This module provides a sort of store data structure - terms can be added to the store and then accessed using a reference term which is returned by store_add//2.

The type ref(A) denotes the type of store references that point to terms of type A.

All predicates except store_new/1 take store input and output arguments at the end so they can easily be used in a DCG with the store as threaded state variable.

 store_new(-H:store) is det

Unifies H with an empty store.

 store_add(+V:A, -R:ref(A), +H1:store, -H2:store) is det

Add V to store and return R as a reference to it.

 store_get(+R:ref(A), -V:A, +H1:store, -H2:store) is det

Get term refered to by reference R.

 store_contains(-R:ref(A), -V:A, +H1:store, -H2:store) is nondet

True if store contains A under reference R.

 store_set(+R:ref(A), -V:A, +H1:store, -H2:store) is det

Update the term referred to by R to take the new values V.

 store_upd(+R:ref(A), X1:A, X2:A, +H1:store, -H2:store) is det

Unify X1 with the value of R in H1 and replace the value with X2 to get H2. The same effect can be achieved with store_apply//2 but this saves a metacall.

 store_apply(+R:ref(A), Op:pred(A,A), +H1:store, -H2:store) is det

Apply binary predicate Op to the term in the store reference by R. The old value is replaced by the new value return by Op in its second argument.