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//! [![github]](https://github.com/dtolnay/dyn-clone) [![crates-io]](https://crates.io/crates/dyn-clone) [![docs-rs]](https://docs.rs/dyn-clone) //! //! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github //! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust //! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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 //! //! <br> //! //! This crate provides a [`DynClone`] trait that can be used in trait objects, //! and a [`clone_box`] function that can clone any sized or dynamically sized //! implementation of `DynClone`. Types that implement the standard library's //! [`std::clone::Clone`] trait are automatically usable by a `DynClone` trait //! object. //! //! [`DynClone`]: trait.DynClone.html //! [`clone_box`]: fn.clone_box.html //! [`std::clone::Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html //! //! # Example //! //! ``` //! use dyn_clone::DynClone; //! //! trait MyTrait: DynClone { //! fn recite(&self); //! } //! //! impl MyTrait for String { //! fn recite(&self) { //! println!("{} ♫", self); //! } //! } //! //! fn main() { //! let line = "The slithy structs did gyre and gimble the namespace"; //! //! // Build a trait object holding a String. //! // This requires String to implement MyTrait and std::clone::Clone. //! let x: Box<dyn MyTrait> = Box::new(String::from(line)); //! //! x.recite(); //! //! // The type of x2 is a Box<dyn MyTrait> cloned from x. //! let x2 = dyn_clone::clone_box(&*x); //! //! x2.recite(); //! } //! ``` //! //! This crate includes a macro for concisely implementing `impl //! std::clone::Clone for Box<dyn MyTrait>` in terms of `dyn_clone::clone_box`. //! //! ``` //! # use dyn_clone::DynClone; //! # //! // As before. //! trait MyTrait: DynClone { //! /* ... */ //! } //! //! dyn_clone::clone_trait_object!(MyTrait); //! //! // Now data structures containing Box<dyn MyTrait> can derive Clone: //! #[derive(Clone)] //! struct Container { //! trait_object: Box<dyn MyTrait>, //! } //! ``` #![doc(html_root_url = "https://docs.rs/dyn_clone/1.0.2")] #![no_std] extern crate alloc; #[macro_use] mod macros; #[doc(hidden)] pub mod private { pub use alloc::boxed::Box; pub use core::clone::Clone; } /// This trait is implemented by any type that implements [`std::clone::Clone`]. /// /// [`std::clone::Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html pub trait DynClone { // Not public API #[doc(hidden)] unsafe fn clone_box(&self) -> *mut (); } use alloc::boxed::Box; pub fn clone<T>(t: &T) -> T where T: DynClone, { unsafe { *Box::from_raw(<T as DynClone>::clone_box(t) as *mut T) } } pub fn clone_box<T>(t: &T) -> Box<T> where T: ?Sized + DynClone, { let mut fat_ptr = t as *const T; unsafe { let data_ptr = &mut fat_ptr as *mut *const T as *mut *mut (); assert_eq!(*data_ptr as *const (), t as *const T as *const ()); *data_ptr = <T as DynClone>::clone_box(t); } unsafe { Box::from_raw(fat_ptr as *mut T) } } impl<T> DynClone for T where T: core::clone::Clone, { unsafe fn clone_box(&self) -> *mut () { Box::into_raw(Box::new(self.clone())) as *mut () } }