/**************************************************************************** ** ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). ** All rights reserved. ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** This file is part of the documentation of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:FDL$ ** GNU Free Documentation License ** Alternatively, this file may be used under the terms of the GNU Free ** Documentation License version 1.3 as published by the Free Software ** Foundation and appearing in the file included in the packaging of ** this file. ** ** Other Usage ** Alternatively, this file may be used in accordance with the terms ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \class QSet \brief The QSet class is a template class that provides a hash-table-based set. \ingroup tools \ingroup shared \reentrant QSet is one of Qt's generic \l{container classes}. It stores values in an unspecified order and provides very fast lookup of the values. Internally, QSet is implemented as a QHash. Here's an example QSet with QString values: \snippet doc/src/snippets/code/doc_src_qset.cpp 0 To insert a value into the set, use insert(): \snippet doc/src/snippets/code/doc_src_qset.cpp 1 Another way to insert items into the set is to use operator<<(): \snippet doc/src/snippets/code/doc_src_qset.cpp 2 To test whether an item belongs to the set or not, use contains(): \snippet doc/src/snippets/code/doc_src_qset.cpp 3 If you want to navigate through all the values stored in a QSet, you can use an iterator. QSet supports both \l{Java-style iterators} (QSetIterator and QMutableSetIterator) and \l{STL-style iterators} (QSet::iterator and QSet::const_iterator). Here's how to iterate over a QSet using a Java-style iterator: \snippet doc/src/snippets/code/doc_src_qset.cpp 4 Here's the same code, but using an STL-style iterator: \snippet doc/src/snippets/code/doc_src_qset.cpp 5 QSet is unordered, so an iterator's sequence cannot be assumed to be predictable. If ordering by key is required, use a QMap. To navigate through a QSet, you can also use \l{foreach}: \snippet doc/src/snippets/code/doc_src_qset.cpp 6 Items can be removed from the set using remove(). There is also a clear() function that removes all items. QSet's value data type must be an \l{assignable data type}. You cannot, for example, store a QWidget as a value; instead, store a QWidget *. In addition, the type must provide \c operator==(), and there must also be a global qHash() function that returns a hash value for an argument of the key's type. See the QHash documentation for a list of types supported by qHash(). Internally, QSet uses a hash table to perform lookups. The hash table automatically grows and shrinks to provide fast lookups without wasting memory. You can still control the size of the hash table by calling reserve(), if you already know approximately how many elements the QSet will contain, but this isn't necessary to obtain good performance. You can also call capacity() to retrieve the hash table's size. \sa QSetIterator, QMutableSetIterator, QHash, QMap */ /*! \fn QSet::QSet() Constructs an empty set. \sa clear() */ /*! \fn QSet::QSet(const QSet &other) Constructs a copy of \a other. This operation occurs in \l{constant time}, because QSet is \l{implicitly shared}. This makes returning a QSet from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), and this takes \l{linear time}. \sa operator=() */ /*! \fn QSet &QSet::operator=(const QSet &other) Assigns the \a other set to this set and returns a reference to this set. */ /*! \fn void QSet::swap(QSet &other) \since 4.8 Swaps set \a other with this set. This operation is very fast and never fails. */ /*! \fn bool QSet::operator==(const QSet &other) const Returns true if the \a other set is equal to this set; otherwise returns false. Two sets are considered equal if they contain the same elements. This function requires the value type to implement \c operator==(). \sa operator!=() */ /*! \fn bool QSet::operator!=(const QSet &other) const Returns true if the \a other set is not equal to this set; otherwise returns false. Two sets are considered equal if they contain the same elements. This function requires the value type to implement \c operator==(). \sa operator==() */ /*! \fn int QSet::size() const Returns the number of items in the set. \sa isEmpty(), count() */ /*! \fn bool QSet::isEmpty() const Returns true if the set contains no elements; otherwise returns false. \sa size() */ /*! \fn int QSet::capacity() const Returns the number of buckets in the set's internal hash table. The sole purpose of this function is to provide a means of fine tuning QSet's memory usage. In general, you will rarely ever need to call this function. If you want to know how many items are in the set, call size(). \sa reserve(), squeeze() */ /*! \fn void QSet::reserve(int size) Ensures that the set's internal hash table consists of at least \a size buckets. This function is useful for code that needs to build a huge set and wants to avoid repeated reallocation. For example: \snippet doc/src/snippets/code/doc_src_qset.cpp 7 Ideally, \a size should be slightly more than the maximum number of elements expected in the set. \a size doesn't have to be prime, because QSet will use a prime number internally anyway. If \a size is an underestimate, the worst that will happen is that the QSet will be a bit slower. In general, you will rarely ever need to call this function. QSet's internal hash table automatically shrinks or grows to provide good performance without wasting too much memory. \sa squeeze(), capacity() */ /*! \fn void QSet::squeeze() Reduces the size of the set's internal hash table to save memory. The sole purpose of this function is to provide a means of fine tuning QSet's memory usage. In general, you will rarely ever need to call this function. \sa reserve(), capacity() */ /*! \fn void QSet::detach() \internal Detaches this set from any other sets with which it may share data. \sa isDetached() */ /*! \fn bool QSet::isDetached() const \internal Returns true if the set's internal data isn't shared with any other set object; otherwise returns false. \sa detach() */ /*! \fn void QSet::setSharable(bool sharable) \internal */ /*! \fn void QSet::clear() Removes all elements from the set. \sa remove() */ /*! \fn bool QSet::remove(const T &value) Removes any occurrence of item \a value from the set. Returns true if an item was actually removed; otherwise returns false. \sa contains(), insert() */ /*! \fn QSet::iterator QSet::erase(iterator pos) \since 4.2 Removes the item at the iterator position \a pos from the set, and returns an iterator positioned at the next item in the set. Unlike remove(), this function never causes QSet to rehash its internal data structure. This means that it can safely be called while iterating, and won't affect the order of items in the set. \sa remove(), find() */ /*! \fn QSet::const_iterator QSet::find(const T &value) const \since 4.2 Returns a const iterator positioned at the item \a value in the set. If the set contains no item \a value, the function returns constEnd(). \sa constFind(), contains() */ /*! \fn QSet::iterator QSet::find(const T &value) \since 4.2 \overload Returns a non-const iterator positioned at the item \a value in the set. If the set contains no item \a value, the function returns end(). */ /*! \fn QSet::const_iterator QSet::constFind(const T &value) const \since 4.2 Returns a const iterator positioned at the item \a value in the set. If the set contains no item \a value, the function returns constEnd(). \sa find(), contains() */ /*! \fn bool QSet::contains(const T &value) const Returns true if the set contains item \a value; otherwise returns false. \sa insert(), remove(), find() */ /*! \fn bool QSet::contains(const QSet &other) const \since 4.6 Returns true if the set contains all items from the \a other set; otherwise returns false. \sa insert(), remove(), find() */ /*! \fn QSet::const_iterator QSet::begin() const Returns a const \l{STL-style iterator} positioned at the first item in the set. \sa constBegin(), end() */ /*! \fn QSet::iterator QSet::begin() \since 4.2 \overload Returns a non-const \l{STL-style iterator} positioned at the first item in the set. */ /*! \fn QSet::const_iterator QSet::constBegin() const Returns a const \l{STL-style iterator} positioned at the first item in the set. \sa begin(), constEnd() */ /*! \fn QSet::const_iterator QSet::end() const Returns a const \l{STL-style iterator} positioned at the imaginary item after the last item in the set. \sa constEnd(), begin() */ /*! \fn QSet::iterator QSet::end() \since 4.2 \overload Returns a non-const \l{STL-style iterator} pointing to the imaginary item after the last item in the set. */ /*! \fn QSet::const_iterator QSet::constEnd() const Returns a const \l{STL-style iterator} pointing to the imaginary item after the last item in the set. \sa constBegin(), end() */ /*! \typedef QSet::Iterator \since 4.2 Qt-style synonym for QSet::iterator. */ /*! \typedef QSet::ConstIterator Qt-style synonym for QSet::const_iterator. */ /*! \typedef QSet::const_pointer Typedef for const T *. Provided for STL compatibility. */ /*! \typedef QSet::const_reference Typedef for const T &. Provided for STL compatibility. */ /*! \typedef QSet::difference_type Typedef for const ptrdiff_t. Provided for STL compatibility. */ /*! \typedef QSet::key_type Typedef for T. Provided for STL compatibility. */ /*! \typedef QSet::pointer Typedef for T *. Provided for STL compatibility. */ /*! \typedef QSet::reference Typedef for T &. Provided for STL compatibility. */ /*! \typedef QSet::size_type Typedef for int. Provided for STL compatibility. */ /*! \typedef QSet::value_type Typedef for T. Provided for STL compatibility. */ /*! \fn QSet::const_iterator QSet::insert(const T &value) Inserts item \a value into the set, if \a value isn't already in the set, and returns an iterator pointing at the inserted item. \sa operator<<(), remove(), contains() */ /*! \fn QSet &QSet::unite(const QSet &other) Each item in the \a other set that isn't already in this set is inserted into this set. A reference to this set is returned. \sa operator|=(), intersect(), subtract() */ /*! \fn QSet &QSet::intersect(const QSet &other) Removes all items from this set that are not contained in the \a other set. A reference to this set is returned. \sa operator&=(), unite(), subtract() */ /*! \fn QSet &QSet::subtract(const QSet &other) Removes all items from this set that are contained in the \a other set. Returns a reference to this set. \sa operator-=(), unite(), intersect() */ /*! \fn bool QSet::empty() const Returns true if the set is empty. This function is provided for STL compatibility. It is equivalent to isEmpty(). */ /*! \fn bool QSet::count() const Same as size(). */ /*! \fn QSet &QSet::operator<<(const T &value) \fn QSet &QSet::operator+=(const T &value) \fn QSet &QSet::operator|=(const T &value) Inserts a new item \a value and returns a reference to the set. If \a value already exists in the set, the set is left unchanged. \sa insert() */ /*! \fn QSet &QSet::operator-=(const T &value) Removes the occurrence of item \a value from the set, if it is found, and returns a reference to the set. If the \a value is not contained the set, nothing is removed. \sa remove() */ /*! \fn QSet &QSet::operator|=(const QSet &other) \fn QSet &QSet::operator+=(const QSet &other) Same as unite(\a other). \sa operator|(), operator&=(), operator-=() */ /*! \fn QSet &QSet::operator&=(const QSet &other) Same as intersect(\a other). \sa operator&(), operator|=(), operator-=() */ /*! \fn QSet &QSet::operator&=(const T &value) \overload Same as intersect(\e{other}), if we consider \e{other} to be a set that contains the singleton \a value. */ /*! \fn QSet &QSet::operator-=(const QSet &other) Same as subtract(\a{other}). \sa operator-(), operator|=(), operator&=() */ /*! \fn QSet QSet::operator|(const QSet &other) const \fn QSet QSet::operator+(const QSet &other) const Returns a new QSet that is the union of this set and the \a other set. \sa unite(), operator|=(), operator&(), operator-() */ /*! \fn QSet QSet::operator&(const QSet &other) const Returns a new QSet that is the intersection of this set and the \a other set. \sa intersect(), operator&=(), operator|(), operator-() */ /*! \fn QSet QSet::operator-(const QSet &other) const Returns a new QSet that is the set difference of this set and the \a other set, i.e., this set - \a other set. \sa subtract(), operator-=(), operator|(), operator&() */ /*! \fn QSet QSet::operator-(const QSet &other) \fn QSet QSet::operator|(const QSet &other) \fn QSet QSet::operator+(const QSet &other) \fn QSet QSet::operator&(const QSet &other) \internal These will go away in Qt 5. */ /*! \class QSet::iterator \since 4.2 \brief The QSet::iterator class provides an STL-style non-const iterator for QSet. QSet features both \l{STL-style iterators} and \l{Java-style iterators}. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity. QSet::iterator allows you to iterate over a QSet and to remove items (using QSet::erase()) while you iterate. (QSet doesn't let you \e modify a value through an iterator, because that would potentially require moving the value in the internal hash table used by QSet.) If you want to iterate over a const QSet, you should use QSet::const_iterator. It is generally good practice to use QSet::const_iterator on a non-const QSet as well, unless you need to change the QSet through the iterator. Const iterators are slightly faster, and can improve code readability. QSet\::iterator allows you to iterate over a QSet\ and modify it as you go (using QSet::erase()). However, The default QSet::iterator constructor creates an uninitialized iterator. You must initialize it using a function like QSet::begin(), QSet::end(), or QSet::insert() before you can start iterating. Here's a typical loop that prints all the items stored in a set: \snippet doc/src/snippets/code/doc_src_qset.cpp 8 Here's a loop that removes certain items (all those that start with 'J') from a set while iterating: \snippet doc/src/snippets/code/doc_src_qset.cpp 9 STL-style iterators can be used as arguments to \l{generic algorithms}. For example, here's how to find an item in the set using the qFind() algorithm: \snippet doc/src/snippets/code/doc_src_qset.cpp 10 Multiple iterators can be used on the same set. However, you may not attempt to modify the container while iterating on it. \sa QSet::const_iterator, QMutableSetIterator */ /*! \class QSet::const_iterator \brief The QSet::const_iterator class provides an STL-style const iterator for QSet. \since 4.2 QSet features both \l{STL-style iterators} and \l{Java-style iterators}. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity. QSet\::const_iterator allows you to iterate over a QSet. If you want to modify the QSet as you iterate over it, you must use QSet::iterator instead. It is generally good practice to use QSet::const_iterator on a non-const QSet as well, unless you need to change the QSet through the iterator. Const iterators are slightly faster, and can improve code readability. The default QSet::const_iterator constructor creates an uninitialized iterator. You must initialize it using a function like QSet::begin(), QSet::end(), or QSet::insert() before you can start iterating. Here's a typical loop that prints all the items stored in a set: \snippet doc/src/snippets/code/doc_src_qset.cpp 11 STL-style iterators can be used as arguments to \l{generic algorithms}. For example, here's how to find an item in the set using the qFind() algorithm: \snippet doc/src/snippets/code/doc_src_qset.cpp 12 Multiple iterators can be used on the same set. However, you may not attempt to modify the container while iterating on it. \sa QSet::iterator, QSetIterator */ /*! \fn QSet::iterator::iterator() \fn QSet::const_iterator::const_iterator() Constructs an uninitialized iterator. Functions like operator*() and operator++() should not be called on an uninitialized iterator. Use operator=() to assign a value to it before using it. \sa QSet::begin(), QSet::end() */ /*! \fn QSet::iterator::iterator(typename Hash::iterator i) \fn QSet::const_iterator::const_iterator(typename Hash::const_iterator i) \internal */ /*! \typedef QSet::iterator::iterator_category \typedef QSet::const_iterator::iterator_category Synonyms for \e {std::bidirectional_iterator_tag} indicating these iterators are bidirectional iterators. */ /*! \typedef QSet::iterator::difference_type \typedef QSet::const_iterator::difference_type \internal */ /*! \typedef QSet::iterator::value_type \typedef QSet::const_iterator::value_type \internal */ /*! \typedef QSet::iterator::pointer \typedef QSet::const_iterator::pointer \internal */ /*! \typedef QSet::iterator::reference \typedef QSet::const_iterator::reference \internal */ /*! \fn QSet::iterator::iterator(const iterator &other) \fn QSet::const_iterator::const_iterator(const const_iterator &other) Constructs a copy of \a other. */ /*! \fn QSet::const_iterator::const_iterator(const iterator &other) \since 4.2 \overload Constructs a copy of \a other. */ /*! \fn QSet::iterator &QSet::iterator::operator=(const iterator &other) \fn QSet::const_iterator &QSet::const_iterator::operator=(const const_iterator &other) Assigns \a other to this iterator. */ /*! \fn const T &QSet::iterator::operator*() const \fn const T &QSet::const_iterator::operator*() const Returns a reference to the current item. \sa operator->() */ /*! \fn const T *QSet::iterator::operator->() const \fn const T *QSet::const_iterator::operator->() const Returns a pointer to the current item. \sa operator*() */ /*! \fn bool QSet::iterator::operator==(const iterator &other) const \fn bool QSet::const_iterator::operator==(const const_iterator &other) const Returns true if \a other points to the same item as this iterator; otherwise returns false. \sa operator!=() */ /*! \fn bool QSet::iterator::operator==(const const_iterator &other) const \fn bool QSet::iterator::operator!=(const const_iterator &other) const \overload */ /*! \fn bool QSet::iterator::operator!=(const iterator &other) const \fn bool QSet::const_iterator::operator!=(const const_iterator &other) const Returns true if \a other points to a different item than this iterator; otherwise returns false. \sa operator==() */ /*! \fn QSet::iterator &QSet::iterator::operator++() \fn QSet::const_iterator &QSet::const_iterator::operator++() The prefix ++ operator (\c{++it}) advances the iterator to the next item in the set and returns an iterator to the new current item. Calling this function on QSet::constEnd() leads to undefined results. \sa operator--() */ /*! \fn QSet::iterator QSet::iterator::operator++(int) \fn QSet::const_iterator QSet::const_iterator::operator++(int) \overload The postfix ++ operator (\c{it++}) advances the iterator to the next item in the set and returns an iterator to the previously current item. */ /*! \fn QSet::iterator &QSet::iterator::operator--() \fn QSet::const_iterator &QSet::const_iterator::operator--() The prefix -- operator (\c{--it}) makes the preceding item current and returns an iterator to the new current item. Calling this function on QSet::begin() leads to undefined results. \sa operator++() */ /*! \fn QSet::iterator QSet::iterator::operator--(int) \fn QSet::const_iterator QSet::const_iterator::operator--(int) \overload The postfix -- operator (\c{it--}) makes the preceding item current and returns an iterator to the previously current item. */ /*! \fn QSet::iterator QSet::iterator::operator+(int j) const \fn QSet::const_iterator QSet::const_iterator::operator+(int j) const Returns an iterator to the item at \a j positions forward from this iterator. (If \a j is negative, the iterator goes backward.) This operation can be slow for large \a j values. \sa operator-() */ /*! \fn QSet::iterator QSet::iterator::operator-(int j) const \fn QSet::const_iterator QSet::const_iterator::operator-(int j) const Returns an iterator to the item at \a j positions backward from this iterator. (If \a j is negative, the iterator goes forward.) This operation can be slow for large \a j values. \sa operator+() */ /*! \fn QSet::iterator &QSet::iterator::operator+=(int j) \fn QSet::const_iterator &QSet::const_iterator::operator+=(int j) Advances the iterator by \a j items. (If \a j is negative, the iterator goes backward.) This operation can be slow for large \a j values. \sa operator-=(), operator+() */ /*! \fn QSet::iterator &QSet::iterator::operator-=(int j) \fn QSet::const_iterator &QSet::const_iterator::operator-=(int j) Makes the iterator go back by \a j items. (If \a j is negative, the iterator goes forward.) This operation can be slow for large \a j values. \sa operator+=(), operator-() */ /*! \fn QList QSet::toList() const Returns a new QList containing the elements in the set. The order of the elements in the QList is undefined. Example: \snippet doc/src/snippets/code/doc_src_qset.cpp 13 \sa fromList(), QList::fromSet(), qSort() */ /*! \fn QList QSet::values() const Returns a new QList containing the elements in the set. The order of the elements in the QList is undefined. This is the same as toList(). \sa fromList(), QList::fromSet(), qSort() */ /*! \fn QSet QSet::fromList(const QList &list) Returns a new QSet object containing the data contained in \a list. Since QSet doesn't allow duplicates, the resulting QSet might be smaller than the \a list, because QList can contain duplicates. Example: \snippet doc/src/snippets/code/doc_src_qset.cpp 14 \sa toList(), QList::toSet() */ /*! \fn QDataStream &operator<<(QDataStream &out, const QSet &set) \relates QSet Writes the \a set to stream \a out. This function requires the value type to implement \c operator<<(). \sa \link datastreamformat.html Format of the QDataStream operators \endlink */ /*! \fn QDataStream &operator>>(QDataStream &in, QSet &set) \relates QSet Reads a set from stream \a in into \a set. This function requires the value type to implement \c operator>>(). \sa \link datastreamformat.html Format of the QDataStream operators \endlink */