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