KDE 4.2 API Reference soprano
Soprano::Iterator< T > Class Template Reference
#include <Soprano/Iterator>
Detailed Description
template<typename T>
class Soprano::Iterator< T >
The basic Soprano iterator class.
Iterators in Soprano are very easy to use through two methods next() and current(). Instead of the latter operator*() can also be used. Both can be called subsequetially to retrieve the current element until next() has been called again.
Soprano::Iterator<X> it; while( it.next() ) { doSomething( *it ); doSomethingElse( it.current() ); }
Many backends do lock the underlying Model during iteration. Thus, it is always a good idea to cache the results if they are to be used to modify the model to prevent a deadlock:
Soprano::StatementIterator it = model->listStatements(); QList<Statement> allStatements = it.allElements(); Q_FOREACH( Soprano::Statement s, allStatements ) { modifyTheModel( model, s ); }
Iterators have to be closed. This can either be achieved by deleting the iterator, finishing it (next() does return false), or calling close(). Before that other operations on the Model may block.
Iterators are not thread-safe. Two threads using the same iterator may result in undefined behaviour and even crashes. An iterator needs to be closed by the same thread that opened it (except if the iterator contains special code to handle such a situation.)
- Warning:
- Be aware that iterators in Soprano are shared objects which means that copies of one iterator object work on the same data.
Definition at line 78 of file iterator.h.
Public Member Functions | |
| QList< T > | allElements () |
| void | close () |
| T | current () const |
| bool | isValid () const |
| Iterator (const Iterator &sti) | |
| Iterator (IteratorBackend< T > *sti) | |
| Iterator () | |
| bool | next () |
| T | operator * () const |
| Iterator & | operator= (const Iterator &) |
| virtual | ~Iterator () |
Protected Member Functions | |
| IteratorBackend< T > * | backend () const |
| void | setBackend (IteratorBackend< T > *b) |
Constructor & Destructor Documentation
| Soprano::Iterator< T >::Iterator | ( | ) |
Creates and empty, invalid iterator.
| Soprano::Iterator< T >::Iterator | ( | IteratorBackend< T > * | sti | ) |
| Soprano::Iterator< T >::Iterator | ( | const Iterator< T > & | sti | ) |
| virtual Soprano::Iterator< T >::~Iterator | ( | ) | [virtual] |
Member Function Documentation
| QList<T> Soprano::Iterator< T >::allElements | ( | ) |
Convenience method which extracts all elements (this does not include the elements that have already been read from the iterator) from the iterator and returns them in a list.
Be aware that after calling this method the iterator will be invalid.
- Returns:
- A list of all elements that rest in the iterator.
| IteratorBackend<T>* Soprano::Iterator< T >::backend | ( | ) | const [protected] |
| void Soprano::Iterator< T >::close | ( | ) |
Close the iterator and release any locks on the underlying Model.
| T Soprano::Iterator< T >::current | ( | ) | const |
Get the element the iterator currently points to.
Be aware that a valid current element is only available if next() returned true.
- Returns:
- the current element.
| bool Soprano::Iterator< T >::isValid | ( | ) | const |
| bool Soprano::Iterator< T >::next | ( | ) |
Advances to the next element in the iterator.
- Returns:
- true if another element can be read from the iterator, false if the end has been reached.
| T Soprano::Iterator< T >::operator * | ( | ) | const |
Retrieve the current element in the iterator.
This is equivalent to current().
- Returns:
- The element the iterator currently points to or an invalid one if next has never been called.
| Iterator& Soprano::Iterator< T >::operator= | ( | const Iterator< T > & | ) |
| void Soprano::Iterator< T >::setBackend | ( | IteratorBackend< T > * | b | ) | [protected] |
Set the backend to read the actual data from.
A previous backend will be deleted if there are no other Iterator instances using it.
The documentation for this class was generated from the following file:
