Trait Extend

1.0.0 · Source

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) { ... }
}

Expand description

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§

1.0.0 · Source

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§

Source

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

Source

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".

Implementors§

1.28.0 · Source§

Trait Extend Copy item path

§Examples

Required Methods§

fn extend<T>(&mut self, iter: T)where T: IntoIterator<Item = A>,

§Examples

Provided Methods§

fn extend_one(&mut self, item: A)

fn extend_reserve(&mut self, additional: usize)

Dyn Compatibility§

Implementors§

impl Extend<()> for ()

impl Extend<(String, Value)> for serde_json::map::Map<String, Value>

impl Extend<(String, Value)> for toml::map::Map<String, Value>

impl Extend<Access> for Access

impl Extend<AsciiChar> for String

impl Extend<AtFlags> for AtFlags

impl Extend<BeginFlags> for BeginFlags

impl Extend<Bytes> for BytesMut

impl Extend<CMSOptions> for CMSOptions

impl Extend<CipherCtxFlags> for CipherCtxFlags

impl Extend<ControlModes> for ControlModes

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

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

impl Extend<DupFlags> for DupFlags

impl Extend<EventFlags> for EventFlags

impl Extend<EventKindMask> for EventKindMask

impl Extend<EventMask> for EventMask

impl Extend<EventfdFlags> for EventfdFlags

impl Extend<ExtensionContext> for ExtensionContext

impl Extend<FallocateFlags> for FallocateFlags

impl Extend<FdFlags> for FdFlags

impl Extend<FloatingPointEmulationControl> for FloatingPointEmulationControl

impl Extend<FloatingPointExceptionMode> for FloatingPointExceptionMode

impl Extend<IFlags> for IFlags

impl Extend<InputModes> for InputModes

impl Extend<LocalModes> for LocalModes

impl Extend<MemfdFlags> for MemfdFlags

impl Extend<Mode> for Mode

impl Extend<OFlags> for OFlags

impl Extend<OcspFlag> for OcspFlag

impl Extend<OsString> for OsString

impl Extend<OutputModes> for OutputModes

impl Extend<PidfdFlags> for PidfdFlags

impl Extend<PidfdGetfdFlags> for PidfdGetfdFlags

impl Extend<PipeFlags> for PipeFlags

impl Extend<Pkcs7Flags> for Pkcs7Flags

impl Extend<PollFlags> for PollFlags

impl Extend<ReadFlags> for ReadFlags

impl Extend<ReadWriteFlags> for ReadWriteFlags

impl Extend<RecvFlags> for RecvFlags

impl Extend<RenameFlags> for RenameFlags

impl Extend<ResolveFlags> for ResolveFlags

impl Extend<ReturnFlags> for ReturnFlags

impl Extend<SealFlags> for SealFlags

impl Extend<SendFlags> for SendFlags

impl Extend<ShutdownState> for ShutdownState

impl Extend<SocketAddrXdpFlags> for SocketAddrXdpFlags

impl Extend<SocketFlags> for SocketFlags

impl Extend<SpeculationFeatureControl> for SpeculationFeatureControl

impl Extend<SpeculationFeatureState> for SpeculationFeatureState

impl Extend<SpliceFlags> for SpliceFlags

impl Extend<SslMode> for SslMode

impl Extend<SslOptions> for SslOptions

impl Extend<SslSessionCacheMode> for SslSessionCacheMode

impl Extend<SslVerifyMode> for SslVerifyMode

impl Extend<StatVfsMountFlags> for StatVfsMountFlags

impl Extend<StatxAttributes> for StatxAttributes

impl Extend<StatxFlags> for StatxFlags

impl Extend<String> for String

impl Extend<Table> for ArrayOfTables

impl Extend<TimerfdFlags> for TimerfdFlags

impl Extend<TimerfdTimerFlags> for TimerfdTimerFlags

impl Extend<TrustAnchor<'static>> for RootCertStore

impl Extend<TxTimeFlags> for TxTimeFlags

impl Extend<UnalignedAccessControl> for UnalignedAccessControl

impl Extend<WaitIdOptions> for WaitIdOptions

impl Extend<WaitOptions> for WaitOptions

impl Extend<WatchFlags> for WatchFlags

impl Extend<WatchMask> for WatchMask

impl Extend<X509CheckFlags> for X509CheckFlags

Trait Extend

fn extend<T>(&mut self, iter: T)
where T: IntoIterator<Item = A>,

impl<'a, 'b, R> Extend<&'b u8> for Modifier<'a, R>
where R: Relocation,

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, A> Extend<&'a (K, V)> for hashbrown::map::HashMap<K, V, S, A>
where K: Eq + Hash + Copy, V: Copy, S: BuildHasher, A: Allocator,

impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for tor_hsservice::internal_prelude::HashMap<K, V, S, A>
where K: Eq + Hash + Copy, V: Copy, S: BuildHasher, A: Allocator,

impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for hashbrown::map::HashMap<K, V, S, A>
where K: Eq + Hash + Copy, V: Copy, S: BuildHasher, A: Allocator,

impl<'a, K, V, S> Extend<(&'a <K as WeakElement>::Strong, &'a V)> for PtrWeakKeyHashMap<K, V, S>
where K: 'a + WeakElement, <K as WeakElement>::Strong: Clone + Deref, V: 'a + Clone, S: BuildHasher,

impl<'a, K, V, S> Extend<(&'a <K as WeakElement>::Strong, &'a V)> for WeakKeyHashMap<K, V, S>
where K: 'a + WeakKey, <K as WeakElement>::Strong: Clone, V: 'a + Clone, S: BuildHasher,

impl<'a, K, V, S> Extend<(&'a K, &'a <V as WeakElement>::Strong)> for WeakValueHashMap<K, V, S>
where K: 'a + Eq + Hash + Clone, V: 'a + WeakElement, <V as WeakElement>::Strong: Clone, S: BuildHasher,

impl<'a, K, V, S> Extend<(&'a K, &'a V)> for IndexMap<K, V, S>
where K: Hash + Eq + Copy, V: Copy, S: BuildHasher,

impl<'a, K, V, S> Extend<(K, &'a V)> for SparseSecondaryMap<K, V, S>
where K: Key, V: 'a + Copy, S: BuildHasher,

impl<'a, K, V> Extend<&'a V> for TiVec<K, V>
where V: 'a + Copy,

impl<'a, K, V> Extend<(&'a K, &'a V)> for EnumMap<K, V>
where K: EnumArray<V> + Copy, V: Copy,

impl<'a, K, V> Extend<(K, &'a V)> for SecondaryMap<K, V>
where K: Key, V: 'a + Copy,

impl<'a, M, T1, T2, O1, O2> Extend<BitRef<'a, M, T2, O2>> for BitVec<T1, O1>
where M: Mutability, T1: BitStore, T2: BitStore, O1: BitOrder, O2: BitOrder,

impl<'a, R> Extend<&'a u8> for Assembler<R>
where R: Relocation,

impl<'a, R> Extend<&'a u8> for VecAssembler<R>
where R: Relocation,

impl<'a, R> Extend<u8> for Modifier<'a, R>
where R: Relocation,

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 BinaryHeap<T, A>
where T: 'a + Ord + Copy, A: Allocator,

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 Vec<T, A>
where T: Copy + 'a, A: Allocator,

impl<'a, T, A> Extend<&'a T> for VecDeque<T, A>
where T: 'a + Copy, A: Allocator,

impl<'a, T, O> Extend<&'a T> for BitVec<T, O>
where T: BitStore, O: BitOrder,

impl<'a, T, O> Extend<&'a bool> for BitVec<T, O>
where T: BitStore, O: BitOrder,

impl<'a, T, S, A> Extend<&'a T> for tor_hsservice::internal_prelude::HashSet<T, S, A>
where T: 'a + Eq + Hash + Copy, S: BuildHasher, A: Allocator,

impl<'a, T, S, A> Extend<&'a T> for hashbrown::set::HashSet<T, S, A>
where T: 'a + Eq + Hash + Copy, S: BuildHasher, A: Allocator,

impl<'a, T, S> Extend<&'a T> for IndexSet<T, S>
where T: Hash + Eq + Copy + 'a, S: BuildHasher,

impl<'a, T> Extend<&'a EnumSet<T>> for EnumSet<T>
where T: EnumSetType,

impl<'a, T> Extend<&'a EnumSet<T>> for MixedEnumSet<T>
where T: EnumSetTypeWithRepr,

impl<'a, T> Extend<&'a MixedEnumSet<T>> for MixedEnumSet<T>
where T: EnumSetTypeWithRepr,

impl<'a, T> Extend<&'a T> for EnumSet<T>
where T: EnumSetType,

impl<'a, T> Extend<&'a T> for MixedEnumSet<T>
where T: EnumSetTypeWithRepr,

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

impl<A> Extend<A> for AsciiString
where A: AsRef<AsciiStr>,

impl<A> Extend<Box<str, A>> for String
where A: Allocator,

impl<F, R> Extend<R> for FlagSet<F>
where F: Flags, R: Into<FlagSet<F>>,

impl<Fut> Extend<Fut> for FuturesOrdered<Fut>
where Fut: Future,

impl<I, P, H> Extend<(I, P)> for DoublePriorityQueue<I, P, H>
where I: Hash + Eq, P: Ord, H: BuildHasher,