QIntCache - Template class that provides a cache based on

       #include <qintcache.h>

       Inherits QGCache.

   Public Members
       QIntCache ( const QIntCache<type> & c ) (internal)
       QIntCache ( int maxCost=100, int size=17 )
       ~QIntCache ()
       QIntCache<type>& operator= ( const QIntCache<type> & c )
           (internal)
       int maxCost () const
       int totalCost () const
       void setMaxCost ( int m )
       virtual uint count () const
       uint size () const
       bool isEmpty () const
       bool insert ( long k, const type * d, int c=1, int p=0 )
       bool remove ( long k )
       type* take ( long k )
       virtual void clear ()
       type* find ( long k, bool ref=TRUE ) const
       type* operator[] ( long k ) const
       void statistics () const


DESCRIPTION

       The QIntCache class is a template class that provides a
       cache based on long keys.

       QIntCache is implemented as a template class. Define a
       template instance QIntCache<X> to create a cache that
       operates on pointers to X, or X*.

       A cache is a least recently used (LRU) list of cache
       items, accessed via long keys. Each cache item has a cost.
       The sum of item costs, totalCost(), will not exceed the
       maximum cache cost, maxCost(). If inserting a new item
       would cause the total cost to exceed the maximum cost, the
       least recently used items in the cache are removed.

       Apart from insert(), by far the most important function is
       find() (which also exists as operator[]). This function
       looks up an item, returns it, and by default marks it as
       being the most recently used item.

       There are also methods to remove() or take() an object
       from the cache. Calling setAutoDelete(TRUE) for a cache
       tells it to delete items that are removed. The default is
       to not delete items when then are removed (i.e. remove()
       and take() are equivalent).

       copied, not the item itself. This is called a shallow
       copy. It is possible to make the dictionary copy all of
       the item's data (known as a deep copy) when an item is
       inserted. insert() calls the virtual function
       QCollection::newItem() for the item to be inserted.
       Inherit a dictionary and reimplement it if you want deep
       copies.

       When removing a cache item, the virtual function
       QCollection::deleteItem() is called. It's default
       implementation in QIntCache is to delete the item if auto-
       deletion is enabled.

       There is a QIntCacheIterator which may be used to traverse
       the items in the cache in arbitrary order.

       See also QIntCacheIterator, QCache, QAsciiCache and
       Collection Classes


MEMBER FUNCTION DOCUMENTATION


QIntCache::QIntCache ( int maxCost=100, int size=17 )

       Constructs a cache with the following properties:

       Arguments:

       maxCost is the maximum allowed total cost.

       size is the size of the internal hash array. Each inserted
              item is associated with a cost. When inserting a
              new item, if the total cost of all items in the
              cache will exceeds maxCost, the cache will start
              throwing out the older (recently least used) items
              until there is room enough for the new item to be
              inserted.

       Setting size to a suitably large prime number (equal to or
       greater than the expected number of entries) makes the
       hash distribution better and hence the loopup faster.


QIntCache::~QIntCache ()

       Removes all items from the cache and destroys it. All
       iterators that access this cache will be reset.


void QIntCache::clear () [virtual]

       Removes all items from the cache, and deletes them if
       auto-deletion has been enabled.

       All cache iterators that operate this on cache are reset.

       See also remove() and take().

       Reimplemented from QCollection.

       Returns the number of items in the cache.

       See also totalCost().

       Reimplemented from QCollection.


type * QIntCache::find ( long k, bool ref=TRUE ) const

       Returns the item associated with k, or null if the key
       does not exist in the cache. If ref is TRUE (the default),
       the item is moved to the front of the LRU list.

       If there are two or more items with equal keys, then the
       one that was inserted last is returned.


bool QIntCache::insert ( long k, const type * d, int c=1, int p=0

       )
       Inserts the item d into the cache with key k and cost c
       (default 1). Returns TRUE if it succeeds and FALSE if it
       fails.

       The cache's size is limited, and if the total cost is too
       high, QIntCache will remove old, least-used items until
       there is room for this new item.

       The parameter p is internal and should be left at the
       default value (0).

       Warning: If this function returns FALSE, you must delete d
       yourself. Additionally, be very careful about using d
       after calling this function, as any other insertions into
       the cache, from anywhere in the application, or within Qt
       itself, could cause the object to be discarded from the
       cache, and the pointer to become invalid.


bool QIntCache::isEmpty () const

       Returns TRUE if the cache is empty, or TRUE if there is at
       least one object in it.


int QIntCache::maxCost () const

       Returns the maximum allowed total cost of the cache.

       See also setMaxCost() and totalCost().


type * QIntCache::operator[] ( long k ) const

       Returns the item associated with k, or null if k does not
       exist in the cache, and moves the item to the front of the
       LRU list.

       If there are two or more items with equal keys, then the
       one that was inserted last is returned.

       This is the same as find( k, TRUE ).



bool QIntCache::remove ( long k )

       Removes the item associated with k, and returns TRUE if
       the item was present in the cache or FALSE if it was not.

       The item is deleted if auto-deletion has been enabled,
       i.e. you have called setAutoDelete(TRUE).

       If there are two or more items with equal keys, then the
       one that was inserted last is is removed.

       All iterators that refer to the removed item are set to
       point to the next item in the cache's traversal order.

       See also take() and clear().


void QIntCache::setMaxCost ( int m )

       Sets the maximum allowed total cost of the cache to m. If
       the current total cost is above m, some items are removed
       immediately.

       See also maxCost() and totalCost().


uint QIntCache::size () const

       Returns the size of the hash array used to implement the
       cache. This should be a bit bigger than count() is likely
       to be.


void QIntCache::statistics () const

       A debug-only utility function. Prints out cache usage,
       hit/miss, and distribution information using qDebug().
       This function does nothing in the release library.


type * QIntCache::take ( long k )

       Takes the item associated with k out of the cache without
       deleting it, and returns a pointer to the item taken out,
       or null if the key does not exist in the cache.

       If there are two or more items with equal keys, then the
       one that was inserted last is taken.

       All iterators that refer to the taken item are set to
       point to the next item in the cache's traversal order.

       See also remove() and clear().


int QIntCache::totalCost () const

       Returns the total cost of the items in the cache. This is
       an integer in the range 0 to maxCost().

       See also setMaxCost().

       For internal use only.


QIntCache& QIntCache::operator= ( const QIntCache & c

       )
       For internal use only.


SEE ALSO

       http://doc.trolltech.com/qintcache.html
       http://www.trolltech.com/faq/tech.html


COPYRIGHT

       Copyright 1992-2001 Trolltech AS,
       http://www.trolltech.com.  See the license file included
       in the distribution for a complete license statement.


AUTHOR

       Generated automatically from the source code.


BUGS

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       make our job much simpler. Thank you.

       In case of content or formattting problems with this
       manual page, please report them to qt-bugs@trolltech.com.
       Please include the name of the manual page (qintcache.3qt)
       and the Qt version (2.3.1).


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