An instance of a stamped hashtable

The changelog datastructure logs stamped bindings added to tables. By separating the log from the table, it is possible to efficiently remove stamped bindings spread accross multiple tables.

create changelog n creates a new table with an initial size of n (see Hashtbl.create) that logs its changes to changelog.

Add a binding, like Hashtbl.add, with an optional stamp. Unlike Hashtbl.add, having multiple bindings with the same key is undefined. (It's ok, this feature is not used by the caches!)

See Hashtbl.mem.

See Hashtbl.find.

See Hashtbl.fold.

Clear the table and empty the changelog. See Hashtbl.clear.

Create a new change log.

This operation is unsafe in general. Only replacements that does not imply re-stamping are safe.