| //@ compile-flags: -Zinline-mir | |
| use std::fmt::Display; | |
| fn main() { | |
| permutations(&['a', 'b', 'c']); | |
| } | |
| #[inline(always)] | |
| fn permutations<T: Copy + Display>(xs: &[T]) { | |
| let mut ys = xs.to_owned(); | |
| permutate(&mut ys, 0); | |
| } | |
| fn permutate<T: Copy + Display>(xs: &mut [T], k: usize) { | |
| let n = length(xs); | |
| if k == n { | |
| display(xs); | |
| } else if k < n { | |
| for i in k..n { | |
| swap(xs, i, k); | |
| permutate(xs, k + 1); | |
| swap(xs, i, k); | |
| } | |
| } else { | |
| error(); | |
| } | |
| } | |
| fn length<T>(xs: &[T]) -> usize { | |
| xs.len() | |
| } | |
| #[inline] | |
| fn swap<T: Copy>(xs: &mut [T], i: usize, j: usize) { | |
| let t = xs[i]; | |
| xs[i] = xs[j]; | |
| xs[j] = t; | |
| } | |
| fn display<T: Display>(xs: &[T]) { | |
| for x in xs { | |
| print!("{}", x); | |
| } | |
| println!(); | |
| } | |
| #[inline(always)] | |
| fn error() { | |
| panic!("error"); | |
| } |