/****************************************************************************

** 

**

** Implementation of QGCache and QGCacheIterator classes

**

** Created : 950208

**

** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.

**

** This file is part of the tools module of the Qt GUI Toolkit.

**

** This file may be distributed under the terms of the Q Public License

** as defined by Trolltech AS of Norway and appearing in the file

** LICENSE.QPL included in the packaging of this file.

**

** This file may be distributed and/or modified under the terms of the

** GNU General Public License version 2 as published by the Free Software

** Foundation and appearing in the file LICENSE.GPL included in the

** packaging of this file.

**

** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition

** licenses may use this file in accordance with the Qt Commercial License

** Agreement provided with the Software.

**

** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE

** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

**

** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for

**   information about Qt Commercial License Agreements.

** See http://www.trolltech.com/qpl/ for QPL licensing information.

** See http://www.trolltech.com/gpl/ for GPL licensing information.

**

** Contact info@trolltech.com if any conditions of this licensing are

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**********************************************************************/

#include "qgcache.h"

#include "qinternallist.h"

#include "qdict.h"

#include "qstring.h"

// NOT REVISED

/*!

  \class QGCache qgcache.h

  \brief The QGCache class is an internal class for implementing QCache template classes.

  QGCache is a strictly internal class that acts as a base class for the

  \link collection.html collection classes\endlink QCache and QIntCache.

*/

/*****************************************************************************

  QGCacheItem class (internal cache item)

 *****************************************************************************/

struct QCacheItem

{

    QCacheItem( void *k, QCollection::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;

    QCollection::Item data;

    QLNode     *node;

};

/*****************************************************************************

  QCList class (internal list of cache items)

 *****************************************************************************/

class QCList : private QInternalList<QCacheItem>

{

friend class QGCacheIterator;

friend class QCListIt;

public:

    QCList()	{}

   ~QCList();

    void	insert( QCacheItem * );		// insert according to priority

    void	insert( int, QCacheItem * );

    void	take( QCacheItem * );

    void	reference( QCacheItem * );

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

    bool	removeFirst()	{ return QInternalList<QCacheItem>::removeFirst(); }

    bool	removeLast()	{ return QInternalList<QCacheItem>::removeLast(); }

    QCacheItem *first()		{ return QInternalList<QCacheItem>::first(); }

    QCacheItem *last()		{ return QInternalList<QCacheItem>::last(); }

    QCacheItem *prev()		{ return QInternalList<QCacheItem>::prev(); }

    QCacheItem *next()		{ return QInternalList<QCacheItem>::next(); }

#if defined(DEBUG)

    int		inserts;			// variables for statistics

    int		insertCosts;

    int		insertMisses;

    int		finds;

    int		hits;

    int		hitCosts;

    int		dumps;

    int		dumpCosts;

#endif

};

QCList::~QCList()

{

#if defined(DEBUG)

    ASSERT( count() == 0 );

#endif

}

void QCList::insert( QCacheItem *ci )

{

    QCacheItem *item = first();

    while( item && item->skipPriority > ci->priority ) {

	item->skipPriority--;

	item = next();

    }

    if ( item )

	QInternalList<QCacheItem>::insert( at(), ci );

    else

	append( ci );

#if defined(DEBUG)

    ASSERT( ci->node == 0 );

#endif

    ci->node = currentNode();

}

inline void QCList::insert( int i, QCacheItem *ci )

{

    QInternalList<QCacheItem>::insert( i, ci );

#if defined(DEBUG)

    ASSERT( ci->node == 0 );

#endif

    ci->node = currentNode();

}

void QCList::take( QCacheItem *ci )

{

    if ( ci ) {

#if defined(DEBUG)

	ASSERT( ci->node != 0 );

#endif

	takeNode( ci->node );

	ci->node = 0;

    }

}

inline void QCList::reference( QCacheItem *ci )

{

#if defined(DEBUG)

    ASSERT( ci != 0 && ci->node != 0 );

#endif

    ci->skipPriority = ci->priority;

    relinkNode( ci->node );			// relink as first item

}

class QCListIt: public QInternalListIterator<QCacheItem>

{

public:

    QCListIt( const QCList *p ): QInternalListIterator<QCacheItem>( *p ) {}

    QCListIt( const QCListIt *p ): QInternalListIterator<QCacheItem>( *p ) {}

};

/*****************************************************************************

  QCDict 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 QGDict.

//

class QCDict : public QGDict

{

public:

    QCDict( uint size, uint kt, bool caseSensitive, bool copyKeys )

	: QGDict( size, (KeyType)kt, caseSensitive, copyKeys ) {}

    QCacheItem *find_string(const QString &key) const

	{ return (QCacheItem*)((QCDict*)this)->look_string(key, 0, 0); }

    QCacheItem *find_ascii(const char *key) const

	{ return (QCacheItem*)((QCDict*)this)->look_ascii(key, 0, 0); }

    QCacheItem *find_int(long key) const

	{ return (QCacheItem*)((QCDict*)this)->look_int(key, 0, 0); }

    QCacheItem *take_string(const QString &key)

	{ return (QCacheItem*)QGDict::take_string(key); }

    QCacheItem *take_ascii(const char *key)

	{ return (QCacheItem*)QGDict::take_ascii(key); }

    QCacheItem *take_int(long key)

	{ return (QCacheItem*)QGDict::take_int(key); }

    bool  insert_string( const QString &key, const QCacheItem *ci )

	{ return QGDict::look_string(key,(Item)ci,1)!=0;}

    bool  insert_ascii( const char *key, const QCacheItem *ci )

	{ return QGDict::look_ascii(key,(Item)ci,1)!=0;}

    bool  insert_int( long key, const QCacheItem *ci )

	{ return QGDict::look_int(key,(Item)ci,1)!=0;}

    bool  remove_string( QCacheItem *item )

	{ return QGDict::remove_string(*((QString*)(item->key)),item); }

    bool  remove_ascii( QCacheItem *item )

	{ return QGDict::remove_ascii((const char *)item->key,item); }

    bool  remove_int( QCacheItem *item )

	{ return QGDict::remove_int((intptr_t)item->key,item);}

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

};

/*****************************************************************************

  QGDict member functions

 *****************************************************************************/

/*!

  \internal

  Constructs a cache.

*/

QGCache::QGCache( int maxCost, uint size, KeyType kt, bool caseSensitive,

		  bool copyKeys )

{

    keytype = kt;

    lruList = new QCList;

    CHECK_PTR( lruList );

    lruList->setAutoDelete( TRUE );

    copyk   = ((keytype == AsciiKey) && copyKeys);

    dict    = new QCDict( size, kt, caseSensitive, FALSE );

    CHECK_PTR( dict );

    mCost   = maxCost;

    tCost   = 0;

#if defined(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

}

/*!

  \internal

  Cannot copy a cache.

*/

QGCache::QGCache( const QGCache & )

    : QCollection()

{

#if defined(CHECK_NULL)

    qFatal( "QGCache::QGCache(QGCache &): Cannot copy a cache" );

#endif

}

/*!

  \internal

  Removes all items from the cache and destroys it.

*/

QGCache::~QGCache()

{

    clear();					// delete everything first

    delete dict;

    delete lruList;

}

/*!

  \internal

  Cannot assign a cache.

*/

QGCache &QGCache::operator=( const QGCache & )

{

#if defined(CHECK_NULL)

    qFatal( "QGCache::operator=: Cannot copy a cache" );

#endif

    return *this;				// satisfy the compiler

}

/*!

  \fn uint QGCache::count() const

  \internal

  Returns the number of items in the cache.

*/

/*!

  \fn uint QGCache::size() const

  \internal

  Returns the size of the hash array.

*/

/*!

  \fn int QGCache::maxCost() const

  \internal

  Returns the maximum cache cost.

*/

/*!

  \fn int QGCache::totalCost() const

  \internal

  Returns the total cache cost.

*/

/*!

  \internal

  Sets the maximum cache cost.

*/

void QGCache::setMaxCost( int maxCost )

{

    if ( maxCost < tCost ) {

	if ( !makeRoomFor(tCost - maxCost) )	// remove excess cost

	    return;

    }

    mCost = maxCost;

}

/*!

  \internal

  Inserts an item into the cache.

  \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.

*/

bool QGCache::insert_string( const QString &key, QCollection::Item data,

			     int cost, int priority)

{

    if ( tCost + cost > mCost ) {

	if ( !makeRoomFor(tCost + cost - mCost, priority) ) {

#if defined(DEBUG)

	    lruList->insertMisses++;

#endif

	    return FALSE;

	}

    }

#if defined(DEBUG)

    ASSERT( keytype == StringKey );

    lruList->inserts++;

    lruList->insertCosts += cost;

#endif

    if ( priority < -32768 )

	priority = -32768;

    else if ( priority > 32767 )

	priority = 32677;

    QCacheItem *ci = new QCacheItem( new QString(key), newItem(data),

				     cost, (short)priority );

    CHECK_PTR( ci );

    lruList->insert( 0, ci );

    dict->insert_string( key, ci );

    tCost += cost;

    return TRUE;

}

/*! \internal */

bool QGCache::insert_other( const char *key, QCollection::Item data,

			    int cost, int priority)

{

    if ( tCost + cost > mCost ) {

	if ( !makeRoomFor(tCost + cost - mCost, priority) ) {

#if defined(DEBUG)

	    lruList->insertMisses++;

#endif

	    return FALSE;

	}

    }

#if defined(DEBUG)

    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;

    QCacheItem *ci = new QCacheItem( (void*)key, newItem(data), cost,

				     (short)priority );

    CHECK_PTR( ci );

    lruList->insert( 0, ci );

    if ( keytype == AsciiKey )

	dict->insert_ascii( key, ci );

    else

	dict->insert_int( (intptr_t)key, ci );

    tCost += cost;

    return TRUE;

}

/*!

  \internal

  Removes an item from the cache.

*/

bool QGCache::remove_string( const QString &key )

{

    Item d = take_string( key );

    if ( d )

	deleteItem( d );

    return d != 0;

}

/*! \internal */

bool QGCache::remove_other( const char *key )

{

    Item d = take_other( key );

    if ( d )

	deleteItem( d );

    return d != 0;

}

/*!

  \internal

  Takes an item out of the cache (no delete).

*/

QCollection::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;

}

/*!

  \internal

  Takes an item out of the cache (no delete).

*/

QCollection::Item QGCache::take_other( const char *key )

{

    QCacheItem *ci;

    if ( keytype == AsciiKey )

	ci = dict->take_ascii( key );

    else

	ci = dict->take_int( (intptr_t)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;

}

/*!

  \internal

  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;

}

/*!

  \internal

  Finds an item in the cache.

*/

QCollection::Item QGCache::find_string( const QString &key, bool ref ) const

{

    QCacheItem *ci = dict->find_string( key );

#if defined(DEBUG)

    lruList->finds++;

#endif

    if ( ci ) {

#if defined(DEBUG)

	lruList->hits++;

	lruList->hitCosts += ci->cost;

#endif

	if ( ref )

	    lruList->reference( ci );

	return ci->data;

    }

    return 0;

}

/*!

  \internal

  Finds an item in the cache.

*/

QCollection::Item QGCache::find_other( const char *key, bool ref ) const

{

    QCacheItem *ci = keytype == AsciiKey ? dict->find_ascii(key)

					 : dict->find_int((intptr_t)key);

#if defined(DEBUG)

    lruList->finds++;

#endif

    if ( ci ) {

#if defined(DEBUG)

	lruList->hits++;

	lruList->hitCosts += ci->cost;

#endif

	if ( ref )

	    lruList->reference( ci );

	return ci->data;

    }

    return 0;

}

/*!

  \internal

  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(DEBUG)

    ASSERT( dumps > 0 );

#endif

    while ( dumps-- ) {

	ci = lruList->last();

#if defined(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;

}

/*!

  \internal

  Outputs debug statistics.

*/

void QGCache::statistics() const

{

#if defined(DEBUG)

    QString line;

    line.fill( '*', 80 );

    qDebug( "%s",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( "%s",line.ascii() );

#endif

}

int QGCache::hits() const

{

  return lruList->hits;

}

int QGCache::misses() const

{

  return lruList->finds - lruList->hits;

}

/*****************************************************************************

  QGCacheIterator member functions

 *****************************************************************************/

/*!

  \class QGCacheIterator qgcache.h

  \brief An internal class for implementing QCacheIterator and QIntCacheIterator.

  QGCacheIterator is a strictly internal class that does the heavy work for

  QCacheIterator and QIntCacheIterator.

*/

/*!

  \internal

  Constructs an iterator that operates on the cache \e c.

*/

QGCacheIterator::QGCacheIterator( const QGCache &c )

{

    it = new QCListIt( c.lruList );

#if defined(DEBUG)

    ASSERT( it != 0 );

#endif

}

/*!

  \internal

  Constructs an iterator that operates on the same cache as \e ci.

*/

QGCacheIterator::QGCacheIterator( const QGCacheIterator &ci )

{

    it = new QCListIt( ci.it );

#if defined(DEBUG)

    ASSERT( it != 0 );

#endif

}

/*!

  \internal

  Destroys the iterator.

*/

QGCacheIterator::~QGCacheIterator()

{

    delete it;

}

/*!

  \internal

  Assigns the iterator \e ci to this cache iterator.

*/

QGCacheIterator &QGCacheIterator::operator=( const QGCacheIterator &ci )

{

    *it = *ci.it;

    return *this;

}

/*!

  \internal

  Returns the number of items in the cache.

*/

uint QGCacheIterator::count() const

{

    return it->count();

}

/*!

  \internal

  Returns TRUE if the iterator points to the first item.

*/

bool  QGCacheIterator::atFirst() const

{

    return it->atFirst();

}

/*!

  \internal

  Returns TRUE if the iterator points to the last item.

*/

bool QGCacheIterator::atLast() const

{

    return it->atLast();

}

/*!

  \internal

  Sets the list iterator to point to the first item in the cache.

*/

QCollection::Item QGCacheIterator::toFirst()

{

    QCacheItem *item = it->toFirst();

    return item ? item->data : 0;

}

/*!

  \internal

  Sets the list iterator to point to the last item in the cache.

*/

QCollection::Item QGCacheIterator::toLast()

{

    QCacheItem *item = it->toLast();

    return item ? item->data : 0;

}

/*!

  \internal

  Returns the current item.

*/

QCollection::Item QGCacheIterator::get() const

{

    QCacheItem *item = it->current();

    return item ? item->data : 0;

}

/*!

  \internal

  Returns the key of the current item.

*/

QString QGCacheIterator::getKeyString() const

{

    QCacheItem *item = it->current();

    return item ? *((QString*)item->key) : QString::null;

}

/*!

  \internal

  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;

}

/*!

  \internal

  Returns the key of the current item, as a long.

*/

intptr_t QGCacheIterator::getKeyInt() const

{

    QCacheItem *item = it->current();

    return item ? (intptr_t)item->key : 0;

}

/*!

  \internal

  Moves to the next item (postfix).

*/

QCollection::Item QGCacheIterator::operator()()

{

    QCacheItem *item = it->operator()();

    return item ? item->data : 0;

}

/*!

  \internal

  Moves to the next item (prefix).

*/

QCollection::Item QGCacheIterator::operator++()

{

    QCacheItem *item = it->operator++();

    return item ? item->data : 0;

}

/*!

  \internal

  Moves \e jumps positions forward.

*/

QCollection::Item QGCacheIterator::operator+=( uint jump )

{

    QCacheItem *item = it->operator+=(jump);

    return item ? item->data : 0;

}

/*!

  \internal

  Moves to the previous item (prefix).

*/

QCollection::Item QGCacheIterator::operator--()

{

    QCacheItem *item = it->operator--();

    return item ? item->data : 0;

}

/*!

  \internal

  Moves \e jumps positions backward.

*/

QCollection::Item QGCacheIterator::operator-=( uint jump )

{

    QCacheItem *item = it->operator-=(jump);

    return item ? item->data : 0;

}