Struct Niche
pub struct Niche;
Available on crate feature
dep_rkyv
only.Expand description
A wrapper that niches some type combinations.
A common type combination is Option<Box<T>>
. By using a null pointer, the
archived version can save some space on-disk.
§Example
use core::mem::size_of;
use rkyv::{with::Niche, Archive, Archived};
#[derive(Archive)]
struct BasicExample {
value: Option<Box<str>>,
}
#[derive(Archive)]
struct NichedExample {
#[rkyv(with = Niche)]
value: Option<Box<str>>,
}
assert!(
size_of::<Archived<BasicExample>>()
> size_of::<Archived<NichedExample>>()
);
Trait Implementations§
§impl<T> ArchiveWith<Option<Box<T>>> for Nichewhere
T: ArchiveUnsized + ?Sized,
<<T as ArchiveUnsized>::Archived as ArchivePointee>::ArchivedMetadata: Default,
impl<T> ArchiveWith<Option<Box<T>>> for Nichewhere
T: ArchiveUnsized + ?Sized,
<<T as ArchiveUnsized>::Archived as ArchivePointee>::ArchivedMetadata: Default,
§type Archived = ArchivedOptionBox<<T as ArchiveUnsized>::Archived>
type Archived = ArchivedOptionBox<<T as ArchiveUnsized>::Archived>
The archived type of
Self
with F
.§type Resolver = OptionBoxResolver
type Resolver = OptionBoxResolver
The resolver of a
Self
with F
.§fn resolve_with(
field: &Option<Box<T>>,
resolver: <Niche as ArchiveWith<Option<Box<T>>>>::Resolver,
out: Place<<Niche as ArchiveWith<Option<Box<T>>>>::Archived>,
)
fn resolve_with( field: &Option<Box<T>>, resolver: <Niche as ArchiveWith<Option<Box<T>>>>::Resolver, out: Place<<Niche as ArchiveWith<Option<Box<T>>>>::Archived>, )
Resolves the archived type using a reference to the field type
F
.§impl ArchiveWith<Option<NonZero<i128>>> for Niche
impl ArchiveWith<Option<NonZero<i128>>> for Niche
§type Archived = ArchivedOptionNonZeroI128
type Archived = ArchivedOptionNonZeroI128
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<i16>>> for Niche
impl ArchiveWith<Option<NonZero<i16>>> for Niche
§type Archived = ArchivedOptionNonZeroI16
type Archived = ArchivedOptionNonZeroI16
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<i32>>> for Niche
impl ArchiveWith<Option<NonZero<i32>>> for Niche
§type Archived = ArchivedOptionNonZeroI32
type Archived = ArchivedOptionNonZeroI32
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<i64>>> for Niche
impl ArchiveWith<Option<NonZero<i64>>> for Niche
§type Archived = ArchivedOptionNonZeroI64
type Archived = ArchivedOptionNonZeroI64
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<i8>>> for Niche
impl ArchiveWith<Option<NonZero<i8>>> for Niche
§type Archived = ArchivedOptionNonZeroI8
type Archived = ArchivedOptionNonZeroI8
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<isize>>> for Niche
impl ArchiveWith<Option<NonZero<isize>>> for Niche
§type Archived = ArchivedOptionNonZeroI32
type Archived = ArchivedOptionNonZeroI32
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<u128>>> for Niche
impl ArchiveWith<Option<NonZero<u128>>> for Niche
§type Archived = ArchivedOptionNonZeroU128
type Archived = ArchivedOptionNonZeroU128
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<u16>>> for Niche
impl ArchiveWith<Option<NonZero<u16>>> for Niche
§type Archived = ArchivedOptionNonZeroU16
type Archived = ArchivedOptionNonZeroU16
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<u32>>> for Niche
impl ArchiveWith<Option<NonZero<u32>>> for Niche
§type Archived = ArchivedOptionNonZeroU32
type Archived = ArchivedOptionNonZeroU32
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<u64>>> for Niche
impl ArchiveWith<Option<NonZero<u64>>> for Niche
§type Archived = ArchivedOptionNonZeroU64
type Archived = ArchivedOptionNonZeroU64
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<u8>>> for Niche
impl ArchiveWith<Option<NonZero<u8>>> for Niche
§type Archived = ArchivedOptionNonZeroU8
type Archived = ArchivedOptionNonZeroU8
The archived type of
Self
with F
.§impl ArchiveWith<Option<NonZero<usize>>> for Niche
impl ArchiveWith<Option<NonZero<usize>>> for Niche
§type Archived = ArchivedOptionNonZeroU32
type Archived = ArchivedOptionNonZeroU32
The archived type of
Self
with F
.§impl<T, D> DeserializeWith<ArchivedOptionBox<<T as ArchiveUnsized>::Archived>, Option<Box<T>>, D> for Nichewhere
T: ArchiveUnsized + LayoutRaw + Pointee + ?Sized,
<T as ArchiveUnsized>::Archived: DeserializeUnsized<T, D>,
D: Fallible + ?Sized,
<D as Fallible>::Error: Source,
impl<T, D> DeserializeWith<ArchivedOptionBox<<T as ArchiveUnsized>::Archived>, Option<Box<T>>, D> for Nichewhere
T: ArchiveUnsized + LayoutRaw + Pointee + ?Sized,
<T as ArchiveUnsized>::Archived: DeserializeUnsized<T, D>,
D: Fallible + ?Sized,
<D as Fallible>::Error: Source,
§fn deserialize_with(
field: &ArchivedOptionBox<<T as ArchiveUnsized>::Archived>,
deserializer: &mut D,
) -> Result<Option<Box<T>>, <D as Fallible>::Error> ⓘ
fn deserialize_with( field: &ArchivedOptionBox<<T as ArchiveUnsized>::Archived>, deserializer: &mut D, ) -> Result<Option<Box<T>>, <D as Fallible>::Error> ⓘ
Deserializes the field type
F
using the given deserializer.§impl<D> DeserializeWith<ArchivedOptionNonZeroI128, Option<NonZero<i128>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroI128, Option<NonZero<i128>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroI16, Option<NonZero<i16>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroI16, Option<NonZero<i16>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroI32, Option<NonZero<i32>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroI32, Option<NonZero<i32>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroI32, Option<NonZero<isize>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroI32, Option<NonZero<isize>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroI64, Option<NonZero<i64>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroI64, Option<NonZero<i64>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroI8, Option<NonZero<i8>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroI8, Option<NonZero<i8>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroU128, Option<NonZero<u128>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroU128, Option<NonZero<u128>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroU16, Option<NonZero<u16>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroU16, Option<NonZero<u16>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroU32, Option<NonZero<u32>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroU32, Option<NonZero<u32>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroU32, Option<NonZero<usize>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroU32, Option<NonZero<usize>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroU64, Option<NonZero<u64>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroU64, Option<NonZero<u64>>, D> for Niche
§impl<D> DeserializeWith<ArchivedOptionNonZeroU8, Option<NonZero<u8>>, D> for Niche
impl<D> DeserializeWith<ArchivedOptionNonZeroU8, Option<NonZero<u8>>, D> for Niche
§impl<T, S> SerializeWith<Option<Box<T>>, S> for Nichewhere
T: SerializeUnsized<S> + ?Sized,
S: Fallible + Writer + ?Sized,
<<T as ArchiveUnsized>::Archived as ArchivePointee>::ArchivedMetadata: Default,
impl<T, S> SerializeWith<Option<Box<T>>, S> for Nichewhere
T: SerializeUnsized<S> + ?Sized,
S: Fallible + Writer + ?Sized,
<<T as ArchiveUnsized>::Archived as ArchivePointee>::ArchivedMetadata: Default,
Auto Trait Implementations§
impl Freeze for Niche
impl RefUnwindSafe for Niche
impl Send for Niche
impl Sync for Niche
impl Unpin for Niche
impl UnwindSafe for Niche
Blanket Implementations§
§impl<T> ArchivePointee for T
impl<T> ArchivePointee for T
§type ArchivedMetadata = ()
type ArchivedMetadata = ()
The archived version of the pointer metadata for this type.
§fn pointer_metadata(
_: &<T as ArchivePointee>::ArchivedMetadata,
) -> <T as Pointee>::Metadata
fn pointer_metadata( _: &<T as ArchivePointee>::ArchivedMetadata, ) -> <T as Pointee>::Metadata
Converts some archived metadata to the pointer metadata for itself.
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
Source§impl<T> ByteSized for T
impl<T> ByteSized for T
Source§const BYTE_ALIGN: usize = _
const BYTE_ALIGN: usize = _
The alignment of this type in bytes.
Source§fn byte_align(&self) -> usize
fn byte_align(&self) -> usize
Returns the alignment of this type in bytes.
Source§fn ptr_size_ratio(&self) -> [usize; 2]
fn ptr_size_ratio(&self) -> [usize; 2]
Source§impl<T, R> Chain<R> for Twhere
T: ?Sized,
impl<T, R> Chain<R> for Twhere
T: ?Sized,
Source§impl<T> ExtAny for T
impl<T> ExtAny for T
Source§fn as_any_mut(&mut self) -> &mut dyn Anywhere
Self: Sized,
fn as_any_mut(&mut self) -> &mut dyn Anywhere
Self: Sized,
Source§impl<T> ExtMem for Twhere
T: ?Sized,
impl<T> ExtMem for Twhere
T: ?Sized,
Source§const NEEDS_DROP: bool = _
const NEEDS_DROP: bool = _
Know whether dropping values of this type matters, in compile-time.
Source§fn mem_align_of<T>() -> usize
fn mem_align_of<T>() -> usize
Returns the minimum alignment of the type in bytes. Read more
Source§fn mem_align_of_val(&self) -> usize
fn mem_align_of_val(&self) -> usize
Returns the alignment of the pointed-to value in bytes. Read more
Source§fn mem_size_of<T>() -> usize
fn mem_size_of<T>() -> usize
Returns the size of a type in bytes. Read more
Source§fn mem_size_of_val(&self) -> usize
fn mem_size_of_val(&self) -> usize
Returns the size of the pointed-to value in bytes. Read more
Source§fn mem_needs_drop(&self) -> bool
fn mem_needs_drop(&self) -> bool
Returns
true
if dropping values of this type matters. Read moreSource§fn mem_forget(self)where
Self: Sized,
fn mem_forget(self)where
Self: Sized,
Forgets about
self
without running its destructor. Read moreSource§fn mem_replace(&mut self, other: Self) -> Selfwhere
Self: Sized,
fn mem_replace(&mut self, other: Self) -> Selfwhere
Self: Sized,
Source§unsafe fn mem_zeroed<T>() -> T
unsafe fn mem_zeroed<T>() -> T
Available on crate feature
unsafe_layout
only.Returns the value of type
T
represented by the all-zero byte-pattern. Read moreSource§unsafe fn mem_transmute_copy<Src, Dst>(src: &Src) -> Dst
unsafe fn mem_transmute_copy<Src, Dst>(src: &Src) -> Dst
Available on crate feature
unsafe_layout
only.Returns the value of type
T
represented by the all-zero byte-pattern. Read moreSource§fn mem_as_bytes(&self) -> &[u8] ⓘ
fn mem_as_bytes(&self) -> &[u8] ⓘ
Available on crate feature
unsafe_slice
only.§impl<S> FromSample<S> for S
impl<S> FromSample<S> for S
fn from_sample_(s: S) -> S
Source§impl<T> Hook for T
impl<T> Hook for T
§impl<T> Instrument for T
impl<T> Instrument for T
§fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
§fn in_current_span(self) -> Instrumented<Self> ⓘ
fn in_current_span(self) -> Instrumented<Self> ⓘ
Source§impl<T> IntoEither for T
impl<T> IntoEither for T
Source§fn into_either(self, into_left: bool) -> Either<Self, Self> ⓘ
fn into_either(self, into_left: bool) -> Either<Self, Self> ⓘ
Converts
self
into a Left
variant of Either<Self, Self>
if into_left
is true
.
Converts self
into a Right
variant of Either<Self, Self>
otherwise. Read moreSource§fn into_either_with<F>(self, into_left: F) -> Either<Self, Self> ⓘ
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self> ⓘ
Converts
self
into a Left
variant of Either<Self, Self>
if into_left(&self)
returns true
.
Converts self
into a Right
variant of Either<Self, Self>
otherwise. Read more§impl<F, T> IntoSample<T> for Fwhere
T: FromSample<F>,
impl<F, T> IntoSample<T> for Fwhere
T: FromSample<F>,
fn into_sample(self) -> T
§impl<T> LayoutRaw for T
impl<T> LayoutRaw for T
§fn layout_raw(_: <T as Pointee>::Metadata) -> Result<Layout, LayoutError> ⓘ
fn layout_raw(_: <T as Pointee>::Metadata) -> Result<Layout, LayoutError> ⓘ
Returns the layout of the type.
§impl<T, N1, N2> Niching<NichedOption<T, N1>> for N2
impl<T, N1, N2> Niching<NichedOption<T, N1>> for N2
§unsafe fn is_niched(niched: *const NichedOption<T, N1>) -> bool
unsafe fn is_niched(niched: *const NichedOption<T, N1>) -> bool
Returns whether the given value has been niched. Read more
§fn resolve_niched(out: Place<NichedOption<T, N1>>)
fn resolve_niched(out: Place<NichedOption<T, N1>>)
Writes data to
out
indicating that a T
is niched.