Struct ChoiceLayers 

pub(crate) struct ChoiceLayers<'a> {
    pub missing: bool,
    pub nullable: bool,
    pub either_right: Option<&'a Type>,
    pub value: &'a Type,
}

The wrappers around the value of a match_arg / choices parameter, peeled outermost first: Missing<..>, then Option<..>, then Either<T, R> with the choice on the left (a scalar choice, or a several_ok list: Either<Vec<T>, R>, #1612). A plain T (or a plain several_ok container) has none.

Each layer changes one contract and leaves the rest to the layer below: Missing reports an omitted argument as Missing::Absent and keeps the choice vector as the R formal (#1551), Option turns NULL into None (#1473), and Either sends every argument that is not character or factor to its R arm instead of the choice check.

Fields

missing: bool

Missing<..> is the outermost wrapper.

nullable: bool

Option<..> wraps the value (inside Missing, if present).

either_right: Option<&'a Type>

Either<T, R> wraps the value (inside the others): its R arm.

value: &'a Type

The type under the layers: the MatchArg type (or the string type of a choices parameter) for a scalar, the container for several_ok.

Trait Implementations

impl<'a> Clone for ChoiceLayers<'a>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Copy for ChoiceLayers<'a>

impl<'a> Debug for ChoiceLayers<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> TrivialClone for ChoiceLayers<'a>

Layout

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: 24 bytes