qhash.cpp

qt-x11-opensource-src-4.1.4.tar.gz源码

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

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

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

    Multiple iterators can be used on the same hash. However, be aware
    that any modification performed directly on the QHash has the
    potential of dramatically changing the order in which the items
    are stored in the hash, as they might cause QHash to rehash its
    internal data structure. If you need to keep iterators over a long
    period of time, we recommend that you use QMap rather than QHash.

    \sa QHash::iterator, QHashIterator
*/

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

    \internal
*/

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

/*! \fn QHash::const_iterator::const_iterator(void *node)

    \internal
*/

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

    Constructs a copy of \a other.
*/

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

    Returns the current item's key.

    \sa value()
*/

/*! \fn const T &QHash::const_iterator::value() const

    Returns the current item's value.

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

/*! \fn const T &QHash::const_iterator::operator*() const

    Returns the current item's value.

    Same as value().

    \sa key()
*/

/*! \fn const T *QHash::const_iterator::operator->() const

    Returns a pointer to the current item's value.

    \sa value()
*/

/*! \fn bool QHash::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 QHash::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 QHash::const_iterator &QHash::const_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 QHash::end() leads to undefined results.

    \sa operator--()
*/

/*! \fn QHash::const_iterator QHash::const_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 previously
    current item.
*/

/*! \fn QHash::const_iterator &QHash::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 QHash::begin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn QHash::const_iterator QHash::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.
*/

/*! \fn QHash::const_iterator QHash::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 QHash::const_iterator QHash::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 QHash::const_iterator &QHash::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 QHash::const_iterator &QHash::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 uint qHash(char key)
    \relates QHash

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(uchar key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(signed char key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(ushort key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(short key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(uint key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(int key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(ulong key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(long key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(quint64 key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(qint64 key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(QChar key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(const QByteArray &key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(const QString &key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn uint qHash(const T *key)
    \relates QHash
    \overload

    Returns the hash value for \a key.
*/

/*! \fn QDataStream &operator<<(QDataStream &out, const QHash<Key, T>& hash)
    \relates QHash

    Writes the hash \a hash to stream \a out.

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

    \sa {Format of the QDataStream operators}
*/

/*! \fn QDataStream &operator>>(QDataStream &in, QHash<Key, T> &hash)
    \relates QHash

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

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

    \sa {Format of the QDataStream operators}
*/

/*! \class QMultiHash
    \brief The QMultiHash class is a convenience QHash subclass that provides multi-valued hashes.

    \ingroup tools
    \ingroup shared
    \mainclass
    \reentrant

    QMultiHash\<Key, T\> is one of Qt's generic \l{container classes}.
    It inherits QHash and extends it with a few convenience functions
    that make it more suitable than QHash for storing multi-valued
    hashes. A multi-valued hash is a hash that allows multiple values
    with the same key; QHash normally doesn't allow that, unless you
    call QHash::insertMulti().

    Because QMultiHash inherits QHash, all of QHash's functionality also
    applies to QMultiHash. For example, you can use isEmpty() to test
    whether the hash is empty, and you can traverse a QMultiHash using
    QHash's iterator classes (for example, QHashIterator). But in
    addition, it provides an insert() function that corresponds to
    QHash::insertMulti(), and a replace() function that corresponds to
    QHash::insert(). It also provides convenient operator+() and
    operator+=().

    Example:
    \code
        QMultiHash<QString, int> hash1, hash2, hash3;

        hash1.insert("plenty", 100);
        hash1.insert("plenty", 2000);
        // hash1.size() == 2

        hash2.insert("plenty", 5000);
        // hash2.size() == 1

        hash3 = hash1 + hash2;
        // hash3.size() == 3
    \endcode

    Unlike QHash, QMultiHash provides no operator[]. Use value() or
    replace() if you want to access the most recently inserted item
    with a certain key.

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

    \code
        QList<int> values = hash.values("plenty");
        for (int i = 0; i < values.size(); ++i)
            cout << values.at(i) << endl;
    \endcode

    The items that share the same key are available from most
    recently to least recently inserted.

    A more efficient approach is to call find() to get
    the STL-style iterator for the first item with a key and iterate from
    there:

    \code
        QMultiHash<QString, int>::iterator i = hash.find("plenty");
        while (i != hash.end() && i.key() == "plenty") {
            cout << i.value() << endl;
            ++i;
        }
    \endcode

    QMultiHash's key and value data types must be \l{assignable data
    types}. You cannot, for example, store a QWidget as a value;
    instead, store a QWidget *. In addition, QMultiHash's key type
    must provide 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 details.

    \sa QHash, QHashIterator, QMutableHashIterator, QMultiMap
*/

/*! \fn QMultiHash::QMultiHash()

    Constructs an empty hash.
*/

/*! \fn QMultiHash::QMultiHash(const QHash<Key, T> &other)

    Constructs a copy of \a other (which can be a QHash or a
    QMultiHash).

    \sa operator=()
*/

/*! \fn QMultiHash::iterator QMultiHash::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()
*/

/*! \fn QMultiHash::iterator QMultiHash::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 hash, 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 QMultiHash &QMultiHash::operator+=(const QMultiHash &other)

    Inserts all the items in the \a other hash into this hash
    and returns a reference to this hash.

    \sa insert()
*/

/*! \fn QMultiHash QMultiHash::operator+(const QMultiHash &other) const

    Returns a hash that contains all the items in this hash in
    addition to all the items in \a other. If a key is common to both
    hashes, the resulting hash will contain the key multiple times.

    \sa operator+=()
*/