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GhostISubset

vstd::resource::iset

Struct GhostISubset 

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pub struct GhostISubset<T> { /* private fields */ }
Expand description

A resource that has client ownership of a subset

The existence of a GhostISubset implies that:

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impl<T> GhostISubset<T>

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pub open spec fn is_singleton(self) -> bool

{
    &&& self@.len() == 1
    &&& self@.finite()
    &&& !self@.is_empty()

}

Checks whether the GhostISubset refers to a single value (and thus can be converted to a GhostISingleton).

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pub closed spec fn id(self) -> Loc

Resource location

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pub closed spec fn view(self) -> ISet<T>

Logically underlying ISet

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pub proof fn dummy() -> tracked result : GhostISubset<T>

Instantiate a dummy GhostISubset

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pub proof fn empty(tracked &self) -> tracked result : GhostISubset<T>

ensures
result.id() == self.id(),
result@ == ISet::<T>::empty(),

Create an empty GhostISubset

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pub proof fn take(tracked &mut self) -> tracked result : GhostISubset<T>

ensures
old(self).id() == final(self).id(),
final(self)@.is_empty(),
result == *old(self),
result.id() == final(self).id(),

Extract the GhostISubset from a mutable reference, leaving behind an empty map.

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pub proof fn agree(tracked self: &GhostISubset<T>, tracked auth: &GhostISetAuth<T>)

requires
self.id() == auth.id(),
ensures
self@ <= auth@,

Agreement between a GhostISubset and a corresponding GhostISetAuth

Verus might not have full context of the GhostISetAuth and a corresponding GhostISubset. However, whenever we know that they refer to the same resource (i.e., have matching ids) we can assert that the GhostISubset is a submap of the GhostISetAuth.

proof fn test(tracked &auth: GhostISetAuth<int>, tracked &sub: GhostISubset<int>)
    requires
        auth.id() == sub.id(),
        sub@.contains(1int),
    ensures
        auth@.contains(1int),
{
    sub.agree(auth);
    assert(sub@ <= auth@);
    assert(auth.contains(1int));
}
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pub proof fn combine(tracked &mut self, tracked other: GhostISubset<T>)

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@.union(other@),
old(self)@.disjoint(other@),

Combining two GhostISubsets is possible. We consume the input GhostISubset and merge it into the first. We also learn that they were disjoint.

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pub proof fn combine_singleton(tracked &mut self, tracked other: GhostISingleton<T>)

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@.insert(other@),
!old(self)@.contains(other@),

Combining a GhostISingleton into GhostISubset is possible, in a similar way to the way to combine GhostISubsets.

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pub proof fn disjoint(tracked &mut self, tracked other: &GhostISubset<T>)

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@,
final(self)@.disjoint(other@),

When we have two GhostISubsets we can prove that they have disjoint domains.

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pub proof fn disjoint_persistent(tracked &mut self, tracked other: &GhostPersistentISubset<T>)

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@,
final(self)@.disjoint(other@),

When we have a GhostISubset and a GhostPersistentISubset we can prove that they are in disjoint domains.

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pub proof fn disjoint_singleton(tracked &mut self, tracked other: &GhostISingleton<T>)

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@,
!final(self)@.contains(other@),

When we have a GhostISubset and a GhostISingleton we can prove that they are in disjoint domains.

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pub proof fn disjoint_persistent_singleton( tracked &mut self, tracked other: &GhostPersistentISingleton<T>, )

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@,
!final(self)@.contains(other@),

When we have a GhostISubset and a GhostPersistentISingleton we can prove that they are in disjoint domains.

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pub proof fn split(tracked &mut self, s: ISet<T>) -> tracked result : GhostISubset<T>

requires
s <= old(self)@,
ensures
final(self).id() == old(self).id(),
result.id() == final(self).id(),
old(self)@ == final(self)@.union(result@),
result@ =~= s,
final(self)@ =~= old(self)@ - s,

We can split a GhostISubset based on a set of values

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pub proof fn split_singleton(tracked &mut self, v: T) -> tracked result : GhostISingleton<T>

requires
old(self)@.contains(v),
ensures
final(self).id() == old(self).id(),
result.id() == final(self).id(),
old(self)@ == final(self)@.insert(result@),
result@ == v,
final(self)@ =~= old(self)@.remove(v),

We can separate a single value out of a GhostISubset

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pub proof fn singleton(tracked self) -> tracked r : GhostISingleton<T>

requires
self.is_singleton(),
ensures
self@ == iset![r @],
self.id() == r.id(),

Converting a GhostISubset into a GhostISingleton

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pub proof fn persist(tracked self) -> tracked r : GhostPersistentISubset<T>

ensures
self@ == r@,
self.id() == r.id(),

Converting a GhostISubset into a GhostPersistentISubset

Auto Trait Implementations§

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impl<T> Freeze for GhostISubset<T>

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impl<T> RefUnwindSafe for GhostISubset<T>
where T: RefUnwindSafe,

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impl<T> Send for GhostISubset<T>
where T: Send,

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impl<T> Sync for GhostISubset<T>
where T: Sync,

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impl<T> Unpin for GhostISubset<T>
where T: Unpin,

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impl<T> UnsafeUnpin for GhostISubset<T>

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impl<T> UnwindSafe for GhostISubset<T>
where T: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, VERUS_SPEC__A> FromSpec<T> for VERUS_SPEC__A
where VERUS_SPEC__A: From<T>,

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exec fn obeys_from_spec() -> bool

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exec fn from_spec(v: T) -> VERUS_SPEC__A

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, VERUS_SPEC__A> IntoSpec<T> for VERUS_SPEC__A
where VERUS_SPEC__A: Into<T>,

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exec fn obeys_into_spec() -> bool

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exec fn into_spec(self) -> T

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impl<T, U> IntoSpecImpl<U> for T
where U: From<T>,

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open spec fn obeys_into_spec() -> bool

{ <U as FromSpec<Self>>::obeys_from_spec() }
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open spec fn into_spec(self) -> U

{ U::from_spec(self) }
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, VERUS_SPEC__A> TryFromSpec<T> for VERUS_SPEC__A
where VERUS_SPEC__A: TryFrom<T>,

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exec fn obeys_try_from_spec() -> bool

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exec fn try_from_spec( v: T, ) -> Result<VERUS_SPEC__A, <VERUS_SPEC__A as TryFrom<T>>::Error>

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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T, VERUS_SPEC__A> TryIntoSpec<T> for VERUS_SPEC__A
where VERUS_SPEC__A: TryInto<T>,

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exec fn obeys_try_into_spec() -> bool

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exec fn try_into_spec(self) -> Result<T, <VERUS_SPEC__A as TryInto<T>>::Error>

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impl<T, U> TryIntoSpecImpl<U> for T
where U: TryFrom<T>,

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open spec fn obeys_try_into_spec() -> bool

{ <U as TryFromSpec<Self>>::obeys_try_from_spec() }
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open spec fn try_into_spec(self) -> Result<U, <U as TryFrom<T>>::Error>

{ <U as TryFromSpec<Self>>::try_from_spec(self) }
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impl<A> SpecEq<&A> for A
where A: ?Sized,

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impl<A> SpecEq<&mut A> for A
where A: ?Sized,

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impl<A> SpecEq<A> for A
where A: ?Sized,

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impl<A> SpecEq<Ghost<A>> for A

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impl<A> SpecEq<Tracked<A>> for A