source: trunk/doc/src/q3ptrdict.qdoc@ 268

/****************************************************************************
**
** 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.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** 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 Q3PtrDict
    \brief The Q3PtrDict class is a template class that provides a dictionary based on void* keys.
    \compat

    Q3PtrDict is implemented as a template class. Define a template
    instance Q3PtrDict\<X\> to create a dictionary that operates on
    pointers to X (X*).

    A dictionary is a collection of key-value pairs. The key is a
    void* used for insertion, removal and lookup. The value is a
    pointer. Dictionaries provide very fast insertion and lookup.

    Example:
    \snippet doc/src/snippets/code/doc_src_q3ptrdict.qdoc 0
    In this example we use a dictionary to add an extra property (a
    char*) to the line edits we're using. 

    See Q3Dict for full details, including the choice of dictionary
    size, and how deletions are handled. 

    \sa Q3PtrDictIterator, Q3Dict, Q3AsciiDict, Q3IntDict
*/


/*!
    \fn Q3PtrDict::Q3PtrDict( int size )

    Constructs a dictionary using an internal hash array with the size
    \a size.

    Setting \a size to a suitably large prime number (equal to or
    greater than the expected number of entries) makes the hash
    distribution better and improves lookup performance.
*/

/*!
    \fn Q3PtrDict::Q3PtrDict( const Q3PtrDict<type> &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 Q3PtrDict::~Q3PtrDict()

    Removes all items from the dictionary and destroys it.

    All iterators that access this dictionary will be reset.

    \sa setAutoDelete()
*/

/*!
    \fn Q3PtrDict<type> &Q3PtrDict::operator=(const Q3PtrDict<type> &dict)

    Assigns \a dict to this dictionary and returns a reference to this
    dictionary.

    This dictionary is first cleared and then each item in \a dict is
    inserted into the dictionary. Only the pointers are copied
    (shallow copy), unless newItem() has been reimplemented.
*/

/*!
    \fn uint Q3PtrDict::count() const

    Returns the number of items in the dictionary.

    \sa isEmpty()
*/

/*!
    \fn uint Q3PtrDict::size() const

    Returns the size of the internal hash table (as specified in the
    constructor).

    \sa count()
*/

/*!
    \fn void Q3PtrDict::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 Q3PtrDict::isEmpty() const

    Returns TRUE if the dictionary is empty; otherwise returns FALSE.

    \sa count()
*/

/*!
    \fn void Q3PtrDict::insert( void *key, const type *item )

    Inserts the \a key with the \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 Q3PtrDict::replace( void *key, const type *item )

    If the dictionary has key \a key, this key's item is replaced with
    \a item. If the dictionary doesn't contain key \a key, \a item is
    inserted into the dictionary using key \a key. 

    \a item may not be 0.

    Equivalent to
    \snippet doc/src/snippets/code/doc_src_q3ptrdict.qdoc 1

    If there are two or more items with equal keys, then the most
    recently inserted item will be replaced.

    \sa insert()
*/

/*!
    \fn bool Q3PtrDict::remove( void *key ) 
    
    Removes the item associated with \a key from the dictionary.
    Returns TRUE if successful, i.e. if \a key is in the dictionary;
    otherwise returns FALSE.

    If there are two or more items with equal keys, then the most
    recently inserted item 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 traversal order.

    \sa take(), clear(), setAutoDelete()
*/

/*!
    \fn type *Q3PtrDict::take( void *key )

    Takes the item associated 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 most
    recently inserted item will be removed.

    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 Q3PtrDict::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 access this dictionary will be
    reset.

    \sa remove(), take(), setAutoDelete()
*/

/*!
    \fn type *Q3PtrDict::find( void *key ) const

    Returns the item associated with \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 operator[].

    \sa operator[]()
*/

/*!
    \fn type *Q3PtrDict::operator[]( void *key ) const

    Returns the item associated with \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 Q3PtrDict::statistics() const

    Debugging-only function that prints out the dictionary
    distribution using qDebug().
*/

/*!
    \fn QDataStream& Q3PtrDict::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& Q3PtrDict::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 Q3PtrDictIterator
    \brief The Q3PtrDictIterator class provides an iterator for Q3PtrDict collections.
    \compat

    Q3PtrDictIterator is implemented as a template class. Define a
    template instance Q3PtrDictIterator\<X\> to create a dictionary
    iterator that operates on Q3PtrDict\<X\> (dictionary of X*).

    Example:
    \snippet doc/src/snippets/code/doc_src_q3ptrdict.qdoc 2
    In the example we insert some line edits into a dictionary,
    associating a string with each. We then iterate over the
    dictionary printing the associated strings.

    Multiple iterators may independently traverse the same dictionary.
    A Q3PtrDict knows about all the iterators that are operating on the
    dictionary. When an item is removed from the dictionary, Q3PtrDict
    updates all iterators that refer the removed item to point to the
    next item in the traversing order.

    \sa Q3PtrDict
*/

/*!
    \fn Q3PtrDictIterator::Q3PtrDictIterator( const Q3PtrDict<type> &dict )

    Constructs an iterator for \a dict. The current iterator item is
    set to point on the first item in the \a dict.
*/

/*!
    \fn Q3PtrDictIterator::~Q3PtrDictIterator()

    Destroys the iterator.
*/

/*!
    \fn uint Q3PtrDictIterator::count() const

    Returns the number of items in the dictionary this iterator
    operates on.

    \sa isEmpty()
*/

/*!
    \fn bool Q3PtrDictIterator::isEmpty() const

    Returns TRUE if the dictionary is empty; otherwise returns FALSE.

    \sa count()
*/

/*!
    \fn type *Q3PtrDictIterator::toFirst()

    Sets the current iterator item to point to the first item in the
    dictionary and returns a pointer to the item. If the dictionary is
    empty, it sets the current item to 0 and returns 0.
*/

/*!
    \fn Q3PtrDictIterator::operator type *() const

    Cast operator. Returns a pointer to the current iterator item.
    Same as current().
*/

/*!
    \fn type *Q3PtrDictIterator::current() const

    Returns a pointer to the current iterator item's value.
*/

/*!
    \fn void *Q3PtrDictIterator::currentKey() const

    Returns the current iterator item's key.
*/

/*!
    \fn type *Q3PtrDictIterator::operator()()

    Makes the succeeding 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 *Q3PtrDictIterator::operator++()

    Prefix ++ makes the succeeding 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 *Q3PtrDictIterator::operator+=( uint jump )

    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.
*/