/**************************************************************************** ** ** 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. ** ** $QT_BEGIN_LICENSE:FDL$ ** 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 ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \class Q3Dict \brief The Q3Dict class is a template class that provides a dictionary based on QString keys. \compat Q3Dict is implemented as a template class. Define a template instance Q3Dict\ to create a dictionary that operates on pointers to X (X *). A dictionary is a collection of key-value pairs. The key is a QString used for insertion, removal and lookup. The value is a pointer. Dictionaries provide very fast insertion and lookup. If you want to use non-Unicode, plain 8-bit \c char* keys, use the Q3AsciiDict template. A Q3Dict has the same performance as a Q3AsciiDict. If you want to have a dictionary that maps QStrings to QStrings use QMap. The size() of the dictionary is very important. In order to get good performance, you should use a suitably large prime number. Suitable means equal to or larger than the maximum expected number of dictionary items. Size is set in the constructor but may be changed with resize(). Items are inserted with insert(); 0 pointers cannot be inserted. Items are removed with remove(). All the items in a dictionary can be removed with clear(). The number of items in the dictionary is returned by count(). If the dictionary contains no items isEmpty() returns TRUE. You can change an item's value with replace(). Items are looked up with operator[](), or with find() which return a pointer to the value or 0 if the given key does not exist. You can take an item out of the dictionary with take(). Calling setAutoDelete(TRUE) for a dictionary tells it to delete items that are removed. The default behavior is not to delete items when they are removed. When an item is inserted, the key is converted (hashed) to an integer index into an internal hash array. This makes lookup very fast. Items with equal keys are allowed. When inserting two items with the same key, only the last inserted item will be accessible (last in, first out) until it is removed. The Q3DictIterator class can traverse the dictionary, but only in an arbitrary order. Multiple iterators may independently traverse the same dictionary. When inserting an item into a dictionary, only the pointer is copied, not the item itself, i.e. a shallow copy is made. It is possible to make the dictionary copy all of the item's data (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 dictionary item, the virtual function Q3PtrCollection::deleteItem() is called. Q3Dict's default implementation is to delete the item if auto-deletion is enabled. \sa Q3DictIterator, Q3AsciiDict, Q3IntDict, Q3PtrDict */ /*! \fn Q3Dict::Q3Dict( int size, bool caseSensitive ) Constructs a dictionary optimized for less than \a size entries. We recommend setting \a size to a suitably large prime number (e.g. a prime that's slightly larger than the expected number of entries). This makes the hash distribution better which will lead to faster lookup. If \a caseSensitive is TRUE (the default), keys which differ only by case are considered different. */ /*! \fn Q3Dict::Q3Dict( const Q3Dict &dict ) Constructs a copy of \a dict. Each item in \a dict is inserted into this dictionary. Only the pointers are copied (shallow copy). */ /*! \fn Q3Dict::~Q3Dict() Removes all items from the dictionary and destroys it. If setAutoDelete() is TRUE, each value is deleted. All iterators that access this dictionary will be reset. \sa setAutoDelete() */ /*! \fn Q3Dict &Q3Dict::operator=(const Q3Dict &dict) Assigns \a dict to this dictionary and returns a reference to this dictionary. This dictionary is first cleared, then each item in \a dict is inserted into this dictionary. Only the pointers are copied (shallow copy), unless newItem() has been reimplemented. */ /*! \fn uint Q3Dict::count() const Returns the number of items in the dictionary. \sa isEmpty() */ /*! \fn uint Q3Dict::size() const Returns the size of the internal hash array (as specified in the constructor). \sa count() */ /*! \fn void Q3Dict::resize( uint newsize ) Changes the size of the hash table to \a newsize. The contents of the dictionary are preserved, but all iterators on the dictionary become invalid. */ /*! \fn bool Q3Dict::isEmpty() const Returns TRUE if the dictionary is empty, i.e. count() == 0; otherwise returns FALSE. \sa count() */ /*! \fn void Q3Dict::insert( const QString &key, const type *item ) Inserts the key \a key with value \a item into the dictionary. Multiple items can have the same key, in which case only the last item will be accessible using \l operator[](). \a item may not be 0. \sa replace() */ /*! \fn void Q3Dict::replace( const QString &key, const type *item ) Replaces the value of the key, \a key with \a item. If the item does not already exist, it will be inserted. \a item may not be 0. Equivalent to: \snippet doc/src/snippets/code/doc_src_q3dict.cpp 0 If there are two or more items with equal keys, then the last item that was inserted will be replaced. \sa insert() */ /*! \fn bool Q3Dict::remove( const QString &key ) Removes the item with \a key from the dictionary. Returns TRUE if successful, i.e. if the item is in the dictionary; otherwise returns FALSE. If there are two or more items with equal keys, then the last item that was inserted will be removed. The removed item is deleted if \link Q3PtrCollection::setAutoDelete() auto-deletion\endlink is enabled. All dictionary iterators that refer to the removed item will be set to point to the next item in the dictionary's traversal order. \sa take(), clear(), setAutoDelete() */ /*! \fn type *Q3Dict::take( const QString &key ) Takes the item with \a key out of the dictionary without deleting it (even if \link Q3PtrCollection::setAutoDelete() auto-deletion\endlink is enabled). If there are two or more items with equal keys, then the last item that was inserted will be taken. Returns a pointer to the item taken out, or 0 if the key does not exist in the dictionary. All dictionary iterators that refer to the taken item will be set to point to the next item in the dictionary traversal order. \sa remove(), clear(), setAutoDelete() */ /*! \fn void Q3Dict::clear() Removes all items from the dictionary. The removed items are deleted if \link Q3PtrCollection::setAutoDelete() auto-deletion\endlink is enabled. All dictionary iterators that operate on the dictionary are reset. \sa remove(), take(), setAutoDelete() */ /*! \fn type *Q3Dict::find( const QString &key ) const Returns the item with key \a key, or 0 if the key does not exist in the dictionary. If there are two or more items with equal keys, then the most recently inserted item will be found. Equivalent to the [] operator. \sa operator[]() */ /*! \fn type *Q3Dict::operator[]( const QString &key ) const Returns the item with key \a key, or 0 if the key does not exist in the dictionary. If there are two or more items with equal keys, then the most recently inserted item will be found. Equivalent to the find() function. \sa find() */ /*! \fn void Q3Dict::statistics() const Debugging-only function that prints out the dictionary distribution using qDebug(). */ /*! \fn QDataStream& Q3Dict::read( QDataStream &s, Q3PtrCollection::Item &item ) Reads a dictionary item from the stream \a s and returns a reference to the stream. The default implementation sets \a item to 0. \sa write() */ /*! \fn QDataStream& Q3Dict::write( QDataStream &s, Q3PtrCollection::Item item ) const Writes a dictionary \a item to the stream \a s and returns a reference to the stream. \sa read() */ /*! \class Q3DictIterator \brief The Q3DictIterator class provides an iterator for Q3Dict collections. \compat Q3DictIterator is implemented as a template class. Define a template instance Q3DictIterator\ to create a dictionary iterator that operates on Q3Dict\ (dictionary of X*). The traversal order is arbitrary; when we speak of the "first", "last" and "next" item we are talking in terms of this arbitrary order. Multiple iterators may independently traverse the same dictionary. A Q3Dict knows about all the iterators that are operating on the dictionary. When an item is removed from the dictionary, Q3Dict updates all iterators that are referring to the removed item to point to the next item in the (arbitrary) traversal order. Example: \snippet doc/src/snippets/code/doc_src_q3dict.cpp 1 In the example we insert some pointers to line edits into a dictionary, then iterate over the dictionary printing the strings associated with the line edits. \sa Q3Dict */ /*! \fn Q3DictIterator::Q3DictIterator( const Q3Dict &dict ) Constructs an iterator for \a dict. The current iterator item is set to point to the first item in the dictionary, \a dict. First in this context means first in the arbitrary traversal order. */ /*! \fn Q3DictIterator::~Q3DictIterator() Destroys the iterator. */ /*! \fn uint Q3DictIterator::count() const Returns the number of items in the dictionary over which the iterator is operating. \sa isEmpty() */ /*! \fn bool Q3DictIterator::isEmpty() const Returns TRUE if the dictionary is empty, i.e. count() == 0; otherwise returns FALSE. \sa count() */ /*! \fn type *Q3DictIterator::toFirst() Resets the iterator, making the first item the first current item. First in this context means first in the arbitrary traversal order. Returns a pointer to this item. If the dictionary is empty it sets the current item to 0 and returns 0. */ /*! \fn type *Q3DictIterator::operator*() \internal */ /*! \fn Q3DictIterator::operator type*() const Cast operator. Returns a pointer to the current iterator item. Same as current(). */ /*! \fn type *Q3DictIterator::current() const Returns a pointer to the current iterator item's value. */ /*! \fn QString Q3DictIterator::currentKey() const Returns the current iterator item's key. */ /*! \fn type *Q3DictIterator::operator()() Makes the next item current and returns the original current item. If the current iterator item was the last item in the dictionary or if it was 0, 0 is returned. */ /*! \fn type *Q3DictIterator::operator++() Prefix ++ makes the next item current and returns the new current item. If the current iterator item was the last item in the dictionary or if it was 0, 0 is returned. */ /*! \fn type *Q3DictIterator::operator+=( uint jump ) \internal Sets the current item to the item \a jump positions after the current item, and returns a pointer to that item. If that item is beyond the last item or if the dictionary is empty, it sets the current item to 0 and returns 0. */