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558 lines
17 KiB
558 lines
17 KiB
/****************************************************************************
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**
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** QDict and QDictIterator class documentation
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**
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** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the Qt GUI Toolkit.
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**
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** This file may be used under the terms of the GNU General
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** Public License versions 2.0 or 3.0 as published by the Free
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** Software Foundation and appearing in the files LICENSE.GPL2
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** and LICENSE.GPL3 included in the packaging of this file.
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** Alternatively you may (at your option) use any later version
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** of the GNU General Public License if such license has been
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** publicly approved by Trolltech ASA (or its successors, if any)
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** and the KDE Free Qt Foundation.
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**
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** Please review the following information to ensure GNU General
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** Public Licensing requirements will be met:
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** http://trolltech.com/products/qt/licenses/licensing/opensource/.
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
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** or contact the sales department at sales@trolltech.com.
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**
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** This file may be used under the terms of the Q Public License as
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** defined by Trolltech ASA and appearing in the file LICENSE.QPL
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** included in the packaging of this file. Licensees holding valid Qt
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** Commercial licenses may use this file in accordance with the Qt
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** Commercial License Agreement provided with the Software.
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**
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** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
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** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
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** herein.
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**
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**********************************************************************/
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/*****************************************************************************
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QDict documentation
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*****************************************************************************/
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/*!
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\class QDict
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\brief The QDict class is a template class that provides a
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dictionary based on QString keys.
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\ingroup collection
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\ingroup tools
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\mainclass
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\important autoDelete setAutoDelete
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QMap is an STL-compatible alternative to this class.
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QDict is implemented as a template class. Define a template
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instance QDict\<X\> to create a dictionary that operates on
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pointers to X (X *).
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A dictionary is a collection of key-value pairs. The key is a
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QString used for insertion, removal and lookup. The value is a
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pointer. Dictionaries provide very fast insertion and lookup.
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If you want to use non-Unicode, plain 8-bit \c char* keys, use the
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QAsciiDict template. A QDict has the same performance as a
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QAsciiDict. If you want to have a dictionary that maps QStrings to
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QStrings use QMap.
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The size() of the dictionary is very important. In order to get
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good performance, you should use a suitably large prime number.
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Suitable means equal to or larger than the maximum expected number
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of dictionary items. Size is set in the constructor but may be
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changed with resize().
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Items are inserted with insert(); 0 pointers cannot be inserted.
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Items are removed with remove(). All the items in a dictionary can
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be removed with clear(). The number of items in the dictionary is
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returned by count(). If the dictionary contains no items isEmpty()
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returns TRUE. You can change an item's value with replace(). Items
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are looked up with operator[](), or with find() which return a
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pointer to the value or 0 if the given key does not exist. You can
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take an item out of the dictionary with take().
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Calling setAutoDelete(TRUE) for a dictionary tells it to delete
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items that are removed. The default behaviour is not to delete
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items when they are removed.
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When an item is inserted, the key is converted (hashed) to an
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integer index into an internal hash array. This makes lookup very
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fast.
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Items with equal keys are allowed. When inserting two items with
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the same key, only the last inserted item will be accessible (last
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in, first out) until it is removed.
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The QDictIterator class can traverse the dictionary, but only in
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an arbitrary order. Multiple iterators may independently traverse
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the same dictionary.
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When inserting an item into a dictionary, only the pointer is
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copied, not the item itself, i.e. a shallow copy is made. It is
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possible to make the dictionary copy all of the item's data (a
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deep copy) when an item is inserted. insert() calls the virtual
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function QPtrCollection::newItem() for the item to be inserted.
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Inherit a dictionary and reimplement newItem() if you want deep
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copies.
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When removing a dictionary item, the virtual function
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QPtrCollection::deleteItem() is called. QDict's default
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implementation is to delete the item if auto-deletion is enabled.
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Example #1:
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\code
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QDict<QLineEdit> fields; // QString keys, QLineEdit* values
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fields.insert( "forename", new QLineEdit( this ) );
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fields.insert( "surname", new QLineEdit( this ) );
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fields["forename"]->setText( "Homer" );
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fields["surname"]->setText( "Simpson" );
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QDictIterator<QLineEdit> it( fields ); // See QDictIterator
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for( ; it.current(); ++it )
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cout << it.currentKey() << ": " << it.current()->text() << endl;
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cout << endl;
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if ( fields["forename"] && fields["surname"] )
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cout << fields["forename"]->text() << " "
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<< fields["surname"]->text() << endl; // Prints "Homer Simpson"
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fields.remove( "forename" ); // Does not delete the line edit
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if ( ! fields["forename"] )
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cout << "forename is not in the dictionary" << endl;
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\endcode
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In this example we use a dictionary to keep track of the line
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edits we're using. We insert each line edit into the dictionary
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with a unique name and then access the line edits via the
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dictionary.
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Example #2:
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\code
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QStringList styleList = QStyleFactory::styles();
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styleList.sort();
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QDict<int> letterDict( 17, FALSE );
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for ( QStringList::Iterator it = styleList.begin(); it != styleList.end(); ++it ) {
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QString styleName = *it;
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QString styleAccel = styleName;
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if ( letterDict[styleAccel.left(1)] ) {
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for ( uint i = 0; i < styleAccel.length(); i++ ) {
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if ( ! letterDict[styleAccel.mid( i, 1 )] ) {
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styleAccel = styleAccel.insert( i, '&' );
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letterDict.insert(styleAccel.mid( i, 1 ), (const int *)1);
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break;
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}
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}
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} else {
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styleAccel = "&" + styleAccel;
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letterDict.insert(styleAccel.left(1), (const int *)1);
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}
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(void) new QAction( styleName, QIconSet(), styleAccel, parent );
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}
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\endcode
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In the example we are using the dictionary to provide fast random
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access to the keys, and we don't care what the values are. The
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example is used to generate a menu of QStyles, each with a unique
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accelerator key (or no accelerator if there are no unused letters
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left).
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We first obtain the list of available styles, then sort them so
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that the menu items will be ordered alphabetically. Next we create
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a dictionary of int pointers. The keys in the dictionary are each
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one character long, representing letters that have been used for
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accelerators. We iterate through our list of style names. If the
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first letter of the style name is in the dictionary, i.e. has been
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used, we iterate over all the characters in the style name to see
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if we can find a letter that hasn't been used. If we find an
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unused letter we put the accelerator ampersand (&) in front of it
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and add that letter to the dictionary. If we can't find an unused
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letter the style will simply have no accelerator. If the first
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letter of the style name is not in the dictionary we use it for
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the accelerator and add it to the dictionary. Finally we create a
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QAction for each style.
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\sa QDictIterator, QAsciiDict, QIntDict, QPtrDict
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*/
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/*!
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\fn QDict::QDict( int size, bool caseSensitive )
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Constructs a dictionary optimized for less than \a size entries.
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We recommend setting \a size to a suitably large prime number
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(e.g. a prime that's slightly larger than the expected number of
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entries). This makes the hash distribution better which will lead
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to faster lookup.
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If \a caseSensitive is TRUE (the default), keys which differ only
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by case are considered different.
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*/
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/*!
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\fn QDict::QDict( const QDict<type> &dict )
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Constructs a copy of \a dict.
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Each item in \a dict is inserted into this dictionary. Only the
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pointers are copied (shallow copy).
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*/
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/*!
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\fn QDict::~QDict()
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Removes all items from the dictionary and destroys it. If
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setAutoDelete() is TRUE, each value is deleted. All iterators that
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access this dictionary will be reset.
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\sa setAutoDelete()
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*/
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/*!
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\fn QDict<type> &QDict::operator=(const QDict<type> &dict)
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Assigns \a dict to this dictionary and returns a reference to this
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dictionary.
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This dictionary is first cleared, then each item in \a dict is
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inserted into this dictionary. Only the pointers are copied
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(shallow copy), unless newItem() has been reimplemented.
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*/
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/*!
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\fn uint QDict::count() const
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Returns the number of items in the dictionary.
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\sa isEmpty()
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*/
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/*!
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\fn uint QDict::size() const
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Returns the size of the internal hash array (as specified in the
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constructor).
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\sa count()
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*/
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/*!
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\fn void QDict::resize( uint newsize )
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Changes the size of the hash table to \a newsize. The contents of
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the dictionary are preserved, but all iterators on the dictionary
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become invalid.
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*/
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/*!
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\fn bool QDict::isEmpty() const
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Returns TRUE if the dictionary is empty, i.e. count() == 0;
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otherwise returns FALSE.
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\sa count()
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*/
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/*!
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\fn void QDict::insert( const QString &key, const type *item )
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Inserts the key \a key with value \a item into the dictionary.
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Multiple items can have the same key, in which case only the last
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item will be accessible using \l operator[]().
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\a item may not be 0.
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\sa replace()
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*/
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/*!
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\fn void QDict::replace( const QString &key, const type *item )
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Replaces the value of the key, \a key with \a item.
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If the item does not already exist, it will be inserted.
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\a item may not be 0.
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Equivalent to:
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\code
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QDict<char> dict;
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...
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if ( dict.find( key ) )
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dict.remove( key );
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dict.insert( key, item );
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\endcode
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If there are two or more items with equal keys, then the last item
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that was inserted will be replaced.
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\sa insert()
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*/
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/*!
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\fn bool QDict::remove( const QString &key )
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Removes the item with \a key from the dictionary. Returns TRUE if
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successful, i.e. if the item is in the dictionary; otherwise
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returns FALSE.
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If there are two or more items with equal keys, then the last item
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that was inserted will be removed.
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The removed item is deleted if \link
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QPtrCollection::setAutoDelete() auto-deletion\endlink is enabled.
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All dictionary iterators that refer to the removed item will be
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set to point to the next item in the dictionary's traversal order.
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\sa take(), clear(), setAutoDelete()
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*/
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/*!
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\fn type *QDict::take( const QString &key )
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Takes the item with \a key out of the dictionary without deleting
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it (even if \link QPtrCollection::setAutoDelete()
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auto-deletion\endlink is enabled).
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If there are two or more items with equal keys, then the last item
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that was inserted will be taken.
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Returns a pointer to the item taken out, or 0 if the key does not
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exist in the dictionary.
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All dictionary iterators that refer to the taken item will be set
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to point to the next item in the dictionary traversal order.
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\sa remove(), clear(), setAutoDelete()
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*/
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/*!
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\fn void QDict::clear()
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Removes all items from the dictionary.
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The removed items are deleted if \link
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QPtrCollection::setAutoDelete() auto-deletion\endlink is enabled.
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All dictionary iterators that operate on the dictionary are reset.
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\sa remove(), take(), setAutoDelete()
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*/
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/*!
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\fn type *QDict::find( const QString &key ) const
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Returns the item with key \a key, or 0 if the key does not exist
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in the dictionary.
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If there are two or more items with equal keys, then the most
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recently inserted item will be found.
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Equivalent to the [] operator.
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\sa operator[]()
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*/
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/*!
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\fn type *QDict::operator[]( const QString &key ) const
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Returns the item with key \a key, or 0 if the key does not
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exist in the dictionary.
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If there are two or more items with equal keys, then the most
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recently inserted item will be found.
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Equivalent to the find() function.
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\sa find()
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*/
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/*!
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\fn void QDict::statistics() const
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Debugging-only function that prints out the dictionary
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distribution using qDebug().
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*/
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/*!
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\fn QDataStream& QDict::read( QDataStream &s, QPtrCollection::Item &item )
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Reads a dictionary item from the stream \a s and returns a
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reference to the stream.
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The default implementation sets \a item to 0.
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\sa write()
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*/
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/*!
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\fn QDataStream& QDict::write( QDataStream &s, QPtrCollection::Item ) const
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Writes a dictionary item to the stream \a s and returns a
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reference to the stream.
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\sa read()
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*/
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/*****************************************************************************
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QDictIterator documentation
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*****************************************************************************/
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/*!
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\class QDictIterator qdict.h
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\brief The QDictIterator class provides an iterator for QDict collections.
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\ingroup collection
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\ingroup tools
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QDictIterator is implemented as a template class. Define a
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template instance QDictIterator\<X\> to create a dictionary
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iterator that operates on QDict\<X\> (dictionary of X*).
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The traversal order is arbitrary; when we speak of the "first",
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"last" and "next" item we are talking in terms of this arbitrary
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order.
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Multiple iterators may independently traverse the same dictionary.
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A QDict knows about all the iterators that are operating on the
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dictionary. When an item is removed from the dictionary, QDict
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updates all iterators that are referring to the removed item to
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point to the next item in the (arbitrary) traversal order.
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Example:
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\code
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QDict<QLineEdit> fields;
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fields.insert( "forename", new QLineEdit( this ) );
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fields.insert( "surname", new QLineEdit( this ) );
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fields.insert( "age", new QLineEdit( this ) );
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fields["forename"]->setText( "Homer" );
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fields["surname"]->setText( "Simpson" );
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fields["age"]->setText( "45" );
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QDictIterator<QLineEdit> it( fields );
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for( ; it.current(); ++it )
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cout << it.currentKey() << ": " << it.current()->text() << endl;
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cout << endl;
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// Output (random order):
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// age: 45
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// surname: Simpson
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// forename: Homer
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\endcode
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In the example we insert some pointers to line edits into a
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dictionary, then iterate over the dictionary printing the strings
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associated with the line edits.
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\sa QDict
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*/
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/*!
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\fn QDictIterator::QDictIterator( const QDict<type> &dict )
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Constructs an iterator for \a dict. The current iterator item is
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set to point to the first item in the dictionary, \a dict. First
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in this context means first in the arbitrary traversal order.
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*/
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/*!
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\fn QDictIterator::~QDictIterator()
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Destroys the iterator.
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*/
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/*!
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\fn uint QDictIterator::count() const
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Returns the number of items in the dictionary over which the
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iterator is operating.
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\sa isEmpty()
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*/
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/*!
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\fn bool QDictIterator::isEmpty() const
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Returns TRUE if the dictionary is empty, i.e. count() == 0;
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otherwise returns FALSE.
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\sa count()
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*/
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/*!
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\fn type *QDictIterator::toFirst()
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Resets the iterator, making the first item the first current item.
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First in this context means first in the arbitrary traversal
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order. Returns a pointer to this item.
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If the dictionary is empty it sets the current item to 0 and
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returns 0.
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*/
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/*!
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\fn type *QDictIterator::operator*()
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\internal
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*/
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/*!
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\fn QDictIterator::operator type*() const
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Cast operator. Returns a pointer to the current iterator item.
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Same as current().
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*/
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/*!
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\fn type *QDictIterator::current() const
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Returns a pointer to the current iterator item's value.
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*/
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/*!
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\fn QString QDictIterator::currentKey() const
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Returns the current iterator item's key.
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*/
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/*!
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\fn type *QDictIterator::operator()()
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Makes the next item current and returns the original current item.
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If the current iterator item was the last item in the dictionary
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or if it was 0, 0 is returned.
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*/
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/*!
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\fn type *QDictIterator::operator++()
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Prefix ++ makes the next item current and returns the new current
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item.
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If the current iterator item was the last item in the dictionary
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or if it was 0, 0 is returned.
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*/
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/*!
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\fn type *QDictIterator::operator+=( uint jump )
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\internal
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Sets the current item to the item \a jump positions after the current item,
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and returns a pointer to that item.
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If that item is beyond the last item or if the dictionary is empty,
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it sets the current item to 0 and returns 0.
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*/
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