1 //! An iterator that returns `(start, end)` tuples from the walk.
2
3 /// An iterator that returns `(start, end)` tuples from the walk.
4 ///
5 /// All the algorithms in this crate should have a `steps()` function associated with them to turn
6 /// them into a [`Steps`] iterator.
7 ///
8 /// Example using [`WalkGrid`]:
9 ///
10 /// ```
11 /// extern crate line_drawing;
12 /// use line_drawing::WalkGrid;
13 ///
14 /// fn main() {
15 /// for (start, end) in WalkGrid::new((0, 0), (5, 3)).steps() {
16 /// println!("{:?} -> {:?}", start, end);
17 /// }
18 /// }
19 /// ```
20 ///
21 /// ```text
22 /// (0, 0) -> (1, 0)
23 /// (1, 0) -> (1, 1)
24 /// (1, 1) -> (2, 1)
25 /// (2, 1) -> (2, 2)
26 /// (2, 2) -> (3, 2)
27 /// (3, 2) -> (4, 2)
28 /// (4, 2) -> (4, 3)
29 /// (4, 3) -> (5, 3)
30 /// ```
31 ///
32 /// [`Steps`]: struct.Steps.html
33 /// [`WalkGrid`]: ../struct.WalkGrid.html
34 pub struct Steps<T, I> {
35 iterator: I,
36 prev: Option<T>,
37 }
38
39 impl<T: Copy, I: Iterator<Item = T>> Steps<T, I> {
40 #[inline]
new(mut iterator: I) -> Self41 pub fn new(mut iterator: I) -> Self {
42 Self {
43 prev: iterator.next(),
44 iterator,
45 }
46 }
47 }
48
49 impl<T: Copy, I: Iterator<Item = T>> Iterator for Steps<T, I> {
50 type Item = (T, T);
51
52 #[inline]
next(&mut self) -> Option<Self::Item>53 fn next(&mut self) -> Option<Self::Item> {
54 self.iterator.next().and_then(|next| {
55 self.prev.map(|prev| {
56 self.prev = Some(next);
57 (prev, next)
58 })
59 })
60 }
61 }
62
63 #[test]
steps()64 fn steps() {
65 use Midpoint;
66
67 assert_eq!(
68 Midpoint::new((0.0, 0.0), (3.0, 4.0))
69 .steps()
70 .collect::<Vec<_>>(),
71 [
72 ((0, 0), (1, 1)),
73 ((1, 1), (2, 2)),
74 ((2, 2), (2, 3)),
75 ((2, 3), (3, 4))
76 ]
77 );
78 }
79