path: root/doc/qasciidict.doc

/****************************************************************************
**
** QAsciiDict and QAsciiDictIterator 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 retquirements 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 [email protected].
**
** 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.
**
**********************************************************************/


/*****************************************************************************
  QAsciiDict documentation
 *****************************************************************************/

/*!
    \class QAsciiDict qasciidict.h
    \brief The QAsciiDict class is a template class that provides a dictionary based on char* keys.

    \ingroup collection
    \ingroup tools

    \important autoDelete setAutoDelete

    QAsciiDict is implemented as a template class. Define a template
    instance QAsciiDict\<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.

    QAsciiDict cannot handle Unicode keys; use the QDict template
    instead, which uses \l QString keys. A QDict has the same
    performace as a QAsciiDict.

    Example:
    \code
    QAsciiDict<QLineEdit> fields; // char* keys, QLineEdit* values
    fields.insert( "forename", new QLineEdit( this ) );
    fields.insert( "surname", new QLineEdit( this ) );

    fields["forename"]->setText( "Homer" );
    fields["surname"]->setText( "Simpson" );

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

    if ( fields["forename"] && fields["surname"] )
	cout << fields["forename"]->text() << " " 
	    << fields["surname"]->text() << endl;  // Prints "Homer Simpson"

    fields.remove( "forename" ); // Does not delete the line edit
    if ( ! fields["forename"] )
	cout << "forename is not in the dictionary" << endl;
    \endcode
    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 QPtrDict, QIntDict and QDict.

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

    \sa QAsciiDictIterator, QDict, QIntDict, QPtrDict,
	\link collection.html Collection Classes\endlink
*/


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

    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 QAsciiDict<type> &QAsciiDict::operator=(const QAsciiDict<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 QAsciiDict::count() const

    Returns the number of items in the dictionary.

    \sa isEmpty()
*/

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

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

    \sa count()
*/

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

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

    \sa count()
*/

/*!
    \fn void QAsciiDict::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 QAsciiDict::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:
    \code
	QAsciiDict<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 QAsciiDict::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
    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 *QAsciiDict::take( const char *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 traversal order.

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

/*!
    \fn void QAsciiDict::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 operate on dictionary are reset.

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

/*!
    \fn type *QAsciiDict::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 *QAsciiDict::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 QAsciiDict::statistics() const

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

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

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

    \sa read()
*/

/*****************************************************************************
  QAsciiDictIterator documentation
 *****************************************************************************/

/*!
    \class QAsciiDictIterator qasciidict.h
    \brief The QAsciiDictIterator class provides an iterator for QAsciiDict collections.

    \ingroup collection
    \ingroup tools

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

    Example:
    \code
    QAsciiDict<QLineEdit> fields;
    fields.insert( "forename", new QLineEdit( this ) );
    fields.insert( "surname", new QLineEdit( this ) );
    fields.insert( "age", new QLineEdit( this ) );

    fields["forename"]->setText( "Homer" );
    fields["surname"]->setText( "Simpson" );
    fields["age"]->setText( "45" );

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

    // Output (random order):
    //	age: 45
    //	surname: Simpson
    //	forename: Homer
    \endcode
    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 QAsciiDict knows about all the iterators that are operating on
    the dictionary. When an item is removed from the dictionary,
    QAsciiDict updates all the iterators that are referring to the
    removed item to point to the next item in the (arbitrary)
    traversal order.

    \sa QAsciiDict
*/

/*!
    \fn QAsciiDictIterator::QAsciiDictIterator( const QAsciiDict<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 QAsciiDictIterator::~QAsciiDictIterator()

    Destroys the iterator.
*/

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

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

    \sa isEmpty()
*/

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

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

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

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

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

    Returns a pointer to the current iterator item.
*/

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

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

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