pub trait Ord: Eq + PartialOrd {
// Required method
fn cmp(&self, other: &Self) -> Ordering;
// Provided methods
fn max(self, other: Self) -> Self
where Self: Sized { ... }
fn min(self, other: Self) -> Self
where Self: Sized { ... }
fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd { ... }
}
Expand description
Trait for types that form a total order.
Implementations must be consistent with the PartialOrd
implementation, and ensure
max
, min
, and clamp
are consistent with cmp
:
partial_cmp(a, b) == Some(cmp(a, b))
.max(a, b) == max_by(a, b, cmp)
(ensured by the default implementation).min(a, b) == min_by(a, b, cmp)
(ensured by the default implementation).- For
a.clamp(min, max)
, see the method docs (ensured by the default implementation).
It’s easy to accidentally make cmp
and partial_cmp
disagree by
deriving some of the traits and manually implementing others.
Violating these requirements is a logic error. The behavior resulting from a logic error is not
specified, but users of the trait must ensure that such logic errors do not result in
undefined behavior. This means that unsafe
code must not rely on the correctness of these
methods.
§Corollaries
From the above and the requirements of PartialOrd
, it follows that for
all a
, b
and c
:
- exactly one of
a < b
,a == b
ora > b
is true; and <
is transitive:a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
Mathematically speaking, the <
operator defines a strict weak order. In
cases where ==
conforms to mathematical equality, it also defines a
strict total order.
§Derivable
This trait can be used with #[derive]
.
When derive
d on structs, it will produce a
lexicographic ordering
based on the top-to-bottom declaration order of the struct’s members.
When derive
d on enums, variants are ordered primarily by their discriminants.
Secondarily, they are ordered by their fields.
By default, the discriminant is smallest for variants at the top, and
largest for variants at the bottom. Here’s an example:
#[derive(PartialEq, Eq, PartialOrd, Ord)]
enum E {
Top,
Bottom,
}
assert!(E::Top < E::Bottom);
However, manually setting the discriminants can override this default behavior:
#[derive(PartialEq, Eq, PartialOrd, Ord)]
enum E {
Top = 2,
Bottom = 1,
}
assert!(E::Bottom < E::Top);
§Lexicographical comparison
Lexicographical comparison is an operation with the following properties:
- Two sequences are compared element by element.
- The first mismatching element defines which sequence is lexicographically less or greater than the other.
- If one sequence is a prefix of another, the shorter sequence is lexicographically less than the other.
- If two sequences have equivalent elements and are of the same length, then the sequences are lexicographically equal.
- An empty sequence is lexicographically less than any non-empty sequence.
- Two empty sequences are lexicographically equal.
§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.
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: &Self) -> Ordering {
self.height.cmp(&other.height)
}
}
impl PartialOrd for Person {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl PartialEq for Person {
fn eq(&self, other: &Self) -> bool {
self.height == other.height
}
}
Required Methods§
sourcefn cmp(&self, other: &Self) -> Ordering
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);
Provided Methods§
1.21.0 · sourcefn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere
Self: Sized,
Compares and returns the maximum of two values.
Returns the second argument if the comparison determines them to be equal.
§Examples
assert_eq!(1.max(2), 2);
assert_eq!(2.max(2), 2);
1.21.0 · sourcefn min(self, other: Self) -> Selfwhere
Self: Sized,
fn min(self, other: Self) -> Selfwhere
Self: Sized,
Compares and returns the minimum of two values.
Returns the first argument if the comparison determines them to be equal.
§Examples
assert_eq!(1.min(2), 1);
assert_eq!(2.min(2), 2);
1.50.0 · sourcefn clamp(self, min: Self, max: Self) -> Selfwhere
Self: Sized + PartialOrd,
fn clamp(self, min: Self, max: Self) -> Selfwhere
Self: Sized + PartialOrd,
Object Safety§
Implementors§
impl Ord for AttachedModuleId
impl Ord for ModuleId
impl Ord for Proposer
impl Ord for Role
impl Ord for DefaultDepositRule
impl Ord for ResourcePreference
impl Ord for PartitionDescription
impl Ord for AccessRule
impl Ord for AccessRuleNode
impl Ord for MethodAccessibility
impl Ord for OwnerRoleUpdater
impl Ord for ProofRule
impl Ord for ResourceFeature
impl Ord for ResourceOrNonFungible
impl Ord for ManifestAddress
impl Ord for NonFungibleIdType
impl Ord for NonFungibleLocalId
impl Ord for BlueprintHook
impl Ord for AccessControllerPartitionOffset
impl Ord for AccountPartitionOffset
impl Ord for AuthZoneField
impl Ord for BootLoaderField
impl Ord for ComponentField
impl Ord for ComponentRoyaltyPartitionOffset
impl Ord for ConsensusManagerPartitionOffset
impl Ord for EntityType
impl Ord for FungibleBucketField
impl Ord for FungibleProofField
impl Ord for FungibleResourceManagerPartitionOffset
impl Ord for FungibleVaultPartitionOffset
impl Ord for Level
impl Ord for MetadataPartitionOffset
impl Ord for MultiResourcePoolPartitionOffset
impl Ord for NonFungibleBucketField
impl Ord for NonFungibleProofField
impl Ord for NonFungibleResourceManagerPartitionOffset
impl Ord for NonFungibleVaultPartitionOffset
impl Ord for OneResourcePoolPartitionOffset
impl Ord for PackagePartitionOffset
impl Ord for RoleAssignmentPartitionOffset
impl Ord for RoyaltyField
impl Ord for SubstateKey
impl Ord for TransactionTrackerField
impl Ord for TwoResourcePoolPartitionOffset
impl Ord for TypeInfoField
impl Ord for ValidatorPartitionOffset
impl Ord for WorktopField
impl Ord for AsciiChar
impl Ord for IpAddr
impl Ord for SocketAddr
impl Ord for ErrorKind
impl Ord for Sign
impl Ord for Ordering
impl Ord for Infallible
impl Ord for bool
impl Ord for char
impl Ord for i8
impl Ord for i16
impl Ord for i32
impl Ord for i64
impl Ord for i128
impl Ord for isize
impl Ord for !
impl Ord for str
Implements ordering of strings.
Strings are ordered lexicographically by their byte values. This orders Unicode code
points based on their positions in the code charts. This is not necessarily the same as
“alphabetical” order, which varies by language and locale. Sorting strings according to
culturally-accepted standards requires locale-specific data that is outside the scope of
the str
type.
impl Ord for u8
impl Ord for u16
impl Ord for u32
impl Ord for u64
impl Ord for u128
impl Ord for ()
impl Ord for usize
impl Ord for EventFlags
impl Ord for FieldValue
impl Ord for LockFlags
impl Ord for BlueprintVersion
impl Ord for BlueprintVersionKey
impl Ord for CanonicalBlueprintId
impl Ord for CodeHash
impl Ord for MethodKey
impl Ord for ModuleRoleKey
impl Ord for NonFungibleGlobalId
impl Ord for OwnerRoleEntry
impl Ord for RoleKey
impl Ord for RoleList
impl Ord for VaultFreezeFlags
impl Ord for Bls12381G1PublicKey
impl Ord for Bls12381G2Signature
impl Ord for Ed25519PublicKey
impl Ord for Hash
impl Ord for Secp256k1PublicKey
impl Ord for ManifestProof
impl Ord for BytesNonFungibleLocalId
impl Ord for IntegerNonFungibleLocalId
impl Ord for RUIDNonFungibleLocalId
impl Ord for Reference
impl Ord for StringNonFungibleLocalId
impl Ord for Decimal
impl Ord for I192
impl Ord for I256
impl Ord for I320
impl Ord for I384
impl Ord for I448
impl Ord for I512
impl Ord for I768
impl Ord for PreciseDecimal
impl Ord for U192
impl Ord for U256
impl Ord for U320
impl Ord for U384
impl Ord for U448
impl Ord for U512
impl Ord for U768
impl Ord for RefTypes
impl Ord for BlueprintId
impl Ord for ComponentAddress
impl Ord for Epoch
impl Ord for GlobalAddress
impl Ord for InternalAddress
impl Ord for NodeId
impl Ord for PackageAddress
impl Ord for PartitionNumber
impl Ord for PartitionOffset
impl Ord for ResourceAddress
impl Ord for SchemaHash
impl Ord for CString
impl Ord for TypeId
impl Ord for CpuidResult
impl Ord for CStr
impl Ord for Ipv4Addr
impl Ord for Ipv6Addr
impl Ord for SocketAddrV4
impl Ord for SocketAddrV6
impl Ord for Duration
impl Ord for OsStr
impl Ord for OsString
impl Ord for Components<'_>
impl Ord for Path
impl Ord for PathBuf
impl Ord for PrefixComponent<'_>
impl Ord for Instant
impl Ord for SystemTime
impl Ord for BigInt
impl Ord for BigUint
impl Ord for ATerm
impl Ord for B0
impl Ord for B1
impl Ord for Z0
impl Ord for Equal
impl Ord for Greater
impl Ord for Less
impl Ord for UTerm
impl Ord for scrypto::prelude::radix_engine_common::prelude::fmt::Error
impl Ord for PhantomPinned
impl Ord for NonZero<i8>
impl Ord for NonZero<i16>
impl Ord for NonZero<i32>
impl Ord for NonZero<i64>
impl Ord for NonZero<i128>
impl Ord for NonZero<isize>
impl Ord for NonZero<u8>
impl Ord for NonZero<u16>
impl Ord for NonZero<u32>
impl Ord for NonZero<u64>
impl Ord for NonZero<u128>
impl Ord for NonZero<usize>
impl Ord for Alignment
impl Ord for String
impl Ord for All
impl Ord for BigEndian
impl Ord for ClassBytesRange
impl Ord for ClassUnicodeRange
impl Ord for Error
impl Ord for Error
impl Ord for InvalidParityValue
impl Ord for KeyPair
impl Ord for KeyPair
impl Ord for Literal
impl Ord for LittleEndian
impl Ord for Message
impl Ord for NonMaxUsize
impl Ord for Parity
impl Ord for PatternID
impl Ord for Position
impl Ord for PublicKey
impl Ord for PublicKey
impl Ord for RecoverableSignature
impl Ord for Scalar
impl Ord for SecretKey
impl Ord for SignOnly
impl Ord for Signature
impl Ord for Signature
impl Ord for SmallIndex
impl Ord for Span
impl Ord for StateID
impl Ord for Unit
impl Ord for Utf8Range
impl Ord for Utf8Sequence
impl Ord for Variant
impl Ord for VerifyOnly
impl Ord for XOnlyPublicKey
impl Ord for XOnlyPublicKey
impl Ord for u5
impl<'a> Ord for Component<'a>
impl<'a> Ord for Prefix<'a>
impl<'a> Ord for Location<'a>
impl<'buf> Ord for AllPreallocated<'buf>
impl<'buf> Ord for SignOnlyPreallocated<'buf>
impl<'buf> Ord for VerifyOnlyPreallocated<'buf>
impl<A> Ord for &A
impl<A> Ord for &mut A
impl<B> Ord for Cow<'_, B>
impl<Dyn> Ord for DynMetadata<Dyn>where
Dyn: ?Sized,
impl<F> Ord for Fwhere
F: FnPtr,
impl<K, V> Ord for scrypto::prelude::radix_engine_common::prelude::indexmap::map::Slice<K, V>
impl<K, V, A> Ord for BTreeMap<K, V, A>
impl<Ptr> Ord for Pin<Ptr>
impl<T> Ord for Option<T>where
T: Ord,
impl<T> Ord for Poll<T>where
T: Ord,
impl<T> Ord for *const Twhere
T: ?Sized,
impl<T> Ord for *mut Twhere
T: ?Sized,
impl<T> Ord for [T]where
T: Ord,
Implements comparison of vectors lexicographically.
impl<T> Ord for (T₁, T₂, …, Tₙ)
This trait is implemented for tuples up to twelve items long.
impl<T> Ord for BurnRoles<T>where
T: Ord,
impl<T> Ord for DepositRoles<T>where
T: Ord,
impl<T> Ord for FreezeRoles<T>where
T: Ord,
impl<T> Ord for MintRoles<T>where
T: Ord,
impl<T> Ord for NonFungibleDataUpdateRoles<T>where
T: Ord,
impl<T> Ord for RecallRoles<T>where
T: Ord,
impl<T> Ord for WithdrawRoles<T>where
T: Ord,
impl<T> Ord for scrypto::prelude::radix_engine_common::prelude::indexmap::set::Slice<T>where
T: Ord,
impl<T> Ord for Reverse<T>where
T: Ord,
impl<T> Ord for ManuallyDrop<T>
impl<T> Ord for Saturating<T>where
T: Ord,
impl<T> Ord for Wrapping<T>where
T: Ord,
impl<T> Ord for NonNull<T>where
T: ?Sized,
impl<T> Ord for Cell<T>
impl<T> Ord for PhantomData<T>where
T: ?Sized,
impl<T> Ord for RefCell<T>
impl<T, A> Ord for Vec<T, A>
Implements ordering of vectors, lexicographically.
impl<T, A> Ord for Arc<T, A>
impl<T, A> Ord for BTreeSet<T, A>
impl<T, A> Ord for Box<T, A>
impl<T, A> Ord for LinkedList<T, A>
impl<T, A> Ord for Rc<T, A>
impl<T, A> Ord for VecDeque<T, A>
impl<T, E> Ord for Result<T, E>
impl<T, N> Ord for GenericArray<T, N>where
T: Ord,
N: ArrayLength<T>,
impl<T, const N: usize> Ord for [T; N]where
T: Ord,
Implements comparison of arrays lexicographically.