| // Copyright 2012 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. |
| |
| #![allow(non_camel_case_types)] |
| #![allow(non_snake_case)] |
| #![allow(dead_code)] |
| #![feature(box_syntax)] |
| |
| // Example from lkuper's intern talk, August 2012. |
| use Color::{cyan, magenta, yellow, black}; |
| use ColorTree::{leaf, branch}; |
| |
| trait Equal { |
| fn isEq(&self, a: &Self) -> bool; |
| } |
| |
| #[derive(Clone, Copy)] |
| enum Color { cyan, magenta, yellow, black } |
| |
| impl Equal for Color { |
| fn isEq(&self, a: &Color) -> bool { |
| match (*self, *a) { |
| (cyan, cyan) => { true } |
| (magenta, magenta) => { true } |
| (yellow, yellow) => { true } |
| (black, black) => { true } |
| _ => { false } |
| } |
| } |
| } |
| |
| #[derive(Clone)] |
| enum ColorTree { |
| leaf(Color), |
| branch(Box<ColorTree>, Box<ColorTree>) |
| } |
| |
| impl Equal for ColorTree { |
| fn isEq(&self, a: &ColorTree) -> bool { |
| match (self, a) { |
| (&leaf(ref x), &leaf(ref y)) => { x.isEq(&(*y).clone()) } |
| (&branch(ref l1, ref r1), &branch(ref l2, ref r2)) => { |
| (*l1).isEq(&(**l2).clone()) && (*r1).isEq(&(**r2).clone()) |
| } |
| _ => { false } |
| } |
| } |
| } |
| |
| pub fn main() { |
| assert!(cyan.isEq(&cyan)); |
| assert!(magenta.isEq(&magenta)); |
| assert!(!cyan.isEq(&yellow)); |
| assert!(!magenta.isEq(&cyan)); |
| |
| assert!(leaf(cyan).isEq(&leaf(cyan))); |
| assert!(!leaf(cyan).isEq(&leaf(yellow))); |
| |
| assert!(branch(box leaf(magenta), box leaf(cyan)) |
| .isEq(&branch(box leaf(magenta), box leaf(cyan)))); |
| |
| assert!(!branch(box leaf(magenta), box leaf(cyan)) |
| .isEq(&branch(box leaf(magenta), box leaf(magenta)))); |
| |
| println!("Assertions all succeeded!"); |
| } |