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use core::{any::TypeId, future, marker::PhantomData};
use crate::CastIdentityBorrowed;
/// Async specialized behavior runner (Borrowed -> Owned)
#[derive(Debug)]
pub struct AsyncSpecializerBorrowedParam<T, U, F>(
T,
F,
PhantomData<fn(T) -> U>,
);
impl<T, U, F> AsyncSpecializerBorrowedParam<T, U, F>
where
F: AsyncFnOnce(T) -> U,
T: CastIdentityBorrowed<T>,
U: 'static,
{
/// Create a new specializer with a fallback function.
#[inline(always)]
pub const fn new(params: T, f: F) -> Self {
Self(params, f, PhantomData)
}
/// Specialize on the parameter and the return type of the closure.
///
/// ```rust
/// use specializer::AsyncSpecializerBorrowedParam;
/// use pasts::Executor;
///
/// async fn specialized<T, U>(ty: &mut T) -> U
/// where
/// T: 'static + Clone,
/// U: 'static + From<T> + From<u8>,
/// {
/// AsyncSpecializerBorrowedParam::new(ty, async |ty| ty.clone().into())
/// .specialize(async |int: &mut i32| -> i32 { *int * 2 })
/// .specialize_param(async |int: &mut u8| { U::from(*int * 3) })
/// .run()
/// .await
/// }
///
/// Executor::default().block_on(async {
/// assert_eq!(specialized::<i16, i32>(&mut 3).await, 3);
/// assert_eq!(specialized::<i32, i32>(&mut 3).await, 6);
/// assert_eq!(specialized::<u8, i32>(&mut 3).await, 9);
/// });
/// ```
#[inline]
pub fn specialize<P, R>(
self,
f: impl AsyncFnOnce(P) -> R,
) -> AsyncSpecializerBorrowedParam<T, U, impl AsyncFnOnce(T) -> U>
where
T: CastIdentityBorrowed<P>,
R: 'static,
{
let AsyncSpecializerBorrowedParam(ty, fallback, phantom_data) = self;
let f = async |t: T| -> U {
if TypeId::of::<U>() == TypeId::of::<R>()
&& <T as CastIdentityBorrowed<P>>::is_same()
{
let param = crate::cast_identity_borrowed::<T, P>(t).unwrap();
return crate::cast_identity::<R, U>(f(param).await).unwrap();
}
fallback(t).await
};
AsyncSpecializerBorrowedParam(ty, f, phantom_data)
}
/// Specialize on the parameter and the return type of the closure, mapping
/// both.
///
/// ```rust
/// use std::{future, convert};
///
/// use pasts::Executor;
/// use specializer::AsyncSpecializerBorrowedParam;
///
/// async fn specialized<T, U>(ty: &mut T) -> U
/// where
/// T: 'static + Clone,
/// U: 'static + From<T> + From<u8>,
/// {
/// let to = async |ty: &mut T| ty.clone().into();
///
/// AsyncSpecializerBorrowedParam::new(ty, to)
/// .specialize(async |int: &mut i32| -> i32 { *int * 2 })
/// .specialize_map(
/// async |int: &mut u8| {
/// *int *= 3;
/// int
/// },
/// to,
/// future::ready::<U>,
/// )
/// .run()
/// .await
/// }
///
/// Executor::default().block_on(async {
/// assert_eq!(specialized::<i16, i32>(&mut 3).await, 3);
/// assert_eq!(specialized::<i32, i32>(&mut 3).await, 6);
/// assert_eq!(specialized::<u8, i32>(&mut 3).await, 9);
/// });
/// ```
#[inline]
pub fn specialize_map<P, R>(
self,
p: impl AsyncFnOnce(P) -> P,
f: impl AsyncFnOnce(T) -> U,
r: impl AsyncFnOnce(R) -> R,
) -> AsyncSpecializerBorrowedParam<T, U, impl AsyncFnOnce(T) -> U>
where
T: CastIdentityBorrowed<P>,
P: CastIdentityBorrowed<T>,
R: 'static,
{
let AsyncSpecializerBorrowedParam(ty, fallback, phantom_data) = self;
let f = async |t: T| -> U {
if TypeId::of::<U>() == TypeId::of::<R>()
&& <T as CastIdentityBorrowed<P>>::is_same()
{
let param = crate::cast_identity_borrowed::<T, P>(t).unwrap();
let param =
crate::cast_identity_borrowed::<P, T>(p(param).await)
.unwrap();
let ret = crate::cast_identity::<U, R>(f(param).await).unwrap();
return crate::cast_identity::<R, U>(r(ret).await).unwrap();
}
fallback(t).await
};
AsyncSpecializerBorrowedParam(ty, f, phantom_data)
}
/// Specialize on the parameter of the closure.
///
/// ```rust
/// use specializer::AsyncSpecializerBorrowedParam;
/// use pasts::Executor;
///
/// async fn specialized<T, U>(ty: &mut T) -> U
/// where
/// T: 'static + Clone,
/// U: 'static + From<T> + From<u8> + From<i32>,
/// {
/// AsyncSpecializerBorrowedParam::new(ty, async |ty| ty.clone().into())
/// .specialize_param(async |int: &mut i32| { U::from(*int * 2) })
/// .specialize_param(async |int: &mut u8| { U::from(*int * 3) })
/// .run()
/// .await
/// }
///
/// Executor::default().block_on(async {
/// assert_eq!(specialized::<i16, i32>(&mut 3).await, 3);
/// assert_eq!(specialized::<i32, i32>(&mut 3).await, 6);
/// assert_eq!(specialized::<u8, i32>(&mut 3).await, 9);
/// });
/// ```
#[inline]
pub fn specialize_param<P>(
self,
f: impl AsyncFnOnce(P) -> U,
) -> AsyncSpecializerBorrowedParam<T, U, impl AsyncFnOnce(T) -> U>
where
T: CastIdentityBorrowed<P>,
{
self.specialize::<P, U>(f)
}
/// Specialize on the return type of the closure.
///
/// ```rust
/// use specializer::AsyncSpecializerBorrowedParam;
/// use pasts::Executor;
///
/// async fn specialized<T>(int: &mut i32) -> T
/// where
/// T: 'static + Default
/// {
/// let fallback = async |_| -> T { Default::default() };
///
/// AsyncSpecializerBorrowedParam::new(int, fallback)
/// .specialize_return(async |&mut int| -> i32 { int * 2 })
/// .specialize_return(async |&mut int| -> String { int.to_string() })
/// .run()
/// .await
/// }
///
/// Executor::default().block_on(async {
/// assert_eq!(specialized::<i32>(&mut 3).await, 6);
/// assert_eq!(specialized::<String>(&mut 3).await, "3");
/// assert_eq!(specialized::<u8>(&mut 3).await, 0);
/// });
/// ```
#[inline]
pub fn specialize_return<R>(
self,
f: impl AsyncFnOnce(T) -> R,
) -> AsyncSpecializerBorrowedParam<T, U, impl AsyncFnOnce(T) -> U>
where
R: 'static,
{
self.specialize::<T, R>(f)
}
/// Specialize on the parameter and the return type of the closure, mapping
/// the parameter.
///
/// ```rust
/// use specializer::AsyncSpecializerBorrowedParam;
/// use pasts::Executor;
///
/// async fn specialized<T, U>(ty: &mut T) -> U
/// where
/// T: 'static + Clone,
/// U: 'static + From<T>,
/// {
/// let f = async |x: &mut T| (*x).clone().into();
///
/// AsyncSpecializerBorrowedParam::new(ty, f)
/// .specialize(async |int: &mut i32| -> i32 { *int * 2 })
/// .specialize_map_param(
/// async |int: &mut u8| {
/// *int *= 3;
/// int
/// },
/// f,
/// )
/// .run()
/// .await
/// }
///
/// Executor::default().block_on(async {
/// assert_eq!(specialized::<i16, i32>(&mut 3).await, 3);
/// assert_eq!(specialized::<i32, i32>(&mut 3).await, 6);
/// assert_eq!(specialized::<u8, i32>(&mut 3).await, 9);
/// });
/// ```
#[inline]
pub fn specialize_map_param<P>(
self,
p: impl AsyncFnOnce(P) -> P,
f: impl AsyncFnOnce(T) -> U,
) -> AsyncSpecializerBorrowedParam<T, U, impl AsyncFnOnce(T) -> U>
where
T: CastIdentityBorrowed<P>,
P: CastIdentityBorrowed<T>,
{
self.specialize_map::<P, U>(p, f, future::ready)
}
/// Specialize on the parameter and the return type of the closure, mapping
/// the parameter.
///
/// ```rust
/// use specializer::AsyncSpecializerBorrowedParam;
/// use pasts::Executor;
///
/// async fn specialized<T, U>(ty: &mut T) -> U
/// where
/// T: 'static + Clone,
/// U: 'static + From<T>,
/// {
/// let f = async |x: &mut T| (*x).clone().into();
///
/// AsyncSpecializerBorrowedParam::new(ty, f)
/// .specialize_map_return(f, async |int: i16| int * 2)
/// .specialize_map_param(
/// async |int: &mut u8| {
/// *int *= 3;
/// int
/// },
/// f,
/// )
/// .run()
/// .await
/// }
///
/// Executor::default().block_on(async {
/// assert_eq!(specialized::<i16, i32>(&mut 3).await, 3);
/// assert_eq!(specialized::<i8, i16>(&mut 3).await, 6);
/// assert_eq!(specialized::<u8, i32>(&mut 3).await, 9);
/// });
/// ```
#[inline]
pub fn specialize_map_return<R>(
self,
f: impl AsyncFnOnce(T) -> U,
r: impl AsyncFnOnce(R) -> R,
) -> AsyncSpecializerBorrowedParam<T, U, impl AsyncFnOnce(T) -> U>
where
R: 'static,
{
self.specialize_map::<T, R>(future::ready, f, r)
}
/// Run the specializer.
#[inline]
pub async fn run(self) -> U {
(self.1)(self.0).await
}
}