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) { ... }
}Available on crate feature
mtls only.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 · 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.
Object Safety§
This trait is not object safe.
Implementors§
impl Extend<(String, Value)> for serde_json::map::Map<String, Value>
impl Extend<(String, Value)> for toml::map::Map<String, Value>
impl Extend<char> for InlinableString
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 CreateFlags
impl Extend<ReadFlags> for ReadFlags
impl Extend<WatchFlags> for WatchFlags
impl Extend<Access> for Access
impl Extend<AtFlags> for AtFlags
impl Extend<FallocateFlags> for FallocateFlags
impl Extend<MemfdFlags> for MemfdFlags
impl Extend<Mode> for Mode
impl Extend<OFlags> for OFlags
impl Extend<RenameFlags> for RenameFlags
impl Extend<ResolveFlags> for ResolveFlags
impl Extend<SealFlags> for SealFlags
impl Extend<StatVfsMountFlags> for StatVfsMountFlags
impl Extend<StatxFlags> for StatxFlags
impl Extend<DupFlags> for DupFlags
impl Extend<FdFlags> for FdFlags
impl Extend<ReadWriteFlags> for ReadWriteFlags
impl Extend<MountFlags> for MountFlags
impl Extend<MountPropagationFlags> for MountPropagationFlags
impl Extend<UnmountFlags> for UnmountFlags
impl Extend<IFlags> for IFlags
impl Extend<XattrFlags> for XattrFlags
impl Extend<Table> for ArrayOfTables
impl<'a> Extend<&'a char> for InlinableString
impl<'a> Extend<&'a char> for String
impl<'a> Extend<&'a str> for InlinableString
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>
impl<'a, K, V, S> Extend<(&'a K, &'a V)> for rocket::mtls::oid::asn1_rs::nom::lib::std::collections::HashMap<K, V, S>
impl<'a, K, V, S> Extend<(&'a K, &'a V)> for AHashMap<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 hashbrown::map::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 hashbrown::map::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 BTreeSet<T, A>
impl<'a, T, A> Extend<&'a T> for BinaryHeap<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 rocket::mtls::oid::asn1_rs::nom::lib::std::vec::Vec<T, A>
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, A> Extend<&'a T> for allocator_api2::stable::vec::Vec<T, A>
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 rocket::mtls::oid::asn1_rs::nom::lib::std::collections::HashSet<T, S>
impl<'a, T, S> Extend<&'a T> for AHashSet<T, S>
impl<'a, T, S> Extend<&'a T> for IndexSet<T, S>
impl<'a, T, S, A> Extend<&'a T> for hashbrown::set::HashSet<T, S, A>
impl<A> Extend<<A as Array>::Item> for SmallVec<A>where
A: Array,
impl<A> Extend<Box<str, A>> for Stringwhere
A: Allocator,
impl<A> Extend<Box<str, A>> for Stringwhere
A: Allocator,
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, V> Extend<(K, V)> for StreamMap<K, V>
impl<K, V> Extend<(K, V)> for InlineTable
impl<K, V> Extend<(K, V)> for Table
impl<K, V, A> Extend<(K, V)> for BTreeMap<K, V, A>
impl<K, V, S> Extend<(K, V)> for rocket::mtls::oid::asn1_rs::nom::lib::std::collections::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 AHashMap<K, V, S>
impl<K, V, S> Extend<(K, V)> for IndexMap<K, V, S>
impl<K, V, S, A> Extend<(K, V)> for hashbrown::map::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.