/**************************************************************************** ** ** ** QValueList and QValueListIterator class documentation ** ** Copyright (C) 1992-2000 Trolltech AS. All rights reserved. ** ** This file is part of the Qt GUI Toolkit. ** ** This file may be distributed under the terms of the Q Public License ** as defined by Trolltech AS of Norway and appearing in the file ** LICENSE.QPL included in the packaging of this file. ** ** This file may be distributed and/or modified under the terms of the ** GNU General Public License version 2 as published by the Free Software ** Foundation and appearing in the file LICENSE.GPL included in the ** packaging of this file. ** ** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition ** 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 ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. ** ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for ** information about Qt Commercial License Agreements. ** See http://www.trolltech.com/qpl/ for QPL licensing information. ** See http://www.trolltech.com/gpl/ for GPL licensing information. ** ** Contact info@trolltech.com if any conditions of this licensing are ** not clear to you. ** **********************************************************************/ /***************************************************************************** QValueList documentation *****************************************************************************/ /*! \class QValueList qvaluelist.h \brief The QValueList class is a value based template class that provides doubly linked lists. \ingroup qtl \ingroup tools \ingroup shared Define a template instance QValueList\ to create a list of values which all have the class X. Please notice that QValueList does not store pointers to the members of the list. It holds a copy of every member. That is the reason why this kind of classes are called "value based" while QList and QDict are "reference based". Some classes can not be used within a QValueList, for example everything derived from QObject and thus all classes that implement widgets. Only values can be used in a QValueList. To qualify as a value, the class must provide

a copy constructor,
an assignment operator and
a default constructor, i.e. a constructor that does not take any arguments.

Note that C++ defaults to field-by-field assignment operators and copy constructors if no explicit version is supplied. In many cases, this is sufficient. Example: \code #include #include #include class Employee { public: Employee(): s(0) {} Employee( const QString& name, int salary ) : n(name), s(salary) {} QString name() const { return n; } int salary() const { return s; } void setSalary( int salary ) { s = salary; } private: QString n; int s; }; void main() { typedef QValueList EmployeeList; EmployeeList list; // list of Employee list.append( Employee("Bill", 50000) ); list.append( Employee("Steve",80000) ); list.append( Employee("Ron", 60000) ); Employee joe( "Joe", 50000 ); list.append( joe ); joe.setSalary( 4000 ); EmployeeList::Iterator it; for( it = list.begin(); it != list.end(); ++it ) printf( "%s earns %d\n", (*it).name().latin1(), (*it).salary().latin1() ); } \endcode Program output: \code Bill earns 50000 Steve earns 80000 Ron earns 60000 Joe earns 50000 \endcode As you can see, the latest changes to Joes salary did not affect the value in the list because the list created a copy of Joes entry. There are three ways of finding items in the list. The first one is by using the at() function. It returns an iterator. The advantages of getting an iterator is that you can now move forward or backward from this position by incrementing/decrementing the iterator. To get the amount of items in the list call count(). Valid indices are 0..count(). The second way of accessing a list is with operator[]. That means you can address it like an array. The return value is a reference to the value stored in the list. There exist two versions of this operator. The first one is const and returns a const reference to the value. The second on is non const and returns a non const reference to the value. It is up to your compiler to choose the correct one. The third method is to use the functions begin() and end(). With a simple for loop as shown in the example you can iterate over the complete list. It is save to have multiple iterators at the same time. If some member of the list is removed then only iterators pointing to the removed member become invalid. Inserting in the list does not invalidate any iterator. For convenience the function last() returns an iterator for the last and first() for the first element in the list. In addition you can search items in the list with the find() function. It exists in a const and a non const version. It starts searching from the beginning of the list, but another flavor of the find() function allows you to specify where searching should start. If you just want to know wether a certain item is at least once in the list, then you can use the contains() function. Since QValueList is value based there is no need to care about deleting elements in the list. The list holds its own copies and will free them if the corresponding member or the list itself is deleted. You can force the list to free all of its item with clear(). QValueList is implicitly shared. That means you can just make copies of the list in time O(1). If multiple QValueList instances share the same data and one is doing a modification of the lists data then this modifying instance makes a copy and modifies its private copy. So it does not affect the other instances. From a developers point of view you can think that a QValueList and a copy of this list have nothing to do with each other. Developers may only notice that copying is very fast. People known to a CPUs MMU architecture will know this pattern as "copy on write". There exist three functions to insert items in the list. append() inserts an item at the end, prepend() inserts at the beginning and insert() inserts in front of the position given by an iterator. Items can be removed from the list in two ways. The first is to pass an iterator to the remove(). The other possibility is to pass a value to remove() which will delete all members which match this value. Lists can be sorted with the algorithms provided by the Qt Template Library, for example with qHeapSort(): Example: \code QValueList l; l.append( 5 ); l.append( 8 ); l.append( 3 ); l.append( 4 ); qHeapSort( l ); \endcode \sa QValueListIterator */ /*! \fn QValueList::QValueList() Constructs an empty list. */ /*! \fn QValueList::QValueList( const QValueList& l ) Constructs a copy of \e l. This operation costs O(1) time since QValueList is implicit shared. The first instance applying modifications to a shared list will create a copy which takes in turn O(n) time. However returning a QValueList from a function is very fast. */ /*! \fn QValueList::~QValueList() Destroys the list. References to the values in the list and all iterators of this list become invalidated. Since QValueList is highly tuned for performance you wont see warnings if you use invalid iterators, because it is impossible for an iterator to check wether it is valid or not. */ /*! \fn QValueList& QValueList::operator= ( const QValueList& l ) Assigns \e l to this list and returns a reference to this list. All iterators of the current list become invalidated by this operation. The cost of such an assignment is O(1) since QValueList is implicitly shared. */ /*! \fn QValueList QValueList::operator+ ( const QValueList& l ) const Creates a new list and fills it with the elements of this list. Then the elements of \e l are appended. Returns the new list. */ /*! \fn QValueList& QValueList::operator+= ( const QValueList& l ) Adds \e list to this list. Returns a reference to this list. */ /*! \fn bool QValueList::operator== ( const QValueList& l ) const Compares both lists. Returns TRUE if both list are equal. */ /*! \fn bool QValueList::operator!= ( const QValueList& l ) const Compares both lists. Returns TRUE if both list are unequal. */ /*! \fn QValueList& QValueList::operator+= ( const T& x ) Adds the value \e x to the end of the list. Returns a reference to the list. */ /*! \fn QValueList& QValueList::operator<< ( const T& x ) Adds the value \e x to the end of the list. Returns a reference to the list. */ /*! \fn const T& QValueList::operator[] ( uint i ) const Returns a const reference to the item with index \e i in the list. It is up to you to check wether this item really exists. You can do that easily with the count() function. However this operator does not check wether \e i is in range and will deliver undefined results if it does not exist. */ /*! \fn T& QValueList::operator[] ( uint i ) Returns a reference to the item with index \e i in the list. It is up to you to check wether this item really exists. You can do that easily with the count() function. However this operator does not check wether \e i is in range and will deliver undefined results if it does not exist. In contrast to the const operator[] you may manipulate the value returned by this operator. */ /*! \fn uint QValueList::count() const Returns the number of items in the list. \sa isEmpty() */ /*! \fn bool QValueList::isEmpty() const Returns TRUE if the list is empty, i.e. count() == 0. Returns FALSE otherwise. \sa count() */ /*! \fn Iterator QValueList::insert( Iterator it, const T& x ) Inserts the value \e x in front of the iterator \e it. Returns an iterator pointing at the inserted item. \sa append(), prepend() */ /*! \fn Iterator QValueList::append( const T& x ) Inserts the value \e x at the end of the list. Returns an iterator pointing at the inserted item. \sa insert(), prepend() */ /*! \fn Iterator QValueList::prepend( const T& x ) Inserts the value \e x at the beginning of the list. Returns an iterator pointing at the inserted item. \sa insert(), append() */ /*! \fn Iterator QValueList::remove( Iterator it ) Removes the item at position \e it in the list. Returns an iterator pointing to the item following the removed on or end() if the last item was deleted. \sa clear() */ /*! \fn void QValueList::remove( const T& x ) Removes all items which have the value \e x. \sa clear() */ /*! \fn void QValueList::clear() Removes all items from the list. \sa remove() */ /*! \fn Iterator QValueList::find( const T& x ) Finds the first occurrence of \e x in the list. Returns end() if no item did match. */ /*! \fn ConstIterator QValueList::find( const T& x ) const Finds the first occurrence of \e x in the list. Returns end() if no item did match. */ /*! \fn Iterator QValueList::find( Iterator it, const T& x ) Finds the first occurrence of \e x in the list starting at the position given by \e it. Returns end() if no item did match. */ /*! \fn ConstIterator QValueList::find( ConstIterator it, const T& x ) const Finds the first occurrence of \e x in the list starting at the position given by \e it. Returns end() if no item did match. */ /*! \fn uint QValueList::contains( const T& x ) const Counts and returns the number of occurrences of the value \e x in the list. */ /*! \fn int QValueList::findIndex( const T& x ) const Returns the first index of the value \e x in the list or -1 if no such value can be found in the list. */ /*! \fn Iterator QValueList::at( uint i ) Returns an iterator pointing to the item at position \e i in the list, or end() if the index is out of range. */ /*! \fn ConstIterator QValueList::at( uint i ) const Returns an iterator pointing to the item at position \e i in the list, or end() if the index is out of range. */ /*! \fn T& QValueList::first() Returns a reference to the first item in the list or the item referenced by end() if no such items exists. Please note that you may not change the value the end() Iterator is pointing to. \sa begin(), last() */ /*! \fn const T& QValueList::first() const Returns a reference to the first item in the list or the item referenced by end() if no such items exists. \sa begin(), last() */ /*! \fn Iterator QValueList::fromLast() Returns an iterator pointing to the last element in the list or end() if no such item exists. \sa last() */ /*! \fn ConstIterator QValueList::fromLast() const Returns an iterator pointing to the last element in the list or end() if no such item exists. \sa last() */ /*! \fn T& QValueList::last() Returns a reference to the last item in the list or the item referenced by end() if no such item exists. Please note that you may not change the value the end() Iterator is pointing to. \sa end(), first(), fromLast() */ /*! \fn const T& QValueList::last() const Returns a reference to the last item in the list or the item referenced by end() if no such item exists. \sa end(), first(), fromLast() */ /*! \fn Iterator QValueList::begin() Returns an iterator pointing to the first element in the list. This iterator equals end() if the list is empty; \sa first(), end() */ /*! \fn ConstIterator QValueList::begin() const Returns an iterator pointing to the first element in the list. This iterator equals end() if the list is empty; \sa first(), end() */ /*! \fn Iterator QValueList::end() Returns an iterator pointing behind the last element in the list. This iterator equals begin() if the list is empty. \sa last(), begin() */ /*! \fn ConstIterator QValueList::end() const Returns an iterator pointing behind the last element in the list. This iterator equals begin() if the list is empty. \sa last(), begin() */ /*! \fn void QValueList::detach() If the list does not share its data with another QValueList instance, then nothing happens, otherwise the function creates a new copy of this data and detaches from the shared one. This function is called whenever the list is modified. The implicit sharing mechanism is implemented this way. */ /*! \fn QDataStream& operator>>( QDataStream& s, QValueList& l ) \relates QValueList Reads a list from the stream. The type \e T stored in the list must implement the streaming operator, too. */ /*! \fn QDataStream& operator<<( QDataStream& s, const QValueList& l ) \relates QValueList Writes a list to the stream. The type \e T stored in the list must implement the streaming operator, too. */ /***************************************************************************** QValueListIterator documentation *****************************************************************************/ /*! \class QValueListIterator qvaluelist.h \brief The QValueListIterator class provides an iterator for QValueList. \ingroup qtl \ingroup tools You can not create an iterator by yourself. Instead you have to ask a list to give you one. An iterator has only the size of a pointer. On 32 bit machines that means 4 bytes otherwise 8 bytes. That makes them very fast. In fact they resemble the semantics of pointers as good as possible and they are almost as fast as usual pointers. Example: \code #include #include #include class Employee { public: Employee(): s(0) {} Employee( const QString& name, int salary ) : n(name), s(salary) {} QString name() const { return n; } int salary() const { return s; } void setSalary( int salary ) { s = salary; } private: QString n; int s; }; void main() { typedef QValueList EmployeeList; EmployeeList list; // list of Employee list.append( Employee("Bill", 50000) ); list.append( Employee("Steve",80000) ); list.append( Employee("Ron", 60000) ); Employee joe( "Joe", 50000 ); list.append( joe ); joe.setSalary( 4000 ); EmployeeList::Iterator it; for( it = list.begin(); it != list.end(); ++it ) printf( "%s earns %d\n", (*it).name().latin1(), (*it).salary() ); } \endcode Program output: \code Bill earns 50000 Steve earns 80000 Ron earns 60000 Joe earns 50000 \endcode In contrast to QList there are no built in functions in QValueList to traverse the list. The only way to do this is to use iterators. QValueList is highly optimized for performance and memory usage. On the other hand that means that you have to be a bit more careful by what you are doing. QValueList does not know about all its iterators and the iterators dont even know to which list they belong. That makes things fast and slim but a bit dangerous because it is up to you to make sure that iterators you are using are still valid. QListIterator will be able to give warnings while QValueListIterator may end up in an undefined state. For every Iterator there is a ConstIterator. When accessing a QValueList in a const environment or if the reference or pointer to the list is itself const, then you have to use the ConstIterator. Its semantics are the same, but it returns only const references to the item it points to. \sa QValueList, QValueListConstIterator */ /*! \fn QValueListIterator::QValueListIterator() Creates un uninitialized iterator. */ /*! \fn QValueListIterator::QValueListIterator( NodePtr p ) Internal function. */ /*! \fn QValueListIterator::QValueListIterator( const QValueListIterator& it ) Constructs a copy of the iterator \e it. */ /*! \fn QValueListIterator::~QValueListIterator() Destroys the iterator. */ /* Unfortunately not with MSVC \fn T *QValueListIterator::operator->() Pointer operator. Returns a pointer to the current iterator item. The great advantage of this operator is that you can treat the iterator like a pointer. Example: \code QValueList::Iterator it = list.begin(); for( ; it != end(); ++it ) it->show(); \endcode */ /*! \fn T& QValueListIterator::operator*() Asterix operator. Returns a reference to the current iterator item. */ /*! \fn const T& QValueListIterator::operator*() const Asterix operator. Returns a reference to the current iterator item. */ /*! \fn QValueListIterator& QValueListIterator::operator++() Prefix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the end of the list. Incrementing the iterator as returned by end() causes undefined results. */ /*! \fn QValueListIterator QValueListIterator::operator++(int) Postfix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the end of the list. Incrementing the iterator as returned by end() causes undefined results. */ /*! \fn QValueListIterator& QValueListIterator::operator--() Prefix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the beginning of the list. Decrementing the iterator as returned by begin() causes undefined results. */ /*! \fn QValueListIterator QValueListIterator::operator--(int) Postfix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the beginning of the list. Decrementing the iterator as returned by begin() causes undefined results. */ /*! \fn bool QValueListIterator::operator==( const QValueListIterator& it ) const Compares both iterators and returns TRUE if they point to the same item. */ /*! \fn bool QValueListIterator::operator!=( const QValueListIterator& it ) const Compares both iterators and returns TRUE if they point to different items. */ /***************************************************************************** QValueListConstIterator documentation *****************************************************************************/ /*! \class QValueListConstIterator qvaluelist.h \brief The QValueListConstIterator class provides an iterator for QValueList. \ingroup qtl \ingroup tools In contrast to QValueListIterator this class is used to iterate over a const list. It does not allow to modify the values of the list since this would break the const semantics. For more informations on QValueList iterators see QValueListIterator. \sa QValueListIterator, QValueList */ /*! \fn QValueListConstIterator::QValueListConstIterator() Creates un uninitialized iterator. */ /*! \fn QValueListConstIterator::QValueListConstIterator( NodePtr p ) Internal function. */ /*! \fn QValueListConstIterator::QValueListConstIterator( const QValueListConstIterator& it ) Constructs a copy of the iterator \e it. */ /*! \fn QValueListConstIterator::QValueListConstIterator( const QValueListIterator& it ) Constructs a copy of the iterator \e it. */ /*! \fn QValueListConstIterator::~QValueListConstIterator() Destroys the iterator. */ /* Unfortunately not with MSVC \fn const T *QValueListConstIterator::operator->() Pointer operator. Returns a pointer to the current iterator item. The great advantage of this operator is that you can treat the iterator like a pointer. Example: \code QValueList::Iterator it = list.begin(); for( ; it != end(); ++it ) it->show(); \endcode */ /*! \fn const T& QValueListConstIterator::operator*() const Asterix operator. Returns a reference to the current iterator item. */ /*! \fn QValueListConstIterator& QValueListConstIterator::operator++() Prefix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the end of the list. Incrementing the iterator as returned by end() causes undefined results. */ /*! \fn QValueListConstIterator QValueListConstIterator::operator++(int) Postfix ++ makes the succeeding item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the end of the list. Incrementing the iterator as returned by end() causes undefined results. */ /*! \fn QValueListConstIterator& QValueListConstIterator::operator--() Prefix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the beginning of the list. Decrementing the iterator as returned by begin() causes undefined results. */ /*! \fn QValueListConstIterator QValueListConstIterator::operator--(int) Postfix -- makes the previous item current and returns an iterator pointing to the new current item. The iterator can not check wether it reached the beginning of the list. Decrementing the iterator as returned by begin() causes undefined results. */ /*! \fn bool QValueListConstIterator::operator==( const QValueListConstIterator& it ) const Compares both iterators and returns TRUE if they point to the same item. */ /*! \fn bool QValueListConstIterator::operator!=( const QValueListConstIterator& it ) const Compares both iterators and returns TRUE if they point to different items. */