Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
libcore: Ensure min and max functions are consistent for equal inputs
- Loading branch information
Showing
3 changed files
with
127 additions
and
28 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| // 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. | ||
|
|
||
| #![feature(core)] | ||
| use std::fmt::Debug; | ||
| use std::cmp::{self, PartialOrd, Ordering}; | ||
| use std::iter::MinMaxResult::MinMax; | ||
|
|
||
| #[derive(Debug, Copy, Clone, PartialEq, Eq)] | ||
| struct Foo { | ||
| n: u8, | ||
| name: &'static str | ||
| } | ||
|
|
||
| impl PartialOrd for Foo { | ||
| fn partial_cmp(&self, other: &Foo) -> Option<Ordering> { | ||
| Some(self.cmp(other)) | ||
| } | ||
| } | ||
|
|
||
| impl Ord for Foo { | ||
| fn cmp(&self, other: &Foo) -> Ordering { | ||
| self.n.cmp(&other.n) | ||
| } | ||
| } | ||
|
|
||
| fn main() { | ||
| let a = Foo { n: 4, name: "a" }; | ||
| let b = Foo { n: 4, name: "b" }; | ||
| let c = Foo { n: 8, name: "c" }; | ||
| let d = Foo { n: 8, name: "d" }; | ||
| let e = Foo { n: 22, name: "e" }; | ||
| let f = Foo { n: 22, name: "f" }; | ||
|
|
||
| let data = [a, b, c, d, e, f]; | ||
|
|
||
| // `min` should return the left when the values are equal | ||
| assert_eq!(data.iter().min(), Some(&a)); | ||
| assert_eq!(data.iter().min_by(|a| a.n), Some(&a)); | ||
| assert_eq!(cmp::min(a, b), a); | ||
| assert_eq!(cmp::min(b, a), b); | ||
| assert_eq!(cmp::partial_min(a, b), Some(a)); | ||
| assert_eq!(cmp::partial_min(b, a), Some(b)); | ||
|
|
||
| // `max` should return the right when the values are equal | ||
| assert_eq!(data.iter().max(), Some(&f)); | ||
| assert_eq!(data.iter().max_by(|a| a.n), Some(&f)); | ||
| assert_eq!(cmp::max(e, f), f); | ||
| assert_eq!(cmp::max(f, e), e); | ||
| assert_eq!(cmp::partial_max(e, f), Some(f)); | ||
| assert_eq!(cmp::partial_max(f, e), Some(e)); | ||
|
|
||
| // Similar for `min_max` | ||
| assert_eq!(data.iter().min_max(), MinMax(&a, &f)); | ||
| assert_eq!(data[1..5].iter().min_max(), MinMax(&b, &e)); | ||
| assert_eq!(data[2..4].iter().min_max(), MinMax(&c, &d)); | ||
|
|
||
| let mut presorted = data.to_vec(); | ||
| presorted.sort(); | ||
| assert_stable(&presorted); | ||
|
|
||
| let mut presorted = data.to_vec(); | ||
| presorted.sort_by(|a, b| a.cmp(b)); | ||
| assert_stable(&presorted); | ||
|
|
||
| // Assert that sorted and min/max are the same | ||
| fn assert_stable<T: Ord + Debug>(presorted: &[T]) { | ||
| for slice in presorted.windows(2) { | ||
| let a = &slice[0]; | ||
| let b = &slice[1]; | ||
|
|
||
| assert_eq!(a, cmp::min(a, b)); | ||
| assert_eq!(b, cmp::max(a, b)); | ||
| } | ||
| } | ||
| } |