#[repr(i8)]
pub enum Ordering {
Less,
Equal,
Greater,
}
Expand description
An Ordering
is the result of a comparison between two values.
Examples
use std::cmp::Ordering;
let result = 1.cmp(&2);
assert_eq!(Ordering::Less, result);
let result = 1.cmp(&1);
assert_eq!(Ordering::Equal, result);
let result = 2.cmp(&1);
assert_eq!(Ordering::Greater, result);
Variants
Less
An ordering where a compared value is less than another.
Equal
An ordering where a compared value is equal to another.
Greater
An ordering where a compared value is greater than another.
Implementations
sourceimpl Ordering
impl Ordering
1.53.0 (const: 1.53.0) · sourcepub const fn is_eq(self) -> bool
pub const fn is_eq(self) -> bool
Returns true
if the ordering is the Equal
variant.
Examples
use std::cmp::Ordering;
assert_eq!(Ordering::Less.is_eq(), false);
assert_eq!(Ordering::Equal.is_eq(), true);
assert_eq!(Ordering::Greater.is_eq(), false);
1.53.0 (const: 1.53.0) · sourcepub const fn is_ne(self) -> bool
pub const fn is_ne(self) -> bool
Returns true
if the ordering is not the Equal
variant.
Examples
use std::cmp::Ordering;
assert_eq!(Ordering::Less.is_ne(), true);
assert_eq!(Ordering::Equal.is_ne(), false);
assert_eq!(Ordering::Greater.is_ne(), true);
1.53.0 (const: 1.53.0) · sourcepub const fn is_lt(self) -> bool
pub const fn is_lt(self) -> bool
Returns true
if the ordering is the Less
variant.
Examples
use std::cmp::Ordering;
assert_eq!(Ordering::Less.is_lt(), true);
assert_eq!(Ordering::Equal.is_lt(), false);
assert_eq!(Ordering::Greater.is_lt(), false);
1.53.0 (const: 1.53.0) · sourcepub const fn is_gt(self) -> bool
pub const fn is_gt(self) -> bool
Returns true
if the ordering is the Greater
variant.
Examples
use std::cmp::Ordering;
assert_eq!(Ordering::Less.is_gt(), false);
assert_eq!(Ordering::Equal.is_gt(), false);
assert_eq!(Ordering::Greater.is_gt(), true);
1.53.0 (const: 1.53.0) · sourcepub const fn is_le(self) -> bool
pub const fn is_le(self) -> bool
Returns true
if the ordering is either the Less
or Equal
variant.
Examples
use std::cmp::Ordering;
assert_eq!(Ordering::Less.is_le(), true);
assert_eq!(Ordering::Equal.is_le(), true);
assert_eq!(Ordering::Greater.is_le(), false);
1.53.0 (const: 1.53.0) · sourcepub const fn is_ge(self) -> bool
pub const fn is_ge(self) -> bool
Returns true
if the ordering is either the Greater
or Equal
variant.
Examples
use std::cmp::Ordering;
assert_eq!(Ordering::Less.is_ge(), false);
assert_eq!(Ordering::Equal.is_ge(), true);
assert_eq!(Ordering::Greater.is_ge(), true);
const: 1.48.0 · sourcepub const fn reverse(self) -> Ordering
pub const fn reverse(self) -> Ordering
Reverses the Ordering
.
Less
becomesGreater
.Greater
becomesLess
.Equal
becomesEqual
.
Examples
Basic behavior:
use std::cmp::Ordering;
assert_eq!(Ordering::Less.reverse(), Ordering::Greater);
assert_eq!(Ordering::Equal.reverse(), Ordering::Equal);
assert_eq!(Ordering::Greater.reverse(), Ordering::Less);
This method can be used to reverse a comparison:
let data: &mut [_] = &mut [2, 10, 5, 8];
// sort the array from largest to smallest.
data.sort_by(|a, b| a.cmp(b).reverse());
let b: &mut [_] = &mut [10, 8, 5, 2];
assert!(data == b);
1.17.0 (const: 1.48.0) · sourcepub const fn then(self, other: Ordering) -> Ordering
pub const fn then(self, other: Ordering) -> Ordering
Chains two orderings.
Returns self
when it’s not Equal
. Otherwise returns other
.
Examples
use std::cmp::Ordering;
let result = Ordering::Equal.then(Ordering::Less);
assert_eq!(result, Ordering::Less);
let result = Ordering::Less.then(Ordering::Equal);
assert_eq!(result, Ordering::Less);
let result = Ordering::Less.then(Ordering::Greater);
assert_eq!(result, Ordering::Less);
let result = Ordering::Equal.then(Ordering::Equal);
assert_eq!(result, Ordering::Equal);
let x: (i64, i64, i64) = (1, 2, 7);
let y: (i64, i64, i64) = (1, 5, 3);
let result = x.0.cmp(&y.0).then(x.1.cmp(&y.1)).then(x.2.cmp(&y.2));
assert_eq!(result, Ordering::Less);
1.17.0 · sourcepub fn then_with<F>(self, f: F) -> Ordering where
F: FnOnce() -> Ordering,
pub fn then_with<F>(self, f: F) -> Ordering where
F: FnOnce() -> Ordering,
Chains the ordering with the given function.
Returns self
when it’s not Equal
. Otherwise calls f
and returns
the result.
Examples
use std::cmp::Ordering;
let result = Ordering::Equal.then_with(|| Ordering::Less);
assert_eq!(result, Ordering::Less);
let result = Ordering::Less.then_with(|| Ordering::Equal);
assert_eq!(result, Ordering::Less);
let result = Ordering::Less.then_with(|| Ordering::Greater);
assert_eq!(result, Ordering::Less);
let result = Ordering::Equal.then_with(|| Ordering::Equal);
assert_eq!(result, Ordering::Equal);
let x: (i64, i64, i64) = (1, 2, 7);
let y: (i64, i64, i64) = (1, 5, 3);
let result = x.0.cmp(&y.0).then_with(|| x.1.cmp(&y.1)).then_with(|| x.2.cmp(&y.2));
assert_eq!(result, Ordering::Less);
Trait Implementations
sourceimpl Enum for Ordering
impl Enum for Ordering
sourcefn from_usize(value: usize) -> Ordering
fn from_usize(value: usize) -> Ordering
Takes an usize, and returns an element matching into_usize
function.
sourcefn into_usize(self) -> usize
fn into_usize(self) -> usize
Returns an unique identifier for a value within range of 0..Array::LENGTH
.
sourceimpl Ord for Ordering
impl Ord for Ordering
sourceimpl PartialOrd<Ordering> for Ordering
impl PartialOrd<Ordering> for Ordering
sourcefn partial_cmp(&self, other: &Ordering) -> Option<Ordering>
fn partial_cmp(&self, other: &Ordering) -> Option<Ordering>
This method returns an ordering between self
and other
values if one exists. Read more
sourcefn lt(&self, other: &Rhs) -> bool
fn lt(&self, other: &Rhs) -> bool
This method tests less than (for self
and other
) and is used by the <
operator. Read more
sourcefn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
impl Copy for Ordering
impl Eq for Ordering
impl StructuralEq for Ordering
impl StructuralPartialEq for Ordering
Auto Trait Implementations
impl RefUnwindSafe for Ordering
impl Send for Ordering
impl Sync for Ordering
impl Unpin for Ordering
impl UnwindSafe for Ordering
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
sourcefn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<W, Global>impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<W, Global>impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcefn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcefn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
sourcefn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
sourceimpl<T> DowncastSync for T where
T: Any + Send + Sync,
impl<T> DowncastSync for T where
T: Any + Send + Sync,
sourceimpl<A> DynCastExt for A
impl<A> DynCastExt for A
sourcefn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
A: DynCastExtHelper<T>,
T: ?Sized,
fn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
A: DynCastExtHelper<T>,
T: ?Sized,
Use this to cast from one trait object type to another. Read more
sourcefn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
T: ?Sized,
fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
T: ?Sized,
Use this to upcast a trait to one of its supertraits. Read more
sourcefn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
T: ?Sized,
fn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
T: ?Sized,
sourcefn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
fn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
Use this to cast from one trait object type to another. With this method the type parameter is a config type that uniquely specifies which cast should be preformed. Read more