rollup merge of #22210: aturon/stab-final-borrow
Conflicts: src/libcollections/btree/map.rs src/libcollections/str.rs src/libcollections/vec.rs src/libcore/borrow.rs src/libcore/hash/mod.rs src/libstd/collections/hash/map.rs src/libstd/collections/hash/set.rs
This commit is contained in:
Alex Crichton
commit
2cdbd288ac
29 changed files with 766 additions and 514 deletions
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@ -1,265 +0,0 @@
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A module for working with borrowed data.
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//!
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//! # The `BorrowFrom` traits
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//!
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//! In general, there may be several ways to "borrow" a piece of data. The
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//! typical ways of borrowing a type `T` are `&T` (a shared borrow) and `&mut T`
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//! (a mutable borrow). But types like `Vec<T>` provide additional kinds of
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//! borrows: the borrowed slices `&[T]` and `&mut [T]`.
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//!
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//! When writing generic code, it is often desirable to abstract over all ways
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//! of borrowing data from a given type. That is the role of the `BorrowFrom`
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//! trait: if `T: BorrowFrom<U>`, then `&T` can be borrowed from `&U`. A given
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//! type can be borrowed as multiple different types. In particular, `Vec<T>:
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//! BorrowFrom<Vec<T>>` and `[T]: BorrowFrom<Vec<T>>`.
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//!
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//! # The `ToOwned` trait
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//!
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//! Some types make it possible to go from borrowed to owned, usually by
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//! implementing the `Clone` trait. But `Clone` works only for going from `&T`
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//! to `T`. The `ToOwned` trait generalizes `Clone` to construct owned data
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//! from any borrow of a given type.
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//!
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//! # The `Cow` (clone-on-write) type
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//!
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//! The type `Cow` is a smart pointer providing clone-on-write functionality: it
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//! can enclose and provide immutable access to borrowed data, and clone the
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//! data lazily when mutation or ownership is required. The type is designed to
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//! work with general borrowed data via the `BorrowFrom` trait.
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//!
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//! `Cow` implements both `Deref`, which means that you can call
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//! non-mutating methods directly on the data it encloses. If mutation
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//! is desired, `to_mut` will obtain a mutable references to an owned
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//! value, cloning if necessary.
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#![unstable(feature = "core",
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reason = "recently added as part of collections reform")]
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use clone::Clone;
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use cmp::{Eq, Ord, Ordering, PartialEq, PartialOrd};
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use fmt;
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use marker::Sized;
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use ops::Deref;
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use option::Option;
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use self::Cow::*;
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/// A trait for borrowing data.
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#[old_orphan_check]
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pub trait BorrowFrom<Owned: ?Sized> {
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/// Immutably borrow from an owned value.
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fn borrow_from(owned: &Owned) -> &Self;
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}
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/// A trait for mutably borrowing data.
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#[old_orphan_check]
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pub trait BorrowFromMut<Owned: ?Sized> : BorrowFrom<Owned> {
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/// Mutably borrow from an owned value.
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fn borrow_from_mut(owned: &mut Owned) -> &mut Self;
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}
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impl<T: ?Sized> BorrowFrom<T> for T {
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fn borrow_from(owned: &T) -> &T { owned }
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}
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impl<T: ?Sized> BorrowFromMut<T> for T {
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fn borrow_from_mut(owned: &mut T) -> &mut T { owned }
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}
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impl<'a, T: ?Sized> BorrowFrom<&'a T> for T {
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fn borrow_from<'b>(owned: &'b &'a T) -> &'b T { &**owned }
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}
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impl<'a, T: ?Sized> BorrowFrom<&'a mut T> for T {
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fn borrow_from<'b>(owned: &'b &'a mut T) -> &'b T { &**owned }
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}
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impl<'a, T: ?Sized> BorrowFromMut<&'a mut T> for T {
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fn borrow_from_mut<'b>(owned: &'b mut &'a mut T) -> &'b mut T { &mut **owned }
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}
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impl<'a, T, B: ?Sized> BorrowFrom<Cow<'a, T, B>> for B where B: ToOwned<T> {
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fn borrow_from<'b>(owned: &'b Cow<'a, T, B>) -> &'b B {
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&**owned
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}
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}
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/// Trait for moving into a `Cow`
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#[old_orphan_check]
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pub trait IntoCow<'a, T, B: ?Sized> {
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/// Moves `self` into `Cow`
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fn into_cow(self) -> Cow<'a, T, B>;
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}
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impl<'a, T, B: ?Sized> IntoCow<'a, T, B> for Cow<'a, T, B> where B: ToOwned<T> {
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fn into_cow(self) -> Cow<'a, T, B> {
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self
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}
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}
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/// A generalization of Clone to borrowed data.
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#[old_orphan_check]
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pub trait ToOwned<Owned>: BorrowFrom<Owned> {
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/// Create owned data from borrowed data, usually by copying.
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fn to_owned(&self) -> Owned;
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}
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impl<T> ToOwned<T> for T where T: Clone {
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fn to_owned(&self) -> T { self.clone() }
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}
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/// A clone-on-write smart pointer.
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///
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/// # Example
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///
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/// ```rust
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/// use std::borrow::Cow;
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///
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/// fn abs_all(input: &mut Cow<Vec<i32>, [i32]>) {
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/// for i in 0..input.len() {
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/// let v = input[i];
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/// if v < 0 {
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/// // clones into a vector the first time (if not already owned)
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/// input.to_mut()[i] = -v;
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/// }
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/// }
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/// }
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/// ```
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pub enum Cow<'a, T, B: ?Sized + 'a> where B: ToOwned<T> {
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/// Borrowed data.
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Borrowed(&'a B),
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/// Owned data.
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Owned(T)
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> Clone for Cow<'a, T, B> where B: ToOwned<T> {
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fn clone(&self) -> Cow<'a, T, B> {
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match *self {
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Borrowed(b) => Borrowed(b),
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Owned(ref o) => {
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let b: &B = BorrowFrom::borrow_from(o);
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Owned(b.to_owned())
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},
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}
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}
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}
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impl<'a, T, B: ?Sized> Cow<'a, T, B> where B: ToOwned<T> {
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/// Acquire a mutable reference to the owned form of the data.
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///
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/// Copies the data if it is not already owned.
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pub fn to_mut(&mut self) -> &mut T {
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match *self {
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Borrowed(borrowed) => {
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*self = Owned(borrowed.to_owned());
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self.to_mut()
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}
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Owned(ref mut owned) => owned
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}
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}
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/// Extract the owned data.
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///
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/// Copies the data if it is not already owned.
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pub fn into_owned(self) -> T {
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match self {
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Borrowed(borrowed) => borrowed.to_owned(),
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Owned(owned) => owned
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}
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}
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/// Returns true if this `Cow` wraps a borrowed value
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pub fn is_borrowed(&self) -> bool {
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match *self {
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Borrowed(_) => true,
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_ => false,
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}
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}
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/// Returns true if this `Cow` wraps an owned value
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pub fn is_owned(&self) -> bool {
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match *self {
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Owned(_) => true,
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_ => false,
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}
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> Deref for Cow<'a, T, B> where B: ToOwned<T> {
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type Target = B;
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fn deref(&self) -> &B {
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match *self {
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Borrowed(borrowed) => borrowed,
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Owned(ref owned) => BorrowFrom::borrow_from(owned)
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}
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> Eq for Cow<'a, T, B> where B: Eq + ToOwned<T> {}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> Ord for Cow<'a, T, B> where B: Ord + ToOwned<T> {
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#[inline]
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fn cmp(&self, other: &Cow<'a, T, B>) -> Ordering {
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Ord::cmp(&**self, &**other)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, 'b, T, U, B: ?Sized, C: ?Sized> PartialEq<Cow<'b, U, C>> for Cow<'a, T, B> where
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B: PartialEq<C> + ToOwned<T>,
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C: ToOwned<U>,
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{
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#[inline]
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fn eq(&self, other: &Cow<'b, U, C>) -> bool {
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PartialEq::eq(&**self, &**other)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> PartialOrd for Cow<'a, T, B> where B: PartialOrd + ToOwned<T> {
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#[inline]
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fn partial_cmp(&self, other: &Cow<'a, T, B>) -> Option<Ordering> {
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PartialOrd::partial_cmp(&**self, &**other)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> fmt::Debug for Cow<'a, T, B> where
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B: fmt::Debug + ToOwned<T>,
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T: fmt::Debug,
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{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match *self {
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Borrowed(ref b) => fmt::Debug::fmt(b, f),
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Owned(ref o) => fmt::Debug::fmt(o, f),
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}
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> fmt::Display for Cow<'a, T, B> where
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B: fmt::Display + ToOwned<T>,
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T: fmt::Display,
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{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match *self {
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Borrowed(ref b) => fmt::Display::fmt(b, f),
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Owned(ref o) => fmt::Display::fmt(o, f),
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}
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}
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}
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@ -58,8 +58,9 @@
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#![stable(feature = "rust1", since = "1.0.0")]
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use prelude::*;
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use default::Default;
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use marker::Sized;
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use mem;
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pub use self::sip::SipHasher;
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@ -398,119 +399,4 @@ mod impls {
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}
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)*}
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}
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impl_write! {
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(u8, write_u8),
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(u16, write_u16),
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(u32, write_u32),
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(u64, write_u64),
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(usize, write_usize),
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(i8, write_i8),
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(i16, write_i16),
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(i32, write_i32),
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(i64, write_i64),
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(isize, write_isize),
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Hash for bool {
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fn hash<H: Hasher>(&self, state: &mut H) {
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state.write_u8(*self as u8)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Hash for char {
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fn hash<H: Hasher>(&self, state: &mut H) {
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state.write_u32(*self as u32)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Hash for str {
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fn hash<H: Hasher>(&self, state: &mut H) {
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state.write(self.as_bytes());
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state.write_u8(0xff)
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}
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}
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macro_rules! impl_hash_tuple {
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() => (
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Hash for () {
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fn hash<H: Hasher>(&self, _state: &mut H) {}
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}
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);
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( $($name:ident)+) => (
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<$($name: Hash),*> Hash for ($($name,)*) {
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#[allow(non_snake_case)]
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fn hash<S: Hasher>(&self, state: &mut S) {
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let ($(ref $name,)*) = *self;
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$($name.hash(state);)*
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}
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}
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);
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}
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impl_hash_tuple! {}
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impl_hash_tuple! { A }
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impl_hash_tuple! { A B }
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impl_hash_tuple! { A B C }
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impl_hash_tuple! { A B C D }
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impl_hash_tuple! { A B C D E }
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impl_hash_tuple! { A B C D E F }
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impl_hash_tuple! { A B C D E F G }
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impl_hash_tuple! { A B C D E F G H }
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impl_hash_tuple! { A B C D E F G H I }
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impl_hash_tuple! { A B C D E F G H I J }
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impl_hash_tuple! { A B C D E F G H I J K }
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impl_hash_tuple! { A B C D E F G H I J K L }
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T: Hash> Hash for [T] {
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fn hash<H: Hasher>(&self, state: &mut H) {
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self.len().hash(state);
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Hash::hash_slice(self, state)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T: ?Sized + Hash> Hash for &'a T {
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fn hash<H: Hasher>(&self, state: &mut H) {
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(**self).hash(state);
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T: ?Sized + Hash> Hash for &'a mut T {
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fn hash<H: Hasher>(&self, state: &mut H) {
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(**self).hash(state);
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T> Hash for *const T {
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fn hash<H: Hasher>(&self, state: &mut H) {
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state.write_usize(*self as usize)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T> Hash for *mut T {
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fn hash<H: Hasher>(&self, state: &mut H) {
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state.write_usize(*self as usize)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<'a, T, B: ?Sized> Hash for Cow<'a, T, B>
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where B: Hash + ToOwned<T>
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{
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fn hash<H: Hasher>(&self, state: &mut H) {
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Hash::hash(&**self, state)
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}
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}
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}
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|
|
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|
@ -126,7 +126,6 @@ pub mod default;
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pub mod any;
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pub mod atomic;
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pub mod borrow;
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pub mod cell;
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pub mod char;
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pub mod panicking;
|
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|
|
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