Trait core::cmp::PartialOrd 1.0.0
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[src]
#[lang = "ord"]pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> { fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>; fn lt(&self, other: &Rhs) -> bool { ... } fn le(&self, other: &Rhs) -> bool { ... } fn gt(&self, other: &Rhs) -> bool { ... } fn ge(&self, other: &Rhs) -> bool { ... } }
Trait for values that can be compared for a sort-order.
The comparison must satisfy, for all a, b and c:
- antisymmetry: if
a < bthen!(a > b), as well asa > bimplying!(a < b); and - transitivity:
a < bandb < cimpliesa < c. The same must hold for both==and>.
Note that these requirements mean that the trait itself must be implemented symmetrically and
transitively: if T: PartialOrd<U> and U: PartialOrd<V> then U: PartialOrd<T> and T: PartialOrd<V>.
Derivable
This trait can be used with #[derive]. When derived on structs, it will produce a
lexicographic ordering based on the top-to-bottom declaration order of the struct's members.
When derived on enums, variants are ordered by their top-to-bottom declaration order.
How can I implement PartialOrd?
PartialOrd only requires implementation of the partial_cmp method, with the others
generated from default implementations.
However it remains possible to implement the others separately for types which do not have a
total order. For example, for floating point numbers, NaN < 0 == false and NaN >= 0 == false (cf. IEEE 754-2008 section 5.11).
PartialOrd requires your type to be PartialEq.
Implementations of PartialEq, PartialOrd, and Ord must agree with each other. It's
easy to accidentally make them disagree by deriving some of the traits and manually
implementing others.
If your type is Ord, you can implement partial_cmp() by using cmp():
use std::cmp::Ordering; #[derive(Eq)] struct Person { id: u32, name: String, height: u32, } impl PartialOrd for Person { fn partial_cmp(&self, other: &Person) -> Option<Ordering> { Some(self.cmp(other)) } } impl Ord for Person { fn cmp(&self, other: &Person) -> Ordering { self.height.cmp(&other.height) } } impl PartialEq for Person { fn eq(&self, other: &Person) -> bool { self.height == other.height } }Run
You may also find it useful to use partial_cmp() on your type's fields. Here
is an example of Person types who have a floating-point height field that
is the only field to be used for sorting:
use std::cmp::Ordering; struct Person { id: u32, name: String, height: f64, } impl PartialOrd for Person { fn partial_cmp(&self, other: &Person) -> Option<Ordering> { self.height.partial_cmp(&other.height) } } impl PartialEq for Person { fn eq(&self, other: &Person) -> bool { self.height == other.height } }Run
Examples
let x : u32 = 0; let y : u32 = 1; assert_eq!(x < y, true); assert_eq!(x.lt(&y), true);Run
Required Methods
fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>
This method returns an ordering between self and other values if one exists.
Examples
use std::cmp::Ordering; let result = 1.0.partial_cmp(&2.0); assert_eq!(result, Some(Ordering::Less)); let result = 1.0.partial_cmp(&1.0); assert_eq!(result, Some(Ordering::Equal)); let result = 2.0.partial_cmp(&1.0); assert_eq!(result, Some(Ordering::Greater));Run
When comparison is impossible:
let result = std::f64::NAN.partial_cmp(&1.0); assert_eq!(result, None);Run
Provided Methods
fn lt(&self, other: &Rhs) -> bool
This method tests less than (for self and other) and is used by the < operator.
Examples
let result = 1.0 < 2.0; assert_eq!(result, true); let result = 2.0 < 1.0; assert_eq!(result, false);Run
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for self and other) and is used by the <=
operator.
Examples
let result = 1.0 <= 2.0; assert_eq!(result, true); let result = 2.0 <= 2.0; assert_eq!(result, true);Run
fn gt(&self, other: &Rhs) -> bool
This method tests greater than (for self and other) and is used by the > operator.
Examples
let result = 1.0 > 2.0; assert_eq!(result, false); let result = 2.0 > 2.0; assert_eq!(result, false);Run
fn ge(&self, other: &Rhs) -> bool
Implementors
impl<T: PartialOrd> PartialOrd for Wrapping<T>impl<T: PartialOrd + Zeroable> PartialOrd for NonZero<T>impl<Ret> PartialOrd for fn() -> Retimpl<Ret> PartialOrd for extern "C" fn() -> Retimpl<Ret> PartialOrd for unsafe fn() -> Retimpl<Ret> PartialOrd for unsafe extern "C" fn() -> Retimpl<Ret, A> PartialOrd for fn(_: A) -> Retimpl<Ret, A> PartialOrd for extern "C" fn(_: A) -> Retimpl<Ret, A> PartialOrd for extern "C" fn(_: A, ...) -> Retimpl<Ret, A> PartialOrd for unsafe fn(_: A) -> Retimpl<Ret, A> PartialOrd for unsafe extern "C" fn(_: A) -> Retimpl<Ret, A> PartialOrd for unsafe extern "C" fn(_: A, ...) -> Retimpl<Ret, A, B> PartialOrd for fn(_: A, _: B) -> Retimpl<Ret, A, B> PartialOrd for extern "C" fn(_: A, _: B) -> Retimpl<Ret, A, B> PartialOrd for extern "C" fn(_: A, _: B, ...) -> Retimpl<Ret, A, B> PartialOrd for unsafe fn(_: A, _: B) -> Retimpl<Ret, A, B> PartialOrd for unsafe extern "C" fn(_: A, _: B) -> Retimpl<Ret, A, B> PartialOrd for unsafe extern "C" fn(_: A, _: B, ...) -> Retimpl<Ret, A, B, C> PartialOrd for fn(_: A, _: B, _: C) -> Retimpl<Ret, A, B, C> PartialOrd for extern "C" fn(_: A, _: B, _: C) -> Retimpl<Ret, A, B, C> PartialOrd for extern "C" fn(_: A, _: B, _: C, ...) -> Retimpl<Ret, A, B, C> PartialOrd for unsafe fn(_: A, _: B, _: C) -> Retimpl<Ret, A, B, C> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C) -> Retimpl<Ret, A, B, C> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, ...) -> Retimpl<Ret, A, B, C, D> PartialOrd for fn(_: A, _: B, _: C, _: D) -> Retimpl<Ret, A, B, C, D> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D) -> Retimpl<Ret, A, B, C, D> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, ...) -> Retimpl<Ret, A, B, C, D> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D) -> Retimpl<Ret, A, B, C, D> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D) -> Retimpl<Ret, A, B, C, D> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, ...) -> Retimpl<Ret, A, B, C, D, E> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E) -> Retimpl<Ret, A, B, C, D, E> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E) -> Retimpl<Ret, A, B, C, D, E> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, ...) -> Retimpl<Ret, A, B, C, D, E> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E) -> Retimpl<Ret, A, B, C, D, E> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E) -> Retimpl<Ret, A, B, C, D, E> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, ...) -> Retimpl<Ret, A, B, C, D, E, F> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F) -> Retimpl<Ret, A, B, C, D, E, F> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F) -> Retimpl<Ret, A, B, C, D, E, F> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, ...) -> Retimpl<Ret, A, B, C, D, E, F> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F) -> Retimpl<Ret, A, B, C, D, E, F> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F) -> Retimpl<Ret, A, B, C, D, E, F> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, ...) -> Retimpl<Ret, A, B, C, D, E, F, G> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G) -> Retimpl<Ret, A, B, C, D, E, F, G> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G) -> Retimpl<Ret, A, B, C, D, E, F, G> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, ...) -> Retimpl<Ret, A, B, C, D, E, F, G> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G) -> Retimpl<Ret, A, B, C, D, E, F, G> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G) -> Retimpl<Ret, A, B, C, D, E, F, G> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H) -> Retimpl<Ret, A, B, C, D, E, F, G, H> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> PartialOrd for fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, _: L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, _: L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> PartialOrd for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, _: L, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> PartialOrd for unsafe fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, _: L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, _: L) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> PartialOrd for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I, _: J, _: K, _: L, ...) -> Retimpl<T: ?Sized> PartialOrd for *const Timpl<T: ?Sized> PartialOrd for *mut Timpl<T: ?Sized> PartialOrd for PhantomData<T>impl PartialOrd for ()impl PartialOrd for boolimpl PartialOrd for f32impl PartialOrd for f64impl PartialOrd for charimpl PartialOrd for usizeimpl PartialOrd for u8impl PartialOrd for u16impl PartialOrd for u32impl PartialOrd for u64impl PartialOrd for u128impl PartialOrd for isizeimpl PartialOrd for i8impl PartialOrd for i16impl PartialOrd for i32impl PartialOrd for i64impl PartialOrd for i128impl PartialOrd for !impl<'a, 'b, A: ?Sized, B: ?Sized> PartialOrd<&'b B> for &'a A where
A: PartialOrd<B>,impl<'a, 'b, A: ?Sized, B: ?Sized> PartialOrd<&'b mut B> for &'a mut A where
A: PartialOrd<B>,impl<T: PartialOrd> PartialOrd for Reverse<T>impl PartialOrd for Orderingimpl PartialOrd for TypeIdimpl<T: PartialOrd> PartialOrd for [T; 0]impl<T: PartialOrd> PartialOrd for [T; 1]impl<T: PartialOrd> PartialOrd for [T; 2]impl<T: PartialOrd> PartialOrd for [T; 3]impl<T: PartialOrd> PartialOrd for [T; 4]impl<T: PartialOrd> PartialOrd for [T; 5]impl<T: PartialOrd> PartialOrd for [T; 6]impl<T: PartialOrd> PartialOrd for [T; 7]impl<T: PartialOrd> PartialOrd for [T; 8]impl<T: PartialOrd> PartialOrd for [T; 9]impl<T: PartialOrd> PartialOrd for [T; 10]impl<T: PartialOrd> PartialOrd for [T; 11]impl<T: PartialOrd> PartialOrd for [T; 12]impl<T: PartialOrd> PartialOrd for [T; 13]impl<T: PartialOrd> PartialOrd for [T; 14]impl<T: PartialOrd> PartialOrd for [T; 15]impl<T: PartialOrd> PartialOrd for [T; 16]impl<T: PartialOrd> PartialOrd for [T; 17]impl<T: PartialOrd> PartialOrd for [T; 18]impl<T: PartialOrd> PartialOrd for [T; 19]impl<T: PartialOrd> PartialOrd for [T; 20]impl<T: PartialOrd> PartialOrd for [T; 21]impl<T: PartialOrd> PartialOrd for [T; 22]impl<T: PartialOrd> PartialOrd for [T; 23]impl<T: PartialOrd> PartialOrd for [T; 24]impl<T: PartialOrd> PartialOrd for [T; 25]impl<T: PartialOrd> PartialOrd for [T; 26]impl<T: PartialOrd> PartialOrd for [T; 27]impl<T: PartialOrd> PartialOrd for [T; 28]impl<T: PartialOrd> PartialOrd for [T; 29]impl<T: PartialOrd> PartialOrd for [T; 30]impl<T: PartialOrd> PartialOrd for [T; 31]impl<T: PartialOrd> PartialOrd for [T; 32]impl<T: PartialOrd + Copy> PartialOrd for Cell<T>impl<T: ?Sized + PartialOrd> PartialOrd for RefCell<T>impl<T: PartialOrd> PartialOrd for Option<T>impl<T: PartialOrd, E: PartialOrd> PartialOrd for Result<T, E>impl<T: PartialOrd> PartialOrd for [T]impl PartialOrd for strimpl PartialOrd for Errorimpl<A: PartialOrd + PartialEq + ?Sized> PartialOrd for (A,) where
A: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B) where
B: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C) where
C: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D) where
D: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E) where
E: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F) where
F: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F, G) where
G: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F, G, H) where
H: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F, G, H, I) where
I: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq, J: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F, G, H, I, J) where
J: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq, J: PartialOrd + PartialEq, K: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F, G, H, I, J, K) where
K: ,impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq, J: PartialOrd + PartialEq, K: PartialOrd + PartialEq, L: PartialOrd + PartialEq + ?Sized> PartialOrd for (A, B, C, D, E, F, G, H, I, J, K, L) where
L: ,