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Diffstat (limited to 'src/liballoc/borrow.rs')
| -rw-r--r-- | src/liballoc/borrow.rs | 476 |
1 files changed, 0 insertions, 476 deletions
diff --git a/src/liballoc/borrow.rs b/src/liballoc/borrow.rs deleted file mode 100644 index 51c233a21f1..00000000000 --- a/src/liballoc/borrow.rs +++ /dev/null @@ -1,476 +0,0 @@ -//! A module for working with borrowed data. - -#![stable(feature = "rust1", since = "1.0.0")] - -use core::cmp::Ordering; -use core::hash::{Hash, Hasher}; -use core::ops::{Add, AddAssign, Deref}; - -#[stable(feature = "rust1", since = "1.0.0")] -pub use core::borrow::{Borrow, BorrowMut}; - -use crate::fmt; -use crate::string::String; - -use Cow::*; - -#[stable(feature = "rust1", since = "1.0.0")] -impl<'a, B: ?Sized> Borrow<B> for Cow<'a, B> -where - B: ToOwned, - <B as ToOwned>::Owned: 'a, -{ - fn borrow(&self) -> &B { - &**self - } -} - -/// A generalization of `Clone` to borrowed data. -/// -/// Some types make it possible to go from borrowed to owned, usually by -/// implementing the `Clone` trait. But `Clone` works only for going from `&T` -/// to `T`. The `ToOwned` trait generalizes `Clone` to construct owned data -/// from any borrow of a given type. -#[stable(feature = "rust1", since = "1.0.0")] -pub trait ToOwned { - /// The resulting type after obtaining ownership. - #[stable(feature = "rust1", since = "1.0.0")] - type Owned: Borrow<Self>; - - /// Creates owned data from borrowed data, usually by cloning. - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let s: &str = "a"; - /// let ss: String = s.to_owned(); - /// - /// let v: &[i32] = &[1, 2]; - /// let vv: Vec<i32> = v.to_owned(); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - #[must_use = "cloning is often expensive and is not expected to have side effects"] - fn to_owned(&self) -> Self::Owned; - - /// Uses borrowed data to replace owned data, usually by cloning. - /// - /// This is borrow-generalized version of `Clone::clone_from`. - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// # #![feature(toowned_clone_into)] - /// let mut s: String = String::new(); - /// "hello".clone_into(&mut s); - /// - /// let mut v: Vec<i32> = Vec::new(); - /// [1, 2][..].clone_into(&mut v); - /// ``` - #[unstable(feature = "toowned_clone_into", reason = "recently added", issue = "41263")] - fn clone_into(&self, target: &mut Self::Owned) { - *target = self.to_owned(); - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T> ToOwned for T -where - T: Clone, -{ - type Owned = T; - fn to_owned(&self) -> T { - self.clone() - } - - fn clone_into(&self, target: &mut T) { - target.clone_from(self); - } -} - -/// A clone-on-write smart pointer. -/// -/// The type `Cow` is a smart pointer providing clone-on-write functionality: it -/// can enclose and provide immutable access to borrowed data, and clone the -/// data lazily when mutation or ownership is required. The type is designed to -/// work with general borrowed data via the `Borrow` trait. -/// -/// `Cow` implements `Deref`, which means that you can call -/// non-mutating methods directly on the data it encloses. If mutation -/// is desired, `to_mut` will obtain a mutable reference to an owned -/// value, cloning if necessary. -/// -/// # Examples -/// -/// ``` -/// use std::borrow::Cow; -/// -/// fn abs_all(input: &mut Cow<[i32]>) { -/// for i in 0..input.len() { -/// let v = input[i]; -/// if v < 0 { -/// // Clones into a vector if not already owned. -/// input.to_mut()[i] = -v; -/// } -/// } -/// } -/// -/// // No clone occurs because `input` doesn't need to be mutated. -/// let slice = [0, 1, 2]; -/// let mut input = Cow::from(&slice[..]); -/// abs_all(&mut input); -/// -/// // Clone occurs because `input` needs to be mutated. -/// let slice = [-1, 0, 1]; -/// let mut input = Cow::from(&slice[..]); -/// abs_all(&mut input); -/// -/// // No clone occurs because `input` is already owned. -/// let mut input = Cow::from(vec![-1, 0, 1]); -/// abs_all(&mut input); -/// ``` -/// -/// Another example showing how to keep `Cow` in a struct: -/// -/// ``` -/// use std::borrow::Cow; -/// -/// struct Items<'a, X: 'a> where [X]: ToOwned<Owned = Vec<X>> { -/// values: Cow<'a, [X]>, -/// } -/// -/// impl<'a, X: Clone + 'a> Items<'a, X> where [X]: ToOwned<Owned = Vec<X>> { -/// fn new(v: Cow<'a, [X]>) -> Self { -/// Items { values: v } -/// } -/// } -/// -/// // Creates a container from borrowed values of a slice -/// let readonly = [1, 2]; -/// let borrowed = Items::new((&readonly[..]).into()); -/// match borrowed { -/// Items { values: Cow::Borrowed(b) } => println!("borrowed {:?}", b), -/// _ => panic!("expect borrowed value"), -/// } -/// -/// let mut clone_on_write = borrowed; -/// // Mutates the data from slice into owned vec and pushes a new value on top -/// clone_on_write.values.to_mut().push(3); -/// println!("clone_on_write = {:?}", clone_on_write.values); -/// -/// // The data was mutated. Let check it out. -/// match clone_on_write { -/// Items { values: Cow::Owned(_) } => println!("clone_on_write contains owned data"), -/// _ => panic!("expect owned data"), -/// } -/// ``` -#[stable(feature = "rust1", since = "1.0.0")] -pub enum Cow<'a, B: ?Sized + 'a> -where - B: ToOwned, -{ - /// Borrowed data. - #[stable(feature = "rust1", since = "1.0.0")] - Borrowed(#[stable(feature = "rust1", since = "1.0.0")] &'a B), - - /// Owned data. - #[stable(feature = "rust1", since = "1.0.0")] - Owned(#[stable(feature = "rust1", since = "1.0.0")] <B as ToOwned>::Owned), -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized + ToOwned> Clone for Cow<'_, B> { - fn clone(&self) -> Self { - match *self { - Borrowed(b) => Borrowed(b), - Owned(ref o) => { - let b: &B = o.borrow(); - Owned(b.to_owned()) - } - } - } - - fn clone_from(&mut self, source: &Self) { - match (self, source) { - (&mut Owned(ref mut dest), &Owned(ref o)) => o.borrow().clone_into(dest), - (t, s) => *t = s.clone(), - } - } -} - -impl<B: ?Sized + ToOwned> Cow<'_, B> { - /// Returns true if the data is borrowed, i.e. if `to_mut` would require additional work. - /// - /// # Examples - /// - /// ``` - /// #![feature(cow_is_borrowed)] - /// use std::borrow::Cow; - /// - /// let cow = Cow::Borrowed("moo"); - /// assert!(cow.is_borrowed()); - /// - /// let bull: Cow<'_, str> = Cow::Owned("...moo?".to_string()); - /// assert!(!bull.is_borrowed()); - /// ``` - #[unstable(feature = "cow_is_borrowed", issue = "65143")] - pub fn is_borrowed(&self) -> bool { - match *self { - Borrowed(_) => true, - Owned(_) => false, - } - } - - /// Returns true if the data is owned, i.e. if `to_mut` would be a no-op. - /// - /// # Examples - /// - /// ``` - /// #![feature(cow_is_borrowed)] - /// use std::borrow::Cow; - /// - /// let cow: Cow<'_, str> = Cow::Owned("moo".to_string()); - /// assert!(cow.is_owned()); - /// - /// let bull = Cow::Borrowed("...moo?"); - /// assert!(!bull.is_owned()); - /// ``` - #[unstable(feature = "cow_is_borrowed", issue = "65143")] - pub fn is_owned(&self) -> bool { - !self.is_borrowed() - } - - /// Acquires a mutable reference to the owned form of the data. - /// - /// Clones the data if it is not already owned. - /// - /// # Examples - /// - /// ``` - /// use std::borrow::Cow; - /// - /// let mut cow = Cow::Borrowed("foo"); - /// cow.to_mut().make_ascii_uppercase(); - /// - /// assert_eq!( - /// cow, - /// Cow::Owned(String::from("FOO")) as Cow<str> - /// ); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn to_mut(&mut self) -> &mut <B as ToOwned>::Owned { - match *self { - Borrowed(borrowed) => { - *self = Owned(borrowed.to_owned()); - match *self { - Borrowed(..) => unreachable!(), - Owned(ref mut owned) => owned, - } - } - Owned(ref mut owned) => owned, - } - } - - /// Extracts the owned data. - /// - /// Clones the data if it is not already owned. - /// - /// # Examples - /// - /// Calling `into_owned` on a `Cow::Borrowed` clones the underlying data - /// and becomes a `Cow::Owned`: - /// - /// ``` - /// use std::borrow::Cow; - /// - /// let s = "Hello world!"; - /// let cow = Cow::Borrowed(s); - /// - /// assert_eq!( - /// cow.into_owned(), - /// String::from(s) - /// ); - /// ``` - /// - /// Calling `into_owned` on a `Cow::Owned` is a no-op: - /// - /// ``` - /// use std::borrow::Cow; - /// - /// let s = "Hello world!"; - /// let cow: Cow<str> = Cow::Owned(String::from(s)); - /// - /// assert_eq!( - /// cow.into_owned(), - /// String::from(s) - /// ); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn into_owned(self) -> <B as ToOwned>::Owned { - match self { - Borrowed(borrowed) => borrowed.to_owned(), - Owned(owned) => owned, - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized + ToOwned> Deref for Cow<'_, B> { - type Target = B; - - fn deref(&self) -> &B { - match *self { - Borrowed(borrowed) => borrowed, - Owned(ref owned) => owned.borrow(), - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized> Eq for Cow<'_, B> where B: Eq + ToOwned {} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized> Ord for Cow<'_, B> -where - B: Ord + ToOwned, -{ - #[inline] - fn cmp(&self, other: &Self) -> Ordering { - Ord::cmp(&**self, &**other) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<'a, 'b, B: ?Sized, C: ?Sized> PartialEq<Cow<'b, C>> for Cow<'a, B> -where - B: PartialEq<C> + ToOwned, - C: ToOwned, -{ - #[inline] - fn eq(&self, other: &Cow<'b, C>) -> bool { - PartialEq::eq(&**self, &**other) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<'a, B: ?Sized> PartialOrd for Cow<'a, B> -where - B: PartialOrd + ToOwned, -{ - #[inline] - fn partial_cmp(&self, other: &Cow<'a, B>) -> Option<Ordering> { - PartialOrd::partial_cmp(&**self, &**other) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized> fmt::Debug for Cow<'_, B> -where - B: fmt::Debug + ToOwned<Owned: fmt::Debug>, -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match *self { - Borrowed(ref b) => fmt::Debug::fmt(b, f), - Owned(ref o) => fmt::Debug::fmt(o, f), - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized> fmt::Display for Cow<'_, B> -where - B: fmt::Display + ToOwned<Owned: fmt::Display>, -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match *self { - Borrowed(ref b) => fmt::Display::fmt(b, f), - Owned(ref o) => fmt::Display::fmt(o, f), - } - } -} - -#[stable(feature = "default", since = "1.11.0")] -impl<B: ?Sized> Default for Cow<'_, B> -where - B: ToOwned<Owned: Default>, -{ - /// Creates an owned Cow<'a, B> with the default value for the contained owned value. - fn default() -> Self { - Owned(<B as ToOwned>::Owned::default()) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<B: ?Sized> Hash for Cow<'_, B> -where - B: Hash + ToOwned, -{ - #[inline] - fn hash<H: Hasher>(&self, state: &mut H) { - Hash::hash(&**self, state) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T: ?Sized + ToOwned> AsRef<T> for Cow<'_, T> { - fn as_ref(&self) -> &T { - self - } -} - -#[stable(feature = "cow_add", since = "1.14.0")] -impl<'a> Add<&'a str> for Cow<'a, str> { - type Output = Cow<'a, str>; - - #[inline] - fn add(mut self, rhs: &'a str) -> Self::Output { - self += rhs; - self - } -} - -#[stable(feature = "cow_add", since = "1.14.0")] -impl<'a> Add<Cow<'a, str>> for Cow<'a, str> { - type Output = Cow<'a, str>; - - #[inline] - fn add(mut self, rhs: Cow<'a, str>) -> Self::Output { - self += rhs; - self - } -} - -#[stable(feature = "cow_add", since = "1.14.0")] -impl<'a> AddAssign<&'a str> for Cow<'a, str> { - fn add_assign(&mut self, rhs: &'a str) { - if self.is_empty() { - *self = Cow::Borrowed(rhs) - } else if !rhs.is_empty() { - if let Cow::Borrowed(lhs) = *self { - let mut s = String::with_capacity(lhs.len() + rhs.len()); - s.push_str(lhs); - *self = Cow::Owned(s); - } - self.to_mut().push_str(rhs); - } - } -} - -#[stable(feature = "cow_add", since = "1.14.0")] -impl<'a> AddAssign<Cow<'a, str>> for Cow<'a, str> { - fn add_assign(&mut self, rhs: Cow<'a, str>) { - if self.is_empty() { - *self = rhs - } else if !rhs.is_empty() { - if let Cow::Borrowed(lhs) = *self { - let mut s = String::with_capacity(lhs.len() + rhs.len()); - s.push_str(lhs); - *self = Cow::Owned(s); - } - self.to_mut().push_str(&rhs); - } - } -} |