diff options
Diffstat (limited to '')
| -rw-r--r-- | library/std/src/primitive_docs.rs | 95 |
1 files changed, 80 insertions, 15 deletions
diff --git a/library/std/src/primitive_docs.rs b/library/std/src/primitive_docs.rs index b8e546164..331714a99 100644 --- a/library/std/src/primitive_docs.rs +++ b/library/std/src/primitive_docs.rs @@ -611,7 +611,19 @@ mod prim_pointer {} /// /// Arrays coerce to [slices (`[T]`)][slice], so a slice method may be called on /// an array. Indeed, this provides most of the API for working with arrays. -/// Slices have a dynamic size and do not coerce to arrays. +/// +/// Slices have a dynamic size and do not coerce to arrays. Instead, use +/// `slice.try_into().unwrap()` or `<ArrayType>::try_from(slice).unwrap()`. +/// +/// Array's `try_from(slice)` implementations (and the corresponding `slice.try_into()` +/// array implementations) succeed if the input slice length is the same as the result +/// array length. They optimize especially well when the optimizer can easily determine +/// the slice length, e.g. `<[u8; 4]>::try_from(&slice[4..8]).unwrap()`. Array implements +/// [TryFrom](crate::convert::TryFrom) returning: +/// +/// - `[T; N]` copies from the slice's elements +/// - `&[T; N]` references the original slice's elements +/// - `&mut [T; N]` references the original slice's elements /// /// You can move elements out of an array with a [slice pattern]. If you want /// one element, see [`mem::replace`]. @@ -640,6 +652,15 @@ mod prim_pointer {} /// for x in &array { } /// ``` /// +/// You can use `<ArrayType>::try_from(slice)` or `slice.try_into()` to get an array from +/// a slice: +/// +/// ``` +/// let bytes: [u8; 3] = [1, 0, 2]; +/// assert_eq!(1, u16::from_le_bytes(<[u8; 2]>::try_from(&bytes[0..2]).unwrap())); +/// assert_eq!(512, u16::from_le_bytes(bytes[1..3].try_into().unwrap())); +/// ``` +/// /// You can use a [slice pattern] to move elements out of an array: /// /// ``` @@ -801,11 +822,53 @@ mod prim_array {} /// assert_eq!(2 * pointer_size, std::mem::size_of::<Box<[u8]>>()); /// assert_eq!(2 * pointer_size, std::mem::size_of::<Rc<[u8]>>()); /// ``` +/// +/// ## Trait Implementations +/// +/// Some traits are implemented for slices if the element type implements +/// that trait. This includes [`Eq`], [`Hash`] and [`Ord`]. +/// +/// ## Iteration +/// +/// The slices implement `IntoIterator`. The iterator yields references to the +/// slice elements. +/// +/// ``` +/// let numbers: &[i32] = &[0, 1, 2]; +/// for n in numbers { +/// println!("{n} is a number!"); +/// } +/// ``` +/// +/// The mutable slice yields mutable references to the elements: +/// +/// ``` +/// let mut scores: &mut [i32] = &mut [7, 8, 9]; +/// for score in scores { +/// *score += 1; +/// } +/// ``` +/// +/// This iterator yields mutable references to the slice's elements, so while +/// the element type of the slice is `i32`, the element type of the iterator is +/// `&mut i32`. +/// +/// * [`.iter`] and [`.iter_mut`] are the explicit methods to return the default +/// iterators. +/// * Further methods that return iterators are [`.split`], [`.splitn`], +/// [`.chunks`], [`.windows`] and more. +/// +/// [`Hash`]: core::hash::Hash +/// [`.iter`]: slice::iter +/// [`.iter_mut`]: slice::iter_mut +/// [`.split`]: slice::split +/// [`.splitn`]: slice::splitn +/// [`.chunks`]: slice::chunks +/// [`.windows`]: slice::windows #[stable(feature = "rust1", since = "1.0.0")] mod prim_slice {} #[doc(primitive = "str")] -// /// String slices. /// /// *[See also the `std::str` module](crate::str).* @@ -816,19 +879,22 @@ mod prim_slice {} /// /// String slices are always valid UTF-8. /// -/// # Examples +/// # Basic Usage /// /// String literals are string slices: /// /// ``` -/// let hello = "Hello, world!"; -/// -/// // with an explicit type annotation -/// let hello: &'static str = "Hello, world!"; +/// let hello_world = "Hello, World!"; /// ``` /// -/// They are `'static` because they're stored directly in the final binary, and -/// so will be valid for the `'static` duration. +/// Here we have declared a string slice initialized with a string literal. +/// String literals have a static lifetime, which means the string `hello_world` +/// is guaranteed to be valid for the duration of the entire program. +/// We can explicitly specify `hello_world`'s lifetime as well: +/// +/// ``` +/// let hello_world: &'static str = "Hello, world!"; +/// ``` /// /// # Representation /// @@ -996,7 +1062,7 @@ impl<T> (T,) {} // Fake impl that's only really used for docs. #[cfg(doc)] #[stable(feature = "rust1", since = "1.0.0")] -#[cfg_attr(not(bootstrap), doc(fake_variadic))] +#[doc(fake_variadic)] /// This trait is implemented on arbitrary-length tuples. impl<T: Clone> Clone for (T,) { fn clone(&self) -> Self { @@ -1007,7 +1073,7 @@ impl<T: Clone> Clone for (T,) { // Fake impl that's only really used for docs. #[cfg(doc)] #[stable(feature = "rust1", since = "1.0.0")] -#[cfg_attr(not(bootstrap), doc(fake_variadic))] +#[doc(fake_variadic)] /// This trait is implemented on arbitrary-length tuples. impl<T: Copy> Copy for (T,) { // empty @@ -1178,7 +1244,7 @@ mod prim_usize {} #[doc(alias = "&")] #[doc(alias = "&mut")] // -/// References, both shared and mutable. +/// References, `&T` and `&mut T`. /// /// A reference represents a borrow of some owned value. You can get one by using the `&` or `&mut` /// operators on a value, or by using a [`ref`](../std/keyword.ref.html) or @@ -1484,13 +1550,12 @@ mod prim_fn {} // Required to make auto trait impls render. // See src/librustdoc/passes/collect_trait_impls.rs:collect_trait_impls #[doc(hidden)] -#[cfg(not(bootstrap))] impl<Ret, T> fn(T) -> Ret {} // Fake impl that's only really used for docs. #[cfg(doc)] #[stable(feature = "rust1", since = "1.0.0")] -#[cfg_attr(not(bootstrap), doc(fake_variadic))] +#[doc(fake_variadic)] /// This trait is implemented on function pointers with any number of arguments. impl<Ret, T> Clone for fn(T) -> Ret { fn clone(&self) -> Self { @@ -1501,7 +1566,7 @@ impl<Ret, T> Clone for fn(T) -> Ret { // Fake impl that's only really used for docs. #[cfg(doc)] #[stable(feature = "rust1", since = "1.0.0")] -#[cfg_attr(not(bootstrap), doc(fake_variadic))] +#[doc(fake_variadic)] /// This trait is implemented on function pointers with any number of arguments. impl<Ret, T> Copy for fn(T) -> Ret { // empty |