Builder

A generic builder of the persistent map. Builder exposes its modification operations through the MutableMap interface.

Builders are reusable, that is build method can be called multiple times with modifications between these calls. However, modifications applied do not affect previously built persistent map instances.

Builder is backed by the same underlying data structure as the persistent map it was created from. Thus, builder and build methods take constant time passing the backing storage to the new builder and persistent map instances, respectively.

The builder tracks which nodes in the structure are shared with the persistent map, and which are owned by it exclusively. It owns the nodes it copied during modification operations and avoids copying them on subsequent modifications.

When build is called the builder forgets about all owned nodes it had created.