| /**************************************************************************** |
| ** |
| ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). |
| ** All rights reserved. |
| ** Contact: Nokia Corporation (qt-info@nokia.com) |
| ** |
| ** This file is part of the documentation of the Qt Toolkit. |
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| ** $QT_BEGIN_LICENSE:FDL$ |
| ** GNU Free Documentation License |
| ** Alternatively, this file may be used under the terms of the GNU Free |
| ** Documentation License version 1.3 as published by the Free Software |
| ** Foundation and appearing in the file included in the packaging of |
| ** this file. |
| ** |
| ** Other Usage |
| ** Alternatively, this file may be used in accordance with the terms |
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| ** and Nokia. |
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| ** |
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| ** $QT_END_LICENSE$ |
| ** |
| ****************************************************************************/ |
| |
| /*! |
| \class Q3IntCache |
| \brief The Q3IntCache class is a template class that provides a cache based on long keys. |
| \compat |
| |
| 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 \c 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. |
| |
| \sa Q3IntCacheIterator, Q3Cache, Q3AsciiCache |
| */ |
| |
| /*! |
| \fn Q3IntCache::Q3IntCache( const Q3IntCache<type> &c ) |
| |
| \internal |
| |
| Do not use. A Q3IntCache cannot be copied. Calls qFatal() in debug version. |
| */ |
| |
| /*! |
| \fn Q3IntCache::Q3IntCache( int maxCost, int size ) |
| |
| Constructs a cache whose contents will never have a total cost |
| greater than \a maxCost and which is expected to contain less than |
| \a size items. |
| |
| \a 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 \a |
| 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. |
| */ |
| |
| /*! |
| \fn Q3IntCache::~Q3IntCache() |
| |
| 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. |
| */ |
| |
| /*! |
| \fn Q3IntCache<type>& Q3IntCache::operator=( const Q3IntCache<type> &c ) |
| |
| \internal |
| |
| Do not use. A Q3IntCache cannot be copied. Calls qFatal() in debug version. |
| */ |
| |
| /*! |
| \fn int Q3IntCache::maxCost() const |
| |
| Returns the maximum allowed total cost of the cache. |
| |
| \sa setMaxCost() totalCost() |
| */ |
| |
| /*! |
| \fn int Q3IntCache::totalCost() const |
| |
| Returns the total cost of the items in the cache. This is an |
| integer in the range 0 to maxCost(). |
| |
| \sa setMaxCost() |
| */ |
| |
| /*! |
| \fn void Q3IntCache::setMaxCost( int m ) |
| |
| Sets the maximum allowed total cost of the cache to \a m. If the |
| current total cost is greater than \a m, some items are removed |
| immediately. |
| |
| \sa maxCost() totalCost() |
| */ |
| |
| /*! |
| \fn uint Q3IntCache::count() const |
| |
| Returns the number of items in the cache. |
| |
| \sa totalCost() |
| */ |
| |
| /*! |
| \fn uint Q3IntCache::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. |
| */ |
| |
| /*! |
| \fn bool Q3IntCache::isEmpty() const |
| |
| Returns TRUE if the cache is empty; otherwise returns FALSE. |
| */ |
| |
| /*! |
| \fn bool Q3IntCache::insert( long k, const type *d, int c, int p ) |
| |
| Inserts the item \a d into the cache with key \a k and assigns it |
| a cost of \a 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, |
| Q3IntCache will remove old, least-used items until there is room |
| for this new item. |
| |
| The parameter \a p is internal and should be left at the default |
| value (0). |
| |
| \warning If this function returns FALSE (for example, the cost \c, |
| exceeds maxCost()), you must delete \a d yourself. Additionally, |
| be very careful about using \a 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. |
| */ |
| |
| /*! |
| \fn bool Q3IntCache::remove( long k ) |
| |
| Removes the item associated with \a 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. |
| |
| \sa take(), clear() |
| */ |
| |
| /*! |
| \fn type * Q3IntCache::take( long k ) |
| |
| Takes the item associated with \a 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. |
| |
| \sa remove(), clear() |
| */ |
| |
| /*! |
| \fn void Q3IntCache::clear() |
| |
| 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. |
| |
| \sa remove() take() |
| */ |
| |
| /*! |
| \fn type * Q3IntCache::find( long k, bool ref ) const |
| |
| Returns the item associated with \a k, or 0 if the key does not |
| exist in the cache. If \a 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. |
| */ |
| |
| /*! |
| \fn type * Q3IntCache::operator[]( long k ) const |
| |
| Returns the item associated with \a k, or 0 if \a 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 ). |
| |
| \sa find() |
| */ |
| |
| /*! |
| \fn void Q3IntCache::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. |
| */ |
| |
| /*! |
| \class Q3IntCacheIterator |
| \brief The Q3IntCacheIterator class provides an iterator for Q3IntCache collections. |
| \compat |
| |
| Note that the traversal order is arbitrary; you are not guaranteed |
| any particular order. If new objects are inserted into the cache |
| while the iterator is active, the iterator may or may not see |
| them. |
| |
| Multiple iterators are completely independent, even when they |
| operate on the same Q3IntCache. Q3IntCache updates all iterators |
| that refer an item when that item is removed. |
| |
| Q3IntCacheIterator provides an operator++(), and an operator+=() to |
| traverse the cache; current() and currentKey() to access the |
| current cache item and its key; atFirst() atLast(), which return |
| TRUE if the iterator points to the first/last item in the cache; |
| isEmpty(), which returns TRUE if the cache is empty; and count(), |
| which returns the number of items in the cache. |
| |
| Note that atFirst() and atLast() refer to the iterator's arbitrary |
| ordering, not to the cache's internal least recently used list. |
| |
| \sa Q3IntCache |
| */ |
| |
| /*! |
| \fn Q3IntCacheIterator::Q3IntCacheIterator( const Q3IntCache<type> &cache ) |
| |
| Constructs an iterator for \a cache. The current iterator item is |
| set to point to the first item in the \a cache (or rather, the |
| first item is defined to be the item at which this constructor |
| sets the iterator to point). |
| */ |
| |
| /*! |
| \fn Q3IntCacheIterator::Q3IntCacheIterator (const Q3IntCacheIterator<type> & ci) |
| |
| Constructs an iterator for the same cache as \a ci. The new |
| iterator starts at the same item as ci.current(), but moves |
| independently from there on. |
| */ |
| |
| /*! |
| \fn Q3IntCacheIterator<type>& Q3IntCacheIterator::operator=( const Q3IntCacheIterator<type> &ci ) |
| |
| Makes this an iterator for the same cache as \a ci. The new |
| iterator starts at the same item as ci.current(), but moves |
| independently thereafter. |
| */ |
| |
| /*! |
| \fn uint Q3IntCacheIterator::count() const |
| |
| Returns the number of items in the cache on which this iterator |
| operates. |
| |
| \sa isEmpty() |
| */ |
| |
| /*! |
| \fn bool Q3IntCacheIterator::isEmpty() const |
| |
| Returns TRUE if the cache is empty; otherwise returns FALSE. |
| |
| \sa count() |
| */ |
| |
| /*! |
| \fn bool Q3IntCacheIterator::atFirst() const |
| |
| Returns TRUE if the iterator points to the first item in the |
| cache; otherwise returns FALSE. Note that this refers to the |
| iterator's arbitrary ordering, not to the cache's internal least |
| recently used list. |
| |
| \sa toFirst(), atLast() |
| */ |
| |
| /*! |
| \fn bool Q3IntCacheIterator::atLast() const |
| |
| Returns TRUE if the iterator points to the last item in the cache; |
| otherwise returns FALSE. Note that this refers to the iterator's |
| arbitrary ordering, not to the cache's internal least recently |
| used list. |
| |
| \sa toLast(), atFirst() |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::toFirst() |
| |
| Sets the iterator to point to the first item in the cache and |
| returns a pointer to the item. |
| |
| Sets the iterator to 0, and returns 0, if the cache is empty. |
| |
| \sa toLast() isEmpty() |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::toLast() |
| |
| Sets the iterator to point to the last item in the cache and |
| returns a pointer to the item. |
| |
| Sets the iterator to 0, and returns 0, if the cache is empty. |
| |
| \sa toFirst() isEmpty() |
| */ |
| |
| /*! |
| \fn Q3IntCacheIterator::operator type *() const |
| |
| Cast operator. Returns a pointer to the current iterator item. |
| Same as current(). |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::current() const |
| |
| Returns a pointer to the current iterator item. |
| */ |
| |
| /*! |
| \fn long Q3IntCacheIterator::currentKey() const |
| |
| Returns the key for the current iterator item. |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::operator()() |
| |
| Makes the succeeding item current and returns the original current |
| item. |
| |
| If the current iterator item was the last item in the cache or if |
| it was 0, 0 is returned. |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::operator+=( uint jump ) |
| |
| Returns the item \a jump positions after the current item, or 0 if |
| it is beyond the last item. Makes this the current item. |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::operator-=( uint jump ) |
| |
| Returns the item \a jump positions before the current item, or 0 |
| if it is beyond the first item. Makes this the current item. |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::operator++() |
| |
| Prefix ++ makes the iterator point to the item just after |
| current(), and makes it the new current item for the iterator. If |
| current() was the last item, operator--() returns 0. |
| */ |
| |
| /*! |
| \fn type *Q3IntCacheIterator::operator--() |
| |
| Prefix -- makes the iterator point to the item just before |
| current(), and makes it the new current item for the iterator. If |
| current() was the first item, operator--() returns 0. |
| */ |