Trait Extend 

pub trait Extend<A> {
    // Required method
    fn extend<T>(&mut self, iter: T)
       where T: IntoIterator<Item = A>;

    // Provided methods
    fn extend_one(&mut self, item: A) { ... }
    fn extend_reserve(&mut self, additional: usize) { ... }
}

Extend a collection with the contents of an iterator.

Iterators produce a series of values, and collections can also be thought of as a series of values. The Extend trait bridges this gap, allowing you to extend a collection by including the contents of that iterator. When extending a collection with an already existing key, that entry is updated or, in the case of collections that permit multiple entries with equal keys, that entry is inserted.

Examples

Basic usage:

// You can extend a String with some chars:
let mut message = String::from("The first three letters are: ");

message.extend(&['a', 'b', 'c']);

assert_eq!("abc", &message[29..32]);

Implementing Extend:

// 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);
    }
}

// since MyCollection has a list of i32s, we implement Extend for i32
impl Extend<i32> for MyCollection {

    // This is a bit simpler with the concrete type signature: we can call
    // extend on anything which can be turned into an Iterator which gives
    // us i32s. Because we need i32s to put into MyCollection.
    fn extend<T: IntoIterator<Item=i32>>(&mut self, iter: T) {

        // The implementation is very straightforward: loop through the
        // iterator, and add() each element to ourselves.
        for elem in iter {
            self.add(elem);
        }
    }
}

let mut c = MyCollection::new();

c.add(5);
c.add(6);
c.add(7);

// let's extend our collection with three more numbers
c.extend(vec![1, 2, 3]);

// we've added these elements onto the end
assert_eq!("MyCollection([5, 6, 7, 1, 2, 3])", format!("{c:?}"));

Required Methods

fn extend<T>(&mut self, iter: T)

where T: IntoIterator<Item = A>,

Extends a collection with the contents of an iterator.

As this is the only required method for this trait, the trait-level docs contain more details.

Examples

// You can extend a String with some chars:
let mut message = String::from("abc");

message.extend(['d', 'e', 'f'].iter());

assert_eq!("abcdef", &message);

Provided Methods

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

The default implementation does nothing.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

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

impl Extend<AsciiChar> for String

impl Extend<char> for String

impl Extend<u8> for BytesMut

impl Extend<()> for ()

impl Extend<String> for String

impl Extend<OsString> for OsString

impl Extend<Bytes> for BytesMut

impl Extend<CreateFlags> for rustix::backend::event::epoll::CreateFlags

impl Extend<EventFlags> for rustix::backend::event::epoll::EventFlags

impl Extend<PollFlags> for rustix::backend::event::poll_fd::PollFlags

impl Extend<EventfdFlags> for rustix::backend::event::types::EventfdFlags

impl Extend<CreateFlags> for rustix::backend::fs::inotify::CreateFlags

impl Extend<CreateFlags> for rustix::backend::fs::inotify::CreateFlags

impl Extend<ReadFlags> for ReadFlags

impl Extend<WatchFlags> for rustix::backend::fs::inotify::WatchFlags

impl Extend<WatchFlags> for rustix::backend::fs::inotify::WatchFlags

impl Extend<Access> for rustix::backend::fs::types::Access

impl Extend<Access> for rustix::backend::fs::types::Access

impl Extend<AtFlags> for rustix::backend::fs::types::AtFlags

impl Extend<AtFlags> for rustix::backend::fs::types::AtFlags

impl Extend<FallocateFlags> for rustix::backend::fs::types::FallocateFlags

impl Extend<FallocateFlags> for rustix::backend::fs::types::FallocateFlags

impl Extend<MemfdFlags> for rustix::backend::fs::types::MemfdFlags

impl Extend<MemfdFlags> for rustix::backend::fs::types::MemfdFlags

impl Extend<Mode> for rustix::backend::fs::types::Mode

impl Extend<Mode> for rustix::backend::fs::types::Mode

impl Extend<MountFlags> for MountFlags

impl Extend<MountPropagationFlags> for MountPropagationFlags

impl Extend<OFlags> for rustix::backend::fs::types::OFlags

impl Extend<OFlags> for rustix::backend::fs::types::OFlags

impl Extend<RenameFlags> for rustix::backend::fs::types::RenameFlags

impl Extend<RenameFlags> for rustix::backend::fs::types::RenameFlags

impl Extend<ResolveFlags> for rustix::backend::fs::types::ResolveFlags

impl Extend<ResolveFlags> for rustix::backend::fs::types::ResolveFlags

impl Extend<SealFlags> for rustix::backend::fs::types::SealFlags

impl Extend<SealFlags> for rustix::backend::fs::types::SealFlags

impl Extend<StatVfsMountFlags> for rustix::backend::fs::types::StatVfsMountFlags

impl Extend<StatVfsMountFlags> for rustix::backend::fs::types::StatVfsMountFlags

impl Extend<StatxFlags> for rustix::backend::fs::types::StatxFlags

impl Extend<UnmountFlags> for UnmountFlags

impl Extend<CreateFlags> for rustix::backend::io::epoll::CreateFlags

impl Extend<EventFlags> for rustix::backend::io::epoll::EventFlags

impl Extend<PollFlags> for rustix::backend::io::poll_fd::PollFlags

impl Extend<DupFlags> for rustix::backend::io::types::DupFlags

impl Extend<DupFlags> for rustix::backend::io::types::DupFlags

impl Extend<EventfdFlags> for rustix::backend::io::types::EventfdFlags

impl Extend<FdFlags> for rustix::backend::io::types::FdFlags

impl Extend<FdFlags> for rustix::backend::io::types::FdFlags

impl Extend<PipeFlags> for rustix::backend::io::types::PipeFlags

impl Extend<ReadWriteFlags> for rustix::backend::io::types::ReadWriteFlags

impl Extend<ReadWriteFlags> for rustix::backend::io::types::ReadWriteFlags

impl Extend<SpliceFlags> for rustix::backend::io::types::SpliceFlags

impl Extend<RecvFlags> for RecvFlags

impl Extend<ReturnFlags> for ReturnFlags

impl Extend<SendFlags> for SendFlags

impl Extend<PipeFlags> for rustix::backend::pipe::types::PipeFlags

impl Extend<SpliceFlags> for rustix::backend::pipe::types::SpliceFlags

impl Extend<TimerfdFlags> for TimerfdFlags

impl Extend<TimerfdTimerFlags> for TimerfdTimerFlags

impl Extend<IFlags> for IFlags

impl Extend<StatxAttributes> for StatxAttributes

impl Extend<StatxFlags> for rustix::fs::statx::StatxFlags

impl Extend<XattrFlags> for rustix::fs::xattr::XattrFlags

impl Extend<XattrFlags> for rustix::fs::xattr::XattrFlags

impl Extend<SocketFlags> for SocketFlags

impl Extend<TxTimeFlags> for TxTimeFlags

impl Extend<SocketAddrXdpFlags> for SocketAddrXdpFlags

impl Extend<XdpDescOptions> for XdpDescOptions

impl Extend<XdpOptionsFlags> for XdpOptionsFlags

impl Extend<XdpRingFlags> for XdpRingFlags

impl Extend<XdpUmemRegFlags> for XdpUmemRegFlags

impl Extend<PidfdFlags> for PidfdFlags

impl Extend<PidfdGetfdFlags> for PidfdGetfdFlags

impl Extend<FloatingPointEmulationControl> for FloatingPointEmulationControl

impl Extend<FloatingPointExceptionMode> for FloatingPointExceptionMode

impl Extend<SpeculationFeatureControl> for SpeculationFeatureControl

impl Extend<SpeculationFeatureState> for SpeculationFeatureState

impl Extend<UnalignedAccessControl> for UnalignedAccessControl

impl Extend<WaitIdOptions> for WaitIdOptions

impl Extend<WaitOptions> for WaitOptions

impl<'a> Extend<&'a AsciiChar> for String

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

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

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

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

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

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

impl<'a, K, V, A> Extend<(&'a K, &'a V)> for BTreeMap<K, V, A>

where K: Ord + Copy, V: Copy, A: Allocator + Clone,

impl<'a, K, V, S> Extend<(&'a K, &'a V)> for HashMap<K, V, S>

where K: Eq + Hash + Copy, V: Copy, S: BuildHasher,

impl<'a, T, A> Extend<&'a T> for BinaryHeap<T, A>

where T: 'a + Ord + Copy, A: Allocator,

impl<'a, T, A> Extend<&'a T> for BTreeSet<T, A>

where T: 'a + Ord + Copy, A: Allocator + Clone,

impl<'a, T, A> Extend<&'a T> for LinkedList<T, A>

where T: 'a + Copy, A: Allocator,

impl<'a, T, A> Extend<&'a T> for VecDeque<T, A>

where T: 'a + Copy, A: Allocator,

impl<'a, T, A> Extend<&'a T> for Vec<T, A>

where T: Copy + 'a, A: Allocator,

Extend implementation that copies elements out of references before pushing them onto the Vec.

This implementation is specialized for slice iterators, where it uses copy_from_slice to append the entire slice at once.

impl<'a, T, S> Extend<&'a T> for HashSet<T, S>

where T: 'a + Eq + Hash + Copy, S: BuildHasher,

impl<'s, T> Extend<T> for SliceVec<'s, T>

impl<'slice, 'fd> Extend<SendAncillaryMessage<'slice, 'fd>> for SendAncillaryBuffer<'_, 'slice, 'fd>

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

where A: Array,

Extend the ArrayVec with an iterator.

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

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

where A: Array,

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

where A: Array,

impl<A> Extend<<A as Array>::Item> for tinyvec::arrayvec::ArrayVec<A>

where A: Array,

impl<A> Extend<Box<str, A>> for String

where A: Allocator,

impl<A, EA> Extend<(A₁, A₂, …, Aₙ)> for (EA₁, EA₂, …, EAₙ)

where EA: Extend<A>,

This trait is implemented for tuples up to twelve items long. The impls for 1- and 3- through 12-ary tuples were stabilized after 2-tuples, in 1.85.0.

impl<Fut> Extend<Fut> for FuturesOrdered<Fut>

where Fut: Future,

impl<Fut> Extend<Fut> for FuturesUnordered<Fut>

impl<K, V, A> Extend<(K, V)> for BTreeMap<K, V, A>

where K: Ord, A: Allocator + Clone,

impl<K, V, S> Extend<(K, V)> for HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher,

Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.

impl<K, V, S> Extend<(K, V)> for LiteMap<K, V, S>

where K: Ord, S: StoreBulkMut<K, V>,

impl<P> Extend<P> for std::path::PathBuf

where P: AsRef<Path>,

impl<P> Extend<P> for async_std::path::pathbuf::PathBuf

where P: AsRef<Path>,

impl<St> Extend<St> for SelectAll<St>

where St: Stream + Unpin,

impl<T, A> Extend<T> for BinaryHeap<T, A>

where T: Ord, A: Allocator,

impl<T, A> Extend<T> for BTreeSet<T, A>

where T: Ord, A: Allocator + Clone,

impl<T, A> Extend<T> for LinkedList<T, A>

where A: Allocator,

impl<T, A> Extend<T> for VecDeque<T, A>

where A: Allocator,

impl<T, A> Extend<T> for Vec<T, A>

where A: Allocator,

impl<T, S> Extend<T> for HashSet<T, S>

where T: Eq + Hash, S: BuildHasher,

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

Extend the ArrayVec with an iterator.

Panics if extending the vector exceeds its capacity.