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//! Either combinator
use crate::{Pipe, Result};
use either::Either;
use std::marker::PhantomData;
use tuplify::Unpack;
/// Either combinator
///
/// Combine 2 [`Pipe`]s that can produce different outputs but share the same input
pub trait EitherExt<I, O, E, R> {
/// Combine 2 [Pipe]s with the same input and remaining but differents outputs
///
/// ```
/// # use pipe_chain::{str::digits, tag, EitherExt, str::TagStrError, Incomplete, MapExt, Pipe};
/// # use either::Either;
/// # use std::error::Error as StdError;
/// # #[derive(Debug, PartialEq, Eq)]
/// # enum Error {
/// # Incomplete(Incomplete),
/// # Tag(TagStrError),
/// # }
/// #
/// # impl std::fmt::Display for Error {
/// # fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
/// # write!(f, "{self:?}")
/// # }
/// # }
/// # impl StdError for Error {}
/// #
/// # impl From<Incomplete> for Error {
/// # fn from(value: Incomplete) -> Error { Error::Incomplete(value) }
/// # }
/// #
/// # impl From<TagStrError> for Error {
/// # fn from(value: TagStrError) -> Error { Error::Tag(value) }
/// # }
/// let mut p =
/// tag::<Error, _, _>("a").either(digits::<Error>(1..).map1(|x: &str| x.parse().unwrap()));
///
/// assert_eq!(p.apply("a"), Ok(("", (Either::Left("a"),))));
/// assert_eq!(p.apply("12"), Ok(("", (Either::Right(12u32),))));
/// ```
fn either<O2, P>(self, p: P) -> EitherPipe<O, O2, Self, P>
where
I: Clone,
Self: Pipe<I, O, E, R> + Sized,
P: Pipe<I, O2, E, R>,
{
EitherPipe::new(self, p)
}
/// Combine 2 [Pipe]s with the same input and differents outputs and remaining
///
/// ```
/// # use pipe_chain::{
/// str::digits, tag, AndThenExt, EitherExt, str::TagStrError, Incomplete, MapExt, Pipe,
/// };
/// # use either::Either;
/// # use std::error::Error as StdError;
/// # #[derive(Debug, PartialEq, Eq)]
/// # enum Error {
/// # Incomplete(Incomplete),
/// # Tag(TagStrError),
/// # }
/// #
/// # impl std::fmt::Display for Error {
/// # fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
/// # write!(f, "{self:?}")
/// # }
/// # }
/// # impl StdError for Error {}
/// #
/// # impl From<Incomplete> for Error {
/// # fn from(value: Incomplete) -> Error { Error::Incomplete(value) }
/// # }
/// #
/// # impl From<TagStrError> for Error {
/// # fn from(value: TagStrError) -> Error { Error::Tag(value) }
/// # }
/// let mut p = tag::<Error, _, _>("a").either_full(
/// digits::<Error>(1..).map1(|x: &str| x.parse().unwrap()).ok_and_then(|_, x| Ok((0, x))),
/// );
///
/// assert_eq!(p.apply("a"), Ok((Either::Left(""), (Either::Left("a"),))));
/// assert_eq!(p.apply("12"), Ok((Either::Right(0), (Either::Right(12u32),))));
/// ```
fn either_full<O2, R2, P>(self, p: P) -> EitherPipeFull<O, O2, Self, P>
where
I: Clone,
Self: Pipe<I, O, E, R> + Sized,
P: Pipe<I, O2, E, R2>,
{
EitherPipeFull::new(self, p)
}
}
impl<I, O, E, R, P> EitherExt<I, O, E, R> for P where P: Pipe<I, O, E, R> {}
/// [EitherExt::either] implementation
pub struct EitherPipe<O, O2, P, P1>(P, P1, PhantomData<O>, PhantomData<O2>);
impl<O, O2, P, P1> EitherPipe<O, O2, P, P1> {
fn new(p: P, p1: P1) -> Self { Self(p, p1, PhantomData, PhantomData) }
}
impl<I, O, O2, E, R, P, P1> Pipe<I, (Either<O::Output, O2::Output>,), E, R>
for EitherPipe<O, O2, P, P1>
where
I: Clone,
O: Unpack,
O2: Unpack,
P: Pipe<I, O, E, R> + Sized,
P1: Pipe<I, O2, E, R>,
{
fn apply(&mut self, input: I) -> Result<R, (Either<O::Output, O2::Output>,), E> {
self.0
.apply(input.clone())
.map(|(i, o)| (i, (Either::Left(o.unpack()),)))
.or_else(|x| {
x.fatality()?;
self.1.apply(input).map(|(i, x)| (i, (Either::Right(x.unpack()),)))
})
}
}
/// [EitherExt::either_full] implementation
pub struct EitherPipeFull<O, O2, P, P1>(P, P1, PhantomData<O>, PhantomData<O2>);
impl<O, O2, P, P1> EitherPipeFull<O, O2, P, P1> {
fn new(p: P, p1: P1) -> Self { Self(p, p1, PhantomData, PhantomData) }
}
impl<I, O, O2, E, R, R2, P, P1>
Pipe<I, (Either<O::Output, O2::Output>,), E, Either<R, R2>>
for EitherPipeFull<O, O2, P, P1>
where
I: Clone,
O: Unpack,
O2: Unpack,
P: Pipe<I, O, E, R> + Sized,
P1: Pipe<I, O2, E, R2>,
{
fn apply(
&mut self, input: I,
) -> Result<Either<R, R2>, (Either<O::Output, O2::Output>,), E> {
self.0
.apply(input.clone())
.map(|(i, o)| (Either::Left(i), (Either::Left(o.unpack()),)))
.or_else(|x| {
x.fatality()?;
self.1
.apply(input)
.map(|(i, x)| (Either::Right(i), (Either::Right(x.unpack()),)))
})
}
}