Struct differential_dataflow::difference::Present
source · pub struct Present;
Expand description
A zero-sized difference that indicates the presence of a record.
This difference type has no negation, and present records cannot be retracted. Addition and multiplication maintain presence, and zero does not inhabit the type.
The primary feature of this type is that it has zero size, which reduces the overhead of differential dataflow’s representations for settings where collections either do not change, or for which records are only added (for example, derived facts in Datalog).
Trait Implementations§
source§impl Abomonation for Present
impl Abomonation for Present
source§impl<'de> Deserialize<'de> for Present
impl<'de> Deserialize<'de> for Present
source§fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where
__D: Deserializer<'de>,
fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where
__D: Deserializer<'de>,
Deserialize this value from the given Serde deserializer. Read more
source§impl Ord for Present
impl Ord for Present
source§impl PartialEq for Present
impl PartialEq for Present
source§impl PartialOrd for Present
impl PartialOrd for Present
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for
self
and other
) and is used by the <=
operator. Read moreimpl Copy for Present
impl Eq for Present
impl StructuralPartialEq for Present
Auto Trait Implementations§
impl Freeze for Present
impl RefUnwindSafe for Present
impl Send for Present
impl Sync for Present
impl Unpin for Present
impl UnwindSafe for Present
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
source§impl<R, O, T> CopyOnto<ConsecutiveOffsetPairs<R, O>> for T
impl<R, O, T> CopyOnto<ConsecutiveOffsetPairs<R, O>> for T
source§fn copy_onto(
self,
target: &mut ConsecutiveOffsetPairs<R, O>
) -> <ConsecutiveOffsetPairs<R, O> as Region>::Index
fn copy_onto( self, target: &mut ConsecutiveOffsetPairs<R, O> ) -> <ConsecutiveOffsetPairs<R, O> as Region>::Index
Copy self into the target container, returning an index that allows to
look up the corresponding read item.
source§impl<T> CopyOnto<MirrorRegion<T>> for Twhere
T: Index,
impl<T> CopyOnto<MirrorRegion<T>> for Twhere
T: Index,
source§fn copy_onto(self, _target: &mut MirrorRegion<T>) -> T
fn copy_onto(self, _target: &mut MirrorRegion<T>) -> T
Copy self into the target container, returning an index that allows to
look up the corresponding read item.
source§impl<T> PreferredContainer for T
impl<T> PreferredContainer for T
source§impl<T> ProgressEventTimestamp for T
impl<T> ProgressEventTimestamp for T
source§impl<T> ReserveItems<MirrorRegion<T>> for Twhere
T: Index,
impl<T> ReserveItems<MirrorRegion<T>> for Twhere
T: Index,
source§fn reserve_items<I>(_target: &mut MirrorRegion<T>, _items: I)
fn reserve_items<I>(_target: &mut MirrorRegion<T>, _items: I)
Ensure that the region can absorb
items
without reallocation.