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pub struct ChainIntoIter<A, B>
where
A: IntoIterator + Copy,
B: IntoIterator<Item = A::Item> + Copy,
{
a: A,
b: B,
}
pub trait Chain
where Self: IntoIterator + Copy
{
fn chain<B>(self, b: B) -> ChainIntoIter<Self, B>
where B: IntoIterator<Item = Self::Item> + Copy;
}
impl<T> Chain for T
where T: IntoIterator + Copy
{
fn chain<B>(self, b: B) -> ChainIntoIter<Self, B>
where B: IntoIterator<Item = Self::Item> + Copy
{
ChainIntoIter { a: self, b: b }
}
}
impl<'t, A, B> IntoIterator for &'t ChainIntoIter<A, B>
where
A: IntoIterator + Copy,
B: IntoIterator<Item = A::Item> + Copy,
{
type Item = A::Item;
type IntoIter = std::iter::Chain<A::IntoIter, B::IntoIter>;
fn into_iter(self) -> Self::IntoIter {
self.a.into_iter().chain(self.b.into_iter())
}
}
impl <A, B> IntoIterator for ChainIntoIter<A, B>
where
A: IntoIterator + Copy,
B: IntoIterator<Item = A::Item> + Copy,
{
type Item = A::Item;
type IntoIter = std::iter::Chain<A::IntoIter, B::IntoIter>;
fn into_iter(self) -> Self::IntoIter {
(&self).into_iter()
}
}
impl<A, B> Copy for ChainIntoIter<A, B>
where
A: IntoIterator + Copy,
B: IntoIterator<Item = A::Item> + Copy,
{
}
impl<A, B> Clone for ChainIntoIter<A, B>
where
A: IntoIterator + Copy,
B: IntoIterator<Item = A::Item> + Copy,
{
fn clone(&self) -> Self {
ChainIntoIter { a: self.a, b: self.b }
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn copy_test() {
let result = [1, 2, 3].chain(&[4, 5, 6]);
let x = result.chain(&[7, 8, 9]);
let v: Vec<isize> = x.into_iter().map(|x| *x).collect();
assert_eq!(vec!(1, 2, 3, 4, 5, 6, 7, 8, 9), v);
}
#[test]
fn ref_test() {
let result = [1, 2, 3].chain(&[4, 5, 6]);
let x = &result.chain(&[7, 8, 9]);
let v: Vec<isize> = x.into_iter().map(|x| *x).collect();
assert_eq!(vec!(1, 2, 3, 4, 5, 6, 7, 8, 9), v);
}
}