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/****************************************************************************
**
** Copyright (C) 2020 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \class QMultiMap
    \inmodule QtCore
    \brief The QMultiMap class is a template class that provides an associative array with multiple equivalent keys.

    \ingroup tools
    \ingroup shared

    \reentrant

    QMultiMap\<Key, T\> is one of Qt's generic \l{container classes}. It
    stores (key, value) pairs and provides fast lookup of the
    value associated with a key.

    QMultiMap and QMultiHash provide very similar functionality. The
    differences are:

    \list
    \li QMultiHash provides average faster lookups than QMultiMap. (See \l{Algorithmic
       Complexity} for details.)
    \li When iterating over a QMultiHash, the items are arbitrarily ordered.
       With QMultiMap, the items are always sorted by key.
    \li The key type of a QMultiHash must provide operator==() and a global
       qHash(Key) function. The key type of a QMultiMap must provide
       operator<() specifying a total order. Since Qt 5.8.1 it is also safe
       to use a pointer type as key, even if the underlying operator<()
       does not provide a total order.
    \endlist

    Here's an example QMultiMap with QString keys and \c int values:
    \snippet code/src_corelib_tools_qmultimap.cpp 0

    To insert a (key, value) pair into the multi map, you can use insert():

    \snippet code/src_corelib_tools_qmultimap.cpp 2

    This inserts the following three (key, value) pairs into the
    QMultiMap: ("a", 1), ("b", 3), ("c", 7), and ("c", -5); note
    that duplicate keys are allowed.

    To look up a value, use find() or value():

    \snippet code/src_corelib_tools_qmultimap.cpp 3

    If there is no item with the specified key in the map, these
    functions return a \l{default-constructed value}.

    If you want to check whether the map contains a certain key, use
    contains():

    \snippet code/src_corelib_tools_qmultimap.cpp 4

    There is also a value() overload that uses its second argument as
    a default value if there is no item with the specified key:

    \snippet code/src_corelib_tools_qmultimap.cpp 5

    If you want to navigate through all the (key, value) pairs stored
    in a QMultiMap, you can use an iterator. QMultiMap provides both
    \l{Java-style iterators} (QMultiMapIterator and QMutableMultiMapIterator)
    and \l{STL-style iterators} (QMultiMap::const_iterator and
    QMultiMap::iterator). Here's how to iterate over a QMultiMap<QString, int>
    using a Java-style iterator:

    \snippet code/src_corelib_tools_qmultimap.cpp 7

    Here's the same code, but using an STL-style iterator this time:

    \snippet code/src_corelib_tools_qmultimap.cpp 8

    The items are traversed in ascending key order.

    A QMultiMap allows multiple values per key. If you call
    insert() with a key that already exists in the map, a
    new (key, value) pair will be inserted. For example:

    \snippet code/src_corelib_tools_qmultimap.cpp 9

    If you want to retrieve all the values for a single key, you can
    use values(const Key &key), which returns a QList<T>:

    \snippet code/src_corelib_tools_qmultimap.cpp 10

    The items that share the same key are available from most
    recently to least recently inserted. Another approach is to call
    find() to get the STL-style iterator for the first item with a
    key and iterate from there:

    \snippet code/src_corelib_tools_qmultimap.cpp 11

    If you only need to extract the values from a map (not the keys),
    you can also use \l{foreach}:

    \snippet code/src_corelib_tools_qmultimap.cpp 12

    Items can be removed from the multi map in several ways. One way is to
    call remove(); this will remove any item with the given key.
    Another way is to use QMutableMultiMapIterator::remove(). In addition,
    you can clear the entire map using clear().

    It is possible to merge two multi maps by calling unite(), by
    using operator+(), and by using operator+=(). Example:

    \snippet code/src_corelib_tools_qmultimap.cpp 25

    QMultiMap's key and value data types must be \l{assignable data
    types}. This covers most data types you are likely to encounter,
    but the compiler won't let you, for example, store a QWidget as a
    value; instead, store a QWidget *. In addition, QMultiMap's key type
    must provide operator<(). QMap uses it to keep its items sorted,
    and assumes that two keys \c x and \c y are equal if neither \c{x
    < y} nor \c{y < x} is true.

    Example:
    \snippet code/src_corelib_tools_qmultimap.cpp 13

    In the example, we start by comparing the employees' names. If
    they're equal, we compare their dates of birth to break the tie.

    \sa QMultiMapIterator, QMutableMultiMapIterator, QMultiHash
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap()

    Constructs an empty multi map.

    \sa clear()
*/

/*!
    \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(QMultiMap<Key, T> &&other)

    Move-constructs a QMultiMap instance, making it point at the same
    object that \a other was pointing to.

    \since 5.2
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(const QMultiMap<Key, T> &other)

    Constructs a copy of \a other.

    This operation occurs in \l{constant time}, because QMultiMap is
    \l{implicitly shared}. This makes returning a QMultiMap 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 template <class Key, class T> QMultiMap<Key, T> &QMultiMap<Key, T>::operator=(const QMultiMap<Key, T> &other)

    Assigns \a other to this multi map and returns a reference to this multi map.
*/

/*!
    \fn template <class Key, class T> QMultiMap<Key, T> &QMultiMap<Key, T>::operator=(QMultiMap<Key, T> &&other)

    Move-assigns \a other to this QMultiMap instance.

    \since 5.2
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::~QMultiMap()

    Destroys the multi map. References to the values in the multi map, and all
    iterators over this multi map, become invalid.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(std::initializer_list<std::pair<Key,T> > list)
    \since 5.1

    Constructs a multi map with a copy of each of the elements in the
    initializer list \a list.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(const QMap<Key, T> &other)
    \since 6.0

    Constructs a multi map as a copy of \a other.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(QMap<Key, T> &&other)
    \since 6.0

    If \a other is shared, constructs a multi map as a copy of \a other.
    Otherwise, constructs a multi map by moving the elements from \a other.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(const std::multimap<Key, T> &other)

    Constructs a copy of \a other.

    \sa toStdMultiMap()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::QMultiMap(std::multimap<Key, T> &&other)

    Constructs a multi map by moving from \a other.

    \sa toStdMultiMap()
*/

/*! \fn template <class Key, class T> std::multimap<Key, T> QMultiMap<Key, T>::toStdMap() const
    \obsolete Use toStdMultiMap() instead.

    Returns an STL multi map equivalent to this QMultiMap.
*/

/*! \fn template <class Key, class T> std::multimap<Key, T> QMultiMap<Key, T>::toStdMultiMap() const

    Returns an STL multi map equivalent to this QMultiMap.
*/

/*! \fn template <class Key, class T> void QMultiMap<Key, T>::swap(QMultiMap<Key, T> &other)
    \since 4.8

    Swaps multi map \a other with this multi map. This operation is very
    fast and never fails.
*/

/*! \fn template<class Key, class T> bool QMultiMap<Key, T>::operator==(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)

    Returns \c true if \a lhs is equal to \a rhs; otherwise returns
    false.

    Two multi maps are considered equal if they contain the same (key,
    value) pairs, in the same order (which matters for duplicate keys).

    This function requires the key and the value types to implement \c
    operator==().

    \sa operator!=()
*/

/*! \fn template<class Key, class T> bool QMultiMap<Key, T>::operator!=(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)

    Returns \c true if \a lhs is not equal to \a rhs; otherwise
    returns \c false.

    Two multi maps are considered equal if they contain the same (key,
    value) pairs, in the same order (which matters for duplicate keys).

    This function requires the key and the value types to implement \c
    operator==().

    \sa operator==()
*/

/*! \fn template <class Key, class T> qsizetype QMultiMap<Key, T>::size() const

    Returns the number of (key, value) pairs in the multi map.

    \sa isEmpty(), count()
*/

/*!
    \fn template <class Key, class T> bool QMultiMap<Key, T>::isEmpty() const

    Returns \c true if the multi map contains no items; otherwise returns
    false.

    \sa size()
*/

/*! \fn template <class Key, class T> void QMultiMap<Key, T>::detach()

    \internal

    Detaches this map from any other multi maps with which it may share
    data.

    \sa isDetached()
*/

/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::isDetached() const

    \internal

    Returns \c true if the multi map's internal data isn't shared with any
    other map object; otherwise returns \c false.

    \sa detach()
*/

/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::isSharedWith(const QMultiMap<Key, T> &other) const

    \internal
*/

/*! \fn template <class Key, class T> void QMultiMap<Key, T>::clear()

    Removes all items from the multi map.

    \sa remove()
*/

/*! \fn template <class Key, class T> qsizetype QMultiMap<Key, T>::remove(const Key &key)

    Removes all the items that have the key \a key from the multi map.
    Returns the number of items removed.

    \sa clear(), take()
*/

/*! \fn template <class Key, class T> qsizetype QMultiMap<Key, T>::remove(const Key &key, const T &value)

    Removes all the items that have the key \a key and value \a value
    from the multi map.
    Returns the number of items removed.

    \sa clear(), take()
*/

/*! \fn template <class Key, class T> T QMultiMap<Key, T>::take(const Key &key)

    Removes the item with the key \a key from the multi map and returns
    the value associated with it.

    If the item does not exist in the multi map, the function simply
    returns a \l{default-constructed value}. If there are multiple
    items for \a key in the map, only the most recently inserted one
    is removed and returned.

    If you don't use the return value, remove() is more efficient.

    \sa remove()
*/

/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::contains(const Key &key) const

    Returns \c true if the multi map contains an item with key \a key;
    otherwise returns \c false.

    \sa count()
*/

/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::contains(const Key &key, const T &value) const
    \since 4.3

    Returns \c true if the multi map contains an item with key \a key
    and value \a value; otherwise returns \c false.

    \sa count()
*/

/*!
    \fn template <class Key, class T> Key QMultiMap<Key, T>::key(const T &value, const Key &defaultKey) const
    \since 4.3
    \overload

    Returns the first key with value \a value, or \a defaultKey if
    the multi map contains no item with value \a value. If no \a defaultKey
    is provided the function returns a
    \l{default-constructed value}{default-constructed key}.

    This function can be slow (\l{linear time}), because QMultiMap's
    internal data structure is optimized for fast lookup by key, not
    by value.

    \sa value(), keys()
*/

/*! \fn template <class Key, class T> T QMultiMap<Key, T>::value(const Key &key, const T &defaultValue) const

    Returns the value associated with the key \a key.

    If the multi map contains no item with key \a key, the function returns
    \a defaultValue. If no \a defaultValue is specified, the function
    returns a \l{default-constructed value}. If there are multiple
    items for \a key in the multi map, the value of the most recently
    inserted one is returned.

    \sa key(), values(), contains()
*/

/*! \fn template <class Key, class T> QList<Key> QMultiMap<Key, T>::keys() const

    Returns a list containing all the keys in the multi map in ascending
    order. Keys that occur multiple times in the multi map
    also occur multiple times in the list.

    The order is guaranteed to be the same as that used by values().

    This function creates a new list, in \l {linear time}. The time and memory
    use that entails can be avoided by iterating from \l keyBegin() to
    \l keyEnd().

    \sa values(), key()
*/

/*! \fn template <class Key, class T> QList<Key> QMultiMap<Key, T>::keys(const T &value) const

    \overload

    Returns a list containing all the keys associated with value \a
    value in ascending order.

    This function can be slow (\l{linear time}), because QMultiMap's
    internal data structure is optimized for fast lookup by key, not
    by value.
*/

/*! \fn template <class Key, class T> QList<Key> QMultiMap<Key, T>::uniqueKeys() const
    \since 4.2

    Returns a list containing all the keys in the map in ascending
    order. Keys that occur multiple times in the map occur only
    once in the returned list.
*/

/*! \fn template <class Key, class T> QList<T> QMultiMap<Key, T>::values() const

    Returns a list containing all the values in the map, in ascending
    order of their keys. If a key is associated with multiple values,
    all of its values will be in the list, and not just the most
    recently inserted one.

    \sa keys(), value()
*/

/*! \fn template <class Key, class T> QList<T> QMultiMap<Key, T>::values(const Key &key) const

    Returns a list containing all the values associated with key
    \a key, from the most recently inserted to the least recently
    inserted one.

    \sa keys(), value()
*/

/*! \fn template <class Key, class T> qsizetype QMultiMap<Key, T>::count() const

    \overload

    Same as size().
*/

/*! \fn template <class Key, class T> qsizetype QMultiMap<Key, T>::count(const Key &key) const

    Returns the number of items associated with key \a key.

    \sa contains(), QMultiMap::count()
*/

/*! \fn template <class Key, class T> qsizetype QMultiMap<Key, T>::count(const Key &key, const T &value) const

    Returns the number of items with key \a key and value \a value.

    \sa contains(), QMultiMap::count()
*/


/*! \fn template <class Key, class T> const Key &QMultiMap<Key, T>::firstKey() const
    \since 5.2

    Returns a reference to the smallest key in the multi map.
    This function assumes that the multi map is not empty.

    This executes in \l{constant time}.

    \sa lastKey(), first(), keyBegin(), isEmpty()
*/

/*! \fn template <class Key, class T> const Key &QMultiMap<Key, T>::lastKey() const
    \since 5.2

    Returns a reference to the largest key in the multi map.
    This function assumes that the multi map is not empty.

    This executes in \l{logarithmic time}.

    \sa firstKey(), last(), keyEnd(), isEmpty()
*/

/*! \fn template <class Key, class T> T &QMultiMap<Key, T>::first()
    \since 5.2

    Returns a reference to the first value in the multi map, that is the value mapped
    to the smallest key. This function assumes that the multi map is not empty.

    When unshared (or const version is called), this executes in \l{constant time}.

    \sa last(), firstKey(), isEmpty()
*/

/*! \fn template <class Key, class T> const T &QMultiMap<Key, T>::first() const
    \since 5.2

    \overload
*/

/*! \fn template <class Key, class T> T &QMultiMap<Key, T>::last()
    \since 5.2

    Returns a reference to the last value in the multi map, that is the value mapped
    to the largest key. This function assumes that the map is not empty.

    When unshared (or const version is called), this executes in \l{logarithmic time}.

    \sa first(), lastKey(), isEmpty()
*/

/*! \fn template <class Key, class T> const T &QMultiMap<Key, T>::last() const
    \since 5.2

    \overload
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::begin()

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the first item in
    the multi map.

    \sa constBegin(), end()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::begin() const

    \overload
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::cbegin() const
    \since 5.0

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first item
    in the multi map.

    \sa begin(), cend()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::constBegin() const

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first item
    in the multi map.

    \sa begin(), constEnd()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_iterator QMultiMap<Key, T>::keyBegin() const
    \since 5.6

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first key
    in the multi map.

    \sa keyEnd(), firstKey()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::end()

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the imaginary item
    after the last item in the multi map.

    \sa begin(), constEnd()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::end() const

    \overload
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::cend() const
    \since 5.0

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    item after the last item in the multi map.

    \sa cbegin(), end()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::constEnd() const

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    item after the last item in the multi map.

    \sa constBegin(), end()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_iterator QMultiMap<Key, T>::keyEnd() const
    \since 5.6

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    item after the last key in the multi map.

    \sa keyBegin(), lastKey()
*/


/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_value_iterator QMultiMap<Key, T>::keyValueBegin()
    \since 5.10

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the first entry
    in the multi map.

    \sa keyValueEnd()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_value_iterator QMultiMap<Key, T>::keyValueEnd()
    \since 5.10

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    entry after the last entry in the multi map.

    \sa keyValueBegin()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_key_value_iterator QMultiMap<Key, T>::keyValueBegin() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first entry
    in the multi map.

    \sa keyValueEnd()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_key_value_iterator QMultiMap<Key, T>::constKeyValueBegin() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first entry
    in the multi map.

    \sa keyValueBegin()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_key_value_iterator QMultiMap<Key, T>::keyValueEnd() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    entry after the last entry in the multi map.

    \sa keyValueBegin()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_key_value_iterator QMultiMap<Key, T>::constKeyValueEnd() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    entry after the last entry in the multi map.

    \sa constKeyValueBegin()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::erase(const_iterator pos)

    Removes the (key, value) pair pointed to by the iterator \a pos
    from the multi map, and returns an iterator to the next item in the
    map.

    \sa remove()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::erase(const_iterator first, const_iterator last)
    \since 6.0

    Removes the (key, value) pairs pointed to by the iterator range
    [\a first, \a last) from the multi map.
    Returns an iterator to the item in the multi map following the last
    removed element.

    \sa remove()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::find(const Key &key)

    Returns an iterator pointing to the item with key \a key in the
    multi map.

    If the multi map contains no item with key \a key, the function
    returns end().

    If the map contains multiple items with key \a key, this
    function returns an iterator that points to the most recently
    inserted value. The other values are accessible by incrementing
    the iterator. For example, here's some code that iterates over all
    the items with the same key:

    \snippet code/src_corelib_tools_qmultimap.cpp 11

    \sa constFind(), value(), values(), lowerBound(), upperBound()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::find(const Key &key) const

    \overload
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::constFind(const Key &key) const
    \since 4.1

    Returns an const iterator pointing to the item with key \a key in the
    multi map.

    If the multi map contains no item with key \a key, the function
    returns constEnd().

    \sa find(), QMultiMap::constFind()
*/

/*!
    \fn template <class Key, class T> typename QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::find(const Key &key, const T &value) const
    \since 4.3
    \overload

    Returns a const iterator pointing to the item with the given \a key and
    \a value in the map.

    If the map contains no such item, the function returns end().

    If the map contains multiple items with the specified \a key, this
    function returns a const iterator that points to the most recently
    inserted value.
*/

/*!
    \fn template <class Key, class T> typename QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::constFind(const Key &key, const T &value) const
    \since 4.3

    Returns an iterator pointing to the item with key \a key and the
    value \a value in the map.

    If the map contains no such item, the function returns
    constEnd().

    \sa QMap::constFind()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::lowerBound(const Key &key)

    Returns an iterator pointing to the first item with key \a key in
    the map. If the map contains no item with key \a key, the
    function returns an iterator to the nearest item with a greater
    key.

    Example:
    \snippet code/src_corelib_tools_qmultimap.cpp 15

    If the map contains multiple items with key \a key, this
    function returns an iterator that points to the most recently
    inserted value. The other values are accessible by incrementing
    the iterator. For example, here's some code that iterates over all
    the items with the same key:

    \snippet code/src_corelib_tools_qmultimap.cpp 16

    \sa upperBound(), find()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::lowerBound(const Key &key) const

    \overload
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::upperBound(const Key &key)

    Returns an iterator pointing to the item that immediately follows
    the last item with key \a key in the map. If the map contains no
    item with key \a key, the function returns an iterator to the
    nearest item with a greater key.

    Example:
    \snippet code/src_corelib_tools_qmultimap.cpp 17

    \sa lowerBound(), find()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::upperBound(const Key &key) const

    \overload
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insert(const Key &key, const T &value)

    Inserts a new item with the key \a key and a value of \a value.

    If there is already an item with the same key in the map, this
    function will simply create a new one. (This behavior is
    different from replace(), which overwrites the value of an
    existing item.)

    \sa replace()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insert(const_iterator pos, const Key &key, const T &value)
    \overload
    \since 5.1
    Inserts a new item with the key \a key and value \a value and with hint \a pos
    suggesting where to do the insert.

    If constBegin() is used as hint it indicates that the \a key is less than any key in the multi map
    while constEnd() suggests that the \a key is (strictly) larger than any key in the multi map.
    Otherwise the hint should meet the condition (\a pos - 1).key() < \a key <= pos.key().
    If the hint \a pos is wrong it is ignored and a regular insert is done.

    If the hint is correct and the multi map is unshared, the insert executes in amortized \l{constant time}.

    If there is already an item with the same key in the map, this function will simply create a new one.

    When creating a multi map from sorted data inserting the largest key first with constBegin()
    is faster than inserting in sorted order with constEnd(), since constEnd() - 1 (which is needed
    to check if the hint is valid) needs \l{logarithmic time}.

    \b {Note:} Be careful with the hint. Providing an iterator from an older shared instance might
    crash but there is also a risk that it will silently corrupt both the multi map and the \a pos multi map.
*/

#if QT_DEPRECATED_SINCE(6, 0)
/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insertMulti(const Key &key, const T &value)
    \obsolete Use insert() instead.

    Inserts a new item with the key \a key and a value of \a value, and returns an iterator pointing to the new item.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::insertMulti(const_iterator pos, const Key &key, const T &value)
    \obsolete Use insert() instead.
    \overload

    Inserts a new item with the key \a key and value \a value and with hint \a pos
    suggesting where to do the insert.
*/

/*! \fn template <class Key, class T> void QMultiMap<Key, T>::insert(const QMultiMap<Key, T> &map)
    \since 5.15
    \obsolete Use unite() instead.

    Inserts all the items in \a map into this map.
*/

/*! \fn template <class Key, class T> void QMultiMap<Key, T>::insert(QMultiMap<Key, T> &&map)
    \since 5.15
    \obsolete Use unite() instead.
    \overload

    Moves all the items from \a map into this map.

    If \a map is shared, then the items will be copied instead.
*/
#endif

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::replace(const Key &key, const T &value)

    Inserts a new item with the key \a key and a value of \a value.

    If there is already an item with the key \a key, that item's value
    is replaced with \a value.

    If there are multiple items with the key \a key, the most
    recently inserted item's value is replaced with \a value.

    \sa insert()
*/

/*! \typedef QMultiMap::Iterator

    Qt-style synonym for QMultiMap<Key, T>::iterator.
*/

/*! \typedef QMultiMap::ConstIterator

    Qt-style synonym for QMultiMap<Key, T>::const_iterator.
*/

/*! \typedef QMultiMap::difference_type

    Typedef for ptrdiff_t. Provided for STL compatibility.
*/

/*! \typedef QMultiMap::key_type

    Typedef for Key. Provided for STL compatibility.
*/

/*! \typedef QMultiMap::mapped_type

    Typedef for T. Provided for STL compatibility.
*/

/*! \typedef QMultiMap::size_type

    Typedef for int. Provided for STL compatibility.
*/

/*!
    \fn template <class Key, class T> bool QMultiMap<Key, T>::empty() const

    This function is provided for STL compatibility. It is equivalent
    to isEmpty(), returning true if the map is empty; otherwise
    returning false.
*/

/*!
  \fn template <class Key, class T> QPair<typename QMultiMap<Key, T>::iterator, typename QMultiMap<Key, T>::iterator> QMultiMap<Key, T>::equal_range(const Key &key)

  Returns a pair of iterators delimiting the range of values \c{[first, second)}, that
  are stored under \a key.
*/

/*!
    \fn template <class Key, class T> QPair<typename QMultiMap<Key, T>::const_iterator, typename QMultiMap<Key, T>::const_iterator> QMultiMap<Key, T>::equal_range(const Key &key) const
    \overload
    \since 5.6
*/

/*!
    \fn template <class Key, class T> QMultiMap<Key, T> &QMultiMap<Key, T>::unite(const QMultiMap<Key, T> &other)

    Inserts all the items in the \a other map into this map. If a
    key is common to both maps, the resulting map will contain the
    key multiple times.
*/

/*!
    \fn template <class Key, class T> QMultiMap<Key, T> &QMultiMap<Key, T>::unite(QMultiMap<Key, T> &&other)

    Moves all the items from the \a other map into this map. If a
    key is common to both maps, the resulting map will contain the
    key multiple times.

    If \a other is shared, then the items will be copied instead.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T> operator+=(QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)

    Inserts all the items in the \a rhs map into the \a lhs map and
    returns the resulting map.

    \sa insert(), operator+()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T> operator+(const QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rhs)

    Returns a map that contains all the items in the \a lhs map in
    addition to all the items in \a rhs. If a key is common to both
    maps, the resulting map will contain the key multiple times.

    \sa operator+=()
*/

/*! \class QMultiMap::iterator
    \inmodule QtCore
    \brief The QMultiMap::iterator class provides an STL-style non-const iterator for QMultiMap.

    QMultiMap 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.

    QMultiMap\<Key, T\>::iterator allows you to iterate over a QMultiMap
    and to modify the value (but not the key) stored under
    a particular key. If you want to iterate over a const QMultiMap, you
    should use QMultiMap::const_iterator. It is generally good practice to
    use QMultiMap::const_iterator on a non-const QMultiMap as well, unless you
    need to change the QMultiMap through the iterator. Const iterators are
    slightly faster, and can improve code readability.

    The default QMultiMap::iterator constructor creates an uninitialized
    iterator. You must initialize it using a QMultiMap function like
    QMultiMap::begin(), QMultiMap::end(), or QMultiMap::find() before you can
    start iterating. Here's a typical loop that prints all the (key,
    value) pairs stored in a map:

    \snippet code/src_corelib_tools_qmultimap.cpp 18

    Unlike QMultiHash, which stores its items in an arbitrary order, QMultiMap
    stores its items ordered by key. Items that share the same key
    will appear consecutively,
    from the most recently to the least recently inserted value.

    Let's see a few examples of things we can do with a
    QMultiMap::iterator that we cannot do with a QMultiMap::const_iterator.
    Here's an example that increments every value stored in the QMultiMap
    by 2:

    \snippet code/src_corelib_tools_qmultimap.cpp 19

    Here's an example that removes all the items whose key is a
    string that starts with an underscore character:

    \snippet code/src_corelib_tools_qmultimap.cpp 20

    The call to QMultiMap::erase() removes the item pointed to by the
    iterator from the map, and returns an iterator to the next item.
    Here's another way of removing an item while iterating:

    \snippet code/src_corelib_tools_qmultimap.cpp 21

    It might be tempting to write code like this:

    \snippet code/src_corelib_tools_qmultimap.cpp 22

    However, this will potentially crash in \c{++i}, because \c i is
    a dangling iterator after the call to erase().

    Multiple iterators can be used on the same map. If you add items
    to the map, existing iterators will remain valid. If you remove
    items from the map, iterators that point to the removed items
    will become dangling iterators.

    \warning Iterators on implicitly shared containers do not work
    exactly like STL-iterators. You should avoid copying a container
    while iterators are active on that container. For more information,
    read \l{Implicit sharing iterator problem}.

    \sa QMultiMap::const_iterator, QMultiMap::key_iterator, QMutableMultiMapIterator
*/

/*! \typedef QMultiMap::iterator::difference_type

    \internal
*/

/*! \typedef QMultiMap::iterator::iterator_category

  A synonym for \e {std::bidirectional_iterator_tag} indicating
  this iterator is a bidirectional iterator.
*/

/*! \typedef QMultiMap::iterator::pointer

    \internal
*/

/*! \typedef QMultiMap::iterator::reference

    \internal
*/

/*! \typedef QMultiMap::iterator::value_type

    \internal
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator::iterator()

    Constructs an uninitialized iterator.

    Functions like key(), value(), and operator++() must not be
    called on an uninitialized iterator. Use operator=() to assign a
    value to it before using it.

    \sa QMultiMap::begin(), QMultiMap::end()
*/

/*! \fn template <class Key, class T> const Key &QMultiMap<Key, T>::iterator::key() const

    Returns the current item's key as a const reference.

    There is no direct way of changing an item's key through an
    iterator, although it can be done by calling QMultiMap::erase()
    followed by QMultiMap::insert().

    \sa value()
*/

/*! \fn template <class Key, class T> T &QMultiMap<Key, T>::iterator::value() const

    Returns a modifiable reference to the current item's value.

    You can change the value of an item by using value() on
    the left side of an assignment, for example:

    \snippet code/src_corelib_tools_qmultimap.cpp 23

    \sa key(), operator*()
*/

/*! \fn template <class Key, class T> T &QMultiMap<Key, T>::iterator::operator*() const

    Returns a modifiable reference to the current item's value.

    Same as value().

    \sa key()
*/

/*! \fn template <class Key, class T> T *QMultiMap<Key, T>::iterator::operator->() const

    Returns a pointer to the current item's value.

    \sa value()
*/

/*!
    \fn template<class Key, class T> bool QMultiMap<Key, T>::iterator::operator==(const iterator &lhs, const iterator &rhs)
    \fn template<class Key, class T> bool QMultiMap<Key, T>::const_iterator::operator==(const const_iterator &lhs, const const_iterator &rhs)

    Returns \c true if \a lhs points to the same item as the \a rhs iterator;
    otherwise returns \c false.

    \sa operator!=()
*/

/*!
    \fn template<class Key, class T> bool QMultiMap<Key, T>::iterator::operator!=(const iterator &lhs, const iterator &rhs)
    \fn template<class Key, class T> bool QMultiMap<Key, T>::const_iterator::operator!=(const const_iterator &lhs, const const_iterator &rhs)

    Returns \c true if \a lhs points to a different item than the \a rhs iterator;
    otherwise returns \c false.

    \sa operator==()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator &QMultiMap<Key, T>::iterator::operator++()

    The prefix ++ operator (\c{++i}) advances the iterator to the
    next item in the multi map and returns an iterator to the new current
    item.

    Calling this function on QMultiMap::end() leads to undefined results.

    \sa operator--()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::iterator::operator++(int)

    \overload

    The postfix ++ operator (\c{i++}) advances the iterator to the
    next item in the multi map and returns an iterator to the previously
    current item.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator &QMultiMap<Key, T>::iterator::operator--()

    The prefix -- operator (\c{--i}) makes the preceding item
    current and returns an iterator pointing to the new current item.

    Calling this function on QMultiMap::begin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::iterator QMultiMap<Key, T>::iterator::operator--(int)

    \overload

    The postfix -- operator (\c{i--}) makes the preceding item
    current and returns an iterator pointing to the previously
    current item.
*/

/*! \class QMultiMap::const_iterator
    \inmodule QtCore
    \brief The QMultiMap::const_iterator class provides an STL-style const iterator for QMultiMap.

    QMultiMap 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.

    QMultiMap\<Key, T\>::const_iterator allows you to iterate over a QMultiMap.
    If you want to modify the QMultiMap as you iterate
    over it, you must use QMultiMap::iterator instead. It is generally
    good practice to use QMultiMap::const_iterator on a non-const QMultiMap as
    well, unless you need to change the QMultiMap through the iterator.
    Const iterators are slightly faster, and can improve code
    readability.

    The default QMultiMap::const_iterator constructor creates an
    uninitialized iterator. You must initialize it using a QMultiMap
    function like QMultiMap::constBegin(), QMultiMap::constEnd(), or
    QMultiMap::find() before you can start iterating. Here's a typical
    loop that prints all the (key, value) pairs stored in a map:

    \snippet code/src_corelib_tools_qmultimap.cpp 24

    Unlike QMultiHash, which stores its items in an arbitrary order, QMultiMap
    stores its items ordered by key. Items that share the same key
    will appear consecutively,
    from the most recently to the least recently inserted value.

    Multiple iterators can be used on the same multi map. If you add items
    to the map, existing iterators will remain valid. If you remove
    items from the map, iterators that point to the removed items
    will become dangling iterators.

    \warning Iterators on implicitly shared containers do not work
    exactly like STL-iterators. You should avoid copying a container
    while iterators are active on that container. For more information,
    read \l{Implicit sharing iterator problem}.

    \sa QMultiMap::iterator, QMultiMap::key_iterator, QMultiMapIterator
*/

/*! \typedef QMultiMap::const_iterator::difference_type

    \internal
*/

/*! \typedef QMultiMap::const_iterator::iterator_category

  A synonym for \e {std::bidirectional_iterator_tag} indicating
  this iterator is a bidirectional iterator.
*/

/*! \typedef QMultiMap::const_iterator::pointer

    \internal
*/

/*! \typedef QMultiMap::const_iterator::reference

    \internal
*/

/*! \typedef QMultiMap::const_iterator::value_type

    \internal
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator::const_iterator()

    Constructs an uninitialized iterator.

    Functions like key(), value(), and operator++() must not be
    called on an uninitialized iterator. Use operator=() to assign a
    value to it before using it.

    \sa QMultiMap::constBegin(), QMultiMap::constEnd()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator::const_iterator(const iterator &other)

    Constructs a copy of \a other.
*/

/*! \fn template <class Key, class T> const Key &QMultiMap<Key, T>::const_iterator::key() const

    Returns the current item's key.

    \sa value()
*/

/*! \fn template <class Key, class T> const T &QMultiMap<Key, T>::const_iterator::value() const

    Returns the current item's value.

    \sa key(), operator*()
*/

/*! \fn template <class Key, class T> const T &QMultiMap<Key, T>::const_iterator::operator*() const

    Returns the current item's value.

    Same as value().

    \sa key()
*/

/*! \fn template <class Key, class T> const T *QMultiMap<Key, T>::const_iterator::operator->() const

    Returns a pointer to the current item's value.

    \sa value()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator &QMultiMap<Key, T>::const_iterator::operator++()

    The prefix ++ operator (\c{++i}) advances the iterator to the
    next item in the map and returns an iterator to the new current
    item.

    Calling this function on QMultiMap::end() leads to undefined results.

    \sa operator--()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::const_iterator::operator++(int)

    \overload

    The postfix ++ operator (\c{i++}) advances the iterator to the
    next item in the map and returns an iterator to the previously
    current item.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator &QMultiMap<Key, T>::const_iterator::operator--()

    The prefix -- operator (\c{--i}) makes the preceding item
    current and returns an iterator pointing to the new current item.

    Calling this function on QMultiMap::begin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::const_iterator QMultiMap<Key, T>::const_iterator::operator--(int)

    \overload

    The postfix -- operator (\c{i--}) makes the preceding item
    current and returns an iterator pointing to the previously
    current item.
*/

/*! \class QMultiMap::key_iterator
    \inmodule QtCore
    \since 5.6
    \brief The QMultiMap::key_iterator class provides an STL-style const iterator for QMultiMap keys.

    QMultiMap::key_iterator is essentially the same as QMultiMap::const_iterator
    with the difference that operator*() and operator->() return a key
    instead of a value.

    For most uses QMultiMap::iterator and QMultiMap::const_iterator should be used,
    you can easily access the key by calling QMultiMap::iterator::key():

    \snippet code/src_corelib_tools_qmultimap.cpp keyiterator1

    However, to have interoperability between QMultiMap's keys and STL-style
    algorithms we need an iterator that dereferences to a key instead
    of a value. With QMultiMap::key_iterator we can apply an algorithm to a
    range of keys without having to call QMultiMap::keys(), which is inefficient
    as it costs one QMultiMap iteration and memory allocation to create a temporary
    QList.

    \snippet code/src_corelib_tools_qmultimap.cpp keyiterator2

    QMultiMap::key_iterator is const, it's not possible to modify the key.

    The default QMultiMap::key_iterator constructor creates an uninitialized
    iterator. You must initialize it using a QMultiMap function like
    QMultiMap::keyBegin() or QMultiMap::keyEnd().

    \warning Iterators on implicitly shared containers do not work
    exactly like STL-iterators. You should avoid copying a container
    while iterators are active on that container. For more information,
    read \l{Implicit sharing iterator problem}.

    \sa QMultiMap::const_iterator, QMultiMap::iterator
*/

/*! \typedef QMultiMap::key_iterator::difference_type
    \internal
*/

/*! \typedef QMultiMap::key_iterator::iterator_category
    \internal
*/

/*! \typedef QMultiMap::key_iterator::pointer
    \internal
*/

/*! \typedef QMultiMap::key_iterator::reference
    \internal
*/

/*! \typedef QMultiMap::key_iterator::value_type
    \internal
*/

/*! \fn template <class Key, class T> const T &QMultiMap<Key, T>::key_iterator::operator*() const

    Returns the current item's key.
*/

/*! \fn template <class Key, class T> const T *QMultiMap<Key, T>::key_iterator::operator->() const

    Returns a pointer to the current item's key.
*/

/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::key_iterator::operator==(key_iterator other) const

    Returns \c true if \a other points to the same item as this
    iterator; otherwise returns \c false.

    \sa operator!=()
*/

/*! \fn template <class Key, class T> bool QMultiMap<Key, T>::key_iterator::operator!=(key_iterator other) const

    Returns \c true if \a other points to a different item than this
    iterator; otherwise returns \c false.

    \sa operator==()
*/

/*!
    \fn template <class Key, class T> QMultiMap<Key, T>::key_iterator &QMultiMap<Key, T>::key_iterator::operator++()

    The prefix ++ operator (\c{++i}) advances the iterator to the
    next item in the hash and returns an iterator to the new current
    item.

    Calling this function on QMultiMap::keyEnd() leads to undefined results.

    \sa operator--()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_iterator QMultiMap<Key, T>::key_iterator::operator++(int)

    \overload

    The postfix ++ operator (\c{i++}) advances the iterator to the
    next item in the hash and returns an iterator to the previous
    item.
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_iterator &QMultiMap<Key, T>::key_iterator::operator--()

    The prefix -- operator (\c{--i}) makes the preceding item
    current and returns an iterator pointing to the new current item.

    Calling this function on QMultiMap::keyBegin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn template <class Key, class T> QMultiMap<Key, T>::key_iterator QMultiMap<Key, T>::key_iterator::operator--(int)

    \overload

    The postfix -- operator (\c{i--}) makes the preceding item
    current and returns an iterator pointing to the previous
    item.
*/

/*! \fn template <class Key, class T> const_iterator QMultiMap<Key, T>::key_iterator::base() const
    Returns the underlying const_iterator this key_iterator is based on.
*/

/*! \typedef QMultiMap::const_key_value_iterator
    \inmodule QtCore
    \since 5.10
    \brief The QMultiMap::const_key_value_iterator typedef provides an STL-style iterator for QMultiMap.

    QMultiMap::const_key_value_iterator is essentially the same as QMultiMap::const_iterator
    with the difference that operator*() returns a key/value pair instead of a
    value.

    \sa QKeyValueIterator
*/

/*! \typedef QMultiMap::key_value_iterator
    \inmodule QtCore
    \since 5.10
    \brief The QMultiMap::key_value_iterator typedef provides an STL-style iterator for QMultiMap.

    QMultiMap::key_value_iterator is essentially the same as QMultiMap::iterator
    with the difference that operator*() returns a key/value pair instead of a
    value.

    \sa QKeyValueIterator
*/

/*! \fn template <class Key, class T> QDataStream &operator<<(QDataStream &out, const QMultiMap<Key, T> &map)
    \relates QMultiMap

    Writes the multi map \a map to stream \a out.

    This function requires the key and value types to implement \c
    operator<<().

    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
*/

/*! \fn template <class Key, class T> QDataStream &operator>>(QDataStream &in, QMultiMap<Key, T> &map)
    \relates QMultiMap

    Reads a map from stream \a in into \a map.

    This function requires the key and value types to implement \c
    operator>>().

    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
*/