Struct LocalInvariant 

pub struct LocalInvariant<T: Protocol> { /* private fields */ }

A ghost structure, that holds a piece of data (T) together with an protocol.

Implementations

impl<T: Protocol> LocalInvariant<T>

pub fn new( value: Ghost<T>, public: Snapshot<T::Public>, namespace: Snapshot<Namespace>, ) -> Ghost<Self>

Construct a LocalInvariant

Parameters

• value: the actual data contained in the invariant. Use Self::open to access it. Also called the ‘private’ part of the invariant.
• public: the ‘public’ part of the invariant.
• namespace: the namespace of the invariant. This is required to avoid opening the same invariant twice.

requires

value.protocol(*public)

ensures

result.public() == *public

ensures

result.namespace() == *namespace

terminates

ghost

pub fn namespace(self) -> Namespace

Get the namespace associated with this invariant.

(opaque)

pub fn public(self) -> T::Public

Get the ‘public’ part of this invariant.

(opaque)

pub fn open<'a, A>( this: Ghost<&'a Self>, tokens: Ghost<Tokens<'a>>, f: impl FnOnce(Ghost<&'a mut T>) -> A, ) -> A

Open the invariant to get the data stored inside.

This will call the closure f with the inner data. You must restore the contained Protocol before returning from the closure.

requires

tokens.contains(this.namespace())

requires

forall<t: Ghost<&mut T>> t.protocol(this.public()) && inv(t) ==>
        f.precondition((t,)) &&
        // f must restore the invariant
        (forall<res: A> f.postcondition_once((t,), res) ==> (^t).protocol(this.public()))

ensures

exists<t: Ghost<&mut T>> t.protocol(this.public()) && f.postcondition_once((t,), result)

pub fn open_const<'a>(&'a self, tokens: &'a Tokens<'_>) -> &'a T

Open the invariant to get the data stored inside, immutably. This allows reentrant access to the invariant.

requires

tokens.contains(self.namespace())

ensures

result.protocol(self.public())

terminates

ghost