Rust macro to impl Eq, PartialEq and Ord
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// From https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=7febfe900dd6be489692040a93b2f7bd | |
macro_rules! impl_comparisons { | |
($ty:ty) => { | |
impl PartialOrd for $ty { | |
fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> { | |
Some(self.cmp(other)) | |
} | |
} | |
impl PartialEq for $ty { | |
fn eq(&self, other: &Self) -> bool { | |
self.cmp(other) == std::cmp::Ordering::Equal | |
} | |
} | |
impl Eq for $ty {} | |
}; | |
} | |
#[derive(Debug)] | |
struct Wow(i64); | |
impl Ord for Wow { | |
fn cmp(&self, other: &Self) -> std::cmp::Ordering { | |
self.0.cmp(&other.0) | |
} | |
} | |
impl_comparisons!(Wow); | |
fn main() { | |
let x = Wow(1); | |
let y = Wow(2); | |
assert_eq!(std::cmp::Ordering::Less, x.cmp(&y)); | |
assert_eq!(x, x); | |
assert_eq!(y, y); | |
assert!(x < y); | |
assert!(y > x); | |
assert_ne!(x, y); | |
assert!(!(x == y)); | |
} |
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// From https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=bce96fea04b6cf0f26a049d935d56ef4 | |
macro_rules! impl_comparisons { | |
($ty:ty, $($field:tt), *) => { | |
impl Ord for $ty { | |
fn cmp(&self, other: &Self) -> std::cmp::Ordering { | |
$( | |
let cmp = self.$field.cmp(&other.$field); | |
if cmp != std::cmp::Ordering::Equal { | |
return cmp; | |
} | |
)* | |
std::cmp::Ordering::Equal | |
} | |
} | |
impl PartialOrd for $ty { | |
fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> { | |
Some(self.cmp(other)) | |
} | |
} | |
impl PartialEq for $ty { | |
fn eq(&self, other: &Self) -> bool { | |
self.cmp(other) == std::cmp::Ordering::Equal | |
} | |
} | |
impl Eq for $ty {} | |
}; | |
} | |
#[derive(Debug)] | |
struct Wow(i64); | |
#[derive(Debug)] | |
struct Wow3(i64, i64, i64); | |
impl_comparisons!(Wow, 0); | |
impl_comparisons!(Wow3, 0, 2, 1); | |
fn main() { | |
let x = Wow(1); | |
let y = Wow(2); | |
assert_eq!(std::cmp::Ordering::Less, x.cmp(&y)); | |
assert_eq!(x, x); | |
assert_eq!(y, y); | |
assert!(x < y); | |
assert!(y > x); | |
assert_ne!(x, y); | |
assert!(!(x == y)); | |
} |
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