pub enum Nullable<T> {
NotNull(T),
Null,
}
Expand description
Wrapper for handling potentially NULL values.
use extendr_api::prelude::*;
test! {
use extendr_api::wrapper::Nullable::*;
// Plain integer.
let s1 = r!(1);
let n1 = <Nullable<i32>>::from_robj(&s1)?;
assert_eq!(n1, NotNull(1));
// NA integer - error.
let sna = r!(NA_INTEGER);
assert_eq!(<Nullable<i32>>::from_robj(&sna).is_err(), true);
// NA integer - option gives none.
assert_eq!(<Nullable<Option<i32>>>::from_robj(&sna)?, NotNull(None));
// NULL object.
let snull = r!(NULL);
let nnull = <Nullable<i32>>::from_robj(&snull)?;
assert_eq!(nnull, Null);
assert_eq!(r!(Nullable::<i32>::Null), r!(NULL));
assert_eq!(r!(Nullable::<i32>::NotNull(1)), r!(1));
}
Variants
NotNull(T)
Null
Trait Implementations
sourceimpl<'a, T> FromRobj<'a> for Nullable<T> where
T: FromRobj<'a>,
impl<'a, T> FromRobj<'a> for Nullable<T> where
T: FromRobj<'a>,
sourcefn from_robj(robj: &'a Robj) -> Result<Self, &'static str>
fn from_robj(robj: &'a Robj) -> Result<Self, &'static str>
Convert an object that may be null to a rust type.
use extendr_api::prelude::*;
test! {
let s1 = r!(1);
let n1 = <Nullable<i32>>::from_robj(&s1)?;
assert_eq!(n1, Nullable::NotNull(1));
let snull = r!(NULL);
let nnull = <Nullable<i32>>::from_robj(&snull)?;
assert_eq!(nnull, Nullable::Null);
}
impl<T> StructuralPartialEq for Nullable<T>
Auto Trait Implementations
impl<T> RefUnwindSafe for Nullable<T> where
T: RefUnwindSafe,
impl<T> Send for Nullable<T> where
T: Send,
impl<T> Sync for Nullable<T> where
T: Sync,
impl<T> Unpin for Nullable<T> where
T: Unpin,
impl<T> UnwindSafe for Nullable<T> where
T: UnwindSafe,
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcepub fn borrow_mut(&mut self) -> &mut T
pub fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcepub fn to_owned(&self) -> T
pub fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
sourcepub fn clone_into(&self, target: &mut T)
pub fn clone_into(&self, target: &mut T)
🔬 This is a nightly-only experimental API. (
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more