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//! Serializable and debuggable closures. //! //! <p style="font-family: 'Fira Sans',sans-serif;padding:0.3em 0"><strong> //! <a href="https://crates.io/crates/serde_closure">📦 Crates.io</a> │ <a href="https://github.com/alecmocatta/serde_closure">📑 GitHub</a> │ <a href="https://constellation.zulipchat.com/#narrow/stream/213236-subprojects">💬 Chat</a> //! </strong></p> //! //! This library provides macros that wrap closures to make them serializable //! and debuggable. //! //! ``` //! use serde_closure::{traits::Fn, Fn}; //! //! let one = 1; //! let plus_one = Fn!(|x: i32| x + one); //! //! assert_eq!(2, plus_one.call((1,))); // this works on stable and nightly //! // assert_eq!(2, plus_one(1)); // this only works on nightly //! println!("{:#?}", plus_one); //! //! // prints: //! // Fn<main::{{closure}} at main.rs:6:15> { //! // one: 1, //! // source: "| x : i32 | x + one", //! // } //! ``` //! //! This library aims to work in as simple and safe a way as possible. On stable //! Rust the wrapped closures implement [`traits::FnOnce`], [`traits::FnMut`] //! and [`traits::Fn`], and on nightly Rust [`std::ops::FnOnce`], //! [`std::ops::FnMut`] and [`std::ops::Fn`] are implemented as well using the //! `unboxed_closures` and `fn_traits` features (rust issue //! [#29625](https://github.com/rust-lang/rust/issues/29625)). //! //! * There are three macros, [`FnOnce`](macro@FnOnce), [`FnMut`](macro@FnMut) //! and [`Fn`](macro@Fn), corresponding to the three types of Rust closure. //! * Wrap your closure with one of the macros and it will now implement //! `Copy`, `Clone`, `PartialEq`, `Eq`, `Hash`, `PartialOrd`, `Ord`, //! `Serialize`, `Deserialize` and `Debug`. //! * There are some minor syntax limitations, which are documented below. //! * This crate has one unavoidable but documented and sound usage of //! `unsafe`. //! //! # Examples of wrapped closures //! **Inferred, non-capturing closure:** //! ``` //! # ( //! |a| a+1 //! # )(0i32); //! ``` //! ``` //! # use serde_closure::{traits::FnMut, FnMut}; //! # ( //! FnMut!(|a| a+1) //! # ).call_mut((0i32,)); //! ``` //! //! **Annotated, non-capturing closure:** //! ``` //! # ( //! |a: String| -> String { a.to_uppercase() } //! # )(String::from("abc")); //! ``` //! ``` //! # use serde_closure::{traits::FnMut, FnMut}; //! # ( //! FnMut!(|a: String| -> String { a.to_uppercase() }) //! # ).call_mut((String::from("abc"),)); //! ``` //! //! **Inferred closure, capturing `num`:** //! ``` //! let mut num = 0; //! # ( //! |a| num += a //! # )(1i32); //! ``` //! ``` //! # use serde_closure::{traits::FnMut, FnMut}; //! let mut num = 0; //! # ( //! FnMut!(|a| num += a) //! # ).call_mut((1i32,)); //! ``` //! //! **`move` closure, capturing `hello` and `world`:** //! ``` //! let hello = String::from("hello"); //! let mut world = String::new(); //! # ( //! move |name| { //! world += (hello.to_uppercase() + name).as_str(); //! } //! # )("abc"); //! ``` //! ``` //! # use serde_closure::{traits::FnMut, FnMut}; //! let hello = String::from("hello"); //! let mut world = String::new(); //! # ( //! FnMut!(move |name| { //! world += (hello.to_uppercase() + name).as_str(); //! }) //! # ).call_mut(("abc",)); //! ``` //! //! # Limitations //! There are currently some minor limitations: //! //! * Use of types that start with a lowercase letter need might need to be //! disambiguated from variables. If you see an error like the following, fix //! the case of the type, or append it with `my_struct::<>` to disambiguate. //! ```text //! error[E0308]: mismatched types //! --> tests/test.rs:450:4 //! | //! 449 | FnOnce!(move || { //! | _____- //! 450 | | my_struct; //! | | ^^^^^^^^^ expected struct `serde_closure::internal::a_variable`, found struct `my_struct` //! 451 | | }); //! | |______- in this macro invocation //! | //! = note: expected type `serde_closure::internal::a_variable` //! found type `my_struct` //! ``` //! //! * Use of variables that start with an uppercase letter might need to be //! disambiguated from types. If you see an error like the following, fix the //! case of the variable, or wrap it with `(MyVariable)` to disambiguate. //! ```text //! error: imports cannot refer to local variables //! --> tests/test.rs:422:3 //! | //! 417 | FnOnce!(move || { //! | _____- //! 418 | | MyVariable; //! | | ^^^^^^^^^^ //! 419 | | }); //! | |______- in this macro invocation //! | //! ``` //! //! * Functions and closures called inside the closure might need to be //! disambiguated. This can be done the same as above with `function::<>` for //! functions and `(closure)` for closures. //! //! # Serializing between processes //! //! Closures created by this crate are unnameable – i.e. just like normal //! closures, there is no Rust syntax available with which to write the type. //! What this means is that to deserialize a closure, you either need to specify //! the precise type you're deserializing without naming it (which is possible //! but not particularly practical), or *erase* the type by storing it in a //! [trait object](https://doc.rust-lang.org/beta/book/ch17-02-trait-objects.html). //! //! The [`serde_traitobject`](https://github.com/alecmocatta/serde_traitobject) //! crate enables trait objects to be safely serialized and sent between other //! processes running the same binary. //! //! For example, if you have multiple forks of a process, or the same binary //! running on each of a cluster of machines, //! [`serde_traitobject`](https://github.com/alecmocatta/serde_traitobject) //! would help you to send serializable closures between them. This can be done //! by upcasting the closure to a `Box<dyn serde_traitobject::Fn()>`, which is //! automatically serializable and deserializable with //! [`serde`](https://github.com/serde-rs/serde). #![doc(html_root_url = "https://docs.rs/serde_closure/0.3.1")] #![cfg_attr(nightly, feature(unboxed_closures, fn_traits))] #![warn( missing_copy_implementations, missing_debug_implementations, missing_docs, trivial_casts, trivial_numeric_casts, unused_import_braces, unused_qualifications, unused_results, clippy::pedantic )] // from https://github.com/rust-unofficial/patterns/blob/master/anti_patterns/deny-warnings.md #![allow(clippy::inline_always)] /// Macro that wraps a closure, evaluating to a [`FnOnce`](structs::FnOnce) /// struct that implements [`traits::FnOnce`] (and [`std::ops::FnOnce`] on /// nightly), [`Debug`](std::fmt::Debug), [`Serialize`](serde::Serialize) and /// [`Deserialize`](serde::Deserialize), and various convenience traits. /// /// See the [readme](self) for examples. pub use serde_closure_derive::FnOnce; /// Macro that wraps a closure, evaluating to a [`FnMut`](structs::FnMut) struct /// that implements [`traits::FnMut`] (and [`std::ops::FnMut`] on nightly), /// [`Debug`](std::fmt::Debug), [`Serialize`](serde::Serialize) and /// [`Deserialize`](serde::Deserialize), and various convenience traits. /// /// See the [readme](self) for examples. pub use serde_closure_derive::FnMut; /// Macro that wraps a closure, evaluating to a [`Fn`](structs::Fn) struct that /// implements [`traits::Fn`] (and [`std::ops::Fn`] on nightly), /// [`Debug`](std::fmt::Debug), [`Serialize`](serde::Serialize) and /// [`Deserialize`](serde::Deserialize), and various convenience traits. /// /// See the [readme](self) for examples. pub use serde_closure_derive::Fn; /// Attribute macro that can be applied to items to desugar trait bounds /// `FnOnce(…) -> …`, `FnMut(…) -> …` and `Fn(…) -> …` to `FnOnce<(…), Output = …>`, /// `FnMut<(…), Output = …>` and `Fn<(…), Output = …>`. This is just a /// convenience to enable parenthesized arguments for non `std::ops::*` traits /// on stable Rust. /// /// See `tests/stable.rs` for examples. pub use serde_closure_derive::desugar; #[doc(hidden)] #[macro_export] macro_rules! FnMutNamed { (pub type $name:ident<$($t:ident),*> = |$self:ident $(,$env:ident: $env_type:ty)*|$($arg:pat=> $arg_type:ty),*| -> $output:ty where $($bound_ty:ident : $bound_trait:tt),* $body:block) => ( #[derive(::serde::Serialize, ::serde::Deserialize)] pub struct $name<$($t),*> where $($bound_ty: $bound_trait),* { $($env: $env_type,)* marker: ::core::marker::PhantomData<fn() -> ($($t,)*)>, } const _: () = { impl<$($t),*> $name<$($t),*> where $($bound_ty: $bound_trait),* { #[allow(clippy::new_without_default)] pub fn new($($env: $env_type),*) -> Self { Self { $($env: $env,)* marker: ::core::marker::PhantomData, } } fn run(&mut $self, ($($arg,)*): ($($arg_type,)*)) -> $output $body } impl<$($t),*> Clone for $name<$($t),*> where $($bound_ty: $bound_trait,)* $($env_type: Clone,)* { fn clone(&self) -> Self { Self { $($env: self.$env.clone(),)* marker: ::core::marker::PhantomData, } } } impl<$($t),*> ::serde_closure::traits::FnOnce<($($arg_type,)*)> for $name<$($t),*> where $($bound_ty: $bound_trait),* { type Output = $output; fn call_once(mut self, args: ($($arg_type,)*)) -> Self::Output { self.run(args) } } impl<$($t),*> ::serde_closure::traits::FnMut<($($arg_type,)*)> for $name<$($t),*> where $($bound_ty: $bound_trait),* { fn call_mut(&mut self, args: ($($arg_type,)*)) -> Self::Output { unsafe { $crate::internal::transmute(self.run(args)) } } } }; ) } #[doc(hidden)] pub mod internal { pub use core; pub use serde; pub use std; use std::marker::PhantomData; pub trait FnOnce<Args> { type Output; fn call_once(self, args: Args) -> Self::Output; } pub trait FnMut<Args>: FnOnce<Args> { fn call_mut(&mut self, args: Args) -> Self::Output; } pub trait Fn<Args>: FnMut<Args> { fn call(&self, args: Args) -> Self::Output; } #[inline(always)] pub fn to_phantom<T>(_t: &T) -> PhantomData<fn(T)> { PhantomData } #[inline(always)] pub fn is_phantom<T>(_t: &T, _marker: PhantomData<fn(T)>) {} #[allow(missing_copy_implementations, missing_debug_implementations)] pub struct ZeroSizedAssertion; #[allow( missing_copy_implementations, missing_debug_implementations, non_camel_case_types )] pub struct a_variable; #[allow(clippy::missing_safety_doc)] pub unsafe fn transmute<T, U>(e: T) -> U { use std::mem::{self, align_of, size_of}; assert_eq!( (size_of::<T>(), align_of::<T>()), (size_of::<U>(), align_of::<U>()) ); let ret = mem::transmute_copy(&e); mem::forget(e); ret } } pub mod traits { //! Supertraits of [`std::ops::FnOnce`], [`std::ops::FnMut`] and //! [`std::ops::Fn`] that are usable on stable Rust. They are implemented //! by closures created by the [`FnOnce`](macro@super::FnOnce), //! [`FnMut`](macro@super::FnMut) and [`Fn`](macro@super::Fn) macros. //! //! See the [readme](super) for examples. #![allow(non_snake_case)] use std::ops; /// Supertrait of [`std::ops::FnOnce`] that is usable on stable Rust. It is /// implemented by closures created by the [`FnOnce`](macro@super::FnOnce) /// macro. /// /// See the [readme](super) for examples. pub trait FnOnce<Args> { /// The returned type after the call operator is used. type Output; /// Performs the call operation. fn call_once(self, args: Args) -> Self::Output; } /// Supertrait of [`std::ops::FnMut`] that is usable on stable Rust. It is /// implemented by closures created by the [`FnMut`](macro@super::FnMut) /// macro. /// /// See the [readme](super) for examples. pub trait FnMut<Args>: FnOnce<Args> { /// Performs the call operation. fn call_mut(&mut self, args: Args) -> Self::Output; } /// Supertrait of [`std::ops::Fn`] that is usable on stable Rust. It is /// implemented by closures created by the [`Fn`](macro@super::Fn) /// macro. /// /// See the [readme](super) for examples. pub trait Fn<Args>: FnMut<Args> { /// Performs the call operation. fn call(&self, args: Args) -> Self::Output; } /// A version of the [`FnOnce`] trait intended to be used for boxed trait /// objects to make them callable on stable Rust. /// /// ```ignore /// let t: Box<dyn FnOnceBox(…) -> …> = …; /// let output = t.call_once_box((…,)); /// ``` pub trait FnOnceBox<A> { /// The returned type after the call operator is used. type Output; /// Performs the call operation on a `Box<dyn FnOnceBox(…) -> …>`. fn call_once_box(self: Box<Self>, args: A) -> Self::Output; } impl<A, F> FnOnceBox<A> for F where F: FnOnce<A>, { type Output = F::Output; fn call_once_box(self: Box<F>, args: A) -> F::Output { self.call_once(args) } } #[cfg(not(nightly))] macro_rules! fn_once { ($($t:ident)*) => { impl<T, $($t,)* O> FnOnce<($($t,)*)> for T where T: ops::FnOnce($($t,)*) -> O, { type Output = O; fn call_once(self, ($($t,)*): ($($t,)*)) -> Self::Output { self($($t,)*) } } fn_once!(@recurse $($t)*); }; (@recurse $first:ident $($t:ident)*) => { fn_once!($($t)*); }; (@recurse) => {}; } #[cfg(not(nightly))] fn_once!(A B C D E F G H I J K L); #[cfg(nightly)] impl<T, Args> FnOnce<Args> for T where T: ops::FnOnce<Args>, { type Output = T::Output; fn call_once(self, args: Args) -> Self::Output { self.call_once(args) } } #[cfg(not(nightly))] macro_rules! fn_mut { ($($t:ident)*) => { impl<T, $($t,)* O> FnMut<($($t,)*)> for T where T: ops::FnMut($($t,)*) -> O, { fn call_mut(&mut self, ($($t,)*): ($($t,)*)) -> Self::Output { self($($t,)*) } } fn_mut!(@recurse $($t)*); }; (@recurse $first:ident $($t:ident)*) => { fn_mut!($($t)*); }; (@recurse) => {}; } #[cfg(not(nightly))] fn_mut!(A B C D E F G H I J K L); #[cfg(nightly)] impl<T, Args> FnMut<Args> for T where T: ops::FnMut<Args>, { fn call_mut(&mut self, args: Args) -> Self::Output { self.call_mut(args) } } #[cfg(not(nightly))] macro_rules! fn_ref { ($($t:ident)*) => { impl<T, $($t,)* O> Fn<($($t,)*)> for T where T: ops::Fn($($t,)*) -> O, { fn call(&self, ($($t,)*): ($($t,)*)) -> Self::Output { self($($t,)*) } } fn_ref!(@recurse $($t)*); }; (@recurse $first:ident $($t:ident)*) => { fn_ref!($($t)*); }; (@recurse) => {}; } #[cfg(not(nightly))] fn_ref!(A B C D E F G H I J K L); #[cfg(nightly)] impl<T, Args> Fn<Args> for T where T: ops::Fn<Args>, { fn call(&self, args: Args) -> Self::Output { self.call(args) } } } pub mod structs { //! Structs representing a serializable closure, created by the //! [`FnOnce`](macro@super::FnOnce), [`FnMut`](macro@super::FnMut) and //! [`Fn`](macro@super::Fn) macros. They implement [`traits::FnOnce`](super::traits::FnOnce), //! [`traits::FnMut`](super::traits::FnMut) and [`traits::Fn`](super::traits::Fn) //! respectively (and [`std::ops::FnOnce`], [`std::ops::FnMut`] and [`std::ops::Fn`] //! on nightly), as well as [`Debug`](std::fmt::Debug), [`Serialize`](serde::Serialize) //! and [`Deserialize`](serde::Deserialize), and various convenience traits. //! //! See the [readme](super) for examples. use serde::{Deserialize, Serialize}; use std::fmt::{self, Debug}; use super::internal; /// A struct representing a serializable closure, created by the /// [`FnOnce`](macro@super::FnOnce) macro. Implements [`traits::FnOnce`](super::traits::FnOnce) /// (and [`std::ops::FnOnce`] on nightly), [`Debug`], [`Serialize`] and /// [`Deserialize`], and various convenience /// traits. /// /// See the [readme](super) for examples. #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)] #[serde(transparent)] pub struct FnOnce<F> { f: F, } impl<F> FnOnce<F> { /// Internal method #[doc(hidden)] #[inline(always)] pub fn internal_new<I>(f: F) -> Self where F: internal::FnOnce<I>, { Self { f } } } #[cfg(not(nightly))] impl<F, I> super::traits::FnOnce<I> for FnOnce<F> where F: internal::FnOnce<I>, { type Output = F::Output; #[inline(always)] fn call_once(self, args: I) -> Self::Output { self.f.call_once(args) } } #[cfg(nightly)] impl<F, I> std::ops::FnOnce<I> for FnOnce<F> where F: internal::FnOnce<I>, { type Output = F::Output; #[inline(always)] extern "rust-call" fn call_once(self, args: I) -> Self::Output { self.f.call_once(args) } } impl<F> Debug for FnOnce<F> where F: Debug, { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { Debug::fmt(&self.f, f) } } /// A struct representing a serializable closure, created by the /// [`FnMut`](macro@super::FnMut) macro. Implements [`traits::FnMut`](super::traits::FnMut) /// (and [`std::ops::FnMut`] on nightly), [`Debug`], [`Serialize`] and /// [`Deserialize`], and various convenience /// traits. /// /// See the [readme](super) for examples. #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)] #[serde(transparent)] pub struct FnMut<F> { f: F, } impl<F> FnMut<F> { /// Internal method #[doc(hidden)] #[inline(always)] pub fn internal_new<I>(f: F) -> Self where F: internal::FnMut<I>, { Self { f } } } #[cfg(not(nightly))] impl<F, I> super::traits::FnOnce<I> for FnMut<F> where F: internal::FnOnce<I>, { type Output = F::Output; #[inline(always)] fn call_once(self, args: I) -> Self::Output { self.f.call_once(args) } } #[cfg(nightly)] impl<F, I> std::ops::FnOnce<I> for FnMut<F> where F: internal::FnOnce<I>, { type Output = F::Output; #[inline(always)] extern "rust-call" fn call_once(self, args: I) -> Self::Output { self.f.call_once(args) } } #[cfg(not(nightly))] impl<F, I> super::traits::FnMut<I> for FnMut<F> where F: internal::FnMut<I>, { #[inline(always)] fn call_mut(&mut self, args: I) -> Self::Output { self.f.call_mut(args) } } #[cfg(nightly)] impl<F, I> std::ops::FnMut<I> for FnMut<F> where F: internal::FnMut<I>, { #[inline(always)] extern "rust-call" fn call_mut(&mut self, args: I) -> Self::Output { self.f.call_mut(args) } } impl<F> Debug for FnMut<F> where F: Debug, { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { Debug::fmt(&self.f, f) } } /// A struct representing a serializable closure, created by the /// [`Fn`](macro@super::Fn) macro. Implements [`traits::Fn`](super::traits::Fn) /// (and [`std::ops::Fn`] on nightly), [`Debug`], [`Serialize`] and /// [`Deserialize`], and various convenience traits. /// /// See the [readme](super) for examples. #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)] #[serde(transparent)] pub struct Fn<F> { f: F, } impl<F> Fn<F> { /// Internal method #[doc(hidden)] #[inline(always)] pub fn internal_new<I>(f: F) -> Self where F: internal::Fn<I>, { Self { f } } } #[cfg(not(nightly))] impl<F, I> super::traits::FnOnce<I> for Fn<F> where F: internal::FnOnce<I>, { type Output = F::Output; #[inline(always)] fn call_once(self, args: I) -> Self::Output { self.f.call_once(args) } } #[cfg(nightly)] impl<F, I> std::ops::FnOnce<I> for Fn<F> where F: internal::FnOnce<I>, { type Output = F::Output; #[inline(always)] extern "rust-call" fn call_once(self, args: I) -> Self::Output { self.f.call_once(args) } } #[cfg(not(nightly))] impl<F, I> super::traits::FnMut<I> for Fn<F> where F: internal::FnMut<I>, { #[inline(always)] fn call_mut(&mut self, args: I) -> Self::Output { self.f.call_mut(args) } } #[cfg(nightly)] impl<F, I> std::ops::FnMut<I> for Fn<F> where F: internal::FnMut<I>, { #[inline(always)] extern "rust-call" fn call_mut(&mut self, args: I) -> Self::Output { self.f.call_mut(args) } } #[cfg(not(nightly))] impl<F, I> super::traits::Fn<I> for Fn<F> where F: internal::Fn<I>, { #[inline(always)] fn call(&self, args: I) -> Self::Output { self.f.call(args) } } #[cfg(nightly)] impl<F, I> std::ops::Fn<I> for Fn<F> where F: internal::Fn<I>, { #[inline(always)] extern "rust-call" fn call(&self, args: I) -> Self::Output { self.f.call(args) } } impl<F> Debug for Fn<F> where F: Debug, { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { Debug::fmt(&self.f, f) } } }