path: root/doc/src/classes/q3asciidict.qdoc

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (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 http://qt.nokia.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \class Q3AsciiDict
    \brief The Q3AsciiDict class is a template class that provides a dictionary based on char* keys.
    \compat

    Q3AsciiDict is implemented as a template class. Define a template
    instance Q3AsciiDict\<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
    char* used for insertion, removal and lookup. The value is a
    pointer. Dictionaries provide very fast insertion and lookup.

    Q3AsciiDict cannot handle Unicode keys; use the Q3Dict template
    instead, which uses QString keys. A Q3Dict has the same
    performace as a Q3AsciiDict.

    Example:
    \snippet doc/src/snippets/code/doc_src_q3asciidict.qdoc 0
    In this example we use a dictionary to keep track of the line
    edits we're using. We insert each line edit into the dictionary
    with a unique name and then access the line edits via the
    dictionary. See Q3PtrDict, Q3IntDict and Q3Dict.

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

    \sa Q3AsciiDictIterator, Q3Dict, Q3IntDict, Q3PtrDict
*/


/*!
    \fn Q3AsciiDict::Q3AsciiDict( int size, bool caseSensitive, bool copyKeys )

    Constructs a dictionary optimized for less than \a size entries.

    We recommend setting \a size to a suitably large prime number (a
    bit larger than the expected number of entries). This makes the
    hash distribution better and will improve lookup performance.

    When \a caseSensitive is TRUE (the default) Q3AsciiDict treats
    "abc" and "Abc" as different keys; when it is FALSE "abc" and
    "Abc" are the same. Case-insensitive comparison only considers the
    26 letters in US-ASCII.

    If \a copyKeys is TRUE (the default), the dictionary copies keys
    using strcpy(); if it is FALSE, the dictionary just copies the
    pointers.
*/

/*!
    \fn Q3AsciiDict::Q3AsciiDict( const Q3AsciiDict<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 Q3AsciiDict::~Q3AsciiDict()

    Removes all items from the dictionary and destroys it.

    The items are deleted if auto-delete is enabled.

    All iterators that access this dictionary will be reset.

    \sa setAutoDelete()
*/

/*!
    \fn Q3AsciiDict<type> &Q3AsciiDict::operator=(const Q3AsciiDict<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 this dictionary. Only the pointers are copied
    (shallow copy) unless newItem() has been reimplemented().
*/

/*!
    \fn uint Q3AsciiDict::count() const

    Returns the number of items in the dictionary.

    \sa isEmpty()
*/

/*!
    \fn uint Q3AsciiDict::size() const

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

    \sa count()
*/

/*!
    \fn void Q3AsciiDict::resize( uint newsize )

    Changes the size of the hashtable to \a newsize. The contents of
    the dictionary are preserved but all iterators on the dictionary
    become invalid.
*/

/*!
    \fn bool Q3AsciiDict::isEmpty() const

    Returns TRUE if the dictionary is empty, i.e. count() == 0;
    otherwise it returns FALSE.

    \sa count()
*/

/*!
    \fn void Q3AsciiDict::insert( const char *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 Q3AsciiDict::replace( const char *key, const type *item )

    Replaces an item that has a key equal to \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_q3asciidict.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 Q3AsciiDict::remove( const char *key )

    Removes the item associated with \a key from the dictionary.
    Returns TRUE if successful, i.e. if the key existed 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 *Q3AsciiDict::take( const char *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 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 Q3AsciiDict::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 dictionary are reset.

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

/*!
    \fn type *Q3AsciiDict::find( const char *key ) const

    Returns the item associated with \a key, or 0 if the key does not
    exist in the dictionary.

    This function uses an internal hashing algorithm to optimize
    lookup.

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

    Equivalent to the [] operator.

    \sa operator[]()
*/

/*!
    \fn type *Q3AsciiDict::operator[]( const char *key ) const

    Returns the item associated with \a key, or 0 if the key does
    not exist in the dictionary.

    This function uses an internal hashing algorithm to optimize
    lookup.

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

    Equivalent to the find() function.

    \sa find()
*/

/*!
    \fn void Q3AsciiDict::statistics() const

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

/*!
    \fn QDataStream& Q3AsciiDict::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& Q3AsciiDict::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 Q3AsciiDictIterator
    \brief The Q3AsciiDictIterator class provides an iterator for Q3AsciiDict collections.
    \compat

    Q3AsciiDictIterator is implemented as a template class. Define a
    template instance Q3AsciiDictIterator\<X\> to create a dictionary
    iterator that operates on Q3AsciiDict\<X\> (dictionary of X*).

    Example:
    \snippet doc/src/snippets/code/doc_src_q3asciidict.qdoc 2
    In the example we insert some line edits into a dictionary, then
    iterate over the dictionary printing the strings associated with
    those line edits.

    Note that the traversal order is arbitrary; you are not guaranteed
    any particular order.

    Multiple iterators may independently traverse the same dictionary.
    A Q3AsciiDict knows about all the iterators that are operating on
    the dictionary. When an item is removed from the dictionary,
    Q3AsciiDict updates all the iterators that are referring to the
    removed item to point to the next item in the (arbitrary)
    traversal order.

    \sa Q3AsciiDict
*/

/*!
    \fn Q3AsciiDictIterator::Q3AsciiDictIterator( const Q3AsciiDict<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 Q3AsciiDictIterator::~Q3AsciiDictIterator()

    Destroys the iterator.
*/

/*!
    \fn uint Q3AsciiDictIterator::count() const

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

    \sa isEmpty()
*/

/*!
    \fn bool Q3AsciiDictIterator::isEmpty() const

    Returns TRUE if the dictionary is empty, i.e. count() == 0,
    otherwise returns FALSE.
    
    \sa count()
*/

/*!
    \fn type *Q3AsciiDictIterator::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 Q3AsciiDictIterator::operator type *() const

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

/*!
    \fn type *Q3AsciiDictIterator::current() const

    Returns a pointer to the current iterator item.
*/

/*!
    \fn const char *Q3AsciiDictIterator::currentKey() const

    Returns a pointer to the key for the current iterator item.
*/

/*!
    \fn type *Q3AsciiDictIterator::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 *Q3AsciiDictIterator::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 *Q3AsciiDictIterator::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.
*/