Trait otter_api_tests::iter::IntoIterator1.0.0[−][src]

pub trait IntoIterator {
    type Item;
    type IntoIter: Iterator;
    fn into_iter(self) -> Self::IntoIter;
}
Expand description

Conversion into an Iterator.

By implementing IntoIterator for a type, you define how it will be converted to an iterator. This is common for types which describe a collection of some kind.

One benefit of implementing IntoIterator is that your type will work with Rust’s for loop syntax.

See also: FromIterator.

Examples

Basic usage:

let v = vec![1, 2, 3];
let mut iter = v.into_iter();

assert_eq!(Some(1), iter.next());
assert_eq!(Some(2), iter.next());
assert_eq!(Some(3), iter.next());
assert_eq!(None, iter.next());

Implementing IntoIterator for your type:

// 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);
    }
}

// and we'll implement IntoIterator
impl IntoIterator for MyCollection {
    type Item = i32;
    type IntoIter = std::vec::IntoIter<Self::Item>;

    fn into_iter(self) -> Self::IntoIter {
        self.0.into_iter()
    }
}

// Now we can make a new collection...
let mut c = MyCollection::new();

// ... add some stuff to it ...
c.add(0);
c.add(1);
c.add(2);

// ... and then turn it into an Iterator:
for (i, n) in c.into_iter().enumerate() {
    assert_eq!(i as i32, n);
}

It is common to use IntoIterator as a trait bound. This allows the input collection type to change, so long as it is still an iterator. Additional bounds can be specified by restricting on Item:

fn collect_as_strings<T>(collection: T) -> Vec<String>
where
    T: IntoIterator,
    T::Item: std::fmt::Debug,
{
    collection
        .into_iter()
        .map(|item| format!("{:?}", item))
        .collect()
}

Associated Types

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Required methods

Creates an iterator from a value.

See the module-level documentation for more.

Examples

Basic usage:

let v = vec![1, 2, 3];
let mut iter = v.into_iter();

assert_eq!(Some(1), iter.next());
assert_eq!(Some(2), iter.next());
assert_eq!(Some(3), iter.next());
assert_eq!(None, iter.next());

Implementations on Foreign Types

Creates a consuming iterator, that is, one that moves each value out of the array (from start to end). The array cannot be used after calling this unless T implements Copy, so the whole array is copied.

Arrays have special behavior when calling .into_iter() prior to the 2021 edition – see the array Editions section for more information.

Consumes the list into an iterator yielding elements by value.

Creates a consuming iterator, that is, one that moves each value out of the vector (from start to end). The vector cannot be used after calling this.

Examples

let v = vec!["a".to_string(), "b".to_string()];
for s in v.into_iter() {
    // s has type String, not &String
    println!("{}", s);
}

Creates a consuming iterator, that is, one that moves each value out of the binary heap in arbitrary order. The binary heap cannot be used after calling this.

Examples

Basic usage:

use std::collections::BinaryHeap;
let heap = BinaryHeap::from(vec![1, 2, 3, 4]);

// Print 1, 2, 3, 4 in arbitrary order
for x in heap.into_iter() {
    // x has type i32, not &i32
    println!("{}", x);
}

Convert into an iterator over the indices as a sequence of usize values

Returns an iterator visiting all key-value pairs in ascending order of the keys, consuming the original VecMap. The iterator’s element type is (usize, &'r V).

Examples

use vec_map::VecMap;

let mut map = VecMap::new();
map.insert(1, "a");
map.insert(3, "c");
map.insert(2, "b");

let vec: Vec<(usize, &str)> = map.into_iter().collect();

assert_eq!(vec, [(1, "a"), (2, "b"), (3, "c")]);

Creates a consuming iterator, that is, one that moves keys and values out of the map in arbitrary order. The map cannot be used after calling this.

For each yielded item that has None provided for the HeaderName, then the associated header name is the same as that of the previously yielded item. The first yielded item will have HeaderName set.

Examples

Basic usage.

let mut map = HeaderMap::new();
map.insert(header::CONTENT_LENGTH, "123".parse().unwrap());
map.insert(header::CONTENT_TYPE, "json".parse().unwrap());

let mut iter = map.into_iter();
assert_eq!(iter.next(), Some((Some(header::CONTENT_LENGTH), "123".parse().unwrap())));
assert_eq!(iter.next(), Some((Some(header::CONTENT_TYPE), "json".parse().unwrap())));
assert!(iter.next().is_none());

Multiple values per key.

let mut map = HeaderMap::new();

map.append(header::CONTENT_LENGTH, "123".parse().unwrap());
map.append(header::CONTENT_LENGTH, "456".parse().unwrap());

map.append(header::CONTENT_TYPE, "json".parse().unwrap());
map.append(header::CONTENT_TYPE, "html".parse().unwrap());
map.append(header::CONTENT_TYPE, "xml".parse().unwrap());

let mut iter = map.into_iter();

assert_eq!(iter.next(), Some((Some(header::CONTENT_LENGTH), "123".parse().unwrap())));
assert_eq!(iter.next(), Some((None, "456".parse().unwrap())));

assert_eq!(iter.next(), Some((Some(header::CONTENT_TYPE), "json".parse().unwrap())));
assert_eq!(iter.next(), Some((None, "html".parse().unwrap())));
assert_eq!(iter.next(), Some((None, "xml".parse().unwrap())));
assert!(iter.next().is_none());

Creates a consuming iterator, that is, one that moves each value out of the set in arbitrary order. The set cannot be used after calling this.

Examples

use hashbrown::HashSet;
let mut set = HashSet::new();
set.insert("a".to_string());
set.insert("b".to_string());

// Not possible to collect to a Vec<String> with a regular `.iter()`.
let v: Vec<String> = set.into_iter().collect();

// Will print in an arbitrary order.
for x in &v {
    println!("{}", x);
}

Creates a consuming iterator, that is, one that moves each key-value pair out of the map in arbitrary order. The map cannot be used after calling this.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

// Not possible with .iter()
let vec: Vec<(&str, i32)> = map.into_iter().collect();

Implementors