You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
qt3/doc/qptrdict.doc

459 lines
12 KiB

/****************************************************************************
**
** QPtrDict and QPtrDictIterator class documentation
**
** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
**
** This file is part of the Qt GUI Toolkit.
**
** This file may be used under the terms of the GNU General
** Public License versions 2.0 or 3.0 as published by the Free
** Software Foundation and appearing in the files LICENSE.GPL2
** and LICENSE.GPL3 included in the packaging of this file.
** Alternatively you may (at your option) use any later version
** of the GNU General Public License if such license has been
** publicly approved by Trolltech ASA (or its successors, if any)
** and the KDE Free Qt Foundation.
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/.
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** This file may be used under the terms of the Q Public License as
** defined by Trolltech ASA and appearing in the file LICENSE.QPL
** included in the packaging of this file. Licensees holding valid Qt
** Commercial licenses may use this file in accordance with the Qt
** Commercial License Agreement provided with the Software.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
** herein.
**
**********************************************************************/
/*****************************************************************************
QPtrDict documentation
*****************************************************************************/
/*!
\class QPtrDict
\brief The QPtrDict class is a template class that provides a dictionary based on void* keys.
\ingroup collection
\ingroup tools
\important autoDelete setAutoDelete
QPtrDict is implemented as a template class. Define a template
instance QPtrDict\<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:
\code
QPtrDict<char> fields; // void* keys, char* values
QLineEdit *le1 = new QLineEdit( this );
le1->setText( "Simpson" );
QLineEdit *le2 = new QLineEdit( this );
le2->setText( "Homer" );
QLineEdit *le3 = new QLineEdit( this );
le3->setText( "45" );
fields.insert( le1, "Surname" );
fields.insert( le2, "Forename" );
fields.insert( le3, "Age" );
QPtrDictIterator<char> it( fields );
for( ; it.current(); ++it )
cout << it.current() << endl;
cout << endl;
if ( fields[le1] ) // Prints "Surname: Simpson"
cout << fields[le1] << ": " << le1->text() << endl;
if ( fields[le2] ) // Prints "Forename: Homer"
cout << fields[le2] << ": " << le2->text() << endl;
fields.remove( le1 ); // Removes le1 from the dictionary
cout << le1->text() << endl; // Prints "Simpson"
\endcode
In this example we use a dictionary to add an extra property (a
char*) to the line edits we're using.
See QDict for full details, including the choice of dictionary
size, and how deletions are handled.
\sa QPtrDictIterator, QDict, QAsciiDict, QIntDict,
\link collection.html Collection Classes\endlink
*/
/*!
\fn QPtrDict::QPtrDict( 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 QPtrDict::QPtrDict( const QPtrDict<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 QPtrDict::~QPtrDict()
Removes all items from the dictionary and destroys it.
All iterators that access this dictionary will be reset.
\sa setAutoDelete()
*/
/*!
\fn QPtrDict<type> &QPtrDict::operator=(const QPtrDict<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 QPtrDict::count() const
Returns the number of items in the dictionary.
\sa isEmpty()
*/
/*!
\fn uint QPtrDict::size() const
Returns the size of the internal hash table (as specified in the
constructor).
\sa count()
*/
/*!
\fn void QPtrDict::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 QPtrDict::isEmpty() const
Returns TRUE if the dictionary is empty; otherwise returns FALSE.
\sa count()
*/
/*!
\fn void QPtrDict::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 QPtrDict::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
\code
QPtrDict<ItemType> 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 QPtrDict::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
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 traversal order.
\sa take(), clear(), setAutoDelete()
*/
/*!
\fn type *QPtrDict::take( void *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 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 QPtrDict::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 *QPtrDict::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 *QPtrDict::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 QPtrDict::statistics() const
Debugging-only function that prints out the dictionary
distribution using qDebug().
*/
/*!
\fn QDataStream& QPtrDict::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& QPtrDict::write( QDataStream &s, QPtrCollection::Item ) const
Writes a dictionary item to the stream \a s and returns a
reference to the stream.
\sa read()
*/
/*****************************************************************************
QPtrDictIterator documentation
*****************************************************************************/
/*!
\class QPtrDictIterator qptrdict.h
\brief The QPtrDictIterator class provides an iterator for QPtrDict collections.
\ingroup collection
\ingroup tools
QPtrDictIterator is implemented as a template class. Define a
template instance QPtrDictIterator\<X\> to create a dictionary
iterator that operates on QPtrDict\<X\> (dictionary of X*).
Example:
\code
QPtrDict<char> fields;
QLineEdit *le1 = new QLineEdit( this );
le1->setText( "Simpson" );
QLineEdit *le2 = new QLineEdit( this );
le2->setText( "Homer" );
QLineEdit *le3 = new QLineEdit( this );
le3->setText( "45" );
fields.insert( le1, "Surname" );
fields.insert( le2, "Forename" );
fields.insert( le3, "Age" );
QPtrDictIterator<char> it( fields );
for( ; it.current(); ++it ) {
QLineEdit *le = (QLineEdit)it.currentKey();
cout << it.current() << ": " << le->text() << endl;
}
cout << endl;
// Output (random order):
// Forename: Homer
// Age: 45
// Surname: Simpson
\endcode
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 QPtrDict knows about all the iterators that are operating on the
dictionary. When an item is removed from the dictionary, QPtrDict
updates all iterators that refer the removed item to point to the
next item in the traversing order.
\sa QPtrDict
*/
/*!
\fn QPtrDictIterator::QPtrDictIterator( const QPtrDict<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 QPtrDictIterator::~QPtrDictIterator()
Destroys the iterator.
*/
/*!
\fn uint QPtrDictIterator::count() const
Returns the number of items in the dictionary this iterator
operates on.
\sa isEmpty()
*/
/*!
\fn bool QPtrDictIterator::isEmpty() const
Returns TRUE if the dictionary is empty; otherwise returns FALSE.
\sa count()
*/
/*!
\fn type *QPtrDictIterator::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 QPtrDictIterator::operator type *() const
Cast operator. Returns a pointer to the current iterator item.
Same as current().
*/
/*!
\fn type *QPtrDictIterator::current() const
Returns a pointer to the current iterator item's value.
*/
/*!
\fn void *QPtrDictIterator::currentKey() const
Returns the current iterator item's key.
*/
/*!
\fn type *QPtrDictIterator::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 *QPtrDictIterator::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 *QPtrDictIterator::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.
*/