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§
1.55.0 · sourcefn extend<T>(&mut self, iter: T)where
T: IntoIterator<Item = A>,
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§
sourcefn extend_one(&mut self, item: A)
🔬This is a nightly-only experimental API. (extend_one)
fn extend_one(&mut self, item: A)
extend_one)Extends a collection with exactly one element.
sourcefn extend_reserve(&mut self, additional: usize)
🔬This is a nightly-only experimental API. (extend_one)
fn extend_reserve(&mut self, additional: usize)
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<char> for CompactString
impl Extend<char> for String
no_global_oom_handling only.impl Extend<u8> for BytesMut
impl Extend<()> for ()
impl Extend<usize> for FixedBitSet
Sets the bit at index i to true for each item i in the input src.
impl Extend<Bytes> for BytesMut
impl Extend<CompactString> for CompactString
impl Extend<CompactString> for String
impl Extend<Box<str>> for CompactString
impl Extend<String> for CompactString
impl Extend<String> for String
no_global_oom_handling only.impl Extend<OsString> for OsString
impl Extend<EventMask> for EventMask
impl Extend<Flags> for Flags
impl Extend<FsyncFlags> for FsyncFlags
impl Extend<TimeoutFlags> for TimeoutFlags
impl Extend<TrustAnchor<'static>> for RootCertStore
impl Extend<WatchMask> for WatchMask
impl<'a> Extend<&'a char> for CompactString
impl<'a> Extend<&'a char> for String
no_global_oom_handling only.impl<'a> Extend<&'a str> for CompactString
impl<'a> Extend<&'a str> for String
no_global_oom_handling only.impl<'a> Extend<&'a u8> for BytesMut
impl<'a> Extend<&'a u8> for PrefixedPayload
impl<'a> Extend<&'a OsStr> for OsString
impl<'a> Extend<Cow<'a, str>> for CompactString
impl<'a> Extend<Cow<'a, str>> for String
no_global_oom_handling only.impl<'a> Extend<Cow<'a, OsStr>> for OsString
impl<'a> Extend<CompactString> for Cow<'a, str>
impl<'a, K, V, A> Extend<(&'a K, &'a V)> for BTreeMap<K, V, A>
impl<'a, K, V, S> Extend<(&'a K, &'a V)> for kvarn::prelude::HashMap<K, V, S>
impl<'a, K, V, S> Extend<(&'a K, &'a V)> for IndexMap<K, V, S>
impl<'a, K, V, S, A> Extend<&'a (K, V)> for HashMap<K, V, S, A>
Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.
impl<'a, K, V, S, A> Extend<&'a (K, V)> for HashMap<K, V, S, A>
Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.
impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for HashMap<K, V, S, A>
Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.
impl<'a, K, V, S, A> Extend<(&'a K, &'a V)> for HashMap<K, V, S, A>
Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.
impl<'a, T, A> Extend<&'a T> for BinaryHeap<T, A>
impl<'a, T, A> Extend<&'a T> for BTreeSet<T, A>
impl<'a, T, A> Extend<&'a T> for LinkedList<T, A>
impl<'a, T, A> Extend<&'a T> for VecDeque<T, A>
impl<'a, T, A> Extend<&'a T> for Vec<T, A>
no_global_oom_handling only.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 std::collections::hash::set::HashSet<T, S>
impl<'a, T, S> Extend<&'a T> for IndexSet<T, S>
impl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A>
impl<'a, T, S, A> Extend<&'a T> for HashSet<T, S, A>
impl<'s, T> Extend<T> for SliceVec<'s, T>
impl<A> Extend<<A as Array>::Item> for ArrayVec<A>where
A: Array,
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<Box<str, A>> for Stringwhere
A: Allocator,
no_global_oom_handling only.impl<A, B, ExtendA, ExtendB> Extend<(A, B)> for (ExtendA, ExtendB)
impl<Fut> Extend<Fut> for FuturesOrdered<Fut>where
Fut: Future,
impl<Fut> Extend<Fut> for FuturesUnordered<Fut>
impl<K, S> Extend<K> for DashSet<K, S>
impl<K, V, A> Extend<(K, V)> for BTreeMap<K, V, A>
impl<K, V, S> Extend<(K, V)> for kvarn::prelude::HashMap<K, V, S>
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 DashMap<K, V, S>
impl<K, V, S> Extend<(K, V)> for IndexMap<K, V, S>
impl<K, V, S, A> Extend<(K, V)> for HashMap<K, V, S, A>
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, A> Extend<(K, V)> for HashMap<K, V, S, A>
Inserts all new key-values from the iterator and replaces values with existing keys with new values returned from the iterator.
impl<N, E, Ty, Item, S> Extend<Item> for GraphMap<N, E, Ty, S>
Extend the graph from an iterable of edges.
Nodes are inserted automatically to match the edges.
impl<P> Extend<P> for PathBuf
impl<St> Extend<St> for SelectAll<St>
impl<T> Extend<(Option<HeaderName>, T)> for HeaderMap<T>
impl<T> Extend<(HeaderName, T)> for HeaderMap<T>
impl<T, A> Extend<T> for BinaryHeap<T, A>
impl<T, A> Extend<T> for BTreeSet<T, A>
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,
no_global_oom_handling only.