Hash tables for hash consing.
Hash consed values are of the
hash_consed. The field
tag contains a unique
integer (for values hash consed with the same table). The field
hkey contains the hash key of the value (without modulo) for
possible use in other hash tables (and internally when hash
consing tables are resized). The field
node contains the value
Hash consing tables are using weak pointers, so that values that are no more referenced from anywhere else can be erased by the GC.
Generic part, using ocaml generic equality and hash function.
create n creates an empty table of initial size
n. The table
will grow as needed.
hashcons t n hash-cons the value
n using table
t i.e. returns
any existing value in
t equal to
n, if any; otherwise, allocates
a new one hash-consed value of node
n and returns it.
As a consequence the returned value is physically equal to
any equal value already hash-consed using table
Return statistics on the table. The numbers are, in order: table length, number of entries, sum of bucket lengths, smallest bucket length, median bucket length, biggest bucket length.