| 1 | use std::ops::{Add, AddAssign, Mul}; |
| 2 | |
| 3 | #[macro_export] |
| 4 | macro_rules! point { |
| 5 | ( $x:expr, $y:expr ) => { |
| 6 | Point2D { x: $x, y: $y } |
| 7 | }; |
| 8 | } |
| 9 | |
| 10 | #[derive(Debug, Copy, Clone, PartialEq)] |
| 11 | pub struct Point2D<T> { |
| 12 | pub x: T, |
| 13 | pub y: T, |
| 14 | } |
| 15 | |
| 16 | impl Point2D<f64> { |
| 17 | pub fn length(self) -> f64 { |
| 18 | ((self.x * self.x) + (self.y * self.y)).sqrt() |
| 19 | } |
| 20 | } |
| 21 | |
| 22 | impl<T: Add<Output = T>> Add for Point2D<T> { |
| 23 | type Output = Point2D<T>; |
| 24 | |
| 25 | fn add(self, rhs: Point2D<T>) -> Self::Output { |
| 26 | Point2D { |
| 27 | x: self.x + rhs.x, |
| 28 | y: self.y + rhs.y, |
| 29 | } |
| 30 | } |
| 31 | } |
| 32 | |
| 33 | impl<T: AddAssign> AddAssign for Point2D<T> { |
| 34 | fn add_assign(&mut self, rhs: Point2D<T>) { |
| 35 | self.x += rhs.x; |
| 36 | self.y += rhs.y; |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | #[macro_export] |
| 41 | macro_rules! rect { |
| 42 | ( $x:expr, $y:expr ) => { |
| 43 | Rect { x: $x, y: $y } |
| 44 | }; |
| 45 | } |
| 46 | |
| 47 | #[derive(Default)] |
| 48 | pub struct Rect<T> { |
| 49 | pub width: T, |
| 50 | pub height: T, |
| 51 | } |
| 52 | |
| 53 | impl<T: Mul<Output = T> + Copy> Rect<T> { |
| 54 | #[allow(dead_code)] |
| 55 | pub fn area(&self) -> T { |
| 56 | self.width * self.height |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | impl<T> From<(T, T)> for Rect<T> { |
| 61 | fn from(item: (T, T)) -> Self { |
| 62 | Rect { |
| 63 | width: item.0, |
| 64 | height: item.1, |
| 65 | } |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | #[cfg(test)] |
| 70 | mod tests { |
| 71 | use super::*; |
| 72 | |
| 73 | #[test] |
| 74 | fn immutable_copy_of_point() { |
| 75 | let a = point!(0, 0); |
| 76 | let mut b = a; // Copy |
| 77 | assert_eq!(a, b); // PartialEq |
| 78 | b.x = 1; |
| 79 | assert_ne!(a, b); // PartialEq |
| 80 | } |
| 81 | |
| 82 | #[test] |
| 83 | fn add_points() { |
| 84 | let mut a = point!(1, 0); |
| 85 | assert_eq!(a + point!(2, 2), point!(3, 2)); // Add |
| 86 | a += point!(2, 2); // AddAssign |
| 87 | assert_eq!(a, point!(3, 2)); |
| 88 | } |
| 89 | |
| 90 | #[test] |
| 91 | fn area_for_rect_of_multipliable_type() { |
| 92 | let r: Rect<_> = (30, 20).into(); // the Into trait uses the From trait |
| 93 | assert_eq!(r.area(), 30 * 20); |
| 94 | // let a = Rect::from(("a".to_string(), "b".to_string())).area(); // this doesn't work, because area() is not implemented for String |
| 95 | } |
| 96 | } |