, kt, caseSensitive, false);
    Q_CHECK_PTR(dict);
    mCost   = maxCost;
    tCost   = 0;
#if defined(QT_DEBUG)
    lruList->inserts      = 0;
    lruList->insertCosts  = 0;
    lruList->insertMisses = 0;
    lruList->finds        = 0;
    lruList->hits   = 0;
    lruList->hitCosts     = 0;
    lruList->dumps        = 0;
    lruList->dumpCosts    = 0;
#endif
}

/*!
  Cannot copy a cache.
*/

00263 Q3GCache::Q3GCache(const Q3GCache &)
    : Q3PtrCollection()
{
#if defined(QT_CHECK_NULL)
    qFatal("Q3GCache::Q3GCache(Q3GCache &): Cannot copy a cache");
#endif
}

/*!
  Removes all items from the cache and destroys it.
*/

00275 Q3GCache::~Q3GCache()
{
    clear();
    delete dict;
    delete lruList;
}

/*!
  Cannot assign a cache.
*/

00286 Q3GCache &Q3GCache::operator=(const Q3GCache &)
{
#if defined(QT_CHECK_NULL)
    qFatal("Q3GCache::operator=: Cannot copy a cache");
#endif
    return *this;
}


/*!
  Returns the number of items in the cache.
*/

00299 uint Q3GCache::count() const
{
    return dict->count();
}

/*!
  Returns the size of the hash array.
*/

00308 uint Q3GCache::size() const
{
    return dict->size();
}

/*!
  \fn int Q3GCache::maxCost() const

  Returns the maximum cache cost.
*/

/*!
  \fn int Q3GCache::totalCost() const

  Returns the total cache cost.
*/

/*!
  Sets the maximum cache cost to \a maxCost.
*/

00329 void Q3GCache::setMaxCost(int maxCost)
{
    if (maxCost < tCost) {
      if (!makeRoomFor(tCost - maxCost))  // remove excess cost
          return;
    }
    mCost = maxCost;
}


/*!
    Inserts an item with data \a data into the cache using key \a key.
    The item has cost \a cost and priority \a priority.

  \warning If this function returns false, you must delete \a data
  yourself.  Additionally, be very careful about using \a data after
  calling this function, as any other insertions into the cache, from
  anywhere in the application, or within Qt itself, could cause the
  data to be discarded from the cache, and the pointer to become
  invalid.
*/

00351 bool Q3GCache::insert_string(const QString &key, Q3PtrCollection::Item data,
                       int cost, int priority)
{
    if (tCost + cost > mCost) {
      if (!makeRoomFor(tCost + cost - mCost, priority)) {
#if defined(QT_DEBUG)
          lruList->insertMisses++;
#endif
          return false;
      }
    }
#if defined(QT_DEBUG)
    Q_ASSERT(keytype == StringKey);
    lruList->inserts++;
    lruList->insertCosts += cost;
#endif
    if (priority < -32768)
      priority = -32768;
    else if (priority > 32767)
      priority = 32677;
    Q3CacheItem *ci = new Q3CacheItem(new QString(key), newItem(data),
                             cost, (short)priority);
    Q_CHECK_PTR(ci);
    lruList->insert(0, ci);
    dict->insert_string(key, ci);
    tCost += cost;
    return true;
}

bool Q3GCache::insert_other(const char *key, Q3PtrCollection::Item data,
                      int cost, int priority)
{
    if (tCost + cost > mCost) {
      if (!makeRoomFor(tCost + cost - mCost, priority)) {
#if defined(QT_DEBUG)
          lruList->insertMisses++;
#endif
          return false;
      }
    }
#if defined(QT_DEBUG)
    Q_ASSERT(keytype != StringKey);
    lruList->inserts++;
    lruList->insertCosts += cost;
#endif
    if (keytype == AsciiKey && copyk)
      key = qstrdup(key);
    if (priority < -32768)
      priority = -32768;
    else if (priority > 32767)
      priority = 32677;
    Q3CacheItem *ci = new Q3CacheItem((void*)key, newItem(data), cost,
                             (short)priority);
    Q_CHECK_PTR(ci);
    lruList->insert(0, ci);
    if (keytype == AsciiKey)
      dict->insert_ascii(key, ci);
    else
      dict->insert_int((long)key, ci);
    tCost += cost;
    return true;
}


/*!
  Removes the item with key \a key from the cache. Returns true if the
  item was removed; otherwise returns false.
*/

00420 bool Q3GCache::remove_string(const QString &key)
{
    Item d = take_string(key);
    if (d)
      deleteItem(d);
    return d != 0;
}

bool Q3GCache::remove_other(const char *key)
{
    Item d = take_other(key);
    if (d)
      deleteItem(d);
    return d != 0;
}


/*!
  Takes the item with key \a key out of the cache. The item is not
  deleted. If no item has this \a key 0 is returned.
*/

00442 Q3PtrCollection::Item Q3GCache::take_string(const QString &key)
{
    Q3CacheItem *ci = dict->take_string(key);   // take from dict
    Item d;
    if (ci) {
      d = ci->data;
      tCost -= ci->cost;
      lruList->take(ci);                  // take from list
      delete (QString*)ci->key;
      delete ci;
    } else {
      d = 0;
    }
    return d;
}

/*!
  Takes the item with key \a key out of the cache. The item is not
  deleted. If no item has this \a key 0 is returned.
*/

00463 Q3PtrCollection::Item Q3GCache::take_other(const char *key)
{
    Q3CacheItem *ci;
    if (keytype == AsciiKey)
      ci = dict->take_ascii(key);
    else
      ci = dict->take_int((long)key);
    Item d;
    if (ci) {
      d = ci->data;
      tCost -= ci->cost;
      lruList->take(ci);                  // take from list
      if (copyk)
          delete [] (char *)ci->key;
      delete ci;
    } else {
      d = 0;
    }
    return d;
}


/*!
  Clears the cache.
*/

00489 void Q3GCache::clear()
{
    Q3CacheItem *ci;
    while ((ci = lruList->first())) {
      switch (keytype) {
          case StringKey:
            dict->remove_string(ci);
            delete (QString*)ci->key;
            break;
          case AsciiKey:
            dict->remove_ascii(ci);
            if (copyk)
                delete [] (char*)ci->key;
            break;
          case IntKey:
            dict->remove_int(ci);
            break;
          case PtrKey:              // unused
            break;
      }
      deleteItem(ci->data);               // delete data
      lruList->removeFirst();             // remove from list
    }
    tCost = 0;
}


/*!
  Finds an item for \a key in the cache and adds a reference if \a ref is true.
*/

00520 Q3PtrCollection::Item Q3GCache::find_string(const QString &key, bool ref) const
{
    Q3CacheItem *ci = dict->find_string(key);
#if defined(QT_DEBUG)
    lruList->finds++;
#endif
    if (ci) {
#if defined(QT_DEBUG)
      lruList->hits++;
      lruList->hitCosts += ci->cost;
#endif
      if (ref)
          lruList->reference(ci);
      return ci->data;
    }
    return 0;
}


/*!
  Finds an item for \a key in the cache and adds a reference if \a ref is true.
*/

00543 Q3PtrCollection::Item Q3GCache::find_other(const char *key, bool ref) const
{
    Q3CacheItem *ci = keytype == AsciiKey ? dict->find_ascii(key)
                               : dict->find_int((long)key);
#if defined(QT_DEBUG)
    lruList->finds++;
#endif
    if (ci) {
#if defined(QT_DEBUG)
      lruList->hits++;
      lruList->hitCosts += ci->cost;
#endif
      if (ref)
          lruList->reference(ci);
      return ci->data;
    }
    return 0;
}


/*!
  Allocates cache space for one or more items.
*/

00567 bool Q3GCache::makeRoomFor(int cost, int priority)
{
    if (cost > mCost)                     // cannot make room for more
      return false;                       //   than maximum cost
    if (priority == -1)
      priority = 32767;
    register Q3CacheItem *ci = lruList->last();
    int cntCost = 0;
    int dumps     = 0;                    // number of items to dump
    while (cntCost < cost && ci && ci->skipPriority <= priority) {
      cntCost += ci->cost;
      ci     = lruList->prev();
      dumps++;
    }
    if (cntCost < cost)             // can enough cost be dumped?
      return false;                       // no
#if defined(QT_DEBUG)
    Q_ASSERT(dumps > 0);
#endif
    while (dumps--) {
      ci = lruList->last();
#if defined(QT_DEBUG)
      lruList->dumps++;
      lruList->dumpCosts += ci->cost;
#endif
      switch (keytype) {
          case StringKey:
            dict->remove_string(ci);
            delete (QString*)ci->key;
            break;
          case AsciiKey:
            dict->remove_ascii(ci);
            if (copyk)
                delete [] (char *)ci->key;
            break;
          case IntKey:
            dict->remove_int(ci);
            break;
          case PtrKey:              // unused
            break;
      }
      deleteItem(ci->data);               // delete data
      lruList->removeLast();              // remove from list
    }
    tCost -= cntCost;
    return true;
}


/*!
  Outputs debug statistics.
*/

00620 void Q3GCache::statistics() const
{
#if defined(QT_DEBUG)
    QString line;
    line.fill('*', 80);
    qDebug(line.ascii());
    qDebug("CACHE STATISTICS:");
    qDebug("cache contains %d item%s, with a total cost of %d",
         count(), count() != 1 ? "s" : "", tCost);
    qDebug("maximum cost is %d, cache is %d%% full.",
         mCost, (200*tCost + mCost) / (mCost*2));
    qDebug("find() has been called %d time%s",
         lruList->finds, lruList->finds != 1 ? "s" : "");
    qDebug("%d of these were hits, items found had a total cost of %d.",
         lruList->hits,lruList->hitCosts);
    qDebug("%d item%s %s been inserted with a total cost of %d.",
         lruList->inserts,lruList->inserts != 1 ? "s" : "",
         lruList->inserts != 1 ? "have" : "has", lruList->insertCosts);
    qDebug("%d item%s %s too large or had too low priority to be inserted.",
         lruList->insertMisses, lruList->insertMisses != 1 ? "s" : "",
         lruList->insertMisses != 1 ? "were" : "was");
    qDebug("%d item%s %s been thrown away with a total cost of %d.",
         lruList->dumps, lruList->dumps != 1 ? "s" : "",
         lruList->dumps != 1 ? "have" : "has", lruList->dumpCosts);
    qDebug("Statistics from internal dictionary class:");
    dict->statistics();
    qDebug(line.ascii());
#endif
}


/*****************************************************************************
  Q3GCacheIterator member functions
 *****************************************************************************/

/*!
  \class Q3GCacheIterator qgcache.h
  \reentrant
  \brief The Q3GCacheIterator class is an internal class for implementing Q3CacheIterator and
  QIntCacheIterator.

  \internal

  Q3GCacheIterator is a strictly internal class that does the heavy work for
  Q3CacheIterator and QIntCacheIterator.
*/

/*!
  Constructs an iterator that operates on the cache \a c.
*/

00671 Q3GCacheIterator::Q3GCacheIterator(const Q3GCache &c)
{
    it = new Q3CListIt(c.lruList);
#if defined(QT_DEBUG)
    Q_ASSERT(it != 0);
#endif
}

/*!
  Constructs an iterator that operates on the same cache as \a ci.
*/

00683 Q3GCacheIterator::Q3GCacheIterator(const Q3GCacheIterator &ci)
{
    it = new Q3CListIt(ci.it);
#if defined(QT_DEBUG)
    Q_ASSERT(it != 0);
#endif
}

/*!
  Destroys the iterator.
*/

00695 Q3GCacheIterator::~Q3GCacheIterator()
{
    delete it;
}

/*!
  Assigns the iterator \a ci to this cache iterator.
*/

00704 Q3GCacheIterator &Q3GCacheIterator::operator=(const Q3GCacheIterator &ci)
{
    *it = *ci.it;
    return *this;
}

/*!
  Returns the number of items in the cache.
*/

00714 uint Q3GCacheIterator::count() const
{
    return it->count();
}

/*!
  Returns true if the iterator points to the first item.
*/

00723 bool  Q3GCacheIterator::atFirst() const
{
    return it->atFirst();
}

/*!
  Returns true if the iterator points to the last item.
*/

00732 bool Q3GCacheIterator::atLast() const
{
    return it->atLast();
}

/*!
  Sets the list iterator to point to the first item in the cache.
*/

00741 Q3PtrCollection::Item Q3GCacheIterator::toFirst()
{
    Q3CacheItem *item = it->toFirst();
    return item ? item->data : 0;
}

/*!
  Sets the list iterator to point to the last item in the cache.
*/

00751 Q3PtrCollection::Item Q3GCacheIterator::toLast()
{
    Q3CacheItem *item = it->toLast();
    return item ? item->data : 0;
}

/*!
  Returns the current item.
*/

00761 Q3PtrCollection::Item Q3GCacheIterator::get() const
{
    Q3CacheItem *item = it->current();
    return item ? item->data : 0;
}

/*!
  Returns the key of the current item.
*/

00771 QString Q3GCacheIterator::getKeyString() const
{
    Q3CacheItem *item = it->current();
    return item ? *((QString*)item->key) : QString();
}

/*!
  Returns the key of the current item, as a \0-terminated C string.
*/

00781 const char *Q3GCacheIterator::getKeyAscii() const
{
    Q3CacheItem *item = it->current();
    return item ? (const char *)item->key : 0;
}

/*!
  Returns the key of the current item, as a long.
*/

00791 long Q3GCacheIterator::getKeyInt() const
{
    Q3CacheItem *item = it->current();
    return item ? (long)item->key : 0;
}

/*!
  Moves to the next item (postfix).
*/

00801 Q3PtrCollection::Item Q3GCacheIterator::operator()()
{
    Q3CacheItem *item = it->operator()();
    return item ? item->data : 0;
}

/*!
  Moves to the next item (prefix).
*/

00811 Q3PtrCollection::Item Q3GCacheIterator::operator++()
{
    Q3CacheItem *item = it->operator++();
    return item ? item->data : 0;
}

/*!
  Moves \a jump positions forward.
*/

00821 Q3PtrCollection::Item Q3GCacheIterator::operator+=(uint jump)
{
    Q3CacheItem *item = it->operator+=(jump);
    return item ? item->data : 0;
}

/*!
  Moves to the previous item (prefix).
*/

00831 Q3PtrCollection::Item Q3GCacheIterator::operator--()
{
    Q3CacheItem *item = it->operator--();
    return item ? item->data : 0;
}

/*!
  Moves \a jump positions backward.
*/

00841 Q3PtrCollection::Item Q3GCacheIterator::operator-=(uint jump)
{
    Q3CacheItem *item = it->operator-=(jump);
    return item ? item->data : 0;
}

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