ufotofu 0.12.0

Abstractions for lazily consuming and producing sequences
Documentation 
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use crate::prelude::*;

/// A (bulk) consumer wrapper which changes the error (type) of the wrapped consumer, by passing errors through a function.
///
/// Use the `AsRef<C>` and `AsMut<C>` impls to access the wrapped consumer.
///
/// Created via [`ConsumerExt::to_map_error`].
///
/// <br/>Counterpart: the [producer::MapError] type.
#[derive(Debug)]

pub struct MapError<C, Fun> {
    inner: C,
    fun: Option<Fun>,
}

impl<C, Fun> MapError<C, Fun> {
    pub(crate) fn new(inner: C, fun: Fun) -> Self {
        Self {
            inner,
            fun: Some(fun),
        }
    }

    /// Consumes `self` and returns the wrapped consumer.
    pub fn into_inner(self) -> C {
        self.inner
    }
}

impl<C, Fun> AsRef<C> for MapError<C, Fun> {
    fn as_ref(&self) -> &C {
        &self.inner
    }
}

impl<C, Fun> AsMut<C> for MapError<C, Fun> {
    fn as_mut(&mut self) -> &mut C {
        &mut self.inner
    }
}

impl<C, Fun, NewErr> Consumer for MapError<C, Fun>
where
    C: Consumer,
    Fun: FnOnce(C::Error) -> NewErr,
{
    type Item = C::Item;
    type Final = C::Final;
    type Error = NewErr;

    async fn consume(&mut self, val: Either<Self::Item, Self::Final>) -> Result<(), Self::Error> {
        self.inner.consume(val).await.map_err(|err| {
            (self
                .fun
                .take()
                .expect("Must not use a consumer after it emitted an error"))(err)
        })
    }

    async fn flush(&mut self) -> Result<(), Self::Error> {
        self.inner.flush().await.map_err(|err| {
            (self
                .fun
                .take()
                .expect("Must not use a consumer after it emitted an error"))(err)
        })
    }
}

impl<C, Fun, NewErr> BulkConsumer for MapError<C, Fun>
where
    C: BulkConsumer,
    Fun: FnOnce(C::Error) -> NewErr,
{
    async fn expose_slots_gracefully<F, R>(&mut self, f: F) -> Result<R, (F, Self::Error)>
    where
        F: AsyncFnOnce(&mut [Self::Item]) -> (usize, R),
    {
        self.inner.expose_slots_gracefully(f).await.map_err(|err| {
            (
                err.0,
                self.fun
                    .take()
                    .expect("Must not use a consumer after it emitted an error")(
                    err.1
                ),
            )
        })
    }
}

/// A (bulk) consumer wrapper which changes the error (type) of the wrapped consumer, by passing errors through an async function.
///
/// Use the `AsRef<C>` and `AsMut<C>` impls to access the wrapped consumer.
///
/// Created via [`ConsumerExt::to_map_async_error`].
///
/// <br/>Counterpart: the [producer::MapAsyncError] type.
#[derive(Debug)]

pub struct MapAsyncError<C, Fun> {
    inner: C,
    fun: Option<Fun>,
}

impl<C, Fun> MapAsyncError<C, Fun> {
    pub(crate) fn new(inner: C, fun: Fun) -> Self {
        Self {
            inner,
            fun: Some(fun),
        }
    }

    /// Consumes `self` and returns the wrapped consumer.
    pub fn into_inner(self) -> C {
        self.inner
    }
}

impl<C, Fun> AsRef<C> for MapAsyncError<C, Fun> {
    fn as_ref(&self) -> &C {
        &self.inner
    }
}

impl<C, Fun> AsMut<C> for MapAsyncError<C, Fun> {
    fn as_mut(&mut self) -> &mut C {
        &mut self.inner
    }
}

impl<C, Fun, NewErr> Consumer for MapAsyncError<C, Fun>
where
    C: Consumer,
    Fun: AsyncFnOnce(C::Error) -> NewErr,
{
    type Item = C::Item;
    type Final = C::Final;
    type Error = NewErr;

    async fn consume(&mut self, val: Either<Self::Item, Self::Final>) -> Result<(), Self::Error> {
        match self.inner.consume(val).await {
            Ok(yay) => Ok(yay),
            Err(err) => Err((self
                .fun
                .take()
                .expect("Must not use a consumer after it emitted an error"))(
                err
            )
            .await),
        }
    }

    async fn flush(&mut self) -> Result<(), Self::Error> {
        match self.inner.flush().await {
            Ok(yay) => Ok(yay),
            Err(err) => Err((self
                .fun
                .take()
                .expect("Must not use a consumer after it emitted an error"))(
                err
            )
            .await),
        }
    }
}

impl<C, Fun, NewErr> BulkConsumer for MapAsyncError<C, Fun>
where
    C: BulkConsumer,
    Fun: AsyncFnOnce(C::Error) -> NewErr,
{
    async fn expose_slots_gracefully<F, R>(&mut self, f: F) -> Result<R, (F, Self::Error)>
    where
        F: AsyncFnOnce(&mut [Self::Item]) -> (usize, R),
    {
        match self.inner.expose_slots_gracefully(f).await {
            Ok(yay) => Ok(yay),
            Err(err) => Err((
                err.0,
                self.fun
                    .take()
                    .expect("Must not use a consumer after it emitted an error")(
                    err.1
                )
                .await,
            )),
        }
    }
}