2 unstable releases
0.2.0 | Sep 28, 2020 |
---|---|
0.1.0 | Sep 22, 2020 |
#1246 in Rust patterns
441 downloads per month
16KB
96 lines
dyn-iter
This tiny crate should help you simplify your code when you need to wrap
Iterator
as trait-object.
Imagine for example a trait like the following.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum Color {
Red,
Green,
Blue,
White,
Black,
}
trait Colors<'a> {
type ColorsIter: Iterator<Item = Color>;
fn colors(&'a self) -> Self::ColorsIter;
}
As an implementor, you have a struct Flag
that looks like this.
struct Flag {
primary_colors: HashSet<Color>,
secondary_colors: HashSet<Color>,
}
you might implement a fn colors()
that look like this
fn colors(&'a self) -> Self::ColorsIter {
self.primary_colors
.iter()
.chain(&self.secondary_colors)
.filter(|color| **color != Color::Black)
.copied()
}
With the above implementation, defining the associated type ColorsIter
might
be difficult. DynIter
should simplify your life because you can just write the
following implementation.
trait Colors<'a> {
type ColorsIter = DynIter<'a, Color>;
fn colors(&'a self) -> Self::ColorsIter {
DynIter::new(
self.primary_colors
.iter()
.chain(&self.secondary_colors)
.filter(|color| **color != Color::Black)
.copied()
)
}
}
Behind the scene, DynIter<'iter, V>
is only providing a wrapper around a
Box<dyn Iterator<Item = V> + 'iter>
.
For more details about why this crate exists, read this blog post.