This section describes the basic tree operations on weight balanced trees. These operations are the usual tree operations for insertion, deletion and lookup, some predicates and a procedure for determining the number of associations in a tree. This operation takes constant time. Returns a new tree containing all the associations in wt-tree and the association of datum with key . If wt-tree already had an association for key , the new association overrides the old.
Associates datum with key in wt-tree and returns an unspecified value.
If wt-tree already has an association for key , that association is replaced. If wt-tree doesn't contain an association for key , default is returned. If wt-tree contains an association for key the association is removed. Returns an unspecified value.