The QFutureIterator class provides a Java-style const iterator for QFuture. More...

Public Methods
	QFutureIterator (const QFuture< T > &future)

bool	findNext (const T &value)

bool	findPrevious (const T &value)

bool	hasNext () const

bool	hasPrevious () const

const T &	next ()

QFutureIterator &	operator= (const QFuture< T > &future)

const T &	peekNext () const

const T &	peekPrevious () const

const T &	previous ()

void	toBack ()

void	toFront ()

Detailed Description

template<class T>
class QFutureIterator< T >

The QFutureIterator class provides a Java-style const iterator for QFuture.

QFuture has both Java-style iterators and STL-style iterators. The Java-style iterators are more high-level and easier to use than the STL-style iterators; on the other hand, they are slightly less efficient.

An alternative to using iterators is to use index positions. Some QFuture member functions take an index as their first parameter, making it possible to access results without using iterators.

QFutureIterator<T> allows you to iterate over a QFuture<T>. There is no mutable iterator for QFuture (unlike the other Java-style iterators).

The QFutureIterator constructor takes a QFuture as its argument. After construction, the iterator is located at the very beginning of the result list (i.e. before the first result). Here is how to iterate over all the results sequentially:

QFuture<QString> future;
 
QFutureIterator<QString> i(future);
while (i.hasNext())  {
   qDebug() << i.next();
}

The next() function returns the next result (waiting for it to become available, if necessary) from the future and advances the iterator. Unlike STL-style iterators, Java-style iterators point between results rather than directly at results. The first call to next() advances the iterator to the position between the first and second result, and returns the first result; the second call to next() advances the iterator to the position between the second and third result, and returns the second result; and so on.

Here is how to iterate over the elements in reverse order:

QFutureIterator<QString> i(future);
i.toBack();
 
while (i.hasPrevious())
    qDebug() << i.previous();

If you want to find all occurrences of a particular value, use findNext() or findPrevious() in a loop.

Multiple iterators can be used on the same future. If the future is modified while a QFutureIterator is active, the QFutureIterator will continue iterating over the original future, ignoring the modified copy.

See also: QFuture::const_iterator, QFuture

Constructor & Destructor Documentation

template<class T >

QFutureIterator< T >::QFutureIterator ( const QFuture< T > & future )

inline

Constructs an iterator for traversing future. The iterator is set to be at the front of the result list (before the first result).

See also: operator=()

Method Documentation

template<class T >

bool QFutureIterator< T >::findNext ( const T & value )

inline

Searches for value starting from the current iterator position and moving forward. Returns true if the specified value is found, otherwise it returns false. If value is found the iterator is positioned just after the matching item, otherwise the iterator is positioned at the end of the result list.

See also: findPrevious()

template<class T >

bool QFutureIterator< T >::findPrevious ( const T & value )

inline

Searches for value starting from the current iterator position and moving backward. Returns true if a (key, value) pair with the specified value is found, otherwise it returns false. If value was found the iterator is positioned just before the matching item. Otherwise the iterator is positioned at the beginning of the container.

See also: findNext()

template<class T >

bool QFutureIterator< T >::hasNext ( ) const

inline

Returns true if there is at least one result ahead of the iterator, e.g., the iterator is not at the back of the result list, otherwise returns false.

See also: hasPrevious(), next()

template<class T >

bool QFutureIterator< T >::hasPrevious ( ) const

inline

Returns true if there is at least one result ahead of the iterator, e.g., the iterator is not at the front of the result list, otherwise returns false.