qmap.cpp

奇趣公司比较新的qt/emd版本

    existing item.)

    \sa insert(), values()
*/

/*! \fn QMap<Key, T> &QMap::unite(const QMap<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.

    \sa insertMulti()
*/

/*! \typedef QMap::Iterator

    Qt-style synonym for QMap::iterator.
*/

/*! \typedef QMap::ConstIterator

    Qt-style synonym for QMap::const_iterator.
*/

/*! \typedef QMap::difference_type

    Typedef for ptrdiff_t. Provided for STL compatibility.
*/

/*! \typedef QMap::key_type

    Typedef for Key. Provided for STL compatibility.
*/

/*! \typedef QMap::mapped_type

    Typedef for T. Provided for STL compatibility.
*/

/*! \typedef QMap::size_type

    Typedef for int. Provided for STL compatibility.
*/

/*! 
    \fn bool QMap::empty() const

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

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

    QMap 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.

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

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

    \code
        QMap<QString, int> map;
        map.insert("January", 1);
        map.insert("February", 2);
        ...
        map.insert("December", 12);

        QMap<QString, int>::iterator i;
        for (i = map.begin(); i != map.end(); ++i)
            cout << i.key() << ": " << i.value() << endl;
    \endcode

    Unlike QHash, which stores its items in an arbitrary order, QMap
    stores its items ordered by key. Items that share the same key
    (because they were inserted using QMap::insertMulti(), or due to a
    unite()) 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
    QMap::iterator that we cannot do with a QMap::const_iterator.
    Here's an example that increments every value stored in the QMap
    by 2:

    \code
        QMap<QString, int>::iterator i;
        for (i = map.begin(); i != map.end(); ++i)
            i.value() += 2;
    \endcode

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

    \code
        QMap<QString, int>::iterator i = map.begin();
        while (i != map.end()) {
            if (i.key().startsWith("_"))
                i = map.erase(i);
            else
                ++i;
        }
    \endcode

    The call to QMap::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:

    \code
        QMap<QString, int>::iterator i = map.begin();
        while (i != map.end()) {
            QMap<QString, int>::iterator prev = i;
            ++i;
            if (prev.key().startsWith("_"))
                map.erase(prev);
        }
    \endcode

    It might be tempting to write code like this:

    \code
        // WRONG
        while (i != map.end()) {
            if (i.key().startsWith("_"))
                map.erase(i);
            ++i;
        }
    \endcode

    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.

    \sa QMap::const_iterator, QMutableMapIterator
*/

/*! \fn QMap::iterator::operator QMapData::Node *() const

    \internal
*/

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

    \internal
*/

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

    \internal
*/

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

    \internal
*/

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

    \internal
*/

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

    \internal
*/

/*! \fn QMap::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 QMap::begin() QMap::end()
*/

/*! \fn QMap::iterator::iterator(QMapData::Node *node)

    \internal
*/

/*! \fn const Key &QMap::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 QMap::erase()
    followed by QMap::insert() or QMap::insertMulti().

    \sa value()
*/

/*! \fn T &QMap::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:

    \code
        if (i.key() == "Hello")
            i.value() = "Bonjour";
    \endcode

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

/*! \fn T &QMap::iterator::operator*() const

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

    Same as value().

    \sa key()
*/

/*! \fn T *QMap::iterator::operator->() const

    Returns a pointer to the current item's value.

    \sa value()
*/

/*!
    \fn bool QMap::iterator::operator==(const iterator &other) const
    \fn bool QMap::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 QMap::iterator::operator!=(const iterator &other) const
    \fn bool QMap::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 QMap::iterator QMap::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 QMap::end() leads to undefined results.

    \sa operator--()
*/

/*! \fn QMap::iterator QMap::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 QMap::iterator QMap::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 QMap::begin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn QMap::iterator QMap::iterator::operator--(int)

    \overload

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

/*! \fn QMap::iterator QMap::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 QMap::iterator QMap::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 QMap::iterator &QMap::iterator::operator+=(int j)

    Advances the iterator by \a j items. (If \a j is negative, the
    iterator goes backward.)

    \sa operator-=(), operator+()
*/

/*! \fn QMap::iterator &QMap::iterator::operator-=(int j)

    Makes the iterator go back by \a j items. (If \a j is negative,
    the iterator goes forward.)

    \sa operator+=(), operator-()
*/

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

    QMap 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.

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

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

    \code
        QMap<QString, int> map;
        map.insert("January", 1);
        map.insert("February", 2);
        ...
        map.insert("December", 12);

        QMap<QString, int>::const_iterator i;
        for (i = map.constBegin(); i != map.constEnd(); ++i)
            cout << i.key() << ": " << i.value() << endl;
    \endcode

    Unlike QHash, which stores its items in an arbitrary order, QMap
    stores its items ordered by key. Items that share the same key
    (because they were inserted using QMap::insertMulti()) will
    appear consecutively, from the most recently to the least
    recently inserted value.

    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.

    \sa QMap::iterator, QMapIterator
*/

/*! \fn QMap::const_iterator::operator QMapData::Node *() const

    \internal
*/

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

    \internal
*/

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

    \internal
*/

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

    \internal
*/

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

    \internal
*/

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

    \internal
*/

/*! \fn QMap::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 QMap::constBegin() QMap::constEnd()
*/

/*! \fn QMap::const_iterator::const_iterator(QMapData::Node *node)

    \internal
*/

/*! \fn QMap::const_iterator::const_iterator(const iterator &other)

    Constructs a copy of \a other.
*/

/*! \fn const Key &QMap::const_iterator::key() const

    Returns the current item's key.