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Make DowncastSync Optional #22

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merged 1 commit into from
Dec 19, 2024
Merged

Make DowncastSync Optional #22

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3 changes: 2 additions & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -12,5 +12,6 @@ keywords = ["downcast", "any", "trait", "associated", "no_std"]
license = "MIT/Apache-2.0"

[features]
default = ["std"]
default = ["std", "sync"]
std = []
sync = []
15 changes: 11 additions & 4 deletions src/lib.rs
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Expand Up @@ -35,7 +35,8 @@
//!
//! Since 1.2.0, the minimum supported Rust version is 1.36 due to needing stable access to alloc.
//!
//! ```
#![cfg_attr(feature = "sync", doc = "```")]
#![cfg_attr(not(feature = "sync"), doc = "```ignore")]
//! # #[macro_use]
//! # extern crate downcast_rs;
//! # use downcast_rs::{Downcast, DowncastSync};
Expand Down Expand Up @@ -72,7 +73,8 @@
//!
//! # Example without generics
//!
//! ```
#![cfg_attr(feature = "sync", doc = "```")]
#![cfg_attr(not(feature = "sync"), doc = "```ignore")]
//! # use std::rc::Rc;
//! # use std::sync::Arc;
//! // Import macro via `macro_use` pre-1.30.
Expand Down Expand Up @@ -168,7 +170,10 @@ pub extern crate std as __std;
pub extern crate alloc as __alloc;

use __std::any::Any;
use __alloc::{boxed::Box, rc::Rc, sync::Arc};
use __alloc::{boxed::Box, rc::Rc};

#[cfg(feature = "sync")]
use __alloc::sync::Arc;

/// Supports conversion to `Any`. Traits to be extended by `impl_downcast!` must extend `Downcast`.
pub trait Downcast: Any {
Expand All @@ -193,13 +198,15 @@ impl<T: Any> Downcast for T {
fn as_any_mut(&mut self) -> &mut dyn Any { self }
}

#[cfg(feature = "sync")]
/// Extends `Downcast` to support `Sync` traits that thus support `Arc` downcasting as well.
pub trait DowncastSync: Downcast + Send + Sync {
/// Convert `Arc<Trait>` (where `Trait: Downcast`) to `Arc<Any>`. `Arc<Any>` can then be
/// further `downcast` into `Arc<ConcreteType>` where `ConcreteType` implements `Trait`.
fn into_any_arc(self: Arc<Self>) -> Arc<dyn Any + Send + Sync>;
}

#[cfg(feature = "sync")]
impl<T: Any + Send + Sync> DowncastSync for T {
fn into_any_arc(self: Arc<Self>) -> Arc<dyn Any + Send + Sync> { self }
}
Expand Down Expand Up @@ -420,7 +427,7 @@ macro_rules! impl_downcast {
}


#[cfg(test)]
#[cfg(all(test, feature = "sync"))]
mod test {
macro_rules! test_mod {
(
Expand Down
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