1 use crate::Itertools;
2
3 /// Combine all an iterator's elements into one element by using [`Extend`].
4 ///
5 /// [`IntoIterator`]-enabled version of [`Itertools::concat`].
6 ///
7 /// This combinator will extend the first item with each of the rest of the
8 /// items of the iterator. If the iterator is empty, the default value of
9 /// `I::Item` is returned.
10 ///
11 /// ```rust
12 /// use itertools::concat;
13 ///
14 /// let input = vec![vec![1], vec![2, 3], vec![4, 5, 6]];
15 /// assert_eq!(concat(input), vec![1, 2, 3, 4, 5, 6]);
16 /// ```
concat<I>(iterable: I) -> I::Item where I: IntoIterator, I::Item: Extend<<<I as IntoIterator>::Item as IntoIterator>::Item> + IntoIterator + Default,17 pub fn concat<I>(iterable: I) -> I::Item
18 where
19 I: IntoIterator,
20 I::Item: Extend<<<I as IntoIterator>::Item as IntoIterator>::Item> + IntoIterator + Default,
21 {
22 #[allow(deprecated)] //TODO: once msrv hits 1.51. replace `fold1` with `reduce`
23 iterable
24 .into_iter()
25 .fold1(|mut a, b| {
26 a.extend(b);
27 a
28 })
29 .unwrap_or_default()
30 }
31