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QIntCache(3qt)									   QIntCache(3qt)

NAME
       QIntCache - Template class that provides a cache based on long keys

SYNOPSIS
       #include <qintcache.h>

       Inherits QPtrCollection.

   Public Members
       QIntCache ( int maxCost = 100, int size = 17 )
       ~QIntCache ()
       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 they are removed (i.e. remove() and take() are equivalent).

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

       When removing a cache item, the item will be automatically deleted 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, Collection Classes, and Non-GUI Classes.

MEMBER FUNCTION DOCUMENTATION
QIntCache::QIntCache ( int maxCost = 100, int size = 17 )
       Constructs a cache whose contents will never have a total cost greater than maxCost and
       which is expected to contain less than size items.

       size is actually the size of an internal hash array; it's usually best to make it prime
       and at least 50% bigger than the largest expected number of items in the cache.

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

QIntCache::~QIntCache ()
       Removes all items from the cache and then destroys the int cache. If auto-deletion is
       enabled the cache's items are deleted. 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 QPtrCollection.

uint QIntCache::count () const [virtual]
       Returns the number of items in the cache.

       See also totalCost().

       Reimplemented from QPtrCollection.

type * QIntCache::find ( long k, bool ref = TRUE ) const
       Returns the item associated with k, or 0 if the key does not exist in the cache. If ref is
       TRUE (the default), the item is moved to the front of the least recently used list.

       If there are two or more items with equal keys, the one that was inserted most recently 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 assigns it a cost of c (default 1).
       Returns TRUE if it succeeds; otherwise returns FALSE.

       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 (for example, the cost , exceeds maxCost()), you
       must delete d yourself. Additionally, be very careful about using d after calling this
       function. 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; otherwise returns FALSE.

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 0 if k does not exist in the cache, and moves the
       item to the front of the least recently used list.

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

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

       See also find().

bool QIntCache::remove ( long k )
       Removes the item associated with k, and returns TRUE if the item was present in the cache;
       otherwise returns FALSE.

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

       If there are two or more items with equal keys, the one that was inserted most recently 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
       greater than 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
       larger 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 0 if the key does not exist in the cache.

       If there are two or more items with equal keys, the one that was inserted most recently 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().

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

COPYRIGHT
       Copyright 1992-2007 Trolltech ASA, 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
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is located at
       $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. This man page is
       provided as a convenience for those users who prefer man pages, although this format is
       not officially supported by Trolltech.

       If you find errors in 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 (3.3.8).

Trolltech AS				 2 February 2007			   QIntCache(3qt)
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