Trait rayon::iter::FromParallelIterator

source · [−]
pub trait FromParallelIterator<T> where
    T: Send, {
    fn from_par_iter<I>(par_iter: I) -> Self
    where
        I: IntoParallelIterator<Item = T>;
}
Expand description

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

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

Collects items from a parallel iterator into a vector.

Collects items from a parallel iterator into a vecdeque.

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

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

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.

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.

Collects values from a parallel iterator into a hashset.

Collects values from a parallel iterator into a btreeset.

Collects characters from a parallel iterator into a string.

Collects characters from a parallel iterator into a string.

Collects string slices from a parallel iterator into a string.

Collects strings from a parallel iterator into one large string.

Collects string slices from a parallel iterator into a string.

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.

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());

Collect an arbitrary Option-wrapped collection.

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

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.

Implementors