| // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| |
| fn pairwise_sub<T:DoubleEndedIterator<Item=isize>>(mut t: T) -> isize { |
| let mut result = 0; |
| loop { |
| let front = t.next(); |
| let back = t.next_back(); |
| match (front, back) { |
| (Some(f), Some(b)) => { result += b - f; } |
| _ => { return result; } |
| } |
| } |
| } |
| |
| fn main() { |
| let v = vec!(1, 2, 3, 4, 5, 6); |
| let r = pairwise_sub(v.into_iter()); |
| assert_eq!(r, 9); |
| } |
