[−][src]Struct permutator::KPermutationRefIter
k-Permutation over data of length "n" where k
must be
less than n
and store result into mutable pointer.
It'll attempt to permute given data by pick k
elements
out of n
data. It use Gosper algorithm to pick the elements.
It then use Heap's algorithm to permute those k
elements
and return each permutation back to caller by given
*mut [&T]>> parameter to
new method of KPermutationRefIter.
Safety
This object use raw mutable pointer provided from user and keep using it
in each next
iteration. Therefore, all raw pointer conditions are applied
up until this object is dropped.
Rationale
It uses unsafe to take a mutable pointer to store the result
to avoid the cost of using Rc<RefCell<>>.
In uncontroll test environment, this struct perform a complete
iteration over 8,648,640 permutations in about 66ms where
KPermutationCellIter
took about 125 ms.
This function is very much alike
unsafe_k_permutation function
but took Iterator
approach.
Examples
- Iterator style permit using 'for-in' style loop along with enable usage of functional paradigm over iterator object.
use permutator::{KPermutationCellIter, IteratorReset}; use std::cell::RefCell; use std::rc::Rc; use std::time::Instant; let data = [1, 2, 3, 4, 5]; let mut result : Vec<&i32> = vec![&data[0]; 3]; let shared = Rc::new(RefCell::new(result.as_mut_slice())); let mut permutator = KPermutationCellIter::new(&data, 3, Rc::clone(&shared)); let mut counter = 0; let timer = Instant::now(); permutator.for_each(|_| { println!("{}:{:?}", counter, &*shared.borrow()); counter += 1; }); println!("Total {} permutations done in {:?}", counter, timer.elapsed()); assert_eq!(60, counter);
Notes
This struct manual iteration performance is about 110% slower than using k-permutation function while the slowest using Iterator style is about 2300% slower. The additional functionality provided by this struct is that it can be pause or completely stop midway while the k-permutation need to be run from start to finish only.
See
Methods
impl<'a, T> KPermutationRefIter<'a, T>
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ⓘImportant traits for KPermutationRefIter<'a, T>pub unsafe fn new(
data: &'a [T],
k: usize,
result: *mut [&'a T]
) -> KPermutationRefIter<'a, T>
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data: &'a [T],
k: usize,
result: *mut [&'a T]
) -> KPermutationRefIter<'a, T>
pub fn into_iter(self) -> Self
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Consume then return self immediately.
It permit functional style operation over iterator
from borrow object as Rust isn't yet support
for _ in borrowed_object
directly.
It need to be for _ in borrowed_object.into_iter()
.
pub fn len(&self) -> usize
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Get total number of permutation this KPermutationIterator object
can permute. It'll be equals to number of possible next
call.
Trait Implementations
impl<'a, T> ExactSizeIterator for KPermutationRefIter<'a, T>
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impl<'a, T> Iterator for KPermutationRefIter<'a, T>
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type Item = ()
The type of the elements being iterated over.
fn next(&mut self) -> Option<()>
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fn size_hint(&self) -> (usize, Option<usize>)
1.0.0[src]
fn count(self) -> usize
1.0.0[src]
fn last(self) -> Option<Self::Item>
1.0.0[src]
fn nth(&mut self, n: usize) -> Option<Self::Item>
1.0.0[src]
fn step_by(self, step: usize) -> StepBy<Self>
1.28.0[src]
fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
1.0.0[src]
U: IntoIterator<Item = Self::Item>,
fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
1.0.0[src]
U: IntoIterator,
fn map<B, F>(self, f: F) -> Map<Self, F> where
F: FnMut(Self::Item) -> B,
1.0.0[src]
F: FnMut(Self::Item) -> B,
fn for_each<F>(self, f: F) where
F: FnMut(Self::Item),
1.21.0[src]
F: FnMut(Self::Item),
fn filter<P>(self, predicate: P) -> Filter<Self, P> where
P: FnMut(&Self::Item) -> bool,
1.0.0[src]
P: FnMut(&Self::Item) -> bool,
fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
F: FnMut(Self::Item) -> Option<B>,
1.0.0[src]
F: FnMut(Self::Item) -> Option<B>,
fn enumerate(self) -> Enumerate<Self>
1.0.0[src]
fn peekable(self) -> Peekable<Self>
1.0.0[src]
fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,
1.0.0[src]
P: FnMut(&Self::Item) -> bool,
fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,
1.0.0[src]
P: FnMut(&Self::Item) -> bool,
fn skip(self, n: usize) -> Skip<Self>
1.0.0[src]
fn take(self, n: usize) -> Take<Self>
1.0.0[src]
fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
F: FnMut(&mut St, Self::Item) -> Option<B>,
1.0.0[src]
F: FnMut(&mut St, Self::Item) -> Option<B>,
fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
F: FnMut(Self::Item) -> U,
U: IntoIterator,
1.0.0[src]
F: FnMut(Self::Item) -> U,
U: IntoIterator,
fn flatten(self) -> Flatten<Self> where
Self::Item: IntoIterator,
1.29.0[src]
Self::Item: IntoIterator,
fn fuse(self) -> Fuse<Self>
1.0.0[src]
fn inspect<F>(self, f: F) -> Inspect<Self, F> where
F: FnMut(&Self::Item),
1.0.0[src]
F: FnMut(&Self::Item),
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]
fn collect<B>(self) -> B where
B: FromIterator<Self::Item>,
1.0.0[src]
B: FromIterator<Self::Item>,
fn partition<B, F>(self, f: F) -> (B, B) where
B: Default + Extend<Self::Item>,
F: FnMut(&Self::Item) -> bool,
1.0.0[src]
B: Default + Extend<Self::Item>,
F: FnMut(&Self::Item) -> bool,
fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
P: FnMut(&T) -> bool,
Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,
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P: FnMut(&T) -> bool,
Self: DoubleEndedIterator<Item = &'a mut T>,
T: 'a,
fn is_partitioned<P>(self, predicate: P) -> bool where
P: FnMut(Self::Item) -> bool,
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P: FnMut(Self::Item) -> bool,
fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
F: FnMut(B, Self::Item) -> R,
R: Try<Ok = B>,
1.27.0[src]
F: FnMut(B, Self::Item) -> R,
R: Try<Ok = B>,
fn try_for_each<F, R>(&mut self, f: F) -> R where
F: FnMut(Self::Item) -> R,
R: Try<Ok = ()>,
1.27.0[src]
F: FnMut(Self::Item) -> R,
R: Try<Ok = ()>,
fn fold<B, F>(self, init: B, f: F) -> B where
F: FnMut(B, Self::Item) -> B,
1.0.0[src]
F: FnMut(B, Self::Item) -> B,
fn all<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,
1.0.0[src]
F: FnMut(Self::Item) -> bool,
fn any<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,
1.0.0[src]
F: FnMut(Self::Item) -> bool,
fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,
1.0.0[src]
P: FnMut(&Self::Item) -> bool,
fn find_map<B, F>(&mut self, f: F) -> Option<B> where
F: FnMut(Self::Item) -> Option<B>,
1.30.0[src]
F: FnMut(Self::Item) -> Option<B>,
fn position<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
1.0.0[src]
P: FnMut(Self::Item) -> bool,
fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,
1.0.0[src]
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,
fn max(self) -> Option<Self::Item> where
Self::Item: Ord,
1.0.0[src]
Self::Item: Ord,
fn min(self) -> Option<Self::Item> where
Self::Item: Ord,
1.0.0[src]
Self::Item: Ord,
fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,
1.6.0[src]
B: Ord,
F: FnMut(&Self::Item) -> B,
fn max_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
1.15.0[src]
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,
1.6.0[src]
B: Ord,
F: FnMut(&Self::Item) -> B,
fn min_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
1.15.0[src]
F: FnMut(&Self::Item, &Self::Item) -> Ordering,
fn rev(self) -> Rev<Self> where
Self: DoubleEndedIterator,
1.0.0[src]
Self: DoubleEndedIterator,
fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
Self: Iterator<Item = (A, B)>,
1.0.0[src]
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
Self: Iterator<Item = (A, B)>,
fn copied<'a, T>(self) -> Copied<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Copy,
1.36.0[src]
Self: Iterator<Item = &'a T>,
T: 'a + Copy,
fn cloned<'a, T>(self) -> Cloned<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Clone,
1.0.0[src]
Self: Iterator<Item = &'a T>,
T: 'a + Clone,
fn cycle(self) -> Cycle<Self> where
Self: Clone,
1.0.0[src]
Self: Clone,
fn sum<S>(self) -> S where
S: Sum<Self::Item>,
1.11.0[src]
S: Sum<Self::Item>,
fn product<P>(self) -> P where
P: Product<Self::Item>,
1.11.0[src]
P: Product<Self::Item>,
fn cmp<I>(self, other: I) -> Ordering where
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,
1.5.0[src]
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,
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,
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>,
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,
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>,
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,
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>,
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>,
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>,
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>,
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>,
fn is_sorted(self) -> bool where
Self::Item: PartialOrd<Self::Item>,
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Self::Item: PartialOrd<Self::Item>,
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>,
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>,
impl<'a, T> IteratorReset for KPermutationRefIter<'a, T>
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Auto Trait Implementations
impl<'a, T> RefUnwindSafe for KPermutationRefIter<'a, T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
impl<'a, T> !Send for KPermutationRefIter<'a, T>
impl<'a, T> !Sync for KPermutationRefIter<'a, T>
impl<'a, T> Unpin for KPermutationRefIter<'a, T>
impl<'a, T> !UnwindSafe for KPermutationRefIter<'a, T>
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,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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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?
fn into_iter(self) -> I
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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.
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>,