Trait rayon::iter::FromParallelIterator

pub trait FromParallelIterator<T> where
    T: Send, {
    fn from_par_iter<I>(par_iter: I) -> Self
    where
        I: IntoParallelIterator<Item = T>;
}

FromParallelIterator implements the creation of a collection from a ParallelIterator. By implementing FromParallelIterator for a given type, you define how it will be created from an iterator.

FromParallelIterator is used through ParallelIterator’s collect() method.

Examples

Implementing FromParallelIterator for your type:

use rayon::prelude::*;
use std::mem;

struct BlackHole {
    mass: usize,
}

impl<T: Send> FromParallelIterator<T> for BlackHole {
    fn from_par_iter<I>(par_iter: I) -> Self
        where I: IntoParallelIterator<Item = T>
    {
        let par_iter = par_iter.into_par_iter();
        BlackHole {
            mass: par_iter.count() * mem::size_of::<T>(),
        }
    }
}

let bh: BlackHole = (0i32..1000).into_par_iter().collect();
assert_eq!(bh.mass, 4000);

Required methods

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = T>, 

Creates an instance of the collection from the parallel iterator par_iter.

If your collection is not naturally parallel, the easiest (and fastest) way to do this is often to collect par_iter into a LinkedList or other intermediate data structure and then sequentially extend your collection. However, a more ‘native’ technique is to use the par_iter.fold or par_iter.fold_with methods to create the collection. Alternatively, if your collection is ‘natively’ parallel, you can use par_iter.for_each to process each element in turn.

Implementations on Foreign Types

impl<T> FromParallelIterator<T> for Vec<T> where
    T: Send, 

Collects items from a parallel iterator into a vector.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = T>, 

impl<T> FromParallelIterator<T> for VecDeque<T> where
    T: Send, 

Collects items from a parallel iterator into a vecdeque.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = T>, 

impl<T> FromParallelIterator<T> for BinaryHeap<T> where
    T: Ord + Send, 

Collects items from a parallel iterator into a binaryheap. The heap-ordering is calculated serially after all items are collected.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = T>, 

impl<T> FromParallelIterator<T> for LinkedList<T> where
    T: Send, 

Collects items from a parallel iterator into a freshly allocated linked list.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = T>, 

impl<K, V, S> FromParallelIterator<(K, V)> for HashMap<K, V, S> where
    K: Eq + Hash + Send,
    V: Send,
    S: BuildHasher + Default + Send, 

Collects (key, value) pairs from a parallel iterator into a hashmap. If multiple pairs correspond to the same key, then the ones produced earlier in the parallel iterator will be overwritten, just as with a sequential iterator.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = (K, V)>, 

impl<K, V> FromParallelIterator<(K, V)> for BTreeMap<K, V> where
    K: Ord + Send,
    V: Send, 

Collects (key, value) pairs from a parallel iterator into a btreemap. If multiple pairs correspond to the same key, then the ones produced earlier in the parallel iterator will be overwritten, just as with a sequential iterator.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = (K, V)>, 

impl<V, S> FromParallelIterator<V> for HashSet<V, S> where
    V: Eq + Hash + Send,
    S: BuildHasher + Default + Send, 

Collects values from a parallel iterator into a hashset.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = V>, 

impl<V> FromParallelIterator<V> for BTreeSet<V> where
    V: Send + Ord, 

Collects values from a parallel iterator into a btreeset.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = V>, 

impl FromParallelIterator<char> for String

Collects characters from a parallel iterator into a string.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = char>, 

impl<'a> FromParallelIterator<&'a char> for String

Collects characters from a parallel iterator into a string.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = &'a char>, 

impl<'a> FromParallelIterator<&'a str> for String

Collects string slices from a parallel iterator into a string.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = &'a str>, 

impl FromParallelIterator<String> for String

Collects strings from a parallel iterator into one large string.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = String>, 

impl<'a> FromParallelIterator<Cow<'a, str>> for String

Collects string slices from a parallel iterator into a string.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = Cow<'a, str>>, 

impl<'a, C: ?Sized, T> FromParallelIterator<T> for Cow<'a, C> where
    C: ToOwned,
    C::Owned: FromParallelIterator<T>,
    T: Send, 

Collects an arbitrary Cow collection.

Note, the standard library only has FromIterator for Cow<'a, str> and Cow<'a, [T]>, because no one thought to add a blanket implementation before it was stabilized.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = T>, 

impl FromParallelIterator<()> for ()

Collapses all unit items from a parallel iterator into one.

This is more useful when combined with higher-level abstractions, like collecting to a Result<(), E> where you only care about errors:

use std::io::*;
use rayon::prelude::*;

let data = vec![1, 2, 3, 4, 5];
let res: Result<()> = data.par_iter()
    .map(|x| writeln!(stdout(), "{}", x))
    .collect();
assert!(res.is_ok());

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = ()>, 

impl<A, B, FromA, FromB> FromParallelIterator<(A, B)> for (FromA, FromB) where
    A: Send,
    B: Send,
    FromA: Send + FromParallelIterator<A>,
    FromB: Send + FromParallelIterator<B>, 

fn from_par_iter<I>(pi: I) -> Self where
    I: IntoParallelIterator<Item = (A, B)>, 

impl<L, R, A, B> FromParallelIterator<Either<L, R>> for (A, B) where
    L: Send,
    R: Send,
    A: Send + FromParallelIterator<L>,
    B: Send + FromParallelIterator<R>, 

fn from_par_iter<I>(pi: I) -> Self where
    I: IntoParallelIterator<Item = Either<L, R>>, 

impl<C, T> FromParallelIterator<Option<T>> for Option<C> where
    C: FromParallelIterator<T>,
    T: Send, 

Collect an arbitrary Option-wrapped collection.

If any item is None, then all previous items collected are discarded, and it returns only None.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = Option<T>>, 

impl<C, T, E> FromParallelIterator<Result<T, E>> for Result<C, E> where
    C: FromParallelIterator<T>,
    T: Send,
    E: Send, 

Collect an arbitrary Result-wrapped collection.

If any item is Err, then all previous Ok items collected are discarded, and it returns that error. If there are multiple errors, the one returned is not deterministic.

fn from_par_iter<I>(par_iter: I) -> Self where
    I: IntoParallelIterator<Item = Result<T, E>>, 

Implementors