pub trait TryExtend<T> {
// Required method
fn try_extend<I>(&mut self, iter: I) -> Result<(), Error>
where I: IntoIterator<Item = T>;
}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§
Sourcefn try_extend<I>(&mut self, iter: I) -> Result<(), Error>where
I: IntoIterator<Item = T>,
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);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<'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>
impl<'a, K, V, S, A> TryExtend<&'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> TryExtend<(&'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> TryExtend<&'a T> for BTreeSet<T, A>
impl<'a, T, S, A> TryExtend<&'a T> for HashSet<T, S, A>
impl<A> TryExtend<char> for String<A>where
A: Allocator,
impl<K, V, A> TryExtend<(K, V)> for BTreeMap<K, V, A>
impl<K, V, S, A> TryExtend<(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.