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Refactor to reduce the amount of unsafe and duplicated code.
- Replace uses of `pin_utils` with the safer `pin_project` crate - Implement macros to allow building new combinators from existing ones more easily - Get rid of Chain as the building block for future combinators, and instead build from `Map` and `Flatten` primitives - Delete a lot of code which is no longer necessary.
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use core::marker::PhantomData; | ||
use core::fmt::{self, Debug}; | ||
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pub trait FnOnce1<A> { | ||
type Output; | ||
fn call_once(self, arg: A) -> Self::Output; | ||
} | ||
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impl<T, A, R> FnOnce1<A> for T | ||
where | ||
T: FnOnce(A) -> R | ||
{ | ||
type Output = R; | ||
fn call_once(self, arg: A) -> R { | ||
self(arg) | ||
} | ||
} | ||
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pub trait FnMut1<A>: FnOnce1<A> { | ||
fn call_mut(&mut self, arg: A) -> Self::Output; | ||
} | ||
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impl<T, A, R> FnMut1<A> for T | ||
where | ||
T: FnMut(A) -> R | ||
{ | ||
fn call_mut(&mut self, arg: A) -> R { | ||
self(arg) | ||
} | ||
} | ||
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// Not used, but present for completeness | ||
#[allow(unreachable_pub)] | ||
pub trait Fn1<A>: FnMut1<A> { | ||
fn call(&self, arg: A) -> Self::Output; | ||
} | ||
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impl<T, A, R> Fn1<A> for T | ||
where | ||
T: Fn(A) -> R | ||
{ | ||
fn call(&self, arg: A) -> R { | ||
self(arg) | ||
} | ||
} | ||
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macro_rules! trivial_fn_impls { | ||
($name:ident <$($arg:ident),*> $t:ty = $debug:literal) => { | ||
impl<$($arg),*> Copy for $t {} | ||
impl<$($arg),*> Clone for $t { | ||
fn clone(&self) -> Self { *self } | ||
} | ||
impl<$($arg),*> Debug for $t { | ||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { | ||
f.write_str($debug) | ||
} | ||
} | ||
impl<$($arg,)* A> FnMut1<A> for $t where Self: FnOnce1<A> { | ||
fn call_mut(&mut self, arg: A) -> Self::Output { | ||
self.call_once(arg) | ||
} | ||
} | ||
impl<$($arg,)* A> Fn1<A> for $t where Self: FnOnce1<A> { | ||
fn call(&self, arg: A) -> Self::Output { | ||
self.call_once(arg) | ||
} | ||
} | ||
pub(crate) fn $name<$($arg),*>() -> $t { | ||
Default::default() | ||
} | ||
} | ||
} | ||
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pub struct OkFn<E>(PhantomData<fn(E)>); | ||
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impl<E> Default for OkFn<E> { | ||
fn default() -> Self { | ||
OkFn(PhantomData) | ||
} | ||
} | ||
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impl<A, E> FnOnce1<A> for OkFn<E> { | ||
type Output = Result<A, E>; | ||
fn call_once(self, arg: A) -> Self::Output { | ||
Ok(arg) | ||
} | ||
} | ||
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trivial_fn_impls!(ok_fn <T> OkFn<T> = "Ok"); | ||
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#[derive(Debug, Copy, Clone, Default)] | ||
pub struct ChainFn<F, G>(F, G); | ||
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impl<F, G, A> FnOnce1<A> for ChainFn<F, G> | ||
where | ||
F: FnOnce1<A>, | ||
G: FnOnce1<F::Output>, | ||
{ | ||
type Output = G::Output; | ||
fn call_once(self, arg: A) -> Self::Output { | ||
self.1.call_once(self.0.call_once(arg)) | ||
} | ||
} | ||
impl<F, G, A> FnMut1<A> for ChainFn<F, G> | ||
where | ||
F: FnMut1<A>, | ||
G: FnMut1<F::Output>, | ||
{ | ||
fn call_mut(&mut self, arg: A) -> Self::Output { | ||
self.1.call_mut(self.0.call_mut(arg)) | ||
} | ||
} | ||
impl<F, G, A> Fn1<A> for ChainFn<F, G> | ||
where | ||
F: Fn1<A>, | ||
G: Fn1<F::Output>, | ||
{ | ||
fn call(&self, arg: A) -> Self::Output { | ||
self.1.call(self.0.call(arg)) | ||
} | ||
} | ||
pub(crate) fn chain_fn<F, G>(f: F, g: G) -> ChainFn<F, G> { | ||
ChainFn(f, g) | ||
} | ||
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#[derive(Default)] | ||
pub struct MergeResultFn; | ||
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impl<T> FnOnce1<Result<T, T>> for MergeResultFn { | ||
type Output = T; | ||
fn call_once(self, arg: Result<T, T>) -> Self::Output { | ||
match arg { | ||
Ok(x) => x, | ||
Err(x) => x, | ||
} | ||
} | ||
} | ||
trivial_fn_impls!(merge_result_fn <> MergeResultFn = "merge_result"); | ||
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#[derive(Debug, Copy, Clone, Default)] | ||
pub struct InspectFn<F>(F); | ||
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impl<F, A> FnOnce1<A> for InspectFn<F> | ||
where | ||
F: for<'a> FnOnce1<&'a A, Output=()>, | ||
{ | ||
type Output = A; | ||
fn call_once(self, arg: A) -> Self::Output { | ||
self.0.call_once(&arg); | ||
arg | ||
} | ||
} | ||
impl<F, A> FnMut1<A> for InspectFn<F> | ||
where | ||
F: for<'a> FnMut1<&'a A, Output=()>, | ||
{ | ||
fn call_mut(&mut self, arg: A) -> Self::Output { | ||
self.0.call_mut(&arg); | ||
arg | ||
} | ||
} | ||
impl<F, A> Fn1<A> for InspectFn<F> | ||
where | ||
F: for<'a> Fn1<&'a A, Output=()>, | ||
{ | ||
fn call(&self, arg: A) -> Self::Output { | ||
self.0.call(&arg); | ||
arg | ||
} | ||
} | ||
pub(crate) fn inspect_fn<F>(f: F) -> InspectFn<F> { | ||
InspectFn(f) | ||
} | ||
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#[derive(Debug, Copy, Clone, Default)] | ||
pub struct MapOkFn<F>(F); | ||
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impl<F, T, E> FnOnce1<Result<T, E>> for MapOkFn<F> | ||
where | ||
F: FnOnce1<T>, | ||
{ | ||
type Output = Result<F::Output, E>; | ||
fn call_once(self, arg: Result<T, E>) -> Self::Output { | ||
arg.map(|x| self.0.call_once(x)) | ||
} | ||
} | ||
impl<F, T, E> FnMut1<Result<T, E>> for MapOkFn<F> | ||
where | ||
F: FnMut1<T>, | ||
{ | ||
fn call_mut(&mut self, arg: Result<T, E>) -> Self::Output { | ||
arg.map(|x| self.0.call_mut(x)) | ||
} | ||
} | ||
impl<F, T, E> Fn1<Result<T, E>> for MapOkFn<F> | ||
where | ||
F: Fn1<T>, | ||
{ | ||
fn call(&self, arg: Result<T, E>) -> Self::Output { | ||
arg.map(|x| self.0.call(x)) | ||
} | ||
} | ||
pub(crate) fn map_ok_fn<F>(f: F) -> MapOkFn<F> { | ||
MapOkFn(f) | ||
} | ||
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#[derive(Debug, Copy, Clone, Default)] | ||
pub struct MapErrFn<F>(F); | ||
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impl<F, T, E> FnOnce1<Result<T, E>> for MapErrFn<F> | ||
where | ||
F: FnOnce1<E>, | ||
{ | ||
type Output = Result<T, F::Output>; | ||
fn call_once(self, arg: Result<T, E>) -> Self::Output { | ||
arg.map_err(|x| self.0.call_once(x)) | ||
} | ||
} | ||
impl<F, T, E> FnMut1<Result<T, E>> for MapErrFn<F> | ||
where | ||
F: FnMut1<E>, | ||
{ | ||
fn call_mut(&mut self, arg: Result<T, E>) -> Self::Output { | ||
arg.map_err(|x| self.0.call_mut(x)) | ||
} | ||
} | ||
impl<F, T, E> Fn1<Result<T, E>> for MapErrFn<F> | ||
where | ||
F: Fn1<E>, | ||
{ | ||
fn call(&self, arg: Result<T, E>) -> Self::Output { | ||
arg.map_err(|x| self.0.call(x)) | ||
} | ||
} | ||
pub(crate) fn map_err_fn<F>(f: F) -> MapErrFn<F> { | ||
MapErrFn(f) | ||
} | ||
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#[derive(Debug, Copy, Clone)] | ||
pub struct InspectOkFn<F>(F); | ||
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impl<'a, F, T, E> FnOnce1<&'a Result<T, E>> for InspectOkFn<F> | ||
where | ||
F: FnOnce1<&'a T, Output=()> | ||
{ | ||
type Output = (); | ||
fn call_once(self, arg: &'a Result<T, E>) -> Self::Output { | ||
if let Ok(x) = arg { self.0.call_once(x) } | ||
} | ||
} | ||
impl<'a, F, T, E> FnMut1<&'a Result<T, E>> for InspectOkFn<F> | ||
where | ||
F: FnMut1<&'a T, Output=()>, | ||
{ | ||
fn call_mut(&mut self, arg: &'a Result<T, E>) -> Self::Output { | ||
if let Ok(x) = arg { self.0.call_mut(x) } | ||
} | ||
} | ||
impl<'a, F, T, E> Fn1<&'a Result<T, E>> for InspectOkFn<F> | ||
where | ||
F: Fn1<&'a T, Output=()>, | ||
{ | ||
fn call(&self, arg: &'a Result<T, E>) -> Self::Output { | ||
if let Ok(x) = arg { self.0.call(x) } | ||
} | ||
} | ||
pub(crate) fn inspect_ok_fn<F>(f: F) -> InspectOkFn<F> { | ||
InspectOkFn(f) | ||
} | ||
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#[derive(Debug, Copy, Clone)] | ||
pub struct InspectErrFn<F>(F); | ||
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impl<'a, F, T, E> FnOnce1<&'a Result<T, E>> for InspectErrFn<F> | ||
where | ||
F: FnOnce1<&'a E, Output=()> | ||
{ | ||
type Output = (); | ||
fn call_once(self, arg: &'a Result<T, E>) -> Self::Output { | ||
if let Err(x) = arg { self.0.call_once(x) } | ||
} | ||
} | ||
impl<'a, F, T, E> FnMut1<&'a Result<T, E>> for InspectErrFn<F> | ||
where | ||
F: FnMut1<&'a E, Output=()>, | ||
{ | ||
fn call_mut(&mut self, arg: &'a Result<T, E>) -> Self::Output { | ||
if let Err(x) = arg { self.0.call_mut(x) } | ||
} | ||
} | ||
impl<'a, F, T, E> Fn1<&'a Result<T, E>> for InspectErrFn<F> | ||
where | ||
F: Fn1<&'a E, Output=()>, | ||
{ | ||
fn call(&self, arg: &'a Result<T, E>) -> Self::Output { | ||
if let Err(x) = arg { self.0.call(x) } | ||
} | ||
} | ||
pub(crate) fn inspect_err_fn<F>(f: F) -> InspectErrFn<F> { | ||
InspectErrFn(f) | ||
} | ||
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pub(crate) type MapOkOrElseFn<F, G> = ChainFn<MapOkFn<F>, ChainFn<MapErrFn<G>, MergeResultFn>>; | ||
pub(crate) fn map_ok_or_else_fn<F, G>(f: F, g: G) -> MapOkOrElseFn<F, G> { | ||
chain_fn(map_ok_fn(f), chain_fn(map_err_fn(g), merge_result_fn())) | ||
} | ||
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#[derive(Debug, Copy, Clone, Default)] | ||
pub struct UnwrapOrElseFn<F>(F); | ||
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impl<F, T, E> FnOnce1<Result<T, E>> for UnwrapOrElseFn<F> | ||
where | ||
F: FnOnce1<E, Output=T>, | ||
{ | ||
type Output = T; | ||
fn call_once(self, arg: Result<T, E>) -> Self::Output { | ||
arg.unwrap_or_else(|x| self.0.call_once(x)) | ||
} | ||
} | ||
impl<F, T, E> FnMut1<Result<T, E>> for UnwrapOrElseFn<F> | ||
where | ||
F: FnMut1<E, Output=T>, | ||
{ | ||
fn call_mut(&mut self, arg: Result<T, E>) -> Self::Output { | ||
arg.unwrap_or_else(|x| self.0.call_mut(x)) | ||
} | ||
} | ||
impl<F, T, E> Fn1<Result<T, E>> for UnwrapOrElseFn<F> | ||
where | ||
F: Fn1<E, Output=T>, | ||
{ | ||
fn call(&self, arg: Result<T, E>) -> Self::Output { | ||
arg.unwrap_or_else(|x| self.0.call(x)) | ||
} | ||
} | ||
pub(crate) fn unwrap_or_else_fn<F>(f: F) -> UnwrapOrElseFn<F> { | ||
UnwrapOrElseFn(f) | ||
} | ||
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pub struct IntoFn<T>(PhantomData<fn() -> T>); | ||
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impl<T> Default for IntoFn<T> { | ||
fn default() -> Self { | ||
IntoFn(PhantomData) | ||
} | ||
} | ||
impl<A, T> FnOnce1<A> for IntoFn<T> where A: Into<T> { | ||
type Output = T; | ||
fn call_once(self, arg: A) -> Self::Output { | ||
arg.into() | ||
} | ||
} | ||
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trivial_fn_impls!(into_fn <T> IntoFn<T> = "Into::into"); |
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