Q3IntCache Class Reference
[Qt3Support module]

Detailed Description

The Q3IntCache class is a template class that provides a cache based on long keys.

Q3IntCache is implemented as a template class. Define a template instance Q3IntCache<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 Q3PtrCollection::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 Q3IntCacheIterator which may be used to traverse the items in the cache in arbitrary order.

See also Q3IntCacheIterator, Q3Cache, and Q3AsciiCache.

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