1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90
// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. //! The `Clone` trait for types that cannot be 'implicitly copied' //! //! In Rust, some simple types are "implicitly copyable" and when you //! assign them or pass them as arguments, the receiver will get a copy, //! leaving the original value in place. These types do not require //! allocation to copy and do not have finalizers (i.e. they do not //! contain owned boxes or implement `Drop`), so the compiler considers //! them cheap and safe to copy. For other types copies must be made //! explicitly, by convention implementing the `Clone` trait and calling //! the `clone` method. #![stable(feature = "rust1", since = "1.0.0")] use marker::Sized; /// A common trait for cloning an object. /// /// This trait can be used with `#[derive]`. #[stable(feature = "rust1", since = "1.0.0")] pub trait Clone : Sized { /// Returns a copy of the value. /// /// # Examples /// /// ``` /// let hello = "Hello"; // &str implements Clone /// /// assert_eq!("Hello", hello.clone()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] fn clone(&self) -> Self; /// Performs copy-assignment from `source`. /// /// `a.clone_from(&b)` is equivalent to `a = b.clone()` in functionality, /// but can be overridden to reuse the resources of `a` to avoid unnecessary /// allocations. #[inline(always)] #[stable(feature = "rust1", since = "1.0.0")] fn clone_from(&mut self, source: &Self) { *self = source.clone() } } #[stable(feature = "rust1", since = "1.0.0")] impl<'a, T: ?Sized> Clone for &'a T { /// Returns a shallow copy of the reference. #[inline] fn clone(&self) -> &'a T { *self } } macro_rules! clone_impl { ($t:ty) => { #[stable(feature = "rust1", since = "1.0.0")] impl Clone for $t { /// Returns a deep copy of the value. #[inline] fn clone(&self) -> $t { *self } } } } clone_impl! { isize } clone_impl! { i8 } clone_impl! { i16 } clone_impl! { i32 } clone_impl! { i64 } clone_impl! { usize } clone_impl! { u8 } clone_impl! { u16 } clone_impl! { u32 } clone_impl! { u64 } clone_impl! { f32 } clone_impl! { f64 } clone_impl! { () } clone_impl! { bool } clone_impl! { char }