Trait gclient::ext::sp_core::sp_std::iter::FromIterator

pub trait FromIterator<A>: Sized {
    // Required method
    fn from_iter<T>(iter: T) -> Self
       where T: IntoIterator<Item = A>;
}

Conversion from an Iterator.

By implementing FromIterator for a type, you define how it will be created from an iterator. This is common for types which describe a collection of some kind.

If you want to create a collection from the contents of an iterator, the Iterator::collect() method is preferred. However, when you need to specify the container type, FromIterator::from_iter() can be more readable than using a turbofish (e.g. ::<Vec<_>>()). See the Iterator::collect() documentation for more examples of its use.

See also: IntoIterator.

Examples

Basic usage:

let five_fives = std::iter::repeat(5).take(5);

let v = Vec::from_iter(five_fives);

assert_eq!(v, vec![5, 5, 5, 5, 5]);

Using Iterator::collect() to implicitly use FromIterator:

let five_fives = std::iter::repeat(5).take(5);

let v: Vec<i32> = five_fives.collect();

assert_eq!(v, vec![5, 5, 5, 5, 5]);

Using FromIterator::from_iter() as a more readable alternative to Iterator::collect():

use std::collections::VecDeque;
let first = (0..10).collect::<VecDeque<i32>>();
let second = VecDeque::from_iter(0..10);

assert_eq!(first, second);

Implementing FromIterator for your type:

// A sample collection, that's just a wrapper over Vec<T>
#[derive(Debug)]
struct MyCollection(Vec<i32>);

// Let's give it some methods so we can create one and add things
// to it.
impl MyCollection {
    fn new() -> MyCollection {
        MyCollection(Vec::new())
    }

    fn add(&mut self, elem: i32) {
        self.0.push(elem);
    }
}

// and we'll implement FromIterator
impl FromIterator<i32> for MyCollection {
    fn from_iter<I: IntoIterator<Item=i32>>(iter: I) -> Self {
        let mut c = MyCollection::new();

        for i in iter {
            c.add(i);
        }

        c
    }
}

// Now we can make a new iterator...
let iter = (0..5).into_iter();

// ... and make a MyCollection out of it
let c = MyCollection::from_iter(iter);

assert_eq!(c.0, vec![0, 1, 2, 3, 4]);

// collect works too!

let iter = (0..5).into_iter();
let c: MyCollection = iter.collect();

assert_eq!(c.0, vec![0, 1, 2, 3, 4]);

Required Methods

fn from_iter<T>(iter: T) -> Self

where T: IntoIterator<Item = A>,

Creates a value from an iterator.

See the module-level documentation for more.

Examples

let five_fives = std::iter::repeat(5).take(5);

let v = Vec::from_iter(five_fives);

assert_eq!(v, vec![5, 5, 5, 5, 5]);

Object Safety

This trait is not object safe.

Implementors

impl FromIterator<(Vec<u8>, Vec<u8>)> for BasicExternalities

impl FromIterator<(String, Value)> for Map<String, Value>

impl FromIterator<bool> for Bits

impl FromIterator<char> for String

impl FromIterator<char> for BString

impl FromIterator<u8> for BString

impl FromIterator<u8> for Bytes

impl FromIterator<u8> for BytesMut

impl FromIterator<()> for ()

Collapses all unit items from an 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::*;
let data = vec![1, 2, 3, 4, 5];
let res: Result<()> = data.iter()
    .map(|x| writeln!(stdout(), "{x}"))
    .collect();
assert!(res.is_ok());

impl FromIterator<Capabilities> for Capabilities

impl FromIterator<String> for String

impl FromIterator<Box<str>> for String

impl FromIterator<OsString> for OsString

impl FromIterator<Access> for Access

impl FromIterator<Access> for Access

impl FromIterator<AtFlags> for AtFlags

impl FromIterator<AtFlags> for AtFlags

impl FromIterator<BString> for BString

impl FromIterator<ControlModes> for ControlModes

impl FromIterator<CreateFlags> for CreateFlags

impl FromIterator<CreateFlags> for CreateFlags

impl FromIterator<CreateFlags> for CreateFlags

impl FromIterator<CreateFlags> for CreateFlags

impl FromIterator<DupFlags> for DupFlags

impl FromIterator<DupFlags> for DupFlags

impl FromIterator<DupFlags> for DupFlags

impl FromIterator<EventFlags> for EventFlags

impl FromIterator<EventFlags> for EventFlags

impl FromIterator<EventfdFlags> for EventfdFlags

impl FromIterator<EventfdFlags> for EventfdFlags

impl FromIterator<FallocateFlags> for FallocateFlags

impl FromIterator<FallocateFlags> for FallocateFlags

impl FromIterator<FdFlags> for FdFlags

impl FromIterator<FdFlags> for FdFlags

impl FromIterator<FdFlags> for FdFlags

impl FromIterator<IFlags> for IFlags

impl FromIterator<InputModes> for InputModes

impl FromIterator<Literal> for Seq

impl FromIterator<LocalModes> for LocalModes

impl FromIterator<MapFlags> for MapFlags

impl FromIterator<MemfdFlags> for MemfdFlags

impl FromIterator<MemfdFlags> for MemfdFlags

impl FromIterator<MlockFlags> for MlockFlags

impl FromIterator<Mode> for Mode

impl FromIterator<Mode> for Mode

impl FromIterator<MountFlags> for MountFlags

impl FromIterator<MountFlags> for MountFlags

impl FromIterator<MountPropagationFlags> for MountPropagationFlags

impl FromIterator<MountPropagationFlags> for MountPropagationFlags

impl FromIterator<MprotectFlags> for MprotectFlags

impl FromIterator<MremapFlags> for MremapFlags

impl FromIterator<MsyncFlags> for MsyncFlags

impl FromIterator<OFlags> for OFlags

impl FromIterator<OFlags> for OFlags

impl FromIterator<OutputModes> for OutputModes

impl FromIterator<PipeFlags> for PipeFlags

impl FromIterator<PipeFlags> for PipeFlags

impl FromIterator<PollFlags> for PollFlags

impl FromIterator<PollFlags> for PollFlags

impl FromIterator<ProtFlags> for ProtFlags

impl FromIterator<Protection> for Protection

impl FromIterator<ReadWriteFlags> for ReadWriteFlags

impl FromIterator<ReadWriteFlags> for ReadWriteFlags

impl FromIterator<ReadWriteFlags> for ReadWriteFlags

impl FromIterator<RenameFlags> for RenameFlags

impl FromIterator<RenameFlags> for RenameFlags

impl FromIterator<ResolveFlags> for ResolveFlags

impl FromIterator<ResolveFlags> for ResolveFlags

impl FromIterator<SealFlags> for SealFlags

impl FromIterator<SealFlags> for SealFlags

impl FromIterator<SpliceFlags> for SpliceFlags

impl FromIterator<SpliceFlags> for SpliceFlags

impl FromIterator<StatVfsMountFlags> for StatVfsMountFlags

impl FromIterator<StatVfsMountFlags> for StatVfsMountFlags

impl FromIterator<StatxFlags> for StatxFlags

impl FromIterator<StatxFlags> for StatxFlags

impl FromIterator<UnmountFlags> for UnmountFlags

impl FromIterator<UnmountFlags> for UnmountFlags

impl FromIterator<UserfaultfdFlags> for UserfaultfdFlags

impl FromIterator<WatchFlags> for WatchFlags

impl FromIterator<WatchFlags> for WatchFlags

impl FromIterator<XattrFlags> for XattrFlags

impl FromIterator<XattrFlags> for XattrFlags

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

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

impl<'a> FromIterator<&'a str> for BString

impl<'a> FromIterator<&'a u8> for BytesMut

impl<'a> FromIterator<&'a OsStr> for OsString

impl<'a> FromIterator<&'a BStr> for BString

impl<'a> FromIterator<&'a [u8]> for BString

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

impl<'a> FromIterator<Cow<'a, OsStr>> for OsString

impl<'a> FromIterator<char> for Cow<'a, str>

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

impl<'a, 'b> FromIterator<&'b str> for Cow<'a, str>

impl<'a, M, T1, T2, O1, O2> FromIterator<BitRef<'a, M, T2, O2>> for BitVec<T1, O1>

where M: Mutability, T1: BitStore, T2: BitStore, O1: BitOrder, O2: BitOrder,

Bit-Vector Collection from Proxy References

DO NOT use this. You clearly have a bit-slice. Use ::from_bitslice() instead!

Iterating over a bit-slice requires loading from memory and constructing a proxy reference for each bit. This is needlessly slow; the specialized method is able to avoid this per-bit cost and possibly even use batched operations.

impl<'a, T> FromIterator<T> for Cow<'a, [T]>

where T: Clone,

impl<'a, T, O> FromIterator<&'a bool> for BitVec<T, O>

where T: BitStore, O: BitOrder,

impl<'a, T, O> FromIterator<&'a T> for BitVec<T, O>

where T: BitStore, O: BitOrder,

impl<A> FromIterator<<A as Array>::Item> for arrayvec::ArrayVec<A>

where A: Array,

Create an ArrayVec from an iterator.

Does not extract more items than there is space for. No error occurs if there are more iterator elements.

impl<A> FromIterator<<A as Array>::Item> for arrayvec::ArrayVec<A>

where A: Array,

Create an ArrayVec from an iterator.

Does not extract more items than there is space for. No error occurs if there are more iterator elements.

impl<A> FromIterator<<A as Array>::Item> for ArrayVec<A>

where A: Array,

impl<A> FromIterator<<A as Array>::Item> for SmallVec<A>

where A: Array,

impl<A> FromIterator<<A as Array>::Item> for TinyVec<A>

where A: Array,

impl<A, E, V> FromIterator<Result<A, E>> for Result<V, E>

where V: FromIterator<A>,

impl<A, V> FromIterator<Option<A>> for Option<V>

where V: FromIterator<A>,

impl<F> FromIterator<F> for JoinAll<F>

where F: Future,

impl<F> FromIterator<F> for TryJoinAll<F>

where F: TryFuture,

impl<Fut> FromIterator<Fut> for FuturesOrdered<Fut>

where Fut: Future,

impl<Fut> FromIterator<Fut> for FuturesUnordered<Fut>

impl<Fut> FromIterator<Fut> for SelectAll<Fut>

where Fut: Future + Unpin,

impl<Fut> FromIterator<Fut> for SelectOk<Fut>

where Fut: TryFuture + Unpin,

impl<I> FromIterator<I> for gclient::ext::sp_core::sp_std::prelude::Box<[I]>

impl<I> FromIterator<I> for Box<[I]>

impl<K, V> FromIterator<(K, V)> for Value

where K: Into<String>, V: Into<Value>,

impl<K, V> FromIterator<(K, V)> for BTreeMap<K, V>

where K: Ord,

impl<K, V> FromIterator<(K, V)> for AHashMap<K, V>

where K: Eq + Hash,

impl<K, V> FromIterator<(K, V)> for IndexMap<K, V>

where K: Ord + Clone,

impl<K, V> FromIterator<(K, V)> for StreamMap<K, V>

where K: Hash + Eq,

impl<K, V> FromIterator<V> for PrimaryMap<K, V>

where K: EntityRef,

impl<K, V, S> FromIterator<(K, V)> for std::collections::hash::map::HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher + Default,

impl<K, V, S> FromIterator<(K, V)> for indexmap::map::IndexMap<K, V, S>

where K: Hash + Eq, S: BuildHasher + Default,

impl<K, V, S> FromIterator<(K, V)> for IndexMap<K, V, S>

where K: Hash + Eq, S: BuildHasher + Default,

impl<K, V, S, A> FromIterator<(K, V)> for HashMap<K, V, S, A>

where K: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator + Clone,

impl<K, V, S, A> FromIterator<(K, V)> for HashMap<K, V, S, A>

where K: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator + Clone,

impl<K, V, S, A> FromIterator<(K, V)> for HashMap<K, V, S, A>

where K: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator,

impl<P> FromIterator<P> for PathBuf

where P: AsRef<Path>,

impl<St> FromIterator<St> for SelectAll<St>

where St: Stream + Unpin,

impl<Store, Order> FromIterator<bool> for DecodedBits<Store, Order>

impl<T> FromIterator<(u32, T)> for IndexMap<T>

impl<T> FromIterator<(u32, T)> for IndexMap<T>

impl<T> FromIterator<(usize, T)> for Slab<T>

Create a slab from an iterator of key-value pairs.

If the iterator produces duplicate keys, the previous value is replaced with the later one. The keys does not need to be sorted beforehand, and this function always takes O(n) time. Note that the returned slab will use space proportional to the largest key, so don’t use Slab with untrusted keys.

Examples

let vec = vec![(2,'a'), (6,'b'), (7,'c')];
let slab = vec.into_iter().collect::<Slab<char>>();
assert_eq!(slab.len(), 3);
assert!(slab.capacity() >= 8);
assert_eq!(slab[2], 'a');

With duplicate and unsorted keys:

let vec = vec![(20,'a'), (10,'b'), (11,'c'), (10,'d')];
let slab = vec.into_iter().collect::<Slab<char>>();
assert_eq!(slab.len(), 3);
assert_eq!(slab[10], 'd');

impl<T> FromIterator<(HeaderName, T)> for HeaderMap<T>

impl<T> FromIterator<T> for Value

where T: Into<Value>,

impl<T> FromIterator<T> for gclient::ext::sp_runtime::app_crypto::Vec<T>

impl<T> FromIterator<T> for BTreeSet<T>

where T: Ord,

impl<T> FromIterator<T> for BinaryHeap<T>

where T: Ord,

impl<T> FromIterator<T> for LinkedList<T>

impl<T> FromIterator<T> for VecDeque<T>

impl<T> FromIterator<T> for Rc<[T]>

impl<T> FromIterator<T> for Arc<[T]>

impl<T> FromIterator<T> for AHashSet<T>

where T: Eq + Hash,

impl<T> FromIterator<T> for IndexSet<T>

where T: Ord + Clone,

impl<T> FromIterator<T> for Vec<T>

impl<T, D> FromIterator<D> for IntervalsTree<T>

where T: Numerated, D: Into<IntervalIterator<T>>,

impl<T, F> FromIterator<F> for JoinSet<T>

where F: Future<Output = T> + Send + 'static, T: Send + 'static,

Collect an iterator of futures into a [JoinSet].

This is equivalent to calling [JoinSet::spawn] on each element of the iterator.

Examples

The main example from [JoinSet]’s documentation can also be written using collect:

use tokio::task::JoinSet;

#[tokio::main]
async fn main() {
    let mut set: JoinSet<_> = (0..10).map(|i| async move { i }).collect();

    let mut seen = [false; 10];
    while let Some(res) = set.join_next().await {
        let idx = res.unwrap();
        seen[idx] = true;
    }

    for i in 0..10 {
        assert!(seen[i]);
    }
}

impl<T, L> FromIterator<(T, L)> for Targets

where T: Into<String>, L: Into<LevelFilter>,

impl<T, N> FromIterator<T> for GenericArray<T, N>

where N: ArrayLength<T>,

impl<T, N> FromIterator<T> for GenericArray<T, N>

where N: ArrayLength<T>,

impl<T, O> FromIterator<bool> for BitVec<T, O>

where T: BitStore, O: BitOrder,

Bit-Vector Collection

This collects a bit-vector from anything that produces individual bits.

Original

impl<T> FromIterator<T> for Vec<T>

Notes

This .collect() call is the second-slowest possible way to collect bits into a bit-vector, faster only than calling iter.for_each(|bit| bv.push(bit)). DO NOT use this if you have any other choice.

If you are collecting a bit-vector from the contents of a bit-slice, then you should use ::from_bitslice() instead. That method is specialized to perform upfront allocation and, where possible, use a batch copy rather than copying each bit individually from the source into the bit-vector.

impl<T, O> FromIterator<T> for BitVec<T, O>

where T: BitStore, O: BitOrder,

impl<T, O, I> FromIterator<I> for BitBox<T, O>

where T: BitStore, O: BitOrder, BitVec<T, O>: FromIterator<I>,

impl<T, S> FromIterator<T> for std::collections::hash::set::HashSet<T, S>

where T: Eq + Hash, S: BuildHasher + Default,

impl<T, S> FromIterator<T> for indexmap::set::IndexSet<T, S>

where T: Hash + Eq, S: BuildHasher + Default,

impl<T, S> FromIterator<T> for IndexSet<T, S>

where T: Hash + Eq, S: BuildHasher + Default,

impl<T, S, A> FromIterator<T> for HashSet<T, S, A>

where T: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator + Clone,

impl<T, S, A> FromIterator<T> for HashSet<T, S, A>

where T: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator + Clone,

impl<T, S, A> FromIterator<T> for HashSet<T, S, A>

where T: Eq + Hash, S: BuildHasher + Default, A: Default + Allocator,

impl<T, const CAP: usize> FromIterator<T> for arrayvec::arrayvec::ArrayVec<T, CAP>

Create an ArrayVec from an iterator.

Panics if the number of elements in the iterator exceeds the arrayvec’s capacity.