Iterators that can predict number of values
PredictiveIterator is a special kind of Iterator that can know how many values it will (still) generate without actually needing to generate those values.
The main addition to the API of the Iterator role, is the
count-only method, which should return the number of values the Iterator is still able to generate.
The other addition is the
bool-only method, that should return a
Bool indicating whether the Iterator is still capable of producing values (aka, is not exhausted yet). By default, this is the Booleanification of the result of the call to the
method count-only(--> Int)
It is expected to return the number of values the iterator can still produce without actually producing them. The returned number must adjust itself for items already pulled, so that the method can be called on a partially consumed
It will be used in situations where only the number of values of an iterator is needed, e.g. when the
.elems method is called.
Important: it's expected the
Iterators that implement this method can return that number without producing any values. In other words, it's expected the user of the class will be able to still pull-one after calling this method, and eventually receive as many values as the return value of this method indicated.
Defaults to the Booleanification of the result of calling the
count-only method. If it is possible to have a faster way of finding out whether the iterator is capable of producing any value, it should be implemented.
method bool-only(--> Bool)