65 lines
1.6 KiB
Rust
65 lines
1.6 KiB
Rust
// run-pass
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use std::fmt::Debug;
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use std::cmp::{self, PartialOrd, Ordering};
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#[derive(Debug, Copy, Clone, PartialEq, Eq)]
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struct Foo {
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n: u8,
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name: &'static str
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}
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impl PartialOrd for Foo {
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fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
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Some(self.cmp(other))
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}
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}
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impl Ord for Foo {
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fn cmp(&self, other: &Foo) -> Ordering {
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self.n.cmp(&other.n)
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}
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}
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fn main() {
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let a = Foo { n: 4, name: "a" };
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let b = Foo { n: 4, name: "b" };
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let c = Foo { n: 8, name: "c" };
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let d = Foo { n: 8, name: "d" };
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let e = Foo { n: 22, name: "e" };
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let f = Foo { n: 22, name: "f" };
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let data = [a, b, c, d, e, f];
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// `min` should return the left when the values are equal
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assert_eq!(data.iter().min(), Some(&a));
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assert_eq!(data.iter().min_by_key(|a| a.n), Some(&a));
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assert_eq!(cmp::min(a, b), a);
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assert_eq!(cmp::min(b, a), b);
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// `max` should return the right when the values are equal
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assert_eq!(data.iter().max(), Some(&f));
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assert_eq!(data.iter().max_by_key(|a| a.n), Some(&f));
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assert_eq!(cmp::max(e, f), f);
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assert_eq!(cmp::max(f, e), e);
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let mut presorted = data.to_vec();
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presorted.sort();
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assert_stable(&presorted);
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let mut presorted = data.to_vec();
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presorted.sort_by(|a, b| a.cmp(b));
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assert_stable(&presorted);
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// Assert that sorted and min/max are the same
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fn assert_stable<T: Ord + Debug>(presorted: &[T]) {
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for slice in presorted.windows(2) {
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let a = &slice[0];
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let b = &slice[1];
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assert_eq!(a, cmp::min(a, b));
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assert_eq!(b, cmp::max(a, b));
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}
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}
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}
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