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GhostISubmap

vstd::resource::imap

Struct GhostISubmap 

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pub struct GhostISubmap<K, V> { /* private fields */ }
Expand description

A resource that asserts client ownership of a submap.

The existence of a GhostISubmap implies that:

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impl<K, V> GhostISubmap<K, V>

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pub open spec fn is_points_to(self) -> bool

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

}

Checks whether the GhostISubmap refers to a single key (and thus can be converted to a GhostIPointsTo).

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pub closed spec fn id(self) -> Loc

Resource location

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pub closed spec fn view(self) -> IMap<K, V>

Logically underlying IMap

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pub open spec fn dom(self) -> ISet<K>

{ self@.dom() }

Domain of the GhostISubmap

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pub open spec fn spec_index(self, key: K) -> V

recommends
self.dom().contains(key),
{ self@[key] }

Indexing operation submap[key]

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pub proof fn dummy() -> tracked result : GhostISubmap<K, V>

Instantiate a dummy GhostISubmap

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pub proof fn empty(tracked &self) -> tracked result : GhostISubmap<K, V>

ensures
result.id() == self.id(),
result@ == IMap::<K, V>::empty(),

Create an empty GhostISubmap

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pub proof fn take(tracked &mut self) -> tracked result : GhostISubmap<K, V>

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

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

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pub proof fn agree(tracked self: &GhostISubmap<K, V>, tracked auth: &GhostIMapAuth<K, V>)

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

Agreement between a GhostISubmap and a corresponding GhostIMapAuth

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

proof fn test(tracked &auth: GhostIMapAuth<int, int>, tracked &sub: GhostISubmap<int, int>)
    requires
        auth.id() == sub.id(),
        sub.dom().contains(1int),
        sub[1int] == 1int,
    ensures
        auth[1int] == 1int
{
    sub.agree(auth);
    assert(sub@ <= auth@);
    assert(auth[1int] == 1int);
}
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pub proof fn combine(tracked &mut self, tracked other: GhostISubmap<K, V>)

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

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

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pub proof fn combine_points_to(tracked &mut self, tracked other: GhostIPointsTo<K, V>)

requires
old(self).id() == other.id(),
ensures
final(self).id() == old(self).id(),
final(self)@ == old(self)@.insert(other.key(), other.value()),
!old(self)@.contains_key(other.key()),

Combining a GhostIPointsTo into GhostISubmap is possible, in a similar way to the way to combine GhostISubmaps.

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pub proof fn disjoint(tracked &mut self, tracked other: &GhostISubmap<K, V>)

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

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

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pub proof fn disjoint_persistent(tracked &mut self, tracked other: &GhostPersistentISubmap<K, V>)

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

When we have a GhostISubmap and a GhostPersistentISubmap we can prove that they are in disjoint domains.

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pub proof fn disjoint_points_to(tracked &mut self, tracked other: &GhostIPointsTo<K, V>)

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

When we have a GhostISubmap and a GhostIPointsTo we can prove that they are in disjoint domains.

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pub proof fn disjoint_persistent_points_to( tracked &mut self, tracked other: &GhostPersistentIPointsTo<K, V>, )

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

When we have a GhostISubmap and a GhostPersistentIPointsTo we can prove that they are in disjoint domains.

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pub proof fn split(tracked &mut self, s: ISet<K>) -> tracked result : GhostISubmap<K, V>

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

We can split a GhostISubmap based on a set of keys in its domain.

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pub proof fn split_with_olddom( tracked &mut self, s: ISet<K>, olddom: ISet<K>, ) -> tracked result : GhostISubmap<K, V>

requires
olddom == old(self)@.dom(),
s <= olddom,
ensures
final(self).id() == old(self).id(),
result.id() == final(self).id(),
old(self)@ == final(self)@.union_prefer_right(result@),
result@.dom() == s,
final(self)@.dom() == olddom - s,
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pub proof fn split_points_to(tracked &mut self, k: K) -> tracked result : GhostIPointsTo<K, V>

requires
old(self)@.contains_key(k),
ensures
final(self).id() == old(self).id(),
result.id() == final(self).id(),
old(self)@ == final(self)@.insert(result.key(), result.value()),
result.key() == k,
final(self)@ == old(self)@.remove(k),

We can separate a single key out of a GhostISubmap

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pub proof fn update(tracked &mut self, tracked auth: &mut GhostIMapAuth<K, V>, m: IMap<K, V>)

requires
m.dom() <= old(self)@.dom(),
old(self).id() == old(auth).id(),
ensures
final(self).id() == old(self).id(),
final(auth).id() == old(auth).id(),
final(self)@ == old(self)@.union_prefer_right(m),
final(auth)@ == old(auth)@.union_prefer_right(m),

When we have both the GhostIMapAuth and a GhostISubmap we can update the values for a subset of keys in our submap.

proof fn test(tracked auth: &mut GhostIMapAuth<int, int>, tracked sub: &mut GhostISubmap<int, int>)
    requires
        auth.id() == sub.id(),
        sub.dom() == set![1int, 2int, 3int]
    ensures
        auth[1int] == 9int
        auth[2int] == 10int
        auth[3int] == 11int
{
    // need to agree on the subset
    sub.agree(auth);
    assert(sub@ <= auth@);
    sub.update(map![1int => 9int, 2int => 10int, 3int => 11int]);
}
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pub proof fn points_to(tracked self) -> tracked r : GhostIPointsTo<K, V>

requires
self.is_points_to(),
ensures
self@ == imap![r.key() => r.value()],
self.id() == r.id(),

Converting a GhostISubmap into a GhostIPointsTo

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pub proof fn persist(tracked self) -> tracked r : GhostPersistentISubmap<K, V>

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

Convert a GhostISubmap into a GhostPersistentISubmap

Auto Trait Implementations§

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impl<K, V> Freeze for GhostISubmap<K, V>

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impl<K, V> RefUnwindSafe for GhostISubmap<K, V>
where K: RefUnwindSafe, V: RefUnwindSafe,

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impl<K, V> Send for GhostISubmap<K, V>
where K: Send, V: Send,

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impl<K, V> Sync for GhostISubmap<K, V>
where K: Sync, V: Sync,

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impl<K, V> Unpin for GhostISubmap<K, V>
where K: Unpin, V: Unpin,

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impl<K, V> UnsafeUnpin for GhostISubmap<K, V>

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impl<K, V> UnwindSafe for GhostISubmap<K, V>
where K: UnwindSafe, V: UnwindSafe,

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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