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Rollup merge of #38189 - GuillaumeGomez:rc_links, r=frewsxcv
Add missing links to Rc doc r? @frewsxcv
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Guillaume Gomez
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@ -12,35 +12,35 @@
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//! Single-threaded reference-counting pointers.
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//!
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//! The type [`Rc<T>`][rc] provides shared ownership of a value of type `T`,
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//! allocated in the heap. Invoking [`clone`][clone] on `Rc` produces a new
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//! pointer to the same value in the heap. When the last `Rc` pointer to a
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//! The type [`Rc<T>`][`Rc`] provides shared ownership of a value of type `T`,
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//! allocated in the heap. Invoking [`clone()`][clone] on [`Rc`] produces a new
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//! pointer to the same value in the heap. When the last [`Rc`] pointer to a
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//! given value is destroyed, the pointed-to value is also destroyed.
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//!
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//! Shared references in Rust disallow mutation by default, and `Rc` is no
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//! exception. If you need to mutate through an `Rc`, use [`Cell`][cell] or
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//! [`RefCell`][refcell].
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//! exception. If you need to mutate through an [`Rc`], use [`Cell`] or
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//! [`RefCell`].
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//!
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//! `Rc` uses non-atomic reference counting. This means that overhead is very
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//! low, but an `Rc` cannot be sent between threads, and consequently `Rc`
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//! [`Rc`] uses non-atomic reference counting. This means that overhead is very
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//! low, but an [`Rc`] cannot be sent between threads, and consequently [`Rc`]
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//! does not implement [`Send`][send]. As a result, the Rust compiler
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//! will check *at compile time* that you are not sending `Rc`s between
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//! will check *at compile time* that you are not sending [`Rc`]s between
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//! threads. If you need multi-threaded, atomic reference counting, use
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//! [`sync::Arc`][arc].
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//!
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//! The [`downgrade`][downgrade] method can be used to create a non-owning
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//! [`Weak`][weak] pointer. A `Weak` pointer can be [`upgrade`][upgrade]d
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//! to an `Rc`, but this will return [`None`][option] if the value has
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//! The [`downgrade()`][downgrade] method can be used to create a non-owning
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//! [`Weak`] pointer. A [`Weak`] pointer can be [`upgrade`][upgrade]d
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//! to an [`Rc`], but this will return [`None`] if the value has
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//! already been dropped.
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//!
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//! A cycle between `Rc` pointers will never be deallocated. For this reason,
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//! `Weak` is used to break cycles. For example, a tree could have strong
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//! `Rc` pointers from parent nodes to children, and `Weak` pointers from
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//! A cycle between [`Rc`] pointers will never be deallocated. For this reason,
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//! [`Weak`] is used to break cycles. For example, a tree could have strong
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//! [`Rc`] pointers from parent nodes to children, and [`Weak`] pointers from
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//! children back to their parents.
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//!
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//! `Rc<T>` automatically dereferences to `T` (via the [`Deref`][deref] trait),
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//! so you can call `T`'s methods on a value of type `Rc<T>`. To avoid name
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//! clashes with `T`'s methods, the methods of `Rc<T>` itself are [associated
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//! `Rc<T>` automatically dereferences to `T` (via the [`Deref`] trait),
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//! so you can call `T`'s methods on a value of type [`Rc<T>`][`Rc`]. To avoid name
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//! clashes with `T`'s methods, the methods of [`Rc<T>`][`Rc`] itself are [associated
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//! functions][assoc], called using function-like syntax:
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//!
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//! ```
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@ -50,28 +50,15 @@
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//! Rc::downgrade(&my_rc);
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//! ```
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//!
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//! `Weak<T>` does not auto-dereference to `T`, because the value may have
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//! [`Weak<T>`][`Weak`] does not auto-dereference to `T`, because the value may have
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//! already been destroyed.
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//!
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//! [rc]: struct.Rc.html
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//! [weak]: struct.Weak.html
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//! [clone]: ../../std/clone/trait.Clone.html#tymethod.clone
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//! [cell]: ../../std/cell/struct.Cell.html
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//! [refcell]: ../../std/cell/struct.RefCell.html
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//! [send]: ../../std/marker/trait.Send.html
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//! [arc]: ../../std/sync/struct.Arc.html
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//! [deref]: ../../std/ops/trait.Deref.html
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//! [downgrade]: struct.Rc.html#method.downgrade
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//! [upgrade]: struct.Weak.html#method.upgrade
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//! [option]: ../../std/option/enum.Option.html
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//! [assoc]: ../../book/method-syntax.html#associated-functions
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//!
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//! # Examples
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//!
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//! Consider a scenario where a set of `Gadget`s are owned by a given `Owner`.
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//! We want to have our `Gadget`s point to their `Owner`. We can't do this with
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//! unique ownership, because more than one gadget may belong to the same
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//! `Owner`. `Rc` allows us to share an `Owner` between multiple `Gadget`s,
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//! `Owner`. [`Rc`] allows us to share an `Owner` between multiple `Gadget`s,
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//! and have the `Owner` remain allocated as long as any `Gadget` points at it.
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//!
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//! ```
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@ -127,20 +114,20 @@
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//! ```
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//!
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//! If our requirements change, and we also need to be able to traverse from
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//! `Owner` to `Gadget`, we will run into problems. An `Rc` pointer from `Owner`
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//! `Owner` to `Gadget`, we will run into problems. An [`Rc`] pointer from `Owner`
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//! to `Gadget` introduces a cycle between the values. This means that their
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//! reference counts can never reach 0, and the values will remain allocated
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//! forever: a memory leak. In order to get around this, we can use `Weak`
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//! forever: a memory leak. In order to get around this, we can use [`Weak`]
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//! pointers.
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//!
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//! Rust actually makes it somewhat difficult to produce this loop in the first
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//! place. In order to end up with two values that point at each other, one of
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//! them needs to be mutable. This is difficult because `Rc` enforces
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//! them needs to be mutable. This is difficult because [`Rc`] enforces
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//! memory safety by only giving out shared references to the value it wraps,
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//! and these don't allow direct mutation. We need to wrap the part of the
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//! value we wish to mutate in a [`RefCell`][refcell], which provides *interior
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//! value we wish to mutate in a [`RefCell`], which provides *interior
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//! mutability*: a method to achieve mutability through a shared reference.
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//! `RefCell` enforces Rust's borrowing rules at runtime.
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//! [`RefCell`] enforces Rust's borrowing rules at runtime.
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//!
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//! ```
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//! use std::rc::Rc;
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@ -214,6 +201,19 @@
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//! // Gadget Man, so he gets destroyed as well.
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//! }
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//! ```
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//!
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//! [`Rc`]: struct.Rc.html
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//! [`Weak`]: struct.Weak.html
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//! [clone]: ../../std/clone/trait.Clone.html#tymethod.clone
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//! [`Cell`]: ../../std/cell/struct.Cell.html
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//! [`RefCell`]: ../../std/cell/struct.RefCell.html
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//! [send]: ../../std/marker/trait.Send.html
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//! [arc]: ../../std/sync/struct.Arc.html
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//! [`Deref`]: ../../std/ops/trait.Deref.html
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//! [downgrade]: struct.Rc.html#method.downgrade
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//! [upgrade]: struct.Weak.html#method.upgrade
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//! [`None`]: ../../std/option/enum.Option.html#variant.None
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//! [assoc]: ../../book/method-syntax.html#associated-functions
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#![stable(feature = "rust1", since = "1.0.0")]
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@ -251,9 +251,11 @@ struct RcBox<T: ?Sized> {
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/// See the [module-level documentation](./index.html) for more details.
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///
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/// The inherent methods of `Rc` are all associated functions, which means
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/// that you have to call them as e.g. `Rc::get_mut(&value)` instead of
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/// `value.get_mut()`. This avoids conflicts with methods of the inner
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/// that you have to call them as e.g. [`Rc::get_mut(&value)`][get_mut] instead of
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/// `value.get_mut()`. This avoids conflicts with methods of the inner
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/// type `T`.
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///
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/// [get_mut]: #method.get_mut
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct Rc<T: ?Sized> {
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ptr: Shared<RcBox<T>>,
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@ -337,10 +339,10 @@ impl<T> Rc<T> {
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}
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/// Checks whether [`Rc::try_unwrap`][try_unwrap] would return
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/// [`Ok`][result].
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/// [`Ok`].
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///
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/// [try_unwrap]: struct.Rc.html#method.try_unwrap
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/// [result]: ../../std/result/enum.Result.html
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/// [`Ok`]: ../../std/result/enum.Result.html#variant.Ok
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///
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/// # Examples
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///
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@ -543,14 +545,14 @@ impl<T: ?Sized> Rc<T> {
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/// Returns a mutable reference to the inner value, if there are
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/// no other `Rc` or [`Weak`][weak] pointers to the same value.
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///
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/// Returns [`None`][option] otherwise, because it is not safe to
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/// Returns [`None`] otherwise, because it is not safe to
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/// mutate a shared value.
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///
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/// See also [`make_mut`][make_mut], which will [`clone`][clone]
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/// the inner value when it's shared.
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///
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/// [weak]: struct.Weak.html
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/// [option]: ../../std/option/enum.Option.html
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/// [`None`]: ../../std/option/enum.Option.html#variant.None
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/// [make_mut]: struct.Rc.html#method.make_mut
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/// [clone]: ../../std/clone/trait.Clone.html#tymethod.clone
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///
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