Added missing operations and type aliases so collection iterators fulfill LegacyInputIterator and std::input_iterator concept
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Fixes: #150, fixes #272
Conflicts: #273
Implement missing features so CollectionIterators and MutableCollectionIterators fulfill the requirements imposed on the C++ iterators (#598). It's expected than not all requirements can be fulfilled as some are in direct conflict with podio design:
LegacyForwardIterator: dereference should return a reference, but in podio iterators are 'proxy iterators' returning user layer objects as a proxy for reference
LegacyForwardItertor: dereferencing two iterators that are equal should give two references bound to the same object, but in podio the returned 'proxies' are different objects
std::forward_iterator: pointers and references obtained from an iterator should be valid as range the range is valid, but in podio the iterators behave like 'stashing iterators' -> pointers point to iterator member variable limiting their validity to the lifetime of the iterator.
As a consequence the iterators can the podio iterators can be at most LegacyInputIterator and std::input_iterator. This PR implements missing features to achieve this.
List of changes:
Named requirements:
[x] LegacyIterator:
[x] copy constructor and assignment
[x] type aliases
[x] LegacyInputIterator:
[x] postfix increment
[ ] LegacForwardIterator:
[x] value-initialization
[ ] dereference return reference not proxy
[ ] dereferencing equal iterators returns references to the same object
[ ] OutputIterator:
[ ] assignment should modify collection
[x] iterator_category is std::input_iterator_tag
[ ] check selected algorithms operating on LegacyInputIterators
Concepts:
[x] semantics checks for concepts
[x] std::input_or_output_iterator
[x] same as LegacyIterator but copyability not required
[x] std::input_iterator
[x] std::indirectly_readable and std::readable (can dereference both iterator and const iterator)
[ ] std::forward_iterator
[x] syntax: constrains (except iterator_concept to be derived fromstd::forward_iterator_tag)
[ ] semantic: pointers obtained from iterator should remain valid as long as range is valid (no-stashing)
[x] iterator_concept is std::input_iterator_tag
[ ] check selected range algorithms constrained to std::input_iterator
BEGINRELEASENOTES
ENDRELEASENOTES
Fixes: #150, fixes #272 Conflicts: #273
Implement missing features so
CollectionIteratorsandMutableCollectionIteratorsfulfill the requirements imposed on the C++ iterators (#598). It's expected than not all requirements can be fulfilled as some are in direct conflict with podio design:std::forward_iterator: pointers and references obtained from an iterator should be valid as range the range is valid, but in podio the iterators behave like 'stashing iterators' -> pointers point to iterator member variable limiting their validity to the lifetime of the iterator.As a consequence the iterators can the podio iterators can be at most LegacyInputIterator and
std::input_iterator. This PR implements missing features to achieve this.List of changes:
Named requirements:
iterator_categoryisstd::input_iterator_tagConcepts:
std::input_or_output_iteratorstd::input_iteratorstd::indirectly_readableandstd::readable(can dereference bothiteratorandconst iterator)std::forward_iteratoriterator_conceptto be derived fromstd::forward_iterator_tag)iterator_conceptisstd::input_iterator_tagstd::input_iterator