Created
December 10, 2021 03:22
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Store any function and call it with borrowed ID.
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| // Cargo.toml | |
| // | |
| // [dependencies] | |
| // resman = { version = "0.11.0", features = ["debug"] } | |
| // futures = "0.3.18" | |
| // tokio = { version = "1.13.0", features = ["rt"] } | |
| use std::{fmt::Debug, marker::PhantomData}; | |
| use futures::{ | |
| future::{FutureExt, LocalBoxFuture}, | |
| StreamExt, | |
| }; | |
| use resman::Resources; | |
| trait FnSpec<R> { | |
| fn call<'f1: 'f2, 'f2>( | |
| &'f2 self, | |
| id: &'f1 mut u8, | |
| map: &'f2 Resources, | |
| ) -> LocalBoxFuture<'f2, R>; | |
| } | |
| struct FnSpecImpl<F, R, Args> { | |
| f: F, | |
| marker: PhantomData<(R, Args)>, | |
| } | |
| impl<F, R> FnSpec<R> for FnSpecImpl<F, R, ()> | |
| where | |
| F: for<'f> Fn(&'f mut u8) -> LocalBoxFuture<'f, R>, | |
| { | |
| fn call<'f1: 'f2, 'f2>(&self, id: &'f1 mut u8, _map: &'f2 Resources) -> LocalBoxFuture<'f2, R> { | |
| (self.f)(id) | |
| } | |
| } | |
| impl<F, R, A0> FnSpec<R> for FnSpecImpl<F, R, (A0,)> | |
| where | |
| F: for<'f> Fn(&'f mut u8, &'f A0) -> LocalBoxFuture<'f, R>, | |
| A0: Debug + Send + Sync + 'static, | |
| { | |
| fn call<'f1: 'f2, 'f2>( | |
| &'f2 self, | |
| mut id: &'f1 mut u8, | |
| map: &'f2 Resources, | |
| ) -> LocalBoxFuture<'f2, R> { | |
| async move { | |
| let id = &mut id; | |
| let a0 = &map.borrow::<A0>(); | |
| (self.f)(id, a0).await | |
| } | |
| .boxed_local() | |
| } | |
| } | |
| struct AnyFnWrapper<R>(Box<dyn FnSpec<R>>); | |
| impl<R> AnyFnWrapper<R> | |
| where | |
| R: 'static, | |
| { | |
| fn new0<F>(f: F) -> Self | |
| where | |
| F: 'static, | |
| FnSpecImpl<F, R, ()>: FnSpec<R>, | |
| { | |
| let fn_spec_impl = FnSpecImpl { | |
| f, | |
| marker: PhantomData, | |
| }; | |
| Self(Box::new(fn_spec_impl)) | |
| } | |
| fn new1<F, A0>(f: F) -> Self | |
| where | |
| F: for<'f> Fn(&'f mut u8, &'f A0) -> LocalBoxFuture<'f, R> + 'static, | |
| A0: 'static, | |
| FnSpecImpl<F, R, (A0,)>: FnSpec<R>, | |
| { | |
| let fn_spec_impl = FnSpecImpl { | |
| f, | |
| marker: PhantomData, | |
| }; | |
| Self(Box::new(fn_spec_impl)) | |
| } | |
| } | |
| fn main() { | |
| let fn1 = AnyFnWrapper::<u64>::new0(|id: &mut u8| async move { *id as u64 }.boxed_local()); | |
| let fn2 = AnyFnWrapper::<u64>::new1(|id: &mut u8, value: &u32| { | |
| async move { (*id as u64) + (*value as u64) }.boxed_local() | |
| }); | |
| let mut resources = Resources::new(); | |
| resources.insert(10u32); | |
| let resources = &resources; | |
| let rt = tokio::runtime::Builder::new_current_thread() | |
| .build() | |
| .expect("Failed to build runtime."); | |
| let sum = rt.block_on( | |
| futures::stream::iter([fn1, fn2].into_iter().enumerate()) | |
| .fold(0, |sum, (id, f)| async move { | |
| sum + f.0.call(&mut ((id + 3) as u8), resources).await | |
| }), | |
| ); | |
| println!("sum: {}", sum); | |
| } |
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