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An ExtensibleSequence is an extensible Sequence
with some special methods to treat both ends as queues. It provides
the following additional protocol:
- addFirst:
- inserts the given object at the beginning of
the sequence.
- addLast:
- inserts the given object at the end of the sequence.
- add:
- inserts the given object at the end of the sequence
(it's addLast:).
- first:
- answers a sequence of the first N elements.
- last:
- answers a sequence of the final N elements.
- removeFirst
- removes the first element from the sequence.
- removeLast
- removes the final element from the sequence.
A SortedSequence behaves similarly except that it will arrange
for its members to remain sorted according to a block closure that
compares two individual elements; as a result, it should not be manipulated
except via add: and remove: since it maintains its
own ordering. A Heap is a SortedSequence designed
for collecting elements in arbitrary order, and removing the first
elements.
Brian Rice
2004-08-24