use super::*;
/// 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));
/// }
/// ```
#[derive(Debug, PartialEq, Clone)]
pub enum Nullable<T> {
NotNull(T),
Null,
}
impl<'a, T> FromRobj<'a> for Nullable<T>
where
T: FromRobj<'a>,
{
/// 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);
/// }
/// ```
fn from_robj(robj: &'a Robj) -> std::result::Result<Self, &'static str> {
if robj.is_null() {
Ok(Nullable::Null)
} else {
Ok(Nullable::NotNull(<T>::from_robj(robj)?))
}
}
}
impl<T> TryFrom<Robj> for Nullable<T>
where
T: TryFrom<Robj, Error = Error>,
{
type Error = Error;
/// Convert an object that may be null to a rust type.
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// let s1 = r!(1);
/// let n1 = <Nullable<i32>>::try_from(s1)?;
/// assert_eq!(n1, Nullable::NotNull(1));
/// let snull = r!(NULL);
/// let nnull = <Nullable<i32>>::try_from(snull)?;
/// assert_eq!(nnull, Nullable::Null);
/// }
/// ```
fn try_from(robj: Robj) -> std::result::Result<Self, Self::Error> {
if robj.is_null() {
Ok(Nullable::Null)
} else {
Ok(Nullable::NotNull(robj.try_into()?))
}
}
}
impl<'a, T> TryFrom<&'a Robj> for Nullable<T>
where
T: TryFrom<&'a Robj, Error = Error>,
{
type Error = Error;
/// Convert an object that may be null to a rust type.
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// let s1 = r!(1);
/// let n1 = <Nullable<i32>>::try_from(&s1)?;
/// assert_eq!(n1, Nullable::NotNull(1));
/// let snull = r!(NULL);
/// let nnull = <Nullable<i32>>::try_from(&snull)?;
/// assert_eq!(nnull, Nullable::Null);
/// }
/// ```
fn try_from(robj: &'a Robj) -> std::result::Result<Self, Self::Error> {
if robj.is_null() {
Ok(Nullable::Null)
} else {
Ok(Nullable::NotNull(robj.try_into()?))
}
}
}
impl<T> From<Nullable<T>> for Robj
where
T: Into<Robj>,
{
/// Convert a rust object to NULL or another type.
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// assert_eq!(r!(Nullable::<i32>::Null), r!(NULL));
/// assert_eq!(r!(Nullable::<i32>::NotNull(1)), r!(1));
/// }
/// ```
fn from(val: Nullable<T>) -> Self {
match val {
Nullable::NotNull(t) => t.into(),
Nullable::Null => r!(NULL),
}
}
}
impl<T> From<Nullable<T>> for Option<T>
where
T: TryFrom<Robj, Error = Error>,
{
/// Convert a Nullable type into Option
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// assert_eq!(<Option<i32>>::from(Nullable::Null), None);
/// assert_eq!(<Option<i32>>::from(Nullable::NotNull(42)), Some(42));
/// }
/// ```
fn from(value: Nullable<T>) -> Self {
match value {
Nullable::NotNull(value) => Some(value),
_ => None,
}
}
}
impl<'a, T> From<&'a Nullable<T>> for Option<&'a T>
where
T: TryFrom<Robj, Error = Error>,
{
/// Convert a Nullable reference type into Option containing reference
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// assert_eq!(<Option<&i32>>::from(&Nullable::Null), None);
/// assert_eq!(<Option<&i32>>::from(&Nullable::NotNull(42)), Some(&42));
/// }
/// ```
fn from(value: &'a Nullable<T>) -> Self {
match value {
Nullable::NotNull(value) => Some(value),
_ => None,
}
}
}
impl<T> From<Option<T>> for Nullable<T>
where
T: Into<Robj>,
{
/// Convert an Option into Nullable type
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// let x : Nullable<_> = From::<Option<i32>>::from(None);
/// assert_eq!(x, Nullable::<i32>::Null);
/// let x : Nullable<_> = From::<Option<i32>>::from(Some(42));
/// assert_eq!(x, Nullable::<i32>::NotNull(42));
/// }
/// ```
fn from(value: Option<T>) -> Self {
match value {
Some(value) => Nullable::NotNull(value),
_ => Nullable::Null,
}
}
}
impl<T> Nullable<T>
where
T: TryFrom<Robj, Error = Error>,
{
/// Convert Nullable R object into `Option`
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// assert_eq!(Nullable::<Rint>::Null.into_option(), None);
/// assert_eq!(Nullable::<Rint>::NotNull(Rint::from(42)).into_option(), Some(Rint::from(42)));
/// }
/// ```
pub fn into_option(self) -> Option<T> {
self.into()
}
}
impl<T> Nullable<T> {
/// Map `Nullable<T>` into `Nullable<U>`
///
/// ```
/// use extendr_api::prelude::*;
/// test! {
/// assert_eq!(Nullable::<Rfloat>::Null.map(|x| x.abs()), Nullable::<Rfloat>::Null);
/// assert_eq!(Nullable::<Rfloat>::NotNull(Rfloat::from(42.0)).map(|x| x.abs()), Nullable::<Rfloat>::NotNull(Rfloat::from(42.0)));
/// }
/// ```
pub fn map<F, U>(self, f: F) -> Nullable<U>
where
F: FnOnce(T) -> U,
{
match self {
Nullable::NotNull(value) => Nullable::NotNull(f(value)),
_ => Nullable::Null,
}
}
}