| // Copyright 2015 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. |
| |
| |
| trait DigitCollection: Sized { |
| type Iter: Iterator<Item = u8>; |
| fn digit_iter(self) -> Self::Iter; |
| |
| fn digit_sum(self) -> u32 { |
| self.digit_iter() |
| .map(|digit: u8| digit as u32) |
| .fold(0, |sum, digit| sum + digit) |
| } |
| } |
| |
| impl<I> DigitCollection for I where I: Iterator<Item=u8> { |
| type Iter = I; |
| |
| fn digit_iter(self) -> I { |
| self |
| } |
| } |
| |
| fn main() { |
| let xs = vec![1, 2, 3, 4, 5]; |
| assert_eq!(xs.into_iter().digit_sum(), 15); |
| } |
