revset: added __sub__ mehtod to _addset This method is intended to duck-type baseset, so we will still have _addset as a private class but now will be able to return it without wrapping it into an orderedlazyset or a lazyset.

revset: added __and__ method to _addset This method is intended to duck-type baseset, so we will still have _addset as a private class but we will be able to return it without wrapping it into an orderedlazyset or a lazyset.

revset: added ascending and descending methods to _addset This methods are intended to duck-type baseset, so we will still have _addset as a private class but will be able return it without wrapping it into an orderedlazyset or a lazyset.

revset: added filter method to _addset This method is intended to duck-type baseset, so we will still have _addset as a private class but we will be able return it without wrapping it into an orderedlazyset or a lazyset.

revset: added comments to all methods needed to duck-type from baseset All this methods are required to duck-type for any class that works as a smart set.

revset: use more explicit argument names for baseset methods Use other instead of x and condition instead of l

revset: added isascending and isdescending methods to smartset classes This methods state if the class is sorted in an ascending or descending order We need this to implement methods based on order on smartset classes in order to be able to create new objects with a given order. We cannot just rely on a simple boolean since unordered set are neither ascending nor descending.

revset: added sort method in addset We need this method to duck-type generatorset since this class is not going to be used outside revset.py and we don't need to duck-type baseset. This sort method will only do something when the addset is not already sorted or is not sorted in the way we want it to be.

revset: added reverse method to addset This method is needed to duck type generatorset.

revset: changed _iterator() method on addset to work with a given order If the two collections are in ascending order, yield their values in an ordered way by iterating both at the same time and picking the values to yield.