[−][src]Struct mongodb::sync::Cursor
sync
only.A Cursor
streams the result of a query. When a query is made, a Cursor
will be returned with
the first batch of results from the server; the documents will be returned as the Cursor
is
iterated. When the batch is exhausted and if there are more results, the Cursor
will fetch the
next batch of documents, and so forth until the results are exhausted. Note that because of this
batching, additional network I/O may occur on any given call to Cursor::next
. Because of this,
a Cursor
iterates over Result<Document>
items rather than simply Document
items.
The batch size of the Cursor
can be configured using the options to the method that returns
it. For example, setting the batch_size
field of
FindOptions
will set the batch size of the
Cursor
returned by Collection::find
.
Note that the batch size determines both the number of documents stored in memory by the
Cursor
at a given time as well as the total number of network round-trips needed to fetch all
results from the server; both of these factors should be taken into account when choosing the
optimal batch size.
A cursor can be used like any other Stream
. The simplest way is just to iterate over the
documents it yields:
for doc in cursor { println!("{}", doc?) }
Additionally, all the other methods that an Stream
has are available on Cursor
as well.
This includes all of the functionality provided by StreamExt
, which provides similar functionality to the standard library Iterator
trait.
For instance, if the number of results from a query is known to be small, it might make sense
to collect them into a vector:
let results: Vec<Result<Document>> = cursor.collect();
Trait Implementations
impl<T: Debug> Debug for Cursor<T> where
T: DeserializeOwned + Unpin + Send,
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T: DeserializeOwned + Unpin + Send,
impl<T> Iterator for Cursor<T> where
T: DeserializeOwned + Unpin + Send,
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T: DeserializeOwned + Unpin + Send,
type Item = Result<T>
The type of the elements being iterated over.
fn next(&mut self) -> Option<Self::Item>
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pub fn size_hint(&self) -> (usize, Option<usize>)
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pub fn count(self) -> usize
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pub fn last(self) -> Option<Self::Item>
1.0.0[src]
pub fn advance_by(&mut self, n: usize) -> Result<(), usize>
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pub fn nth(&mut self, n: usize) -> Option<Self::Item>
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pub fn step_by(self, step: usize) -> StepBy<Self>
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pub fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
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U: IntoIterator<Item = Self::Item>,
pub fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
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U: IntoIterator,
pub fn intersperse(self, separator: Self::Item) -> Intersperse<Self> where
Self::Item: Clone,
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Self::Item: Clone,
pub fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
G: FnMut() -> Self::Item,
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G: FnMut() -> Self::Item,
pub fn map<B, F>(self, f: F) -> Map<Self, F> where
F: FnMut(Self::Item) -> B,
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F: FnMut(Self::Item) -> B,
pub fn for_each<F>(self, f: F) where
F: FnMut(Self::Item),
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F: FnMut(Self::Item),
pub fn filter<P>(self, predicate: P) -> Filter<Self, P> where
P: FnMut(&Self::Item) -> bool,
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P: FnMut(&Self::Item) -> bool,
pub fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
F: FnMut(Self::Item) -> Option<B>,
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F: FnMut(Self::Item) -> Option<B>,
pub fn enumerate(self) -> Enumerate<Self>
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pub fn peekable(self) -> Peekable<Self>
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pub fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,
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P: FnMut(&Self::Item) -> bool,
pub fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,
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P: FnMut(&Self::Item) -> bool,
pub fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> where
P: FnMut(Self::Item) -> Option<B>,
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P: FnMut(Self::Item) -> Option<B>,
pub fn skip(self, n: usize) -> Skip<Self>
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pub fn take(self, n: usize) -> Take<Self>
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pub fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
F: FnMut(&mut St, Self::Item) -> Option<B>,
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F: FnMut(&mut St, Self::Item) -> Option<B>,
pub fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
F: FnMut(Self::Item) -> U,
U: IntoIterator,
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F: FnMut(Self::Item) -> U,
U: IntoIterator,
pub fn flatten(self) -> Flatten<Self> where
Self::Item: IntoIterator,
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Self::Item: IntoIterator,
pub fn fuse(self) -> Fuse<Self>
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pub fn inspect<F>(self, f: F) -> Inspect<Self, F> where
F: FnMut(&Self::Item),
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F: FnMut(&Self::Item),
pub fn by_ref(&mut self) -> &mut Self
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#[must_use =
"if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]pub fn collect<B>(self) -> B where
B: FromIterator<Self::Item>,
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B: FromIterator<Self::Item>,
pub fn partition<B, F>(self, f: F) -> (B, B) where
F: FnMut(&Self::Item) -> bool,
B: Default + Extend<Self::Item>,
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F: FnMut(&Self::Item) -> bool,
B: Default + Extend<Self::Item>,
pub fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,
P: FnMut(&T) -> bool,
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Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,
P: FnMut(&T) -> bool,
pub fn is_partitioned<P>(self, predicate: P) -> bool where
P: FnMut(Self::Item) -> bool,
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P: FnMut(Self::Item) -> bool,
pub fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
R: Try<Ok = B>,
F: FnMut(B, Self::Item) -> R,
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R: Try<Ok = B>,
F: FnMut(B, Self::Item) -> R,
pub fn try_for_each<F, R>(&mut self, f: F) -> R where
R: Try<Ok = ()>,
F: FnMut(Self::Item) -> R,
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R: Try<Ok = ()>,
F: FnMut(Self::Item) -> R,
pub fn fold<B, F>(self, init: B, f: F) -> B where
F: FnMut(B, Self::Item) -> B,
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F: FnMut(B, Self::Item) -> B,
pub fn fold_first<F>(self, f: F) -> Option<Self::Item> where
F: FnMut(Self::Item, Self::Item) -> Self::Item,
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F: FnMut(Self::Item, Self::Item) -> Self::Item,
pub fn all<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,
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F: FnMut(Self::Item) -> bool,
pub fn any<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,
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F: FnMut(Self::Item) -> bool,
pub fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,
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P: FnMut(&Self::Item) -> bool,
pub fn find_map<B, F>(&mut self, f: F) -> Option<B> where
F: FnMut(Self::Item) -> Option<B>,
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F: FnMut(Self::Item) -> Option<B>,
pub fn try_find<F, R>(
&mut self,
f: F
) -> Result<Option<Self::Item>, <R as Try>::Error> where
R: Try<Ok = bool>,
F: FnMut(&Self::Item) -> R,
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&mut self,
f: F
) -> Result<Option<Self::Item>, <R as Try>::Error> where
R: Try<Ok = bool>,
F: FnMut(&Self::Item) -> R,
pub fn position<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
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P: FnMut(Self::Item) -> bool,
pub fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
Self: ExactSizeIterator + DoubleEndedIterator,
P: FnMut(Self::Item) -> bool,
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Self: ExactSizeIterator + DoubleEndedIterator,
P: FnMut(Self::Item) -> bool,
pub fn max(self) -> Option<Self::Item> where
Self::Item: Ord,
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Self::Item: Ord,
pub fn min(self) -> Option<Self::Item> where
Self::Item: Ord,
1.0.0[src]
Self::Item: Ord,
pub fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
F: FnMut(&Self::Item) -> B,
B: Ord,
1.6.0[src]
F: FnMut(&Self::Item) -> B,
B: Ord,
pub fn max_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
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F: FnMut(&Self::Item, &Self::Item) -> Ordering,
pub fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
F: FnMut(&Self::Item) -> B,
B: Ord,
1.6.0[src]
F: FnMut(&Self::Item) -> B,
B: Ord,
pub fn min_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
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F: FnMut(&Self::Item, &Self::Item) -> Ordering,
pub fn rev(self) -> Rev<Self> where
Self: DoubleEndedIterator,
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Self: DoubleEndedIterator,
pub fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
Self: Iterator<Item = (A, B)>,
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
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Self: Iterator<Item = (A, B)>,
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
pub fn copied<'a, T>(self) -> Copied<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Copy,
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Self: Iterator<Item = &'a T>,
T: 'a + Copy,
pub fn cloned<'a, T>(self) -> Cloned<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Clone,
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Self: Iterator<Item = &'a T>,
T: 'a + Clone,
pub fn cycle(self) -> Cycle<Self> where
Self: Clone,
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Self: Clone,
pub fn sum<S>(self) -> S where
S: Sum<Self::Item>,
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S: Sum<Self::Item>,
pub fn product<P>(self) -> P where
P: Product<Self::Item>,
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P: Product<Self::Item>,
pub fn cmp<I>(self, other: I) -> Ordering where
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,
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I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,
pub fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
I: IntoIterator,
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F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
I: IntoIterator,
pub fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
pub fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
I: IntoIterator,
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F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
I: IntoIterator,
pub fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
pub fn eq_by<I, F>(self, other: I, eq: F) -> bool where
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
I: IntoIterator,
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F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
I: IntoIterator,
pub fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
pub fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
pub fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
pub fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
pub fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
1.5.0[src]
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
pub fn is_sorted(self) -> bool where
Self::Item: PartialOrd<Self::Item>,
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Self::Item: PartialOrd<Self::Item>,
pub fn is_sorted_by<F>(self, compare: F) -> bool where
F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>,
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F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>,
pub fn is_sorted_by_key<F, K>(self, f: F) -> bool where
F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,
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F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,
Auto Trait Implementations
impl<T = Document> !RefUnwindSafe for Cursor<T>
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impl<T> Send for Cursor<T>
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impl<T = Document> !Sync for Cursor<T>
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impl<T> Unpin for Cursor<T>
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impl<T = Document> !UnwindSafe for Cursor<T>
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Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T> Instrument for T
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pub fn instrument(self, span: Span) -> Instrumented<Self>
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pub fn in_current_span(self) -> Instrumented<Self>
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impl<T> Instrument for T
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pub fn instrument(self, span: Span) -> Instrumented<Self>
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pub fn in_current_span(self) -> Instrumented<Self>
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<I> IntoIterator for I where
I: Iterator,
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I: Iterator,
type Item = <I as Iterator>::Item
The type of the elements being iterated over.
type IntoIter = I
Which kind of iterator are we turning this into?
pub fn into_iter(self) -> I
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impl<I> IteratorRandom for I where
I: Iterator,
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I: Iterator,
pub fn choose<R>(self, rng: &mut R) -> Option<Self::Item> where
R: Rng + ?Sized,
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R: Rng + ?Sized,
pub fn choose_multiple_fill<R>(
self,
rng: &mut R,
buf: &mut [Self::Item]
) -> usize where
R: Rng + ?Sized,
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self,
rng: &mut R,
buf: &mut [Self::Item]
) -> usize where
R: Rng + ?Sized,
pub fn choose_multiple<R>(
self,
rng: &mut R,
amount: usize
) -> Vec<Self::Item, Global>ⓘ where
R: Rng + ?Sized,
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self,
rng: &mut R,
amount: usize
) -> Vec<Self::Item, Global>ⓘ where
R: Rng + ?Sized,
impl<I> IteratorRandom for I where
I: Iterator,
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I: Iterator,
pub fn choose<R>(self, rng: &mut R) -> Option<Self::Item> where
R: Rng + ?Sized,
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R: Rng + ?Sized,
pub fn choose_stable<R>(self, rng: &mut R) -> Option<Self::Item> where
R: Rng + ?Sized,
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R: Rng + ?Sized,
pub fn choose_multiple_fill<R>(
self,
rng: &mut R,
buf: &mut [Self::Item]
) -> usize where
R: Rng + ?Sized,
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self,
rng: &mut R,
buf: &mut [Self::Item]
) -> usize where
R: Rng + ?Sized,
pub fn choose_multiple<R>(
self,
rng: &mut R,
amount: usize
) -> Vec<Self::Item, Global>ⓘ where
R: Rng + ?Sized,
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self,
rng: &mut R,
amount: usize
) -> Vec<Self::Item, Global>ⓘ where
R: Rng + ?Sized,
impl<T> Same<T> for T
type Output = T
Should always be Self
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<V, T> VZip<V> for T where
V: MultiLane<T>,
V: MultiLane<T>,