path: root/doc/qintdict.doc

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** QIntDict and QIntDictIterator class documentation
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/*****************************************************************************
  QIntDict documentation
 *****************************************************************************/

/*!
    \class QIntDict ntqintdict.h
    \brief The QIntDict class is a template class that provides a dictionary based on long keys.

    \ingroup collection
    \ingroup tools

    \important autoDelete setAutoDelete

    QMap is an STL-compatible alternative to this class.

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

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

    Example:
    \code
    QIntDict<QLineEdit> fields; // long int keys, QLineEdit* values
    for ( int i = 0; i < 3; i++ )
	fields.insert( i, new QLineEdit( this ) );

    fields[0]->setText( "Homer" );
    fields[1]->setText( "Simpson" );
    fields[2]->setText( "45" );

    QIntDictIterator<QLineEdit> it( fields );
    for ( ; it.current(); ++it )
	cout << it.currentKey() << ": " << it.current()->text() << endl;

    for ( int i = 0; i < 3; i++ )
	cout << fields[i]->text() << " "; // Prints "Homer Simpson 45"
    cout << endl;

    fields.remove( 1 ); // Does not delete the line edit
    for ( int i = 0; i < 3; i++ )
	if ( fields[i] )
	    cout << fields[i]->text() << " "; // Prints "Homer 45"
    \endcode

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

    \sa QIntDictIterator, QDict, QAsciiDict, QPtrDict,
	\link collection.html Collection Classes\endlink
*/


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

    Constructs a dictionary using an internal hash array of 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 which leads to faster lookup.
*/

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

    Removes all items from the dictionary and destroys it.

    All iterators that access this dictionary will be reset.

    \sa setAutoDelete()
*/

/*!
    \fn QIntDict<type> &QIntDict::operator=(const QIntDict<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 QIntDict::count() const

    Returns the number of items in the dictionary.

    \sa isEmpty()
*/

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

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

    \sa count()
*/

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

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

    \sa count()
*/

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

    Insert item \a item into the dictionary using key \a key.

    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 QIntDict::replace( long 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:
    \code
	QIntDict<char> dict;
	//	...
	if ( dict.find(key) )
	    dict.remove( key );
	dict.insert( key, item );
    \endcode

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

    \sa insert()
*/

/*!
    \fn bool QIntDict::remove( long key )

    Removes the item associated with \a key from the dictionary.
    Returns TRUE if successful, i.e. if the \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
    QPtrCollection::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 *QIntDict::take( long key )

    Takes the item associated with \a key out of the dictionary
    without deleting it (even if \link QPtrCollection::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's traversing order.

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

/*!
    \fn void QIntDict::clear()

    Removes all items from the dictionary.

    The removed items are deleted if \link
    QPtrCollection::setAutoDelete() auto-deletion\endlink is enabled.

    All dictionary iterators that access this dictionary will be reset.

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

/*!
    \fn type *QIntDict::find( long 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 *QIntDict::operator[]( long 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 QIntDict::statistics() const

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

/*!
    \fn QDataStream& QIntDict::read( QDataStream &s, QPtrCollection::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& QIntDict::write( QDataStream &s, QPtrCollection::Item ) const

    Writes a dictionary item to the stream \a s and returns a
    reference to the stream.

    \sa read()
*/

/*****************************************************************************
  QIntDictIterator documentation
 *****************************************************************************/

/*!
    \class QIntDictIterator ntqintdict.h
    \brief The QIntDictIterator class provides an iterator for QIntDict collections.

    \ingroup collection
    \ingroup tools

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

    Example:
    \code
    QIntDict<QLineEdit> fields;
    for ( int i = 0; i < 3; i++ )
	fields.insert( i, new QLineEdit( this ) );

    fields[0]->setText( "Homer" );
    fields[1]->setText( "Simpson" );
    fields[2]->setText( "45" );

    QIntDictIterator<QLineEdit> it( fields ); 
    for ( ; it.current(); ++it )
	cout << it.currentKey() << ": " << it.current()->text() << endl;

    // Output (random order):
    //	0: Homer
    //	1: Simpson
    //	2: 45
    \endcode

    Note that the traversal order is arbitrary; you are not guaranteed the
    order shown above.

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

    \sa QIntDict
*/

/*!
    \fn QIntDictIterator::QIntDictIterator( const QIntDict<type> &dict )

    Constructs an iterator for \a dict. The current iterator item is
    set to point to the 'first' item in the \a dict. The first item
    refers to the first item in the dictionary's arbitrary internal
    ordering.
*/

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

    Destroys the iterator.
*/

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

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

    \sa isEmpty()
*/

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

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

    \sa count()
*/

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

    Sets the current iterator item to point to the first item in the
    dictionary and returns a pointer to the item. The first item
    refers to the first item in the dictionary's arbitrary internal
    ordering. If the dictionary is  empty it sets the current item to
    0 and returns 0.
*/

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

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

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

    Returns a pointer to the current iterator item.
*/

/*!
    \fn long QIntDictIterator::currentKey() const

    Returns the key for the current iterator item.
*/

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