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//! <div align="center"> //! <a href="https://github.com/nvzqz/impls"> //! <img src="https://raw.githubusercontent.com/nvzqz/impls/assets/banner.svg?sanitize=true" //! height="250px"> //! </a> //! <br> //! <a href="https://crates.io/crates/impls"> //! <img src="https://img.shields.io/crates/v/impls.svg" alt="Crates.io"> //! <img src="https://img.shields.io/crates/d/impls.svg" alt="Downloads"> //! </a> //! <a href="https://github.com/nvzqz/impls/actions?query=workflow%3ACI"> //! <img src="https://github.com/nvzqz/impls/workflows/CI/badge.svg" alt="Build Status"> //! </a> //! <img src="https://img.shields.io/badge/rustc-^1.37.0-blue.svg" alt="rustc ^1.37.0"> //! <br> //! <a href="https://www.patreon.com/nvzqz"> //! <img src="https://c5.patreon.com/external/logo/become_a_patron_button.png" alt="Become a Patron!" height="35"> //! </a> //! <a href="https://www.paypal.me/nvzqz"> //! <img src="https://buymecoffee.intm.org/img/button-paypal-white.png" alt="Buy me a coffee" height="35"> //! </a> //! </div> //! <br> //! //! Determine if a type implements a logical trait //! expression<sup>[**?**](#logical-trait-expression)</sup>, brought to you by //! [@NikolaiVazquez]! //! //! This library defines [`impls!`], a macro<sup>[**?**](#macro)</sup> that //! returns a [`bool`] indicating whether a type implements a boolean-like //! expression over a set of traits<sup>[**?**](#trait)</sup>. //! //! ``` //! # #[macro_use] extern crate impls; //! assert!(impls!(String: Clone & !Copy & Send & Sync)); //! ``` //! //! See ["Examples"](#examples) for detailed use cases and, if you're brave, see //! ["Trait-Dependent Type Sizes"](#trait-dependent-type-sizes) for some cursed //! code. //! //! # Index //! //! - [Reasoning](#reasoning) //! - [Usage](#usage) //! - [Vocabulary](#vocabulary) //! - [Macro](#macro) //! - [Trait](#trait) //! - [Logical Trait Expression](#logical-trait-expression) //! - [Examples](#examples) //! - [Constant Evaluation](#constant-evaluation) //! - [Precedence and Nesting](#precedence-and-nesting) //! - [Mutual Exclusion](#mutual-exclusion) //! - [Reference Types](#reference-types) //! - [Unsized Types](#unsized-types) //! - [Generic Types](#generic-types) //! - [Lifetimes](#lifetimes) //! - [Trait-Dependent Type Sizes](#trait-dependent-type-sizes) //! - [Authors](#authors) //! - [License](#license) //! //! # Reasoning //! //! As a library author, it's important to ensure that your API remains stable. //! Trait implementations are part of API stability. For example: if you //! accidentally introduce an inner type that makes your publicly-exposed type //! no longer be [`Send`] or [`Sync`], you've now broken your API without //! noticing it! The most common case of this happening is adding a [raw //! pointer][ptr] (i.e. `*const T`, `*mut T`) as a type field. //! //! By checking situations like this with [`impls!`], either at [compile-time] //! or in a unit test, you can ensure that no API-breaking changes are made //! without noticing until it's too late. //! //! # Usage //! //! This crate is available [on crates.io][crate] and can be used by adding the //! following to your project's [`Cargo.toml`]: //! //! ```toml //! [dependencies] //! impls = "1" //! ``` //! //! and this to your crate root (`main.rs` or `lib.rs`): //! //! ``` //! # #[allow(unused_imports)] //! #[macro_use] //! extern crate impls; //! # fn main() {} //! ``` //! //! When using [Rust 2018 edition][2018], the following import can help if //! having `#[macro_use]` is undesirable. //! //! ```edition2018 //! use impls::impls; //! ``` //! //! # Vocabulary //! //! This documentation uses jargon that may be new to inexperienced Rust users. //! This section exists to make these terms easier to understand. Feel free to //! skip this section if these are already familiar to you. //! //! ## Macro //! //! In Rust, macros are functions over the [abstract syntax tree (AST)][AST]. //! They map input tokens to output tokens by performing some operation over //! them through a set of rules. Because of this, only their outputs are ever //! type-checked. //! //! If you wish to learn about implementing macros, I recommend: //! - [The Little Book of Rust Macros](https://danielkeep.github.io/tlborm/book/index.html) //! - ["Macros" - The Rust Programming Language](https://doc.rust-lang.org/book/ch19-06-macros.html) //! - ["Macros" - The Rust Reference](https://doc.rust-lang.org/stable/reference/macros.html) //! - ["Macros By Example" - The Rust Reference](https://doc.rust-lang.org/stable/reference/macros-by-example.html) //! //! To use this crate, you do not need to know how macros are defined. //! //! ## Trait //! //! In Rust, traits are a way of defining a generalized property. They should be //! thought of expressing what a type is capable of doing. For example: if a //! type implements [`Into`] for some type `T`, then we know it can be converted //! into `T` by just calling the `.into()` method on it. //! //! If you wish to learn about traits in detail, I recommend: //! - ["Traits: Defining Shared Behavior" - The Rust Programming Language](https://doc.rust-lang.org/book/ch10-02-traits.html) //! - ["Traits" - The Rust Reference](https://doc.rust-lang.org/stable/reference/items/traits.html) //! //! ## Logical Trait Expression //! //! In this crate, traits should be thought of as [`bool`]s where the condition //! is whether the given type implements the trait or not. //! //! An expression can be formed from these trait operations: //! //! - And (`&`): also known as [logical conjunction], this returns `true` if //! **both** operands are `true`. This is usually defined in Rust via the //! [`BitAnd`] trait. //! //! - Or (`|`): also known as [logical disjunction], this returns `true` if //! **either** of two operands is `true`. This is usually defined in Rust via //! the [`BitOr`] trait. //! //! - Exclusive-or (`^`): also known as [exclusive disjunction], this returns //! `true` if **only one** of two operands is `true`. This is usually defined //! in Rust via the [`BitXor`] trait. //! //! - Not (`!`): a negation that returns `false` if the operand is `true`, or //! `true` if the operand is `false`. This is usually defined in Rust via the //! [`Not`] trait. //! //! See ["Precedence and Nesting"](#precedence-and-nesting) for information //! about the order in which these operations are performed. //! // IMPORTANT: These examples are copy and pasted directly from `impls!` //! # Examples //! //! This macro works in every type context. See below for use cases. //! //! ## Constant Evaluation //! //! Because types are [compile-time] constructs, the result of this macro can be //! used as a `const` value: //! //! ``` //! # #[macro_use] extern crate impls; //! const IMPLS: bool = impls!(u8: From<u32>); //! ``` //! //! Using [`static_assertions`], we can fail to compile if the trait expression //! evaluates to `false`: //! //! ```compile_fail //! # #[macro_use] extern crate impls; //! # macro_rules! const_assert { //! # ($x:expr) => { let _: [(); 1] = [(); $x as usize]; } //! # } //! const_assert!(impls!(*const u8: Send | Sync)); //! ``` //! //! ## Precedence and Nesting //! //! Trait operations abide by [Rust's expression precedence][precedence]. To //! define a custom order of operations (e.g. left-to-right), simply nest the //! expressions with parentheses. //! //! ``` //! # #[macro_use] extern crate impls; //! let pre = impls!(u64: From<u8> | From<u16> ^ From<u32> & From<u64>); //! let ltr = impls!(u64: ((From<u8> | From<u16>) ^ From<u32>) & From<u64>); //! //! assert_eq!(pre, true | true ^ true & true); //! assert_ne!(pre, ltr); //! ``` //! //! ## Mutual Exclusion //! //! Because exclusive-or (`^`) is a trait operation, we can check that a type //! implements one of two traits, but not both: //! //! ``` //! # #[macro_use] extern crate impls; //! struct T; //! //! trait Foo {} //! trait Bar {} //! //! impl Foo for T {} //! //! assert!(impls!(T: Foo ^ Bar)); //! ``` //! //! ## Reference Types //! //! Something that's surprising to many Rust users is that [`&mut T`] _does not_ //! implement [`Copy`] _nor_ [`Clone`]: //! //! ``` //! # #[macro_use] extern crate impls; //! assert!(impls!(&mut u32: !Copy & !Clone)); //! ``` //! //! Surely you're thinking now that this macro must be broken, because you've //! been able to reuse `&mut T` throughout your lifetime with Rust. This works //! because, in certain contexts, the compiler silently adds "re-borrows" //! (`&mut *ref`) with a shorter lifetime and shadows the original. In reality, //! `&mut T` is a move-only type. //! //! ## Unsized Types //! //! There's a variety of types in Rust that don't implement [`Sized`]: //! //! ``` //! # #[macro_use] extern crate impls; //! // Slices store their size with their pointer. //! assert!(impls!(str: !Sized)); //! assert!(impls!([u8]: !Sized)); //! //! // Trait objects store their size in a vtable. //! trait Foo {} //! assert!(impls!(dyn Foo: !Sized)); //! //! // Wrappers around unsized types are also unsized themselves. //! struct Bar([u8]); //! assert!(impls!(Bar: !Sized)); //! ``` //! //! ## Generic Types //! //! When called from a generic function, the returned value is based on the //! constraints of the generic type: //! //! ``` //! # #[macro_use] extern crate impls; //! use std::cell::Cell; //! //! struct Value<T> { //! // ... //! # value: T //! } //! //! impl<T: Send> Value<T> { //! fn do_stuff() { //! assert!(impls!(Cell<T>: Send)); //! // ... //! } //! } //! ``` //! //! Keep in mind that this can result in false negatives: //! //! ``` //! # #[macro_use] extern crate impls; //! const fn is_copy<T>() -> bool { //! impls!(T: Copy) //! } //! //! assert_ne!(is_copy::<u32>(), impls!(u32: Copy)); //! ``` //! //! [precedence]: https://doc.rust-lang.org/reference/expressions.html#expression-precedence //! [`static_assertions`]: https://docs.rs/static_assertions //! //! ## Lifetimes //! //! Traits with lifetimes are also supported: //! //! ``` //! # #[macro_use] extern crate impls; //! trait Ref<'a> {} //! impl<'a, T: ?Sized> Ref<'a> for &'a T {} //! impl<'a, T: ?Sized> Ref<'a> for &'a mut T {} //! //! assert!(impls!(&'static str: Ref<'static>)); //! assert!(impls!(&'static mut [u8]: Ref<'static>)); //! assert!(impls!(String: !Ref<'static>)); //! ``` //! //! ## Trait-Dependent Type Sizes //! //! This macro enables something really cool (read cursed) that couldn't be done //! before: making a type's size dependent on what traits it implements! Note //! that this probably is a bad idea and shouldn't be used in production. //! //! Here `Foo` becomes 32 bytes for no other reason than it implementing //! [`Clone`]: //! //! ``` //! # #[macro_use] extern crate impls; //! const SIZE: usize = 32 * (impls!(Foo: Clone) as usize); //! //! #[derive(Clone)] //! struct Foo([u8; SIZE]); //! //! assert_eq!(std::mem::size_of::<Foo>(), 32); //! ``` //! //! The [`bool`] returned from [`impls!`] gets casted to a [`usize`], becoming 1 //! or 0 depending on if it's `true` or `false` respectively. If `true`, this //! becomes 32 × 1, which is 32. This then becomes the length of the byte array //! in `Foo`. //! //! # Authors //! //! - Nikolai Vazquez //! (GitHub: [@nvzqz](https://github.com/nvzqz), Twitter: [@NikolaiVazquez]) //! //! Implemented the `impls!` macro with support for all logical operators and //! without the limitations of the initial `does_impl!` macro by Nadrieril. //! //! - Nadrieril Feneanar //! (GitHub: [@Nadrieril](https://github.com/Nadrieril)) //! //! Implemented the initial `does_impl!` macro in //! [nvzqz/static-assertions-rs#28](https://github.com/nvzqz/static-assertions-rs/pull/28) //! upon which this crate was originally based. //! //! # License //! //! This project is released under either: //! //! - [MIT License](https://github.com/nvzqz/impls/blob/master/LICENSE-MIT) //! - [Apache License (Version 2.0)](https://github.com/nvzqz/impls/blob/master/LICENSE-APACHE) //! //! at your choosing. //! //! [@NikolaiVazquez]: https://twitter.com/NikolaiVazquez //! //! [compile-time]: https://en.wikipedia.org/wiki/Compile_time //! //! [`&mut T`]: https://doc.rust-lang.org/std/primitive.reference.html //! [`bool`]: https://doc.rust-lang.org/std/primitive.bool.html //! [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html //! [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html //! [`Sized`]: https://doc.rust-lang.org/std/marker/trait.Sized.html //! [`usize`]: https://doc.rust-lang.org/std/primitive.usize.html //! //! [`Cargo.toml`]: https://doc.rust-lang.org/cargo/reference/manifest.html //! [`impls!`]: macro.impls.html //! [2018]: https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html#rust-2018 //! [crate]: https://crates.io/crates/impls //! //! [`BitAnd`]: https://doc.rust-lang.org/std/ops/trait.BitAnd.html //! [`BitOr`]: https://doc.rust-lang.org/std/ops/trait.BitOr.html //! [`BitXor`]: https://doc.rust-lang.org/std/ops/trait.BitXor.html //! [`Into`]: https://doc.rust-lang.org/std/convert/trait.Into.html //! [`Not`]: https://doc.rust-lang.org/std/ops/trait.Not.html //! [`Send`]: https://doc.rust-lang.org/std/marker/trait.Send.html //! [`Sync`]: https://doc.rust-lang.org/std/marker/trait.Send.html //! [ptr]: https://doc.rust-lang.org/std/primitive.pointer.html //! //! [AST]: https://en.wikipedia.org/wiki/Abstract_syntax_tree //! [exclusive disjunction]: https://en.wikipedia.org/wiki/Exclusive_disjunction //! [logical conjunction]: https://en.wikipedia.org/wiki/Logical_conjunction //! [logical disjunction]: https://en.wikipedia.org/wiki/Logical_disjunction #![deny(missing_docs)] #![doc( html_root_url = "https://docs.rs/impls/1.0.3", html_logo_url = "https://raw.githubusercontent.com/nvzqz/impls/assets/logo.svg?sanitize=true" )] // Allocating types like `String` are used when testing. #![cfg_attr(not(test), no_std)] #[doc(hidden)] pub extern crate core as _core; /// Returns `true` if a type implements a logical trait expression. /// // IMPORTANT: Update crate level docs when updating these examples! /// # Examples /// /// This macro works in every type context. See below for use cases. /// /// ## Constant Evaluation /// /// Because types are [compile-time] constructs, the result of this macro can be /// used as a `const` value: /// /// ``` /// # #[macro_use] extern crate impls; /// const IMPLS: bool = impls!(u8: From<u32>); /// ``` /// /// Using [`static_assertions`], we can fail to compile if the trait expression /// evaluates to `false`: /// /// ```compile_fail /// # #[macro_use] extern crate impls; /// # macro_rules! const_assert { /// # ($x:expr) => { let _: [(); 1] = [(); $x as usize]; } /// # } /// const_assert!(impls!(*const u8: Send | Sync)); /// ``` /// /// ## Precedence and Nesting /// /// Trait operations abide by [Rust's expression precedence][precedence]. To /// define a custom order of operations (e.g. left-to-right), simply nest the /// expressions with parentheses. /// /// ``` /// # #[macro_use] extern crate impls; /// let pre = impls!(u64: From<u8> | From<u16> ^ From<u32> & From<u64>); /// let ltr = impls!(u64: ((From<u8> | From<u16>) ^ From<u32>) & From<u64>); /// /// assert_eq!(pre, true | true ^ true & true); /// assert_ne!(pre, ltr); /// ``` /// /// ## Mutual Exclusion /// /// Because exclusive-or (`^`) is a trait operation, we can check that a type /// implements one of two traits, but not both: /// /// ``` /// # #[macro_use] extern crate impls; /// struct T; /// /// trait Foo {} /// trait Bar {} /// /// impl Foo for T {} /// /// assert!(impls!(T: Foo ^ Bar)); /// ``` /// /// ## Reference Types /// /// Something that's surprising to many Rust users is that [`&mut T`] _does not_ /// implement [`Copy`] _nor_ [`Clone`]: /// /// ``` /// # #[macro_use] extern crate impls; /// assert!(impls!(&mut u32: !Copy & !Clone)); /// ``` /// /// Surely you're thinking now that this macro must be broken, because you've /// been able to reuse `&mut T` throughout your lifetime with Rust. This works /// because, in certain contexts, the compiler silently adds "re-borrows" /// (`&mut *ref`) with a shorter lifetime and shadows the original. In reality, /// `&mut T` is a move-only type. /// /// ## Unsized Types /// /// There's a variety of types in Rust that don't implement [`Sized`]: /// /// ``` /// # #[macro_use] extern crate impls; /// // Slices store their size with their pointer. /// assert!(impls!(str: !Sized)); /// assert!(impls!([u8]: !Sized)); /// /// // Trait objects store their size in a vtable. /// trait Foo {} /// assert!(impls!(dyn Foo: !Sized)); /// /// // Wrappers around unsized types are also unsized themselves. /// struct Bar([u8]); /// assert!(impls!(Bar: !Sized)); /// ``` /// /// ## Generic Types /// /// When called from a generic function, the returned value is based on the /// constraints of the generic type: /// /// ``` /// # #[macro_use] extern crate impls; /// use std::cell::Cell; /// /// struct Value<T> { /// // ... /// # value: T /// } /// /// impl<T: Send> Value<T> { /// fn do_stuff() { /// assert!(impls!(Cell<T>: Send)); /// // ... /// } /// } /// ``` /// /// Keep in mind that this can result in false negatives: /// /// ``` /// # #[macro_use] extern crate impls; /// const fn is_copy<T>() -> bool { /// impls!(T: Copy) /// } /// /// assert_ne!(is_copy::<u32>(), impls!(u32: Copy)); /// ``` /// /// [precedence]: https://doc.rust-lang.org/reference/expressions.html#expression-precedence /// [`static_assertions`]: https://docs.rs/static_assertions /// /// ## Lifetimes /// /// Traits with lifetimes are also supported: /// /// ``` /// # #[macro_use] extern crate impls; /// trait Ref<'a> {} /// impl<'a, T: ?Sized> Ref<'a> for &'a T {} /// impl<'a, T: ?Sized> Ref<'a> for &'a mut T {} /// /// assert!(impls!(&'static str: Ref<'static>)); /// assert!(impls!(&'static mut [u8]: Ref<'static>)); /// assert!(impls!(String: !Ref<'static>)); /// ``` /// /// ## Trait-Dependent Type Sizes /// /// This macro enables something really cool (read cursed) that couldn't be done /// before: making a type's size dependent on what traits it implements! Note /// that this probably is a bad idea and shouldn't be used in production. /// /// Here `Foo` becomes 32 bytes for no other reason than it implementing /// [`Clone`]: /// /// ``` /// # #[macro_use] extern crate impls; /// const SIZE: usize = 32 * (impls!(Foo: Clone) as usize); /// /// #[derive(Clone)] /// struct Foo([u8; SIZE]); /// /// assert_eq!(std::mem::size_of::<Foo>(), 32); /// ``` /// /// The [`bool`] returned from `impls!` gets casted to a [`usize`], becoming 1 /// or 0 depending on if it's `true` or `false` respectively. If `true`, this /// becomes 32 × 1, which is 32. This then becomes the length of the byte array /// in `Foo`. /// /// [compile-time]: https://en.wikipedia.org/wiki/Compile_time /// /// [`&mut T`]: https://doc.rust-lang.org/std/primitive.reference.html /// [`bool`]: https://doc.rust-lang.org/std/primitive.bool.html /// [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html /// [`Copy`]: https://doc.rust-lang.org/std/marker/trait.Copy.html /// [`Sized`]: https://doc.rust-lang.org/std/marker/trait.Sized.html /// [`usize`]: https://doc.rust-lang.org/std/primitive.usize.html #[macro_export(local_inner_macros)] macro_rules! impls { ($type:ty: $($trait_expr:tt)+) => { _impls!($type: $($trait_expr)+) }; } /// Handles the dirty work of `impls`. #[doc(hidden)] #[macro_export(local_inner_macros)] macro_rules! _impls { // ONE: Turn `$trait` into `true` or `false` based on whether `$type` // implements it. ($type:ty: $(! !)* $trait:path) => {{ // Do not import types in order to prevent trait name collisions. /// Fallback trait with `False` for `IMPLS` if the type does not /// implement the given trait. trait DoesNotImpl { const IMPLS: bool = false; } impl<T: ?Sized> DoesNotImpl for T {} /// Concrete type with `True` for `IMPLS` if the type implements the /// given trait. Otherwise, it falls back to `DoesNotImpl`. struct Wrapper<T: ?Sized>($crate::_core::marker::PhantomData<T>); #[allow(dead_code)] impl<T: ?Sized + $trait> Wrapper<T> { const IMPLS: bool = true; } <Wrapper<$type>>::IMPLS }}; // NOT ($type:ty: $(! !)* !$trait:path) => { !_impls!($type: $trait) }; // PAREN ($type:ty: $(! !)* ($($trait_expr:tt)+)) => { _impls!($type: $($trait_expr)+) }; // PAREN+NOT ($type:ty: $(! !)* !($($trait_expr:tt)+)) => { !_impls!($type: $($trait_expr)+) }; // PAREN+OR ($type:ty: $(! !)* ($($t1:tt)+) | $($t2:tt)+) => { _impls!($type: $($t1)+) | _impls!($type: $($t2)+) }; // PAREN+OR+NOT ($type:ty: $(! !)* !($($t1:tt)+) | $($t2:tt)+) => { !_impls!($type: $($t1)+) | _impls!($type: $($t2)+) }; // PAREN+AND ($type:ty: $(! !)* ($($t1:tt)+) & $($t2:tt)+) => { _impls!($type: $($t1)+) & _impls!($type: $($t2)+) }; // PAREN+AND+NOT ($type:ty: $(! !)* !($($t1:tt)+) & $($t2:tt)+) => { !_impls!($type: $($t1)+) & _impls!($type: $($t2)+) }; // PAREN+XOR ($type:ty: $(! !)* ($($t1:tt)+) ^ $($t2:tt)+) => { _impls!($type: $($t1)+) ^ _impls!($type: $($t2)+) }; // PAREN+XOR+NOT ($type:ty: $(! !)* !($($t1:tt)+) ^ $($t2:tt)+) => { !_impls!($type: $($t1)+) ^ _impls!($type: $($t2)+) }; // OR: Any. ($type:ty: $(! !)* $t1:path | $($t2:tt)+) => {{ _impls!($type: $t1) | _impls!($type: $($t2)+) }}; // OR+NOT: Any. ($type:ty: $(! !)* !$t1:path | $($t2:tt)+) => {{ !_impls!($type: $t1) | _impls!($type: $($t2)+) }}; // AND: 0 lifetimes, 0 generics. ($type:ty: $(! !)* $t1:ident & $($t2:tt)+) => {{ _impls!($type: $t1) & _impls!($type: $($t2)+) }}; // AND+NOT: 0 lifetimes, 0 generics. ($type:ty: $(! !)* !$t1:ident & $($t2:tt)+) => {{ !_impls!($type: $t1) & _impls!($type: $($t2)+) }}; // AND: 1+ lifetimes, 0+ generics. ( $type:ty: $(! !)* $t1:ident < $($t1_lifetime:lifetime),+ $(, $t1_generic:ty)* $(,)? > & $($t2:tt)+ ) => {{ _impls!($type: $t1 < $($t1_lifetime),+ $(, $t1_generic)* >) & _impls!($type: $($t2)+) }}; // AND+NOT: 1+ lifetimes, 0+ generics. ( $type:ty: $(! !)* !$t1:ident < $($t1_lifetime:lifetime),+ $(, $t1_generic:ty)* $(,)? > & $($t2:tt)+ ) => {{ !_impls!($type: $t1 < $($t1_lifetime),+ $(, $t1_generic)* >) & _impls!($type: $($t2)+) }}; // AND: 0 lifetimes, 1+ generics. ( $type:ty: $(! !)* $t1:ident < $($t1_generic:ty),+ $(,)? > & $($t2:tt)+ ) => {{ _impls!($type: $t1 < $($t1_generic),+ >) & _impls!($type: $($t2)+) }}; // AND+NOT: 0 lifetimes, 1+ generics. ( $type:ty: $(! !)* !$t1:ident < $($t1_generic:ty),+ $(,)? > & $($t2:tt)+ ) => {{ !_impls!($type: $t1 < $($t1_generic),+ >) & _impls!($type: $($t2)+) }}; // XOR: 0 lifetimes, 0 generics. ($type:ty: $(! !)* $t1:ident ^ $($t2:tt)+) => {{ _impls!($type: $t1) ^ _impls!($type: $($t2)+) }}; // XOR+NOT: 0 lifetimes, 0 generics. ($type:ty: $(! !)* !$t1:ident ^ $($t2:tt)+) => {{ ! _impls!($type: $t1) ^ _impls!($type: $($t2)+) }}; // XOR: 1+ lifetimes, 0+ generics. ( $type:ty: $(! !)* $t1:ident < $($t1_lifetime:lifetime),+ $(, $t1_generic:ty)* $(,)? > ^ $($t2:tt)+ ) => {{ _impls!($type: $t1 < $($t1_lifetime),+ $(, $t1_generic)* >) ^ _impls!($type: $($t2)+) }}; // XOR+NOT: 1+ lifetimes, 0+ generics. ( $type:ty: $(! !)* ! $t1:ident < $($t1_lifetime:lifetime),+ $(, $t1_generic:ty)* $(,)? > ^ $($t2:tt)+ ) => {{ !_impls!($type: $t1 < $($t1_lifetime),+ $(, $t1_generic)* >) ^ _impls!($type: $($t2)+) }}; // XOR: 0 lifetimes, 1+ generics. ( $type:ty: $(! !)* $t1:ident < $($t1_generic:ty),+ $(,)? > ^ $($t2:tt)+ ) => {{ _impls!($type: $t1 < $($t1_generic),+ >) ^ _impls!($type: $($t2)+) }}; // XOR+NOT: 0 lifetimes, 1+ generics. ( $type:ty: $(! !)* ! $t1:ident < $($t1_generic:ty),+ $(,)? > ^ $($t2:tt)+ ) => {{ ! _impls!($type: $t1 < $($t1_generic),+ >) ^ _impls!($type: $($t2)+) }}; } // Declare after macros in order to be able to use them. #[cfg(test)] mod tests;