| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/downcast-rs-1.2.0/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../downcast_rs/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../downcast_rs/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="attribute">#![deny(unsafe_code)] |
| #![cfg_attr(not(feature = <span class="string">"std"</span>), no_std)] |
| </span><span class="doccomment">//! [](https://github.com/marcianx/downcast-rs/actions) |
| //! [](https://crates.io/crates/downcast-rs) |
| //! [](https://docs.rs/downcast-rs) |
| //! |
| //! Rust enums are great for types where all variations are known beforehand. But a |
| //! container of user-defined types requires an open-ended type like a **trait |
| //! object**. Some applications may want to cast these trait objects back to the |
| //! original concrete types to access additional functionality and performant |
| //! inlined implementations. |
| //! |
| //! `downcast-rs` adds this downcasting support to trait objects using only safe |
| //! Rust. It supports **type parameters**, **associated types**, and **constraints**. |
| //! |
| //! # Usage |
| //! |
| //! Add the following to your `Cargo.toml`: |
| //! |
| //! ```toml |
| //! [dependencies] |
| //! downcast-rs = "1.2.0" |
| //! ``` |
| //! |
| //! This crate is `no_std` compatible. To use it without `std`: |
| //! |
| //! ```toml |
| //! [dependencies] |
| //! downcast-rs = { version = "1.2.0", default-features = false } |
| //! ``` |
| //! |
| //! To make a trait downcastable, make it extend either `downcast::Downcast` or |
| //! `downcast::DowncastSync` and invoke `impl_downcast!` on it as in the examples |
| //! below. |
| //! |
| //! Since 1.1.0, the minimum supported Rust version is 1.33 to support `Rc` and `Arc` |
| //! in the receiver position. |
| //! |
| //! ``` |
| //! # #[macro_use] |
| //! # extern crate downcast_rs; |
| //! # use downcast_rs::{Downcast, DowncastSync}; |
| //! trait Trait: Downcast {} |
| //! impl_downcast!(Trait); |
| //! |
| //! // Also supports downcasting `Arc`-ed trait objects by extending `DowncastSync` |
| //! // and starting `impl_downcast!` with `sync`. |
| //! trait TraitSync: DowncastSync {} |
| //! impl_downcast!(sync TraitSync); |
| //! |
| //! // With type parameters. |
| //! trait TraitGeneric1<T>: Downcast {} |
| //! impl_downcast!(TraitGeneric1<T>); |
| //! |
| //! // With associated types. |
| //! trait TraitGeneric2: Downcast { type G; type H; } |
| //! impl_downcast!(TraitGeneric2 assoc G, H); |
| //! |
| //! // With constraints on types. |
| //! trait TraitGeneric3<T: Copy>: Downcast { |
| //! type H: Clone; |
| //! } |
| //! impl_downcast!(TraitGeneric3<T> assoc H where T: Copy, H: Clone); |
| //! |
| //! // With concrete types. |
| //! trait TraitConcrete1<T: Copy>: Downcast {} |
| //! impl_downcast!(concrete TraitConcrete1<u32>); |
| //! |
| //! trait TraitConcrete2<T: Copy>: Downcast { type H; } |
| //! impl_downcast!(concrete TraitConcrete2<u32> assoc H=f64); |
| //! # fn main() {} |
| //! ``` |
| //! |
| //! # Example without generics |
| //! |
| //! ``` |
| //! # use std::rc::Rc; |
| //! # use std::sync::Arc; |
| //! // Import macro via `macro_use` pre-1.30. |
| //! #[macro_use] |
| //! extern crate downcast_rs; |
| //! use downcast_rs::DowncastSync; |
| //! |
| //! // To create a trait with downcasting methods, extend `Downcast` or `DowncastSync` |
| //! // and run `impl_downcast!()` on the trait. |
| //! trait Base: DowncastSync {} |
| //! impl_downcast!(sync Base); // `sync` => also produce `Arc` downcasts. |
| //! |
| //! // Concrete types implementing Base. |
| //! #[derive(Debug)] |
| //! struct Foo(u32); |
| //! impl Base for Foo {} |
| //! #[derive(Debug)] |
| //! struct Bar(f64); |
| //! impl Base for Bar {} |
| //! |
| //! fn main() { |
| //! // Create a trait object. |
| //! let mut base: Box<Base> = Box::new(Foo(42)); |
| //! |
| //! // Try sequential downcasts. |
| //! if let Some(foo) = base.downcast_ref::<Foo>() { |
| //! assert_eq!(foo.0, 42); |
| //! } else if let Some(bar) = base.downcast_ref::<Bar>() { |
| //! assert_eq!(bar.0, 42.0); |
| //! } |
| //! |
| //! assert!(base.is::<Foo>()); |
| //! |
| //! // Fail to convert `Box<Base>` into `Box<Bar>`. |
| //! let res = base.downcast::<Bar>(); |
| //! assert!(res.is_err()); |
| //! let base = res.unwrap_err(); |
| //! // Convert `Box<Base>` into `Box<Foo>`. |
| //! assert_eq!(42, base.downcast::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0); |
| //! |
| //! // Also works with `Rc`. |
| //! let mut rc: Rc<Base> = Rc::new(Foo(42)); |
| //! assert_eq!(42, rc.downcast_rc::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0); |
| //! |
| //! // Since this trait is `Sync`, it also supports `Arc` downcasts. |
| //! let mut arc: Arc<Base> = Arc::new(Foo(42)); |
| //! assert_eq!(42, arc.downcast_arc::<Foo>().map_err(|_| "Shouldn't happen.").unwrap().0); |
| //! } |
| //! ``` |
| //! |
| //! # Example with a generic trait with associated types and constraints |
| //! |
| //! ``` |
| //! // Can call macro via namespace since rust 1.30. |
| //! extern crate downcast_rs; |
| //! use downcast_rs::Downcast; |
| //! |
| //! // To create a trait with downcasting methods, extend `Downcast` or `DowncastSync` |
| //! // and run `impl_downcast!()` on the trait. |
| //! trait Base<T: Clone>: Downcast { type H: Copy; } |
| //! downcast_rs::impl_downcast!(Base<T> assoc H where T: Clone, H: Copy); |
| //! // or: impl_downcast!(concrete Base<u32> assoc H=f32) |
| //! |
| //! // Concrete types implementing Base. |
| //! struct Foo(u32); |
| //! impl Base<u32> for Foo { type H = f32; } |
| //! struct Bar(f64); |
| //! impl Base<u32> for Bar { type H = f32; } |
| //! |
| //! fn main() { |
| //! // Create a trait object. |
| //! let mut base: Box<Base<u32, H=f32>> = Box::new(Bar(42.0)); |
| //! |
| //! // Try sequential downcasts. |
| //! if let Some(foo) = base.downcast_ref::<Foo>() { |
| //! assert_eq!(foo.0, 42); |
| //! } else if let Some(bar) = base.downcast_ref::<Bar>() { |
| //! assert_eq!(bar.0, 42.0); |
| //! } |
| //! |
| //! assert!(base.is::<Bar>()); |
| //! } |
| //! ``` |
| |
| </span><span class="comment">// for compatibility with no std and macros |
| </span><span class="attribute">#[doc(hidden)] |
| #[cfg(not(feature = <span class="string">"std"</span>))] |
| </span><span class="kw">pub extern crate </span>core <span class="kw">as </span>__std; |
| <span class="attribute">#[doc(hidden)] |
| #[cfg(feature = <span class="string">"std"</span>)] |
| </span><span class="kw">pub extern crate </span>std <span class="kw">as </span>__std; |
| <span class="attribute">#[doc(hidden)] |
| </span><span class="kw">pub extern crate </span>alloc <span class="kw">as </span>__alloc; |
| |
| <span class="kw">use </span>__std::any::Any; |
| <span class="kw">use </span>__alloc::{boxed::Box, rc::Rc, sync::Arc}; |
| |
| <span class="doccomment">/// Supports conversion to `Any`. Traits to be extended by `impl_downcast!` must extend `Downcast`. |
| </span><span class="kw">pub trait </span>Downcast: Any { |
| <span class="doccomment">/// Convert `Box<dyn Trait>` (where `Trait: Downcast`) to `Box<dyn Any>`. `Box<dyn Any>` can |
| /// then be further `downcast` into `Box<ConcreteType>` where `ConcreteType` implements `Trait`. |
| </span><span class="kw">fn </span>into_any(<span class="self">self</span>: Box<<span class="self">Self</span>>) -> Box<<span class="kw">dyn </span>Any>; |
| <span class="doccomment">/// Convert `Rc<Trait>` (where `Trait: Downcast`) to `Rc<Any>`. `Rc<Any>` can then be |
| /// further `downcast` into `Rc<ConcreteType>` where `ConcreteType` implements `Trait`. |
| </span><span class="kw">fn </span>into_any_rc(<span class="self">self</span>: Rc<<span class="self">Self</span>>) -> Rc<<span class="kw">dyn </span>Any>; |
| <span class="doccomment">/// Convert `&Trait` (where `Trait: Downcast`) to `&Any`. This is needed since Rust cannot |
| /// generate `&Any`'s vtable from `&Trait`'s. |
| </span><span class="kw">fn </span>as_any(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="kw">dyn </span>Any; |
| <span class="doccomment">/// Convert `&mut Trait` (where `Trait: Downcast`) to `&Any`. This is needed since Rust cannot |
| /// generate `&mut Any`'s vtable from `&mut Trait`'s. |
| </span><span class="kw">fn </span>as_any_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="kw">dyn </span>Any; |
| } |
| |
| <span class="kw">impl</span><T: Any> Downcast <span class="kw">for </span>T { |
| <span class="kw">fn </span>into_any(<span class="self">self</span>: Box<<span class="self">Self</span>>) -> Box<<span class="kw">dyn </span>Any> { <span class="self">self </span>} |
| <span class="kw">fn </span>into_any_rc(<span class="self">self</span>: Rc<<span class="self">Self</span>>) -> Rc<<span class="kw">dyn </span>Any> { <span class="self">self </span>} |
| <span class="kw">fn </span>as_any(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="kw">dyn </span>Any { <span class="self">self </span>} |
| <span class="kw">fn </span>as_any_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="kw">dyn </span>Any { <span class="self">self </span>} |
| } |
| |
| <span class="doccomment">/// Extends `Downcast` to support `Sync` traits that thus support `Arc` downcasting as well. |
| </span><span class="kw">pub trait </span>DowncastSync: Downcast + Send + Sync { |
| <span class="doccomment">/// Convert `Arc<Trait>` (where `Trait: Downcast`) to `Arc<Any>`. `Arc<Any>` can then be |
| /// further `downcast` into `Arc<ConcreteType>` where `ConcreteType` implements `Trait`. |
| </span><span class="kw">fn </span>into_any_arc(<span class="self">self</span>: Arc<<span class="self">Self</span>>) -> Arc<<span class="kw">dyn </span>Any + Send + Sync>; |
| } |
| |
| <span class="kw">impl</span><T: Any + Send + Sync> DowncastSync <span class="kw">for </span>T { |
| <span class="kw">fn </span>into_any_arc(<span class="self">self</span>: Arc<<span class="self">Self</span>>) -> Arc<<span class="kw">dyn </span>Any + Send + Sync> { <span class="self">self </span>} |
| } |
| |
| <span class="doccomment">/// Adds downcasting support to traits that extend `downcast::Downcast` by defining forwarding |
| /// methods to the corresponding implementations on `std::any::Any` in the standard library. |
| /// |
| /// See https://users.rust-lang.org/t/how-to-create-a-macro-to-impl-a-provided-type-parametrized-trait/5289 |
| /// for why this is implemented this way to support templatized traits. |
| </span><span class="attribute">#[macro_export(local_inner_macros)] |
| </span><span class="macro">macro_rules! </span>impl_downcast { |
| (@impl_full |
| <span class="macro-nonterminal">$trait_</span>:ident [$(<span class="macro-nonterminal">$param_types</span>:tt)<span class="kw-2">*</span>] |
| <span class="kw">for </span>[$(<span class="macro-nonterminal">$forall_types</span>:ident),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>:tt)<span class="kw-2">*</span>] |
| ) => { |
| <span class="macro">impl_downcast! </span>{ |
| @inject_where |
| [<span class="kw">impl</span><$(<span class="macro-nonterminal">$forall_types</span>),<span class="kw-2">*</span>> <span class="kw">dyn </span><span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$param_types</span>)<span class="kw-2">*</span>>] |
| types [$(<span class="macro-nonterminal">$forall_types</span>),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] |
| [{ |
| <span class="macro">impl_downcast! </span>{ @impl_body <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$param_types</span>)<span class="kw-2">*</span>] } |
| }] |
| } |
| }; |
| |
| (@impl_full_sync |
| <span class="macro-nonterminal">$trait_</span>:ident [$(<span class="macro-nonterminal">$param_types</span>:tt)<span class="kw-2">*</span>] |
| <span class="kw">for </span>[$(<span class="macro-nonterminal">$forall_types</span>:ident),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>:tt)<span class="kw-2">*</span>] |
| ) => { |
| <span class="macro">impl_downcast! </span>{ |
| @inject_where |
| [<span class="kw">impl</span><$(<span class="macro-nonterminal">$forall_types</span>),<span class="kw-2">*</span>> <span class="kw">dyn </span><span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$param_types</span>)<span class="kw-2">*</span>>] |
| types [$(<span class="macro-nonterminal">$forall_types</span>),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] |
| [{ |
| <span class="macro">impl_downcast! </span>{ @impl_body <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$param_types</span>)<span class="kw-2">*</span>] } |
| <span class="macro">impl_downcast! </span>{ @impl_body_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$param_types</span>)<span class="kw-2">*</span>] } |
| }] |
| } |
| }; |
| |
| (@impl_body <span class="macro-nonterminal">$trait_</span>:ident [$(<span class="macro-nonterminal">$types</span>:tt)<span class="kw-2">*</span>]) => { |
| <span class="doccomment">/// Returns true if the trait object wraps an object of type `__T`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>is<__T: <span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$types</span>)<span class="kw-2">*</span>>>(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="macro-nonterminal">$crate::Downcast::as_any</span>(<span class="self">self</span>).is::<__T>() |
| } |
| <span class="doccomment">/// Returns a boxed object from a boxed trait object if the underlying object is of type |
| /// `__T`. Returns the original boxed trait if it isn't. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>downcast<__T: <span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$types</span>)<span class="kw-2">*</span>>>( |
| <span class="self">self</span>: <span class="macro-nonterminal">$crate::__alloc::boxed::Box</span><<span class="self">Self</span>> |
| ) -> <span class="macro-nonterminal">$crate::__std::result::Result</span><<span class="macro-nonterminal">$crate::__alloc::boxed::Box</span><__T>, <span class="macro-nonterminal">$crate::__alloc::boxed::Box</span><<span class="self">Self</span>>> { |
| <span class="kw">if </span><span class="self">self</span>.is::<__T>() { |
| <span class="prelude-val">Ok</span>(<span class="macro-nonterminal">$crate::Downcast::into_any</span>(<span class="self">self</span>).downcast::<__T>().unwrap()) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(<span class="self">self</span>) |
| } |
| } |
| <span class="doccomment">/// Returns an `Rc`-ed object from an `Rc`-ed trait object if the underlying object is of |
| /// type `__T`. Returns the original `Rc`-ed trait if it isn't. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>downcast_rc<__T: <span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$types</span>)<span class="kw-2">*</span>>>( |
| <span class="self">self</span>: <span class="macro-nonterminal">$crate::__alloc::rc::Rc</span><<span class="self">Self</span>> |
| ) -> <span class="macro-nonterminal">$crate::__std::result::Result</span><<span class="macro-nonterminal">$crate::__alloc::rc::Rc</span><__T>, <span class="macro-nonterminal">$crate::__alloc::rc::Rc</span><<span class="self">Self</span>>> { |
| <span class="kw">if </span><span class="self">self</span>.is::<__T>() { |
| <span class="prelude-val">Ok</span>(<span class="macro-nonterminal">$crate::Downcast::into_any_rc</span>(<span class="self">self</span>).downcast::<__T>().unwrap()) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(<span class="self">self</span>) |
| } |
| } |
| <span class="doccomment">/// Returns a reference to the object within the trait object if it is of type `__T`, or |
| /// `None` if it isn't. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>downcast_ref<__T: <span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$types</span>)<span class="kw-2">*</span>>>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="macro-nonterminal">$crate::__std::option::Option</span><<span class="kw-2">&</span>__T> { |
| <span class="macro-nonterminal">$crate::Downcast::as_any</span>(<span class="self">self</span>).downcast_ref::<__T>() |
| } |
| <span class="doccomment">/// Returns a mutable reference to the object within the trait object if it is of type |
| /// `__T`, or `None` if it isn't. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>downcast_mut<__T: <span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$types</span>)<span class="kw-2">*</span>>>(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="macro-nonterminal">$crate::__std::option::Option</span><<span class="kw-2">&mut </span>__T> { |
| <span class="macro-nonterminal">$crate::Downcast::as_any_mut</span>(<span class="self">self</span>).downcast_mut::<__T>() |
| } |
| }; |
| |
| (@impl_body_sync <span class="macro-nonterminal">$trait_</span>:ident [$(<span class="macro-nonterminal">$types</span>:tt)<span class="kw-2">*</span>]) => { |
| <span class="doccomment">/// Returns an `Arc`-ed object from an `Arc`-ed trait object if the underlying object is of |
| /// type `__T`. Returns the original `Arc`-ed trait if it isn't. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>downcast_arc<__T: <span class="macro-nonterminal">$trait_</span><$(<span class="macro-nonterminal">$types</span>)<span class="kw-2">*</span>>>( |
| <span class="self">self</span>: <span class="macro-nonterminal">$crate::__alloc::sync::Arc</span><<span class="self">Self</span>>, |
| ) -> <span class="macro-nonterminal">$crate::__std::result::Result</span><<span class="macro-nonterminal">$crate::__alloc::sync::Arc</span><__T>, <span class="macro-nonterminal">$crate::__alloc::sync::Arc</span><<span class="self">Self</span>>> |
| <span class="kw">where </span>__T: <span class="macro-nonterminal">$crate::__std::any::Any </span>+ <span class="macro-nonterminal">$crate::__std::marker::Send </span>+ <span class="macro-nonterminal">$crate::__std::marker::Sync |
| </span>{ |
| <span class="kw">if </span><span class="self">self</span>.is::<__T>() { |
| <span class="prelude-val">Ok</span>(<span class="macro-nonterminal">$crate::DowncastSync::into_any_arc</span>(<span class="self">self</span>).downcast::<__T>().unwrap()) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(<span class="self">self</span>) |
| } |
| } |
| }; |
| |
| (@inject_where [$(<span class="macro-nonterminal">$before</span>:tt)<span class="kw-2">*</span>] types [] <span class="kw">where </span>[] [$(<span class="macro-nonterminal">$after</span>:tt)<span class="kw-2">*</span>]) => { |
| <span class="macro">impl_downcast! </span>{ @as_item $(<span class="macro-nonterminal">$before</span>)* $(<span class="macro-nonterminal">$after</span>)* } |
| }; |
| |
| (@inject_where [$(<span class="macro-nonterminal">$before</span>:tt)<span class="kw-2">*</span>] types [$(<span class="macro-nonterminal">$types</span>:ident),<span class="kw-2">*</span>] <span class="kw">where </span>[] [$(<span class="macro-nonterminal">$after</span>:tt)<span class="kw-2">*</span>]) => { |
| <span class="macro">impl_downcast! </span>{ |
| @as_item |
| $(<span class="macro-nonterminal">$before</span>)* |
| <span class="kw">where </span>$( <span class="macro-nonterminal">$types</span>: <span class="macro-nonterminal">$crate::__std::any::Any </span>+ <span class="lifetime">'static </span>),* |
| $(<span class="macro-nonterminal">$after</span>)* |
| } |
| }; |
| (@inject_where [$(<span class="macro-nonterminal">$before</span>:tt)<span class="kw-2">*</span>] types [$(<span class="macro-nonterminal">$types</span>:ident),<span class="kw-2">*</span>] <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>:tt)+] [$(<span class="macro-nonterminal">$after</span>:tt)<span class="kw-2">*</span>]) => { |
| <span class="macro">impl_downcast! </span>{ |
| @as_item |
| $(<span class="macro-nonterminal">$before</span>)* |
| <span class="kw">where |
| </span>$( <span class="macro-nonterminal">$types</span>: <span class="macro-nonterminal">$crate::__std::any::Any </span>+ <span class="lifetime">'static</span>, )* |
| $(<span class="macro-nonterminal">$preds</span>)* |
| $(<span class="macro-nonterminal">$after</span>)* |
| } |
| }; |
| |
| (@as_item <span class="macro-nonterminal">$i</span>:item) => { <span class="macro-nonterminal">$i </span>}; |
| |
| <span class="comment">// No type parameters. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident ) => { <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[] <span class="kw">for </span>[] <span class="kw">where </span>[] } }; |
| (<span class="macro-nonterminal">$trait_</span>:ident <>) => { <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[] <span class="kw">for </span>[] <span class="kw">where </span>[] } }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident ) => { <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[] <span class="kw">for </span>[] <span class="kw">where </span>[] } }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident <>) => { <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[] <span class="kw">for </span>[] <span class="kw">where </span>[] } }; |
| <span class="comment">// Type parameters. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* >) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[] } |
| }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* >) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[] } |
| }; |
| <span class="comment">// Type parameters and where clauses. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > <span class="kw">where </span>$(<span class="macro-nonterminal">$preds</span>:tt)+) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] } |
| }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > <span class="kw">where </span>$(<span class="macro-nonterminal">$preds</span>:tt)+) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] } |
| }; |
| <span class="comment">// Associated types. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident assoc $(<span class="macro-nonterminal">$atypes</span>:ident),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[] } |
| }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident assoc $(<span class="macro-nonterminal">$atypes</span>:ident),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[] } |
| }; |
| <span class="comment">// Associated types and where clauses. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident assoc $(<span class="macro-nonterminal">$atypes</span>:ident),* <span class="kw">where </span>$(<span class="macro-nonterminal">$preds</span>:tt)+) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] } |
| }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident assoc $(<span class="macro-nonterminal">$atypes</span>:ident),* <span class="kw">where </span>$(<span class="macro-nonterminal">$preds</span>:tt)+) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[$(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] } |
| }; |
| <span class="comment">// Type parameters and associated types. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > assoc $(<span class="macro-nonterminal">$atypes</span>:ident),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ |
| @impl_full |
| <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[] |
| } |
| }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > assoc $(<span class="macro-nonterminal">$atypes</span>:ident),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ |
| @impl_full_sync |
| <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[] |
| } |
| }; |
| <span class="comment">// Type parameters, associated types, and where clauses. |
| </span>(<span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > assoc $(<span class="macro-nonterminal">$atypes</span>:ident),* <span class="kw">where </span>$(<span class="macro-nonterminal">$preds</span>:tt)+) => { |
| <span class="macro">impl_downcast! </span>{ |
| @impl_full |
| <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] |
| } |
| }; |
| (sync <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > assoc $(<span class="macro-nonterminal">$atypes</span>:ident),* <span class="kw">where </span>$(<span class="macro-nonterminal">$preds</span>:tt)+) => { |
| <span class="macro">impl_downcast! </span>{ |
| @impl_full_sync |
| <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">for </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes</span>),<span class="kw-2">*</span>] |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$preds</span>)<span class="kw-2">*</span>] |
| } |
| }; |
| <span class="comment">// Concretely-parametrized types. |
| </span>(concrete <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* >) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[] <span class="kw">where </span>[] } |
| }; |
| (sync concrete <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* >) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[] <span class="kw">where </span>[] } |
| }; |
| <span class="comment">// Concretely-associated types types. |
| </span>(concrete <span class="macro-nonterminal">$trait_</span>:ident assoc $(<span class="macro-nonterminal">$atypes</span>:ident = <span class="macro-nonterminal">$aty</span>:ty),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$aty</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[] <span class="kw">where </span>[] } |
| }; |
| (sync concrete <span class="macro-nonterminal">$trait_</span>:ident assoc $(<span class="macro-nonterminal">$atypes</span>:ident = <span class="macro-nonterminal">$aty</span>:ty),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$aty</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[] <span class="kw">where </span>[] } |
| }; |
| <span class="comment">// Concretely-parametrized types with concrete associated types. |
| </span>(concrete <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > assoc $(<span class="macro-nonterminal">$atypes</span>:ident = <span class="macro-nonterminal">$aty</span>:ty),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$aty</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[] <span class="kw">where </span>[] } |
| }; |
| (sync concrete <span class="macro-nonterminal">$trait_</span>:ident < $(<span class="macro-nonterminal">$types</span>:ident),* > assoc $(<span class="macro-nonterminal">$atypes</span>:ident = <span class="macro-nonterminal">$aty</span>:ty),<span class="kw-2">*</span>) => { |
| <span class="macro">impl_downcast! </span>{ @impl_full_sync <span class="macro-nonterminal">$trait_ </span>[$(<span class="macro-nonterminal">$types</span>),<span class="kw-2">*</span>, $(<span class="macro-nonterminal">$atypes </span>= <span class="macro-nonterminal">$aty</span>),<span class="kw-2">*</span>] <span class="kw">for </span>[] <span class="kw">where </span>[] } |
| }; |
| } |
| |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>test { |
| <span class="macro">macro_rules! </span>test_mod { |
| ( |
| <span class="macro-nonterminal">$test_mod_name</span>:ident, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait</span>:path { $(<span class="macro-nonterminal">$base_impl</span>:tt)* }, |
| non_sync: { $(<span class="macro-nonterminal">$non_sync_def</span>:tt)+ }, |
| sync: { $(<span class="macro-nonterminal">$sync_def</span>:tt)+ } |
| ) => { |
| <span class="macro">test_mod! </span>{ |
| <span class="macro-nonterminal">$test_mod_name</span>, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait </span>{ $(<span class="macro-nonterminal">$base_impl</span>:tt)* }, |
| <span class="kw">type dyn </span><span class="macro-nonterminal">$base_trait</span>, |
| non_sync: { $(<span class="macro-nonterminal">$non_sync_def</span>)* }, |
| sync: { $(<span class="macro-nonterminal">$sync_def</span>)* } |
| } |
| }; |
| |
| ( |
| <span class="macro-nonterminal">$test_mod_name</span>:ident, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait</span>:path { $(<span class="macro-nonterminal">$base_impl</span>:tt)* }, |
| <span class="kw">type </span><span class="macro-nonterminal">$base_type</span>:ty, |
| non_sync: { $(<span class="macro-nonterminal">$non_sync_def</span>:tt)+ }, |
| sync: { $(<span class="macro-nonterminal">$sync_def</span>:tt)+ } |
| ) => { |
| <span class="kw">mod </span><span class="macro-nonterminal">$test_mod_name </span>{ |
| <span class="macro">test_mod!</span>( |
| @test |
| <span class="macro-nonterminal">$test_mod_name</span>, |
| test_name: test_non_sync, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait </span>{ $(<span class="macro-nonterminal">$base_impl</span>)* }, |
| <span class="kw">type </span><span class="macro-nonterminal">$base_type</span>, |
| { $(<span class="macro-nonterminal">$non_sync_def</span>)+ }, |
| []); |
| |
| <span class="macro">test_mod!</span>( |
| @test |
| <span class="macro-nonterminal">$test_mod_name</span>, |
| test_name: test_sync, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait </span>{ $(<span class="macro-nonterminal">$base_impl</span>)* }, |
| <span class="kw">type </span><span class="macro-nonterminal">$base_type</span>, |
| { $(<span class="macro-nonterminal">$sync_def</span>)+ }, |
| [{ |
| <span class="comment">// Fail to convert Arc<Base> into Arc<Bar>. |
| </span><span class="kw">let </span>arc: <span class="macro-nonterminal">$crate::__alloc::sync::Arc</span><<span class="macro-nonterminal">$base_type</span>> = <span class="macro-nonterminal">$crate::__alloc::sync::Arc::new</span>(Foo(<span class="number">42</span>)); |
| <span class="kw">let </span>res = arc.downcast_arc::<Bar>(); |
| <span class="macro">assert!</span>(res.is_err()); |
| <span class="kw">let </span>arc = res.unwrap_err(); |
| <span class="comment">// Convert Arc<Base> into Arc<Foo>. |
| </span><span class="macro">assert_eq!</span>( |
| <span class="number">42</span>, arc.downcast_arc::<Foo>().map_err(|<span class="kw">_</span>| <span class="string">"Shouldn't happen."</span>).unwrap().<span class="number">0</span>); |
| }]); |
| } |
| }; |
| |
| ( |
| @test |
| <span class="macro-nonterminal">$test_mod_name</span>:ident, |
| test_name: <span class="macro-nonterminal">$test_name</span>:ident, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait</span>:path { $(<span class="macro-nonterminal">$base_impl</span>:tt)* }, |
| <span class="kw">type </span><span class="macro-nonterminal">$base_type</span>:ty, |
| { $(<span class="macro-nonterminal">$def</span>:tt)+ }, |
| [ $(<span class="macro-nonterminal">$more_tests</span>:block)* ] |
| ) => { |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span><span class="macro-nonterminal">$test_name</span>() { |
| <span class="attribute">#[allow(unused_imports)] |
| </span><span class="kw">use </span><span class="kw">super</span>::<span class="kw">super</span>::{Downcast, DowncastSync}; |
| |
| <span class="comment">// Should work even if standard objects (especially those in the prelude) are |
| // aliased to something else. |
| </span><span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span>Any; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span>Arc; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span>Box; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span><span class="prelude-ty">Option</span>; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span><span class="prelude-ty">Result</span>; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span>Rc; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span>Send; |
| <span class="attribute">#[allow(dead_code)] </span><span class="kw">struct </span>Sync; |
| |
| <span class="comment">// A trait that can be downcast. |
| </span>$(<span class="macro-nonterminal">$def</span>)* |
| |
| <span class="comment">// Concrete type implementing Base. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">struct </span>Foo(u32); |
| <span class="kw">impl </span><span class="macro-nonterminal">$base_trait </span><span class="kw">for </span>Foo { $(<span class="macro-nonterminal">$base_impl</span>)* } |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">struct </span>Bar(f64); |
| <span class="kw">impl </span><span class="macro-nonterminal">$base_trait </span><span class="kw">for </span>Bar { $(<span class="macro-nonterminal">$base_impl</span>)* } |
| |
| <span class="comment">// Functions that can work on references to Base trait objects. |
| </span><span class="kw">fn </span>get_val(base: <span class="kw-2">&</span><span class="macro-nonterminal">$crate::__alloc::boxed::Box</span><<span class="macro-nonterminal">$base_type</span>>) -> u32 { |
| <span class="kw">match </span>base.downcast_ref::<Foo>() { |
| <span class="prelude-val">Some</span>(val) => val.<span class="number">0</span>, |
| <span class="prelude-val">None </span>=> <span class="number">0 |
| </span>} |
| } |
| <span class="kw">fn </span>set_val(base: <span class="kw-2">&mut </span><span class="macro-nonterminal">$crate::__alloc::boxed::Box</span><<span class="macro-nonterminal">$base_type</span>>, val: u32) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(foo) = base.downcast_mut::<Foo>() { |
| foo.<span class="number">0 </span>= val; |
| } |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>base: <span class="macro-nonterminal">$crate::__alloc::boxed::Box</span><<span class="macro-nonterminal">$base_type</span>> = <span class="macro-nonterminal">$crate::__alloc::boxed::Box::new</span>(Foo(<span class="number">42</span>)); |
| <span class="macro">assert_eq!</span>(get_val(<span class="kw-2">&</span>base), <span class="number">42</span>); |
| |
| <span class="comment">// Try sequential downcasts. |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(foo) = base.downcast_ref::<Foo>() { |
| <span class="macro">assert_eq!</span>(foo.<span class="number">0</span>, <span class="number">42</span>); |
| } <span class="kw">else if let </span><span class="prelude-val">Some</span>(bar) = base.downcast_ref::<Bar>() { |
| <span class="macro">assert_eq!</span>(bar.<span class="number">0</span>, <span class="number">42.0</span>); |
| } |
| |
| set_val(<span class="kw-2">&mut </span>base, <span class="number">6</span><span class="kw-2">*</span><span class="number">9</span>); |
| <span class="macro">assert_eq!</span>(get_val(<span class="kw-2">&</span>base), <span class="number">6</span><span class="kw-2">*</span><span class="number">9</span>); |
| |
| <span class="macro">assert!</span>(base.is::<Foo>()); |
| |
| <span class="comment">// Fail to convert Box<Base> into Box<Bar>. |
| </span><span class="kw">let </span>res = base.downcast::<Bar>(); |
| <span class="macro">assert!</span>(res.is_err()); |
| <span class="kw">let </span>base = res.unwrap_err(); |
| <span class="comment">// Convert Box<Base> into Box<Foo>. |
| </span><span class="macro">assert_eq!</span>( |
| <span class="number">6</span><span class="kw-2">*</span><span class="number">9</span>, base.downcast::<Foo>().map_err(|<span class="kw">_</span>| <span class="string">"Shouldn't happen."</span>).unwrap().<span class="number">0</span>); |
| |
| <span class="comment">// Fail to convert Rc<Base> into Rc<Bar>. |
| </span><span class="kw">let </span>rc: <span class="macro-nonterminal">$crate::__alloc::rc::Rc</span><<span class="macro-nonterminal">$base_type</span>> = <span class="macro-nonterminal">$crate::__alloc::rc::Rc::new</span>(Foo(<span class="number">42</span>)); |
| <span class="kw">let </span>res = rc.downcast_rc::<Bar>(); |
| <span class="macro">assert!</span>(res.is_err()); |
| <span class="kw">let </span>rc = res.unwrap_err(); |
| <span class="comment">// Convert Rc<Base> into Rc<Foo>. |
| </span><span class="macro">assert_eq!</span>( |
| <span class="number">42</span>, rc.downcast_rc::<Foo>().map_err(|<span class="kw">_</span>| <span class="string">"Shouldn't happen."</span>).unwrap().<span class="number">0</span>); |
| |
| $(<span class="macro-nonterminal">$more_tests</span>)* |
| } |
| }; |
| ( |
| <span class="macro-nonterminal">$test_mod_name</span>:ident, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait</span>:path { $(<span class="macro-nonterminal">$base_impl</span>:tt)* }, |
| non_sync: { $(<span class="macro-nonterminal">$non_sync_def</span>:tt)+ }, |
| sync: { $(<span class="macro-nonterminal">$sync_def</span>:tt)+ } |
| ) => { |
| <span class="macro">test_mod! </span>{ |
| <span class="macro-nonterminal">$test_mod_name</span>, |
| <span class="kw">trait </span><span class="macro-nonterminal">$base_trait </span>{ $(<span class="macro-nonterminal">$base_impl</span>:tt)* }, |
| <span class="kw">type </span><span class="macro-nonterminal">$base_trait</span>, |
| non_sync: { $(<span class="macro-nonterminal">$non_sync_def</span>)* }, |
| sync: { $(<span class="macro-nonterminal">$sync_def</span>)* } |
| } |
| }; |
| |
| } |
| |
| <span class="macro">test_mod!</span>(non_generic, <span class="kw">trait </span>Base {}, |
| non_sync: { |
| <span class="kw">trait </span>Base: Downcast {} |
| <span class="macro">impl_downcast!</span>(Base); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base: DowncastSync {} |
| <span class="macro">impl_downcast!</span>(sync Base); |
| }); |
| |
| <span class="macro">test_mod!</span>(generic, <span class="kw">trait </span>Base<u32> {}, |
| non_sync: { |
| <span class="kw">trait </span>Base<T>: Downcast {} |
| <span class="macro">impl_downcast!</span>(Base<T>); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base<T>: DowncastSync {} |
| <span class="macro">impl_downcast!</span>(sync Base<T>); |
| }); |
| |
| <span class="macro">test_mod!</span>(constrained_generic, <span class="kw">trait </span>Base<u32> {}, |
| non_sync: { |
| <span class="kw">trait </span>Base<T: Copy>: Downcast {} |
| <span class="macro">impl_downcast!</span>(Base<T> <span class="kw">where </span>T: Copy); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base<T: Copy>: DowncastSync {} |
| <span class="macro">impl_downcast!</span>(sync Base<T> <span class="kw">where </span>T: Copy); |
| }); |
| |
| <span class="macro">test_mod!</span>(associated, |
| <span class="kw">trait </span>Base { <span class="kw">type </span>H = f32; }, |
| <span class="kw">type dyn </span>Base<H=f32>, |
| non_sync: { |
| <span class="kw">trait </span>Base: Downcast { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(Base assoc H); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base: DowncastSync { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(sync Base assoc H); |
| }); |
| |
| <span class="macro">test_mod!</span>(constrained_associated, |
| <span class="kw">trait </span>Base { <span class="kw">type </span>H = f32; }, |
| <span class="kw">type dyn </span>Base<H=f32>, |
| non_sync: { |
| <span class="kw">trait </span>Base: Downcast { <span class="kw">type </span>H: Copy; } |
| <span class="macro">impl_downcast!</span>(Base assoc H <span class="kw">where </span>H: Copy); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base: DowncastSync { <span class="kw">type </span>H: Copy; } |
| <span class="macro">impl_downcast!</span>(sync Base assoc H <span class="kw">where </span>H: Copy); |
| }); |
| |
| <span class="macro">test_mod!</span>(param_and_associated, |
| <span class="kw">trait </span>Base<u32> { <span class="kw">type </span>H = f32; }, |
| <span class="kw">type dyn </span>Base<u32, H=f32>, |
| non_sync: { |
| <span class="kw">trait </span>Base<T>: Downcast { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(Base<T> assoc H); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base<T>: DowncastSync { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(sync Base<T> assoc H); |
| }); |
| |
| <span class="macro">test_mod!</span>(constrained_param_and_associated, |
| <span class="kw">trait </span>Base<u32> { <span class="kw">type </span>H = f32; }, |
| <span class="kw">type dyn </span>Base<u32, H=f32>, |
| non_sync: { |
| <span class="kw">trait </span>Base<T: Clone>: Downcast { <span class="kw">type </span>H: Copy; } |
| <span class="macro">impl_downcast!</span>(Base<T> assoc H <span class="kw">where </span>T: Clone, H: Copy); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base<T: Clone>: DowncastSync { <span class="kw">type </span>H: Copy; } |
| <span class="macro">impl_downcast!</span>(sync Base<T> assoc H <span class="kw">where </span>T: Clone, H: Copy); |
| }); |
| |
| <span class="macro">test_mod!</span>(concrete_parametrized, <span class="kw">trait </span>Base<u32> {}, |
| non_sync: { |
| <span class="kw">trait </span>Base<T>: Downcast {} |
| <span class="macro">impl_downcast!</span>(concrete Base<u32>); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base<T>: DowncastSync {} |
| <span class="macro">impl_downcast!</span>(sync concrete Base<u32>); |
| }); |
| |
| <span class="macro">test_mod!</span>(concrete_associated, |
| <span class="kw">trait </span>Base { <span class="kw">type </span>H = u32; }, |
| <span class="kw">type dyn </span>Base<H=u32>, |
| non_sync: { |
| <span class="kw">trait </span>Base: Downcast { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(concrete Base assoc H=u32); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base: DowncastSync { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(sync concrete Base assoc H=u32); |
| }); |
| |
| <span class="macro">test_mod!</span>(concrete_parametrized_associated, |
| <span class="kw">trait </span>Base<u32> { <span class="kw">type </span>H = f32; }, |
| <span class="kw">type dyn </span>Base<u32, H=f32>, |
| non_sync: { |
| <span class="kw">trait </span>Base<T>: Downcast { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(concrete Base<u32> assoc H=f32); |
| }, |
| sync: { |
| <span class="kw">trait </span>Base<T>: DowncastSync { <span class="kw">type </span>H; } |
| <span class="macro">impl_downcast!</span>(sync concrete Base<u32> assoc H=f32); |
| }); |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="downcast_rs" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
