1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

use std::cmp::Ordering;
use super::{SortOrder, IsSorted};

pub struct Intersection<I, J>
    where I: Iterator + IsSorted,
          J: Iterator + IsSorted
{
    i: I,
    j: J,
    a: Option<I::Item>,
    b: Option<J::Item>,
}


impl<I, J> IsSorted for Intersection<I, J>
    where I: Iterator + IsSorted,
          I::Ordering: SortOrder<I::Item>,
          J: Iterator<Item = I::Item> + IsSorted<Ordering = I::Ordering>
{
    type Ordering = I::Ordering;
}

impl<I, J> Iterator for Intersection<I, J>
    where I: Iterator + IsSorted,
          I::Item: Ord,
          I::Ordering: SortOrder<I::Item>,
          J: Iterator<Item = I::Item> + IsSorted<Ordering = I::Ordering>
{
    type Item = I::Item;

    fn next(&mut self) -> Option<Self::Item> {
        loop {
            let a = self.a.take().or_else(|| self.i.next());
            let b = self.b.take().or_else(|| self.j.next());
            match (a, b) {
                (Some(a), Some(b)) => {
                    match I::Ordering::cmp(&a, &b) {
                        Ordering::Equal => return Some(a),
                        Ordering::Less => self.b = Some(b),
                        Ordering::Greater => self.a = Some(a),
                    }
                }
                _ => return None,
            }
        }
    }
}


pub trait IntersectionExt
    where Self: Sized + Iterator + IsSorted
{
    fn intersection<J>(self, J) -> Intersection<Self, J>
        where J: Iterator<Item = Self::Item> + IsSorted<Ordering = Self::Ordering>;
}

impl<I> IntersectionExt for I
    where I: Sized + Iterator + IsSorted
{
    fn intersection<J>(self, j: J) -> Intersection<Self, J>
        where J: Iterator<Item = Self::Item> + IsSorted<Ordering = Self::Ordering>
    {
        Intersection {
            i: self,
            j,
            a: None,
            b: None,
        }
    }
}