CopperSpice API  1.7.2
QHashIterator< Key, Val, Hash, KeyEqual > Class Template Reference

Java style const iterator for QHash. More...

Public Methods

 QHashIterator (const QHash< Key, Val, Hash, KeyEqual > &hash)
 
 ~QHashIterator ()
 
bool findNext (const Val &value)
 
bool findPrevious (const Val &value)
 
bool hasNext () const
 
bool hasPrevious () const
 
const Key & key () const
 
Item next ()
 
QHashIterator & operator= (const QHash< Key, Val, Hash, KeyEqual > &hash)
 
Item peekNext () const
 
Item peekPrevious () const
 
Item previous ()
 
void toBack ()
 
void toFront ()
 
const Val & value () const
 

Detailed Description

template<typename Key, typename Val, typename Hash, typename KeyEqual>
class QHashIterator< Key, Val, Hash, KeyEqual >

The QHashIterator class provides a Java style const iterator for QHash. QHash has both Java style iterators and STL style iterators.

QMutableHashIterator allows you to iterate over a QHash and modify the map. If you do not want to modify the map use QHashIterator instead.

After construction the iterator is located at the very beginning of the hash, before the first item. The following code shows how to iterate over all the elements sequentially.

while (iter.hasNext()) {
iter.next();
qDebug() << iter.key() << ": " << iter.value();
}

The next() method returns the next item in the map and advances the iterator. The key() and value() methods return the key and value of the last item which that was jumped over.

Unlike STL style iterators, Java style iterators point between items rather than directly at items. The first call to next() advances the iterator to the position between the first and second item, and returns the first item; the second call to next() advances the iterator to the position between the second and third item, and so on.

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

iter.toBack();
while (iter.hasPrevious()) {
iter.previous();
qDebug() << iter.key() << ": " << iter.value();
}

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

while (iter.findNext(widget)) {
qDebug() << "Found widget " << widget << " under key " << iter.key();
}
See also
QMutableHashIterator

Constructor & Destructor Documentation

template<typename Key , typename Val , typename Hash , typename KeyEqual >
QHashIterator< Key, Val, Hash, KeyEqual >::QHashIterator ( const QHash< Key, Val, Hash, KeyEqual > &  hash)
inline

Constructs an iterator for traversing hash. The iterator is set to the front of the hash, before the first item.

See also
operator=()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
QHashIterator< Key, Val, Hash, KeyEqual >::~QHashIterator ( )
inline

Destroys the iterator.

See also
operator=()

Method Documentation

template<typename Key , typename Val , typename Hash , typename KeyEqual >
bool QHashIterator< Key, Val, Hash, KeyEqual >::findNext ( const Val &  value)
inline

Searches for value starting from the current iterator position forward. Returns true if a (key, value) pair with value value is found, otherwise it returns false.

If value was found the iterator is positioned just after the matching item, otherwise the iterator is positioned at the end of the container.

See also
findPrevious()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
bool QHashIterator< Key, Val, Hash, KeyEqual >::findPrevious ( const Val &  value)
inline

Searches for value starting from the current iterator position backward. Returns true if a (key, value) pair with value 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 front of the container.

See also
findNext()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
bool QHashIterator< Key, Val, Hash, KeyEqual >::hasNext ( ) const
inline

Returns true if there is at least one item ahead of the iterator. For example, the iterator is not at the end of the container. Otherwise this method returns false.

See also
hasPrevious(), next()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
bool QHashIterator< Key, Val, Hash, KeyEqual >::hasPrevious ( ) const
inline

Returns true if there is at least one item behind the iterator. For example, the iterator is not at the front of the container. Otherwise this method returns false.

See also
hasNext(), previous()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
const Key & QHashIterator< Key, Val, Hash, KeyEqual >::key ( ) const
inline

Returns the key of the last item that was jumped over using one of the traversal methods (next(), previous(), findNext(), findPrevious()).

After a call to next() or findNext(), key() is equivalent to peekPrevious().key(). After a call to previous() or findPrevious(), key() is equivalent to peekNext().key().

See also
value()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
Item QHashIterator< Key, Val, Hash, KeyEqual >::next ( )
inline

Returns the next item and advances the iterator by one position. Use the key() method on the return value to obtain the item's key, and value() to obtain the value.

This method must not be called on an iterator located at the end of the container, it has undefined behavior.

See also
hasNext(), peekNext(), previous()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
QHashIterator & QHashIterator< Key, Val, Hash, KeyEqual >::operator= ( const QHash< Key, Val, Hash, KeyEqual > &  hash)
inline

Resets the iterator to the front of the given hash, before the first item.

See also
toFront(), toBack()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
Item QHashIterator< Key, Val, Hash, KeyEqual >::peekNext ( ) const
inline

Returns the next item without moving the iterator. Call key() on the return value to obtain the item's key, and value() to obtain the value.

This method must not be called on an iterator located at the end of the container, it has undefined behavior.

See also
hasNext(), next(), peekPrevious()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
Item QHashIterator< Key, Val, Hash, KeyEqual >::peekPrevious ( ) const
inline

Returns the previous item without moving the iterator. Call key() on the return value to obtain the item's key, and value() to obtain the value.

This method must not be called on an iterator located at the front of the container, it has undefined behavior.

See also
hasPrevious(), previous(), peekNext()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
Item QHashIterator< Key, Val, Hash, KeyEqual >::previous ( )
inline

Returns the previous item and moves the iterator back by one position. Call key() on the return value to obtain the item's key, and value() to obtain the value.

This method must not be called on an iterator located at the front of the container, it has undefined behavior.

See also
hasPrevious(), peekPrevious(), next()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
void QHashIterator< Key, Val, Hash, KeyEqual >::toBack ( )
inline

Moves the iterator to the end of the container, after the last item.

See also
toFront(), previous()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
void QHashIterator< Key, Val, Hash, KeyEqual >::toFront ( )
inline

Moves the iterator to the front of the container, before the first item.

See also
toBack(), next()
template<typename Key , typename Val , typename Hash , typename KeyEqual >
const Val & QHashIterator< Key, Val, Hash, KeyEqual >::value ( ) const
inline

Returns the value of the last item that was jumped over using one of the traversal methods (next(), previous(), findNext(), findPrevious()).

After a call to next() or findNext(), value() is equivalent to peekPrevious().value(). After a call to previous() or findPrevious(), value() is equivalent to peekNext().value().

See also
key()