Matthias Benkard | 848739c | 2019-02-28 13:59:58 +0100 | [diff] [blame^] | 1 | // Fearless Abstraction |
| 2 | |
Matthias Benkard | f3a3b30 | 2019-02-28 12:13:56 +0100 | [diff] [blame] | 3 | #![allow(dead_code)] |
| 4 | #![allow(unused_imports)] |
| 5 | |
| 6 | use rust_tutorial::*; |
| 7 | |
| 8 | /// Run this to see the disassembly of `compute_sum_of_squares_{1,2}`: |
| 9 | /// |
| 10 | /// ```bash |
Matthias Benkard | 848739c | 2019-02-28 13:59:58 +0100 | [diff] [blame^] | 11 | /// cargo objdump --bin tut3 --release -- -d | awk -v RS= '/^([[:xdigit:]]+ )?tut2::compute_sum_of_squares/' |
Matthias Benkard | f3a3b30 | 2019-02-28 12:13:56 +0100 | [diff] [blame] | 12 | /// ``` |
| 13 | |
| 14 | #[inline(never)] |
| 15 | fn compute_sum_of_squares_1(xs: &Vec<i32>) -> i32 { |
| 16 | let mut acc = 0; |
| 17 | for x in xs { |
| 18 | acc += x * x; |
| 19 | } |
| 20 | acc |
| 21 | } |
| 22 | |
| 23 | #[inline(never)] |
| 24 | fn compute_sum_of_squares_2(xs: &Vec<i32>) -> i32 { |
| 25 | xs.iter() |
| 26 | .map(|x| x * x) |
| 27 | .fold(0, |acc, x| acc + x) |
| 28 | } |
| 29 | |
| 30 | #[test] |
| 31 | fn test_compute_sum_of_squares() { |
| 32 | let numbers = vec![1, 2, 3, 4, 5]; |
| 33 | assert_eq!(compute_sum_of_squares_1(&numbers), compute_sum_of_squares_2(&numbers)); |
| 34 | } |
| 35 | |
| 36 | fn main() { |
| 37 | let numbers = vec![1, 2, 3, 4, 5]; |
| 38 | |
| 39 | let sum_of_squares_1 = compute_sum_of_squares_1(&numbers); |
| 40 | let sum_of_squares_2 = compute_sum_of_squares_2(&numbers); |
| 41 | |
| 42 | println!("sum #1 = {}", sum_of_squares_1); |
| 43 | println!("sum #2 = {}", sum_of_squares_2); |
| 44 | } |