qgcache.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

*/

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

bool QGCache::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.
*/

QPtrCollection::Item QGCache::take_string( const QString &key )
{
    QCacheItem *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.
*/

QPtrCollection::Item QGCache::take_other( const char *key )
{
    QCacheItem *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.
*/

void QGCache::clear()
{
    QCacheItem *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.
*/

QPtrCollection::Item QGCache::find_string( const QString &key, bool ref ) const
{
    QCacheItem *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.
*/

QPtrCollection::Item QGCache::find_other( const char *key, bool ref ) const
{
    QCacheItem *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.
*/

bool QGCache::makeRoomFor( int cost, int priority )
{
    if ( cost > mCost )				// cannot make room for more
	return FALSE;				//   than maximum cost
    if ( priority == -1 )
	priority = 32767;
    register QCacheItem *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.
*/

void QGCache::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
}


/*****************************************************************************
  QGCacheIterator member functions
 *****************************************************************************/

/*!
  \class QGCacheIterator qgcache.h
  \reentrant
  \ingroup shared
  \ingroup collection
  \brief The QGCacheIterator class is an internal class for implementing QCacheIterator and
  QIntCacheIterator.

  \internal

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

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

QGCacheIterator::QGCacheIterator( const QGCache &c )
{
    it = new QCListIt( c.lruList );
#if defined(QT_DEBUG)
    Q_ASSERT( it != 0 );
#endif
}

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

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

/*!
  Destroys the iterator.
*/

QGCacheIterator::~QGCacheIterator()
{
    delete it;
}

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

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

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

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

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

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

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

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

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

QPtrCollection::Item QGCacheIterator::toFirst()
{
    QCacheItem *item = it->toFirst();
    return item ? item->data : 0;
}

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

QPtrCollection::Item QGCacheIterator::toLast()
{
    QCacheItem *item = it->toLast();
    return item ? item->data : 0;
}

/*!
  Returns the current item.
*/

QPtrCollection::Item QGCacheIterator::get() const
{
    QCacheItem *item = it->current();
    return item ? item->data : 0;
}

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

QString QGCacheIterator::getKeyString() const
{
    QCacheItem *item = it->current();
    return item ? *((QString*)item->key) : QString::null;
}

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

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

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

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

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

QPtrCollection::Item QGCacheIterator::operator()()
{
    QCacheItem *item = it->operator()();
    return item ? item->data : 0;
}

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

QPtrCollection::Item QGCacheIterator::operator++()
{
    QCacheItem *item = it->operator++();
    return item ? item->data : 0;
}

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

QPtrCollection::Item QGCacheIterator::operator+=( uint jump )
{
    QCacheItem *item = it->operator+=(jump);
    return item ? item->data : 0;
}

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

QPtrCollection::Item QGCacheIterator::operator--()
{
    QCacheItem *item = it->operator--();
    return item ? item->data : 0;
}

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

QPtrCollection::Item QGCacheIterator::operator-=( uint jump )
{
    QCacheItem *item = it->operator-=(jump);
    return item ? item->data : 0;
}