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use crate::Counter;
use num_traits::Zero;
use std::hash::{BuildHasher, Hash};
use std::ops::{Add, AddAssign};
impl<T, N, S> Add for Counter<T, N, S>
where
T: Clone + Hash + Eq,
N: AddAssign + Zero,
S: BuildHasher,
{
type Output = Counter<T, N, S>;
/// Add two counters together.
///
/// `out = c + d;` -> `out[x] == c[x] + d[x]` for all `x`
///
/// ```rust
/// # use counter::Counter;
/// # use std::collections::HashMap;
/// let c = "aaab".chars().collect::<Counter<_>>();
/// let d = "abb".chars().collect::<Counter<_>>();
///
/// let e = c + d;
///
/// let expect = [('a', 4), ('b', 3)].iter().cloned().collect::<HashMap<_, _>>();
/// assert_eq!(e.into_map(), expect);
/// ```
fn add(mut self, rhs: Counter<T, N, S>) -> Self::Output {
self += rhs;
self
}
}
impl<T, N, S> AddAssign for Counter<T, N, S>
where
T: Hash + Eq,
N: Zero + AddAssign,
S: BuildHasher,
{
/// Add another counter to this counter.
///
/// `c += d;` -> `c[x] += d[x]` for all `x`
///
/// ```rust
/// # use counter::Counter;
/// # use std::collections::HashMap;
/// let mut c = "aaab".chars().collect::<Counter<_>>();
/// let d = "abb".chars().collect::<Counter<_>>();
///
/// c += d;
///
/// let expect = [('a', 4), ('b', 3)].iter().cloned().collect::<HashMap<_, _>>();
/// assert_eq!(c.into_map(), expect);
/// ```
fn add_assign(&mut self, rhs: Self) {
for (key, value) in rhs.map {
let entry = self.map.entry(key).or_insert_with(N::zero);
*entry += value;
}
}
}