Day 2 Morning Exercises

Points and Polygons

(back to exercise)

// Copyright 2022 Google LLC // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #[derive(Debug, Copy, Clone, PartialEq, Eq)] // ANCHOR: Point pub struct Point { // ANCHOR_END: Point x: i32, y: i32, } // ANCHOR: Point-impl impl Point { // ANCHOR_END: Point-impl pub fn new(x: i32, y: i32) -> Point { Point { x, y } } pub fn magnitude(self) -> f64 { f64::from(self.x.pow(2) + self.y.pow(2)).sqrt() } pub fn dist(self, other: Point) -> f64 { (self - other).magnitude() } } impl std::ops::Add for Point { type Output = Self; fn add(self, other: Self) -> Self::Output { Self { x: self.x + other.x, y: self.y + other.y, } } } impl std::ops::Sub for Point { type Output = Self; fn sub(self, other: Self) -> Self::Output { Self { x: self.x - other.x, y: self.y - other.y, } } } // ANCHOR: Polygon pub struct Polygon { // ANCHOR_END: Polygon points: Vec<Point>, } // ANCHOR: Polygon-impl impl Polygon { // ANCHOR_END: Polygon-impl pub fn new() -> Polygon { Polygon { points: Vec::new() } } pub fn add_point(&mut self, point: Point) { self.points.push(point); } pub fn left_most_point(&self) -> Option<Point> { self.points.iter().min_by_key(|p| p.x).copied() } pub fn iter(&self) -> impl Iterator<Item = &Point> { self.points.iter() } pub fn length(&self) -> f64 { if self.points.is_empty() { return 0.0; } let mut result = 0.0; let mut last_point = self.points[0]; for point in &self.points[1..] { result += last_point.dist(*point); last_point = *point; } result += last_point.dist(self.points[0]); result } } // ANCHOR: Circle pub struct Circle { // ANCHOR_END: Circle center: Point, radius: i32, } // ANCHOR: Circle-impl impl Circle { // ANCHOR_END: Circle-impl pub fn new(center: Point, radius: i32) -> Circle { Circle { center, radius } } pub fn circumference(&self) -> f64 { 2.0 * std::f64::consts::PI * f64::from(self.radius) } pub fn dist(&self, other: &Self) -> f64 { self.center.dist(other.center) } } // ANCHOR: Shape pub enum Shape { Polygon(Polygon), Circle(Circle), } // ANCHOR_END: Shape impl From<Polygon> for Shape { fn from(poly: Polygon) -> Self { Shape::Polygon(poly) } } impl From<Circle> for Shape { fn from(circle: Circle) -> Self { Shape::Circle(circle) } } impl Shape { pub fn circumference(&self) -> f64 { match self { Shape::Polygon(poly) => poly.length(), Shape::Circle(circle) => circle.circumference(), } } } // ANCHOR: unit-tests #[cfg(test)] mod tests { use super::*; fn round_two_digits(x: f64) -> f64 { (x * 100.0).round() / 100.0 } #[test] fn test_point_magnitude() { let p1 = Point::new(12, 13); assert_eq!(round_two_digits(p1.magnitude()), 17.69); } #[test] fn test_point_dist() { let p1 = Point::new(10, 10); let p2 = Point::new(14, 13); assert_eq!(round_two_digits(p1.dist(p2)), 5.00); } #[test] fn test_point_add() { let p1 = Point::new(16, 16); let p2 = p1 + Point::new(-4, 3); assert_eq!(p2, Point::new(12, 19)); } #[test] fn test_polygon_left_most_point() { let p1 = Point::new(12, 13); let p2 = Point::new(16, 16); let mut poly = Polygon::new(); poly.add_point(p1); poly.add_point(p2); assert_eq!(poly.left_most_point(), Some(p1)); } #[test] fn test_polygon_iter() { let p1 = Point::new(12, 13); let p2 = Point::new(16, 16); let mut poly = Polygon::new(); poly.add_point(p1); poly.add_point(p2); let points = poly.iter().cloned().collect::<Vec<_>>(); assert_eq!(points, vec![Point::new(12, 13), Point::new(16, 16)]); } #[test] fn test_shape_circumferences() { let mut poly = Polygon::new(); poly.add_point(Point::new(12, 13)); poly.add_point(Point::new(17, 11)); poly.add_point(Point::new(16, 16)); let shapes = vec![ Shape::from(poly), Shape::from(Circle::new(Point::new(10, 20), 5)), ]; let circumferences = shapes .iter() .map(Shape::circumference) .map(round_two_digits) .collect::<Vec<_>>(); assert_eq!(circumferences, vec![15.48, 31.42]); } } // ANCHOR_END: unit-tests #[allow(dead_code)] fn main() {}