Trait std::cmp::Ord 1.0.0
[−]
[src]
pub trait Ord: Eq + PartialOrd<Self> { fn cmp(&self, other: &Self) -> Ordering; }
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 == b
ora > b
is true; and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
Derivable
This trait can be used with #[derive]
. When derive
d, it will produce a lexicographic
ordering based on the top-to-bottom declaration order of the struct's members.
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
Implementors
impl<T> Ord for Box<T> where
T: Ord + ?Sized,impl<T> Ord for Rc<T> where
T: Ord + ?Sized,impl<T> Ord for Arc<T> where
T: Ord + ?Sized,impl<T> Ord for Vec<T> where
T: Ord,impl<T> Ord for BTreeSet<T> where
T: Ord,impl<T> Ord for LinkedList<T> where
T: Ord,impl<K, V> Ord for BTreeMap<K, V> where
K: Ord,
V: Ord,impl<A> Ord for VecDeque<A> where
A: Ord,impl Ord for String
impl<'a, B> Ord for Cow<'a, B> where
B: Ord + ToOwned + ?Sized,impl<T> Ord for Option<T> where
T: Ord,impl<Ret, A, B, C, D> Ord for extern "C" fn(A, B, C, D) -> Ret
impl<Ret> Ord for unsafe fn() -> Ret
impl<T> Ord for [T; 32] where
T: Ord,impl<Ret, A, B, C, D> Ord for fn(A, B, C, D) -> Ret
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) -> Ret
impl<Ret, A, B, C, D, E> Ord for unsafe fn(A, B, C, D, E) -> Ret
impl<T> Ord for [T; 28] where
T: Ord,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) -> Ret
impl<Ret, A, B, C, D, E, F> Ord for unsafe extern "C" fn(A, B, C, D, E, F) -> Ret
impl<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,impl Ord for isize
impl<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) -> Ret
impl<Ret, A> Ord for unsafe extern "C" fn(A) -> Ret
impl Ord for usize
impl<T> Ord for *mut T where
T: ?Sized,impl<'a, A> Ord for &'a mut A where
A: Ord + ?Sized,impl<Ret, A, B, C, D> Ord for unsafe fn(A, B, C, D) -> Ret
impl Ord for Ordering
impl<Ret, A> Ord for unsafe extern "C" fn(A, ...) -> Ret
impl<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) -> Ret
impl<Ret, A, B, C, D, E, F, G> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
impl Ord for char
impl<A, B, C, D> Ord for (A, B, C, D) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,impl<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,impl<T> Ord for [T; 17] where
T: Ord,impl Ord for u8
impl<T> Ord for [T] where
T: Ord,impl<T, E> Ord for Result<T, E> where
E: Ord,
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) -> Ret
impl<T> Ord for [T; 6] where
T: Ord,impl<T> Ord for [T; 9] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H, I> Ord for fn(A, B, C, D, E, F, G, H, I) -> Ret
impl<Ret, A, B, C, D, E, F, G> Ord for unsafe fn(A, B, C, D, E, F, G) -> Ret
impl<Ret, A, B, C, D, E, F, G, H> Ord for fn(A, B, C, D, E, F, G, H) -> Ret
impl<T> Ord for RefCell<T> where
T: Ord + ?Sized,impl Ord for i128
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, ...) -> Ret
impl<Ret, A, B, C, D, E> Ord for unsafe extern "C" fn(A, B, C, D, E, ...) -> Ret
impl<Ret, A, B, C, D, E, F, G, H> Ord for extern "C" fn(A, B, C, D, E, F, G, H) -> Ret
impl<T> Ord for [T; 12] where
T: Ord,impl Ord for bool
impl Ord for u16
impl<Ret, A, B, C, D> Ord for extern "C" fn(A, B, C, D, ...) -> Ret
impl<T> Ord for [T; 22] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for extern "C" fn(A, B, C, D, E, F, ...) -> Ret
impl<T> Ord for [T; 11] where
T: Ord,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, ...) -> Ret
impl Ord for TypeId
impl<T> Ord for [T; 29] where
T: Ord,impl<Ret, A, B, C> Ord for fn(A, B, C) -> Ret
impl<T> Ord for [T; 24] where
T: Ord,impl Ord for u128
impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe fn(A, B, C, D, E, F, G, H) -> Ret
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) -> Ret
impl<Ret, A, B, C, D, E> Ord for extern "C" fn(A, B, C, D, E) -> Ret
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) -> Ret
impl<T> Ord for [T; 23] where
T: Ord,impl<A, B, C> Ord for (A, B, C) where
A: Ord,
B: Ord,
C: Ord,impl<Ret, A, B, C> Ord for unsafe extern "C" fn(A, B, C, ...) -> Ret
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, ...) -> Ret
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) -> Ret
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) -> Ret
impl Ord for Error
impl<Ret, A, B, C, D> Ord for unsafe extern "C" fn(A, B, C, D, ...) -> Ret
impl<Ret, A, B> Ord for extern "C" fn(A, B, ...) -> Ret
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, ...) -> Ret
impl<T> Ord for [T; 2] where
T: Ord,impl<T> Ord for Reverse<T> 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, ...) -> Ret
impl<Ret, A, B> Ord for extern "C" fn(A, B) -> Ret
impl<Ret, A, B, C, D, E, F> Ord for fn(A, B, C, D, E, F) -> Ret
impl<Ret, A, B, C> Ord for extern "C" fn(A, B, C, ...) -> Ret
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, ...) -> Ret
impl<T> Ord for [T; 26] where
T: Ord,impl<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) -> Ret
impl<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) -> Ret
impl Ord for ()
impl<T> Ord for [T; 18] 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,impl<Ret, A, B, C, D, E, F, G> Ord for fn(A, B, C, D, E, F, G) -> Ret
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,impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
impl<Ret, A, B, C, D, E> Ord for fn(A, B, C, D, E) -> Ret
impl<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,impl<Ret, A, B> Ord for unsafe extern "C" fn(A, B, ...) -> Ret
impl<Ret, A, B, C> Ord for extern "C" fn(A, B, C) -> Ret
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,impl<T> Ord for Cell<T> where
T: Copy + Ord,impl<A> Ord for (A,) where
A: Ord,impl<Ret, A> Ord for unsafe fn(A) -> Ret
impl<T> Ord for [T; 3] where
T: Ord,impl<Ret, A, B, C> Ord for unsafe fn(A, B, C) -> Ret
impl<T> Ord for NonZero<T> where
T: Zeroable + Ord,impl<T> Ord for [T; 16] where
T: Ord,impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Ret
impl<'a, A> Ord for &'a A where
A: Ord + ?Sized,impl<Ret, A> Ord for extern "C" fn(A, ...) -> Ret
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, ...) -> Ret
impl<Ret, A, B, C, D, E, F> Ord for unsafe fn(A, B, C, D, E, F) -> Ret
impl<T> Ord for [T; 14] where
T: Ord,impl<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, ...) -> Ret
impl<Ret, A, B, C, D, E, F, G, H> Ord for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
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) -> Ret
impl<T> Ord for [T; 1] where
T: Ord,impl Ord for i8
impl<T> Ord for *const T where
T: ?Sized,impl<Ret, A, B> Ord for fn(A, B) -> Ret
impl<T> Ord for [T; 10] where
T: Ord,impl Ord for u64
impl<T> Ord for [T; 15] where
T: Ord,impl<T> Ord for [T; 30] where
T: Ord,impl<T> Ord for [T; 20] where
T: Ord,impl<T> Ord for [T; 19] where
T: Ord,impl<Ret, A, B, C, D, E, F> Ord for extern "C" fn(A, B, C, D, E, F) -> Ret
impl Ord for i64
impl<Ret, A, B, C, D> Ord for unsafe extern "C" fn(A, B, C, D) -> Ret
impl<T> Ord for [T; 27] where
T: Ord,impl<A, B, C, D, E> Ord for (A, B, C, D, E) where
A: Ord,
B: Ord,
C: Ord,
D: Ord,
E: Ord,impl<Ret> Ord for extern "C" fn() -> Ret
impl<T> Ord for [T; 8] where
T: Ord,impl<Ret, A, B> Ord for unsafe extern "C" fn(A, B) -> Ret
impl Ord for i16
impl<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,impl<Ret, A> Ord for fn(A) -> Ret
impl Ord for str
impl<Ret> Ord for unsafe extern "C" fn() -> Ret
impl<Ret, A, B, C, D, E, F, G, H, I> Ord for unsafe fn(A, B, C, D, E, F, G, H, I) -> Ret
impl<Ret, A, B> Ord for unsafe fn(A, B) -> Ret
impl<Ret, A, B, C> Ord for unsafe extern "C" fn(A, B, C) -> Ret
impl<T> Ord for [T; 13] where
T: Ord,impl<A, B> Ord for (A, B) where
A: Ord,
B: Ord,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) -> Ret
impl<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) -> Ret
impl<T> Ord for PhantomData<T> where
T: ?Sized,impl<Ret, A, B, C, D, E, F, G> Ord for extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
impl<T> Ord for [T; 7] where
T: Ord,impl<T> Ord for [T; 0] where
T: Ord,impl<Ret, A, B, C, D, E> Ord for unsafe extern "C" fn(A, B, C, D, E) -> Ret
impl Ord for !
impl Ord for i32
impl<T> Ord for Wrapping<T> where
T: Ord,impl Ord for u32
impl<T> Ord for [T; 4] where
T: Ord,impl<Ret, A, B, C, D, E, F, G> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Ret
impl<T> Ord for [T; 25] where
T: Ord,impl<Ret> Ord for fn() -> Ret
impl<T> Ord for [T; 21] where
T: Ord,impl<Ret, A, B, C, D, E> Ord for extern "C" fn(A, B, C, D, E, ...) -> Ret
impl<T> Ord for [T; 5] where
T: Ord,impl<Ret, A> Ord for extern "C" fn(A) -> Ret
impl<Ret, A, B, C, D, E, F> Ord for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Ret
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) -> Ret
impl Ord for CString
impl Ord for CStr
impl Ord for OsString
impl Ord for OsStr
impl Ord for ErrorKind
impl Ord for IpAddr
impl Ord for Ipv4Addr
impl Ord for Ipv6Addr
impl<'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 PathBuf
impl Ord for Path
impl Ord for Duration
impl Ord for Instant
impl Ord for SystemTime