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", so this trait is not object safe.

Trait ExtendCopy 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<(String, Value)> for geng::prelude::serde_json::Map<String, Value>

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

impl Extend<AsciiChar> for String

impl Extend<char> for String

impl Extend<u8> for Bytes

impl Extend<u8> for bytes::bytes::BytesMut

impl Extend<u8> for bytes::bytes_mut::BytesMut

impl Extend<()> for ()

impl Extend<Extensions> for Extensions

impl Extend<String> for String

impl Extend<OsString> for OsString

impl Extend<Flags> for alsa::poll::Flags

impl Extend<PortCap> for PortCap

impl Extend<PortType> for PortType

impl Extend<Remove> for Remove

impl Extend<Bytes> for bytes::bytes_mut::BytesMut

impl Extend<Api> for Api

impl Extend<ConfigSurfaceTypes> for ConfigSurfaceTypes

impl Extend<DisplayFeatures> for DisplayFeatures

impl Extend<EventMask> for inotify::events::EventMask

impl Extend<EventMask> for inotify::events::EventMask

impl Extend<WatchMask> for inotify::watches::WatchMask

impl Extend<WatchMask> for inotify::watches::WatchMask

impl Extend<EpollCreateFlags> for EpollCreateFlags

impl Extend<EpollFlags> for EpollFlags

impl Extend<EfdFlags> for EfdFlags

impl Extend<Transformations> for Transformations

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

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

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

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

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

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

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

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 rustix::backend::fs::inotify::ReadFlags

impl Extend<ReadFlags> for rustix::backend::fs::inotify::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<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<DupFlags> for rustix::backend::io::types::DupFlags

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

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

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

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

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

impl Extend<MountFlags> for MountFlags

impl Extend<MountPropagationFlags> for MountPropagationFlags

Trait Extend

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