enum ChoiceLayer<'a> {
Missing,
Null,
Either(&'a Type),
}Expand description
A layer around a choice parameter’s value, outermost first.
Variants§
Missing
Missing<..>: the missing-argument sentinel is Missing::Absent.
Null
Option<..>: NULL is None.
Either(&'a Type)
Either<.., R>: character or factor input is the choice (Left),
anything else converts to R (Right).
Auto Trait Implementations§
impl<'a> !Send for ChoiceLayer<'a>
impl<'a> !Sync for ChoiceLayer<'a>
impl<'a> Freeze for ChoiceLayer<'a>
impl<'a> RefUnwindSafe for ChoiceLayer<'a>
impl<'a> Unpin for ChoiceLayer<'a>
impl<'a> UnsafeUnpin for ChoiceLayer<'a>
impl<'a> UnwindSafe for ChoiceLayer<'a>
Blanket Implementations§
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> SizeHint for Twhere
T: ?Sized,
impl<T> SizeHint for Twhere
T: ?Sized,
Source§default fn lower_bound(&self) -> usize
default fn lower_bound(&self) -> usize
🔬This is a nightly-only experimental API. (
core_io_internals)Returns a lower bound on the number of elements this container-like item
contains.
For example, an array
[u8; 12] could return any value between 0 and
12 inclusively as a correct implementation. Read moreSource§impl<T> SizedTypeProperties for T
impl<T> SizedTypeProperties for T
Source§#[doc(hidden)]const SIZE: usize = _
#[doc(hidden)]const SIZE: usize = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const ALIGN: usize = _
#[doc(hidden)]const ALIGN: usize = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const ALIGNMENT: Alignment = _
#[doc(hidden)]const ALIGNMENT: Alignment = _
🔬This is a nightly-only experimental API. (
ptr_alignment_type)Source§#[doc(hidden)]const IS_ZST: bool = _
#[doc(hidden)]const IS_ZST: bool = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const LAYOUT: Layout = _
#[doc(hidden)]const LAYOUT: Layout = _
🔬This is a nightly-only experimental API. (
sized_type_properties)Source§#[doc(hidden)]const MAX_SLICE_LEN: usize = _
#[doc(hidden)]const MAX_SLICE_LEN: usize = _
🔬This is a nightly-only experimental API. (
sized_type_properties)The largest safe length for a
[Self]. Read moreLayout§
Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.
Size: 16 bytes
Size for each variant:
Missing: 0 bytesNull: 0 bytesEither: 8 bytes