Trait rune::alloc::prelude::TryExtend

pub trait TryExtend<T> {
    // Required method
    fn try_extend<I>(&mut self, iter: I) -> Result<(), Error>
       where I: IntoIterator<Item = T>;
}

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 try_extend<I>(&mut self, iter: I) -> Result<(), Error>

where I: IntoIterator<Item = T>,

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

Basic usage:

use rune::alloc::String;
use rune::alloc::prelude::*;

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

message.try_extend(['d', 'e', 'f'].into_iter())?;

assert_eq!("abcdef", &message);

Object Safety

This trait is not object safe.

Implementors

impl<'a, A> TryExtend<&'a str> for String<A>

where A: Allocator,

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

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

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

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

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> TryExtend<(&'a K, &'a V)> for HashMap<K, V, S, A>

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

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> TryExtend<&'a T> for BTreeSet<T, A>

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

impl<'a, T, S, A> TryExtend<&'a T> for HashSet<T, S, A>

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

impl<A> TryExtend<char> for String<A>

where A: Allocator,

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

where K: Ord, A: Allocator + Clone,

impl<K, V, S, A> TryExtend<(K, V)> for HashMap<K, V, S, A>

where K: Eq + Hash, S: BuildHasher, A: Allocator,

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

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

where A: Allocator, T: Ord,

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

where A: Allocator,

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

where A: Allocator,

impl<T, S, A> TryExtend<T> for HashSet<T, S, A>

where T: Eq + Hash, S: BuildHasher, A: Allocator,