Trait std::cmp::Ord 1.0.0
[−]
[src]
pub trait Ord: Eq + PartialOrd<Self> {
fn cmp(&self, other: &Self) -> Ordering;
fn max(self, other: Self) -> Self { ... }
fn min(self, other: Self) -> Self { ... }
}Trait for types that form a total order.
An order is a total order if it is (for all a, b and c):
- total and antisymmetric: exactly one of
a < b,a == bora > bis true; and - transitive,
a < bandb < cimpliesa < c. The same must hold for both==and>.
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 Ord?
Ord requires that the type also be PartialOrd and Eq (which requires PartialEq).
Then you must define an implementation for cmp(). You may find it useful to use
cmp() on your type's fields.
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.
Here's an example where you want to sort people by height only, disregarding id
and name:
use std::cmp::Ordering; #[derive(Eq)] struct Person { id: u32, name: String, height: u32, } impl Ord for Person { fn cmp(&self, other: &Person) -> Ordering { self.height.cmp(&other.height) } } impl PartialOrd for Person { fn partial_cmp(&self, other: &Person) -> Option<Ordering> { Some(self.cmp(other)) } } impl PartialEq for Person { fn eq(&self, other: &Person) -> bool { self.height == other.height } }Run
Required Methods
fn cmp(&self, other: &Self) -> Ordering
This method returns an Ordering between self and other.
By convention, self.cmp(&other) returns the ordering matching the expression
self <operator> other if true.
Examples
use std::cmp::Ordering; assert_eq!(5.cmp(&10), Ordering::Less); assert_eq!(10.cmp(&5), Ordering::Greater); assert_eq!(5.cmp(&5), Ordering::Equal);Run
Provided Methods
fn max(self, other: Self) -> Self
Compares and returns the maximum of two values.
Returns the second argument if the comparison determines them to be equal.
Examples
#![feature(ord_max_min)] assert_eq!(2, 1.max(2)); assert_eq!(2, 2.max(2));Run
fn min(self, other: Self) -> Self
Implementors
impl<T> Ord for [T; 1] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for extern "C" fn(A, B, C, D, E, F, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I) -> Retimpl<Ret, A> Ord for extern "C" fn(A) -> Retimpl Ord for isizeimpl Ord for charimpl Ord for Orderingimpl<T> Ord for [T] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for extern "C" fn(A, B, C, D, E, F) -> Retimpl<Ret, A, B> Ord for unsafe fn(A, B) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Retimpl Ord for u32impl<T> Ord for [T; 25] where
T: Ord,impl<Ret, A, B, C, D, E, F, G> Ord for unsafe fn(A, B, C, D, E, F, G) -> Retimpl<Ret, A, B, C, D> Ord for unsafe extern "C" fn(A, B, C, D, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Retimpl Ord for i64impl<T> Ord for [T; 17] where
T: Ord,impl<A, B, C, D, E, F, G, H, I, J, K> Ord for (A, B, C, D, E, F, G, H, I, J, K) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord,
G: Ord,
H: Ord,
I: Ord,
J: Ord,
K: Ord + ?Sized,impl<Ret, A, B, C, D, E> Ord for unsafe extern "C" fn(A, B, C, D, E) -> Retimpl<T> Ord for [T; 12] where
T: Ord,impl<A, B, C> Ord for (A, B, C) where
A: Ord,
B: Ord,
C: Ord + ?Sized,impl<T> Ord for [T; 7] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Retimpl Ord for i16impl Ord for ()impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord 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, L> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Retimpl Ord for i32impl<Ret, A, B> Ord for unsafe extern "C" fn(A, B, ...) -> Retimpl<Ret, A, B, C, D> Ord for extern "C" fn(A, B, C, D, ...) -> Retimpl<Ret, A, B> Ord for fn(A, B) -> Retimpl<Ret, A, B, C, D, E, F, G> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Retimpl<T> Ord for [T; 2] where
T: Ord,impl Ord for u16impl Ord for u128impl Ord for u64impl<Ret, A> Ord for unsafe fn(A) -> Retimpl<T> Ord for [T; 10] where
T: Ord,impl<T> Ord for [T; 15] where
T: Ord,impl<Ret> Ord for fn() -> Retimpl<T> Ord for [T; 5] where
T: Ord,impl Ord for i128impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord 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, K> Ord for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<T> Ord for [T; 29] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Retimpl<T> Ord for [T; 11] where
T: Ord,impl<T> Ord for [T; 30] where
T: Ord,impl<Ret, A, B, C> Ord for unsafe extern "C" fn(A, B, C) -> Retimpl<Ret, A, B, C> Ord for unsafe fn(A, B, C) -> Retimpl Ord for i8impl Ord for strimpl<Ret, A, B, C, D> Ord for unsafe fn(A, B, C, D) -> Retimpl<T> Ord for [T; 16] where
T: Ord,impl Ord for usizeimpl<A, B, C, D, E, F, G, H, I, J> Ord for (A, B, C, D, E, F, G, H, I, J) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord,
G: Ord,
H: Ord,
I: Ord,
J: Ord + ?Sized,impl<Ret, A, B, C> Ord for extern "C" fn(A, B, C) -> Retimpl<Ret, A, B, C> Ord for extern "C" fn(A, B, C, ...) -> Retimpl<T> Ord for [T; 32] where
T: Ord,impl<A, B, C, D, E, F, G, H> Ord for (A, B, C, D, E, F, G, H) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord,
G: Ord,
H: Ord + ?Sized,impl<A, B> Ord for (A, B) where
A: Ord,
B: Ord + ?Sized,impl<Ret, A, B, C, D, E, F, G, H, I> Ord for unsafe fn(A, B, C, D, E, F, G, H, I) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord 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, L> Ord 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> Ord 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> Ord for fn(A, B, C, D, E, F, G, H, I) -> Retimpl<T> Ord for [T; 9] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Retimpl<T> Ord for Reverse<T> where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H> Ord for fn(A, B, C, D, E, F, G, H) -> Retimpl<A> Ord for (A,) where
A: Ord + ?Sized,impl<Ret, A> Ord for unsafe extern "C" fn(A, ...) -> Retimpl<T> Ord for [T; 8] where
T: Ord,impl<T> Ord for PhantomData<T> where
T: ?Sized,impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<Ret, A> Ord for fn(A) -> Retimpl<T> Ord for NonZero<T> where
T: Zeroable + Ord,impl Ord for boolimpl<Ret, A, B, C> Ord for unsafe extern "C" fn(A, B, C, ...) -> Retimpl<T> Ord for [T; 27] where
T: Ord,impl<A, B, C, D, E, F, G, H, I> Ord for (A, B, C, D, E, F, G, H, I) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord,
G: Ord,
H: Ord,
I: Ord + ?Sized,impl<T> Ord for [T; 14] where
T: Ord,impl<T> Ord for [T; 6] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Ord for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Retimpl Ord for !impl<Ret, A, B, C, D, E> Ord for unsafe fn(A, B, C, D, E) -> Retimpl<'a, A> Ord for &'a mut A where
A: Ord + ?Sized,impl Ord for u8impl<T> Ord for [T; 24] where
T: Ord,impl<Ret, A, B, C> Ord for fn(A, B, C) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Ord for extern "C" fn(A, B, C, D, E, F, G, H) -> Retimpl<'a, A> Ord for &'a A where
A: Ord + ?Sized,impl<Ret, A, B, C, D, E, F, G, H, I> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Retimpl<Ret, A, B> Ord for extern "C" fn(A, B, ...) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<Ret, A, B, C, D> Ord for unsafe extern "C" fn(A, B, C, D) -> Retimpl<T> Ord for [T; 3] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for unsafe extern "C" fn(A, B, C, D, E, F) -> Retimpl<T> Ord for *const T where
T: ?Sized,impl<Ret> Ord for unsafe extern "C" fn() -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Retimpl<A, B, C, D, E, F> Ord for (A, B, C, D, E, F) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord + ?Sized,impl<T> Ord for Cell<T> where
T: Copy + Ord,impl<T> Ord for [T; 13] where
T: Ord,impl<A, B, C, D> Ord for (A, B, C, D) where
A: Ord,
B: Ord,
C: Ord,
D: Ord + ?Sized,impl<T> Ord for Wrapping<T> where
T: Ord,impl<Ret> Ord for unsafe fn() -> Retimpl Ord for Errorimpl<T> Ord for Option<T> where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe fn(A, B, C, D, E, F, G, H) -> Retimpl<T> Ord for [T; 28] where
T: Ord,impl<Ret, A, B> Ord for extern "C" fn(A, B) -> Retimpl<A, B, C, D, E, F, G, H, I, J, K, L> Ord for (A, B, C, D, E, F, G, H, I, J, K, L) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord,
G: Ord,
H: Ord,
I: Ord,
J: Ord,
K: Ord,
L: Ord + ?Sized,impl<Ret, A, B> Ord for unsafe extern "C" fn(A, B) -> Retimpl<T, E> Ord for Result<T, E> where
E: Ord,
T: Ord,impl<T> Ord for *mut T where
T: ?Sized,impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Retimpl<A, B, C, D, E> Ord for (A, B, C, D, E) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord + ?Sized,impl<T> Ord for [T; 19] where
T: Ord,impl<T> Ord for RefCell<T> where
T: Ord + ?Sized,impl<T> Ord for [T; 31] where
T: Ord,impl<Ret, A, B, C, D, E, F, G> Ord for extern "C" fn(A, B, C, D, E, F, G, ...) -> Retimpl<Ret, A, B, C, D, E, F, G> Ord for extern "C" fn(A, B, C, D, E, F, G) -> Retimpl<T> Ord for [T; 23] where
T: Ord,impl<T> Ord for [T; 22] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Retimpl<T> Ord for [T; 20] where
T: Ord,impl<T> Ord for [T; 26] where
T: Ord,impl<T> Ord for [T; 21] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H, I> Ord 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, K> Ord for fn(A, B, C, D, E, F, G, H, I, J, K) -> Retimpl<Ret, A, B, C, D, E, F, G> Ord for fn(A, B, C, D, E, F, G) -> Retimpl<Ret, A> Ord for unsafe extern "C" fn(A) -> Retimpl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Retimpl<A, B, C, D, E, F, G> Ord for (A, B, C, D, E, F, G) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,
F: Ord,
G: Ord + ?Sized,impl<Ret> Ord for extern "C" fn() -> Retimpl<Ret, A, B, C, D, E, F> Ord for unsafe fn(A, B, C, D, E, F) -> Retimpl<T> Ord for [T; 0] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for fn(A, B, C, D, E, F) -> Retimpl<T> Ord for [T; 18] where
T: Ord,impl<Ret, A, B, C, D> Ord for extern "C" fn(A, B, C, D) -> Retimpl<Ret, A, B, C, D, E> Ord for unsafe extern "C" fn(A, B, C, D, E, ...) -> Retimpl Ord for TypeIdimpl<Ret, A, B, C, D, E> Ord for extern "C" fn(A, B, C, D, E, ...) -> Retimpl<Ret, A, B, C, D, E> Ord for extern "C" fn(A, B, C, D, E) -> Retimpl<Ret, A, B, C, D, E> Ord for fn(A, B, C, D, E) -> Retimpl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Retimpl<T> Ord for [T; 4] where
T: Ord,impl<Ret, A, B, C, D> Ord for fn(A, B, C, D) -> Retimpl<Ret, A> Ord for extern "C" fn(A, ...) -> Retimpl<Ret, A, B, C, D, E, F, G> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Retimpl<T> Ord for Vec<T> where
T: Ord,impl<T> Ord for Rc<T> where
T: Ord + ?Sized,impl<T> Ord for Box<T> where
T: Ord + ?Sized,impl Ord for Stringimpl<T> Ord for LinkedList<T> where
T: Ord,impl<T> Ord for BTreeSet<T> where
T: Ord,impl<K, V> Ord for BTreeMap<K, V> where
K: Ord,
V: Ord,impl<'a, B> Ord for Cow<'a, B> where
B: Ord + ToOwned + ?Sized,impl<T> Ord for Arc<T> where
T: Ord + ?Sized,impl<A> Ord for VecDeque<A> where
A: Ord,impl Ord for CStringimpl Ord for CStrimpl Ord for OsStringimpl Ord for OsStrimpl Ord for ErrorKindimpl Ord for IpAddrimpl Ord for Ipv4Addrimpl Ord for Ipv6Addrimpl<'a> Ord for Prefix<'a>impl<'a> Ord for PrefixComponent<'a>impl<'a> Ord for Component<'a>impl<'a> Ord for Components<'a>impl Ord for PathBufimpl Ord for Pathimpl Ord for Durationimpl Ord for Instantimpl Ord for SystemTime