qmap.cpp

qt-x11-opensource-src-4.1.4.tar.gz源码

    \sa count()
*/

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

    Returns the value associated with the key \a key.

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

    \sa key(), values(), contains(), operator[]()
*/

/*! \fn const T QMap::value(const Key &key, const T &defaultValue) const

    \overload

    If the map contains no item with key \a key, the function returns
    \a defaultValue.
*/

/*! \fn T &QMap::operator[](const Key &key)

    Returns the value associated with the key \a key as a modifiable
    reference.

    If the map contains no item with key \a key, the function inserts
    a \l{default-constructed value} into the map with key \a key, and
    returns a reference to it. If the map contains multiple items
    with key \a key, this function returns a reference to the most
    recently inserted value.

    \sa insert(), value()
*/

/*! \fn const T QMap::operator[](const Key &key) const

    \overload

    Same as value().
*/

/*! \fn QList<Key> QMap::keys() const

    Returns a list containing all the keys in the map in ascending
    order. Keys that occur multiple times in the map (because items
    were inserted with insertMulti(), or unite() was used), also
    occur multiple times in the list.

    To obtain a list of unique keys, where each key from the map only
    occurs once, use an intermediate QSet object to filter out
    duplicates.

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

    \sa values(), key()
*/

/*! \fn QList<Key> QMap::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 QMap's
    internal data structure is optimized for fast lookup by key, not
    by value.
*/

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

    Returns the first key with value \a value.

    If the map contains no item with value \a value, the function
    returns a \link {default-constructed value} default-constructed
    key \endlink.

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

    \sa value(), values()
*/

/*! \fn QList<T> QMap::values() const

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

    \sa keys()
*/

/*! \fn QList<T> QMap::values(const Key &key) const

    \overload

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

    \sa count(), insertMulti()
*/

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

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

    \sa contains(), insertMulti()
*/

/*! \fn int QMap::count() const

    \overload

    Same as size().
*/

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

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

    \sa constBegin(), end()
*/

/*! \fn QMap::const_iterator QMap::begin() const

    \overload
*/

/*! \fn QMap::const_iterator QMap::constBegin() const

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

    \sa begin(), constEnd()
*/

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

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

    \sa begin(), constEnd()
*/

/*! \fn QMap::const_iterator QMap::end() const

    \overload
*/

/*! \fn QMap::const_iterator QMap::constEnd() const

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

    \sa constBegin(), end()
*/

/*! \fn QMap::iterator QMap::erase(iterator pos)

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

    \sa remove()
*/

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

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

    If the 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:

    \code
        QMap<QString, int> map;
        ...
        QMap<QString, int>::const_iterator i = map.find("HDR");
        while (i != map.end() && i.key() == "HDR") {
            cout << i.value() << endl;
            ++i;
        }
    \endcode

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

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

    \overload
*/

/*! \fn QMap::iterator QMap::constFind(const Key &key) const
    \since 4.1

    Returns an const iterator pointing to the item with key \a key in the
    map.
    
    If the map contains no item with key \a key, the function
    returns constEnd().

    \sa find()
*/

/*! \fn QMap::iterator QMap::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:
    \code
        QMap<int, QString> map;
        map.insert(1, "one");
        map.insert(5, "five");
        map.insert(10, "ten");

        map.lowerBound(0);      // returns iterator to (1, "one")
        map.lowerBound(1);      // returns iterator to (1, "one")
        map.lowerBound(2);      // returns iterator to (5, "five")
        map.lowerBound(10);     // returns iterator to (10, "ten")
        map.lowerBound(999);    // returns end()
    \endcode

    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:

    \code
        QMap<QString, int> map;
        ...
        QMap<QString, int>::const_iterator i = map.lowerBound("HDR");
        QMap<QString, int>::const_iterator upperBound = map.upperBound("HDR");
        while (i != upperBound) {
            cout << i.value() << endl;
            ++i;
        }
    \endcode

    \sa qLowerBound(), upperBound(), find()
*/

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

    \overload
*/

/*! \fn QMap::iterator QMap::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:
    \code
        QMap<int, QString> map;
        map.insert(1, "one");
        map.insert(5, "five");
        map.insert(10, "ten");

        map.upperBound(0);      // returns iterator to (1, "one")
        map.upperBound(1);      // returns iterator to (5, "five")
        map.upperBound(2);      // returns iterator to (5, "five")
        map.upperBound(10);     // returns end()
        map.upperBound(999);    // returns end()
    \endcode

    \sa qUpperBound(), lowerBound(), find()
*/

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

    \overload
*/

/*! \fn QMap::iterator QMap::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 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 insertMulti()
*/

/*! \fn QMap::iterator QMap::insertMulti(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 insert(), which overwrites the value of an
    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.
*/

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

    This function is provided for STL compatibility. It is equivalent
    to isEmpty().
*/

/*! \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.