pub struct EnumKey<T>(pub T)
where
T: ToPrimitive + FromPrimitive + Clone + Eq + Ord + Debug + Send + Sync;
Expand description
Adds Key
support to an enum. Requires implementing
ToPrimitive
and
FromPrimitive
, or using a crate like
num-derive to do it automatically.
Take care when using enums as keys: if the order changes or if the meaning
of existing numerical values changes, make sure to update any related views’
version number to ensure the values are re-evaluated.
Tuple Fields§
§0: T
Trait Implementations§
source§impl<'k, T> Key<'k> for EnumKey<T>
impl<'k, T> Key<'k> for EnumKey<T>
source§const CAN_OWN_BYTES: bool = false
const CAN_OWN_BYTES: bool = false
If true, this type can benefit from an owned
Vec<u8>
. This flag is
used as a hint of whether to attempt to do memcpy operations in some
decoding operations to avoid extra allocations.source§fn from_ord_bytes<'b>(
bytes: ByteSource<'k, 'b>
) -> Result<EnumKey<T>, <EnumKey<T> as KeyEncoding>::Error>
fn from_ord_bytes<'b>( bytes: ByteSource<'k, 'b> ) -> Result<EnumKey<T>, <EnumKey<T> as KeyEncoding>::Error>
Deserialize a sequence of bytes previously encoded with
KeyEncoding::as_ord_bytes
.source§fn first_value() -> Result<Self, NextValueError>
fn first_value() -> Result<Self, NextValueError>
Return the first value in sequence for this type. Not all types
implement this.
source§fn next_value(&self) -> Result<Self, NextValueError>
fn next_value(&self) -> Result<Self, NextValueError>
Return the next value in sequence for this type. Not all types implement
this. Instead of wrapping/overflowing, None should be returned.
source§impl<T> KeyEncoding for EnumKey<T>
impl<T> KeyEncoding for EnumKey<T>
source§const LENGTH: Option<usize> = None
const LENGTH: Option<usize> = None
The size of the key, if constant. If this type doesn’t produce the same
number of bytes for each value, this should be
None
.source§fn describe<Visitor>(visitor: &mut Visitor)where
Visitor: KeyVisitor,
fn describe<Visitor>(visitor: &mut Visitor)where
Visitor: KeyVisitor,
Describes this type by invoking functions on
visitor
describing the
key being encoded. Read moresource§fn as_ord_bytes(
&self
) -> Result<Cow<'_, [u8]>, <EnumKey<T> as KeyEncoding>::Error>
fn as_ord_bytes( &self ) -> Result<Cow<'_, [u8]>, <EnumKey<T> as KeyEncoding>::Error>
Convert
self
into a Cow<'_, [u8]>
containing bytes that are able to be
compared via memcmp
in a way that is comptaible with its own Ord
implementation.source§impl<T> Ord for EnumKey<T>
impl<T> Ord for EnumKey<T>
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere
Self: Sized,
Compares and returns the maximum of two values. Read more
source§impl<T> PartialEq for EnumKey<T>
impl<T> PartialEq for EnumKey<T>
source§impl<T> PartialOrd for EnumKey<T>
impl<T> PartialOrd for EnumKey<T>
1.0.0 · source§fn 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 moreimpl<T> Copy for EnumKey<T>
impl<T> Eq for EnumKey<T>
impl<T> StructuralEq for EnumKey<T>
impl<T> StructuralPartialEq for EnumKey<T>
Auto Trait Implementations§
impl<T> RefUnwindSafe for EnumKey<T>where
T: RefUnwindSafe,
impl<T> Send for EnumKey<T>
impl<T> Sync for EnumKey<T>
impl<T> Unpin for EnumKey<T>where
T: Unpin,
impl<T> UnwindSafe for EnumKey<T>where
T: UnwindSafe,
Blanket Implementations§
§impl<'a, T, E> AsTaggedExplicit<'a, E> for Twhere
T: 'a,
impl<'a, T, E> AsTaggedExplicit<'a, E> for Twhere
T: 'a,
§impl<'a, T, E> AsTaggedImplicit<'a, E> for Twhere
T: 'a,
impl<'a, T, E> AsTaggedImplicit<'a, E> for Twhere
T: 'a,
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
§impl<Q, K> Comparable<K> for Q
impl<Q, K> Comparable<K> for Q
§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
Checks if this value is equivalent to the given key. Read more
§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
Compare self to
key
and return true
if they are equal.