Module type State.Local

module type Local = sig .. end
Operations on the local state required for registering a new state via State_builder.Register. The local state is the mutable value which you would like to be project-compliant.

type t 
Type of the state to register.
val create : unit -> t
How to create a new fresh state which must be equal to the initial state: that is, if you never change the state, create () and get
        ()
must be equal (see invariant 1 below).
val clear : t -> unit
How to clear a state. After clearing, the state should be observationally the same that after its creation (see invariant 2 below).
val get : unit -> t
How to access to the current state. Be aware of invariants 3 and 4 below.
val set : t -> unit
How to change the current state. Be aware of invariants 3 and 4 below.

The four following invariants must hold.
  1. create () returns a fresh value
  2. forall (p:t) copy p returns a fresh value
  3. forall (p:t), create () = (clear p; set p; get ())
  4. forall (p1:t),(p2:t) such that p1 != p2, (set p1; get ()) != s2

val clear_some_projects : (Project_skeleton.t -> bool) -> t -> bool
clear_if_project f x must clear any value v of type project of x such that f v is true. Of course, if the type t does not contain any object of type project, this function should do nothing and safely returns fun _ -> false.
Since Boron-20100401
Returns true iff at least one element of x has been cleared.