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use core::fmt::{self, Debug};
use core::marker::PhantomData;
pub trait FnOnce1<A> {
type Output;
fn call_once(self, arg: A) -> Self::Output;
}
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)
}
}
pub trait FnMut1<A>: FnOnce1<A> {
fn call_mut(&mut self, arg: A) -> Self::Output;
}
impl<T, A, R> FnMut1<A> for T
where
T: FnMut(A) -> R,
{
fn call_mut(&mut self, arg: A) -> R {
self(arg)
}
}
// Not used, but present for completeness
#[allow(unreachable_pub)]
pub trait Fn1<A>: FnMut1<A> {
fn call(&self, arg: A) -> Self::Output;
}
impl<T, A, R> Fn1<A> for T
where
T: Fn(A) -> R,
{
fn call(&self, arg: A) -> R {
self(arg)
}
}
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()
}
}
}
pub struct OkFn<E>(PhantomData<fn(E)>);
impl<E> Default for OkFn<E> {
fn default() -> Self {
Self(PhantomData)
}
}
impl<A, E> FnOnce1<A> for OkFn<E> {
type Output = Result<A, E>;
fn call_once(self, arg: A) -> Self::Output {
Ok(arg)
}
}
trivial_fn_impls!(ok_fn <T> OkFn<T> = "Ok");
#[derive(Debug, Copy, Clone, Default)]
pub struct ChainFn<F, G>(F, G);
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)
}
#[derive(Default)]
pub struct MergeResultFn;
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");
#[derive(Debug, Copy, Clone, Default)]
pub struct InspectFn<F>(F);
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)
}
#[derive(Debug, Copy, Clone, Default)]
pub struct MapOkFn<F>(F);
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)
}
#[derive(Debug, Copy, Clone, Default)]
pub struct MapErrFn<F>(F);
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)
}
#[derive(Debug, Copy, Clone)]
pub struct InspectOkFn<F>(F);
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)
}
#[derive(Debug, Copy, Clone)]
pub struct InspectErrFn<F>(F);
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)
}
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()))
}
#[derive(Debug, Copy, Clone, Default)]
pub struct UnwrapOrElseFn<F>(F);
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)
}
pub struct IntoFn<T>(PhantomData<fn() -> T>);
impl<T> Default for IntoFn<T> {
fn default() -> Self {
Self(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()
}
}
trivial_fn_impls!(into_fn <T> IntoFn<T> = "Into::into");