collected/
count.rs

1use crate::common::*;
2
3/// A counter that counts witnessed items when collected or extended from an iterator.
4#[derive(Debug, Clone)]
5pub struct Count<T> {
6    count: usize,
7    _phantom: PhantomData<T>,
8}
9
10impl<T> Count<T> {
11    pub fn get(&self) -> usize {
12        self.count
13    }
14}
15
16impl<T> Default for Count<T> {
17    fn default() -> Self {
18        Self {
19            count: 0,
20            _phantom: PhantomData,
21        }
22    }
23}
24
25impl<A> FromIterator<A> for Count<A> {
26    fn from_iter<T: IntoIterator<Item = A>>(iter: T) -> Self {
27        Self {
28            count: iter.into_iter().count(),
29            _phantom: PhantomData,
30        }
31    }
32}
33
34impl<A> Extend<A> for Count<A> {
35    fn extend<T: IntoIterator<Item = A>>(&mut self, iter: T) {
36        self.count += iter.into_iter().count();
37    }
38}
39
40#[cfg(test)]
41mod tests {
42    use super::*;
43
44    #[test]
45    fn count_test() {
46        {
47            let mut count: Count<_> = iter::empty().collect();
48            count.extend(0..10);
49            assert!(count.get() == 10);
50        }
51
52        {
53            let mut count: Count<_> = (0..10).collect();
54            assert!(count.get() == 10);
55
56            count.extend(10..20);
57            assert!(count.get() == 20);
58
59            count.extend(iter::empty());
60            assert!(count.get() == 20);
61        }
62    }
63}
collected/count.rs

collected/
count.rs
