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diff --git a/doc/src/q3asciicache.qdoc b/doc/src/q3asciicache.qdoc new file mode 100644 index 0000000000..fbbb21bad8 --- /dev/null +++ b/doc/src/q3asciicache.qdoc @@ -0,0 +1,465 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \class Q3AsciiCache + \brief The Q3AsciiCache class is a template class that provides a cache based on char* keys. + \compat + + Q3AsciiCache is implemented as a template class. Define a template + instance Q3AsciiCache\<X\> to create a cache that operates on + pointers to X (X*). + + A cache is a least recently used (LRU) list of cache items. The + cache items are accessed via \c char* keys. For Unicode keys use + the Q3Cache template instead, which uses QString keys. A Q3Cache + has the same performace as a Q3AsciiCache. + + 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 \link Q3PtrCollection::setAutoDelete() + setAutoDelete(TRUE)\endlink tells the cache to delete items that + are removed. The default is to not delete items when then 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 cache and reimplement newItem() if you want deep copies. + + When removing a cache item the virtual function + Q3PtrCollection::deleteItem() is called. Its default implementation + in Q3AsciiCache is to delete the item if \link + Q3PtrCollection::setAutoDelete() auto-deletion\endlink is enabled. + + There is a Q3AsciiCacheIterator which may be used to traverse the + items in the cache in arbitrary order. + + \sa Q3AsciiCacheIterator, Q3Cache, Q3IntCache +*/ + +/*! + \fn Q3AsciiCache::Q3AsciiCache( const Q3AsciiCache<type> &c ) + + \internal + + Do not use. A Q3AsciiCache cannot be copied. Calls qFatal() in debug version. +*/ + + +/*! + \fn Q3AsciiCache::Q3AsciiCache( int maxCost, int size, bool caseSensitive, bool copyKeys ) + + 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 has an associated 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. + + If \a caseSensitive is TRUE (the default), the cache keys are case + sensitive; if it is FALSE, they are case-insensitive. + Case-insensitive comparison only affects the 26 letters in + US-ASCII. If \a copyKeys is TRUE (the default), Q3AsciiCache makes + a copy of the cache keys, otherwise it copies just the const char + * pointer - slightly faster if you can guarantee that the keys + will never change, but very risky. +*/ + +/*! + \fn Q3AsciiCache::~Q3AsciiCache() + + Removes all items from the cache and destroys it. + All iterators that access this cache will be reset. +*/ + +/*! + \fn Q3AsciiCache<type>& Q3AsciiCache::operator=( const Q3AsciiCache<type> &c ) + + \internal + + Do not use. A Q3AsciiCache cannot be copied. Calls qFatal() in debug version. +*/ + +/*! + \fn int Q3AsciiCache::maxCost() const + + Returns the maximum allowed total cost of the cache. + + \sa setMaxCost() totalCost() +*/ + +/*! + \fn int Q3AsciiCache::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 Q3AsciiCache::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 Q3AsciiCache::count() const + + Returns the number of items in the cache. + + \sa totalCost() size() +*/ + +/*! + \fn uint Q3AsciiCache::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. +*/ + +/*! + \fn bool Q3AsciiCache::isEmpty() const + + Returns TRUE if the cache is empty; otherwise returns FALSE. +*/ + +/*! + \fn bool Q3AsciiCache::insert( const char *k, const type *d, int c, int p ) + + Inserts the item \a d into the cache using key \a k, and with an + associated cost of \a c. Returns TRUE if the item is successfully + inserted. Returns FALSE if the item is not inserted, for example, + if the cost of the item exceeds maxCost(). + + The cache's size is limited, and if the total cost is too high, + Q3AsciiCache will remove old, least recently used items until there + is room for this new item. + + Items with duplicate keys can be inserted. + + The parameter \a p is internal and should be left at the default + value (0). + + \warning If this function returns FALSE, you must delete \a d + yourself. Additionally, be very careful about using \a d after + calling this function, because 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 Q3AsciiCache::remove( const char *k ) + + Removes the item with key \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 \link Q3PtrCollection::setAutoDelete() + setAutoDelete(TRUE)\endlink. + + If there are two or more items with equal keys, the one that was + inserted last 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 *Q3AsciiCache::take( const char *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 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. + + \sa remove(), clear() +*/ + +/*! + \fn void Q3AsciiCache::clear() + + Removes all items from the cache, and deletes them if \link + Q3PtrCollection::setAutoDelete() auto-deletion\endlink has been + enabled. + + All cache iterators that operate on this cache are reset. + + \sa remove() take() +*/ + +/*! + \fn type *Q3AsciiCache::find( const char *k, bool ref ) const + + Returns the item with key \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 last is returned. +*/ + +/*! + \fn type *Q3AsciiCache::operator[]( const char *k ) const + + Returns the item with key \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 last is returned. + + This is the same as find( k, TRUE ). + + \sa find() +*/ + +/*! + \fn void Q3AsciiCache::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 Q3AsciiCacheIterator + \brief The Q3AsciiCacheIterator class provides an iterator for Q3AsciiCache 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 Q3AsciiCache. Q3AsciiCache updates all iterators + that refer an item when that item is removed. + + Q3AsciiCacheIterator provides an operator++() and an operator+=() + to traverse the cache; current() and currentKey() to access the + current cache item and its key. It also provides atFirst() and + atLast(), which return TRUE if the iterator points to the first or + last item in the cache respectively. The isEmpty() function + returns TRUE if the cache is empty; and count() 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 Q3AsciiCache +*/ + +/*! + \fn Q3AsciiCacheIterator::Q3AsciiCacheIterator( const Q3AsciiCache<type> &cache ) + + Constructs an iterator for \a cache. The current iterator item is + set to point to the first item in the \a cache. +*/ + +/*! + \fn Q3AsciiCacheIterator::Q3AsciiCacheIterator (const Q3AsciiCacheIterator<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 Q3AsciiCacheIterator<type>& Q3AsciiCacheIterator::operator=( const Q3AsciiCacheIterator<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 Q3AsciiCacheIterator::count() const + + Returns the number of items in the cache over which this iterator + operates. + + \sa isEmpty() +*/ + +/*! + \fn bool Q3AsciiCacheIterator::isEmpty() const + + Returns TRUE if the cache is empty, i.e. count() == 0; otherwise + returns FALSE. + + \sa count() +*/ + +/*! + \fn bool Q3AsciiCacheIterator::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 Q3AsciiCacheIterator::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 *Q3AsciiCacheIterator::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 *Q3AsciiCacheIterator::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 Q3AsciiCacheIterator::operator type *() const + + Cast operator. Returns a pointer to the current iterator item. + Same as current(). +*/ + +/*! + \fn type *Q3AsciiCacheIterator::current() const + + Returns a pointer to the current iterator item. +*/ + +/*! + \fn const char *Q3AsciiCacheIterator::currentKey() const + + Returns the key for the current iterator item. +*/ + +/*! + \fn type *Q3AsciiCacheIterator::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 *Q3AsciiCacheIterator::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 *Q3AsciiCacheIterator::operator-=( uint jump ) + + Returns the item \a jump positions before the current item, or 0 + if it is before the first item. Makes this the current item. +*/ + +/*! + \fn type *Q3AsciiCacheIterator::operator++() + + Prefix ++ makes the iterator point to the item just after + current(), and makes that the new current item for the iterator. If + current() was the last item, operator++() returns 0. +*/ + +/*! + \fn type *Q3AsciiCacheIterator::operator--() + + Prefix -- makes the iterator point to the item just before + current(), and makes that the new current item for the iterator. If + current() was the first item, operator--() returns 0. +*/ + |