Primitive Type reference

References, both shared and mutable.

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 or ref mut pattern.

For those familiar with pointers, a reference is just a pointer that is assumed to be aligned, not null, and pointing to memory containing a valid value of T - for example, &bool can only point to an allocation containing the integer values 1 (true) or 0 (false), but creating a &bool that points to an allocation containing the value 3 causes undefined behaviour. In fact, Option<&T> has the same memory representation as a nullable but aligned pointer, and can be passed across FFI boundaries as such.

In most cases, references can be used much like the original value. Field access, method calling, and indexing work the same (save for mutability rules, of course). In addition, the comparison operators transparently defer to the referent's implementation, allowing references to be compared the same as owned values.

References have a lifetime attached to them, which represents the scope for which the borrow is valid. A lifetime is said to "outlive" another one if its representative scope is as long or longer than the other. The 'static lifetime is the longest lifetime, which represents the total life of the program. For example, string literals have a 'static lifetime because the text data is embedded into the binary of the program, rather than in an allocation that needs to be dynamically managed.

&mut T references can be freely coerced into &T references with the same referent type, and references with longer lifetimes can be freely coerced into references with shorter ones.

Reference equality by address, instead of comparing the values pointed to, is accomplished via implicit reference-pointer coercion and raw pointer equality via ptr::eq, while PartialEq compares values.

use std::ptr;

let five = 5;
let other_five = 5;
let five_ref = &five;
let same_five_ref = &five;
let other_five_ref = &other_five;

assert!(five_ref == same_five_ref);
assert!(five_ref == other_five_ref);

assert!(ptr::eq(five_ref, same_five_ref));
assert!(!ptr::eq(five_ref, other_five_ref));

For more information on how to use references, see the book's section on "References and Borrowing".

Trait implementations

The following traits are implemented for all &T, regardless of the type of its referent:

• Copy
• Clone (Note that this will not defer to T's Clone implementation if it exists!)
• Deref
• Borrow
• Pointer

&mut T references get all of the above except Copy and Clone (to prevent creating multiple simultaneous mutable borrows), plus the following, regardless of the type of its referent:

• DerefMut
• BorrowMut

The following traits are implemented on &T references if the underlying T also implements that trait:

• All the traits in std::fmt except Pointer and fmt::Write
• PartialOrd
• Ord
• PartialEq
• Eq
• AsRef
• Fn (in addition, &T references get FnMut and FnOnce if T: Fn)
• Hash
• ToSocketAddrs

&mut T references get all of the above except ToSocketAddrs, plus the following, if T implements that trait:

• AsMut
• FnMut (in addition, &mut T references get FnOnce if T: FnMut)
• fmt::Write
• Iterator
• DoubleEndedIterator
• ExactSizeIterator
• FusedIterator
• TrustedLen
• Send (note that &T references only get Send if T: Sync)
• io::Write
• Read
• Seek
• BufRead

Note that due to method call deref coercion, simply calling a trait method will act like they work on references as well as they do on owned values! The implementations described here are meant for generic contexts, where the final type T is a type parameter or otherwise not locally known.

Trait Implementations

impl<'_, A> AllocRef for &'_ A where
    A: AllocRef + ?Sized, 

fn alloc(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Attempts to allocate a block of memory.

fn alloc_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Behaves like alloc, but also ensures that the returned memory is zero-initialized.

unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout)

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Deallocates the memory referenced by ptr.

unsafe fn grow(
    &self,
    ptr: NonNull<u8>,
    old_layout: Layout,
    new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Attempts to extend the memory block.

unsafe fn grow_zeroed(
    &self,
    ptr: NonNull<u8>,
    old_layout: Layout,
    new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Behaves like grow, but also ensures that the new contents are set to zero before being returned.

unsafe fn shrink(
    &self,
    ptr: NonNull<u8>,
    old_layout: Layout,
    new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Attempts to shrink the memory block.

fn by_ref(&self) -> &Self

🔬 This is a nightly-only experimental API. (allocator_api #32838)

Creates a "by reference" adaptor for this instance of AllocRef.

impl<'_, T, U> AsMut<U> for &'_ mut T where
    T: AsMut<U> + ?Sized,
    U: ?Sized, 

fn as_mut(&mut self) -> &mut U

Performs the conversion.

impl<'_, T, U> AsRef<U> for &'_ T where
    T: AsRef<U> + ?Sized,
    U: ?Sized, 

fn as_ref(&self) -> &U

Performs the conversion.

impl<'_, T, U> AsRef<U> for &'_ mut T where
    T: AsRef<U> + ?Sized,
    U: ?Sized, 

fn as_ref(&self) -> &U

Performs the conversion.

impl<'_, T> Binary for &'_ T where
    T: Binary + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Binary for &'_ mut T where
    T: Binary + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Borrow<T> for &'_ mut T where
    T: ?Sized, 

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<'_, T> Borrow<T> for &'_ T where
    T: ?Sized, 

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<'_, T> BorrowMut<T> for &'_ mut T where
    T: ?Sized, 

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value.

impl<B: BufRead + ?Sized, '_> BufRead for &'_ mut B

fn fill_buf(&mut self) -> Result<&[u8]>

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(&mut self, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read.

fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>

Read all bytes into buf until the delimiter byte or EOF is reached.

fn read_line(&mut self, buf: &mut String) -> Result<usize>

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer.

fn split(self, byte: u8) -> Split<Self> where
    Self: Sized, 

Returns an iterator over the contents of this reader split on the byte byte.

fn lines(self) -> Lines<Self> where
    Self: Sized, 

Returns an iterator over the lines of this reader.

impl<'_, T> !Clone for &'_ mut T where
    T: ?Sized, 

Shared references can be cloned, but mutable references cannot!

#[must_use = "cloning is often expensive and is not expected to have side effects"]fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'_, T> Clone for &'_ T where
    T: ?Sized, 

Shared references can be cloned, but mutable references cannot!

fn clone(&self) -> &'_ T

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a, 'b, T, U> CoerceUnsized<&'a U> for &'b mut T where
    'b: 'a,
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'a, 'b, T, U> CoerceUnsized<&'a U> for &'b T where
    'b: 'a,
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'a, T, U> CoerceUnsized<&'a mut U> for &'a mut T where
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'a, T, U> CoerceUnsized<*const U> for &'a mut T where
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'a, T, U> CoerceUnsized<*const U> for &'a T where
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'a, T, U> CoerceUnsized<*mut U> for &'a mut T where
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'_, T> Copy for &'_ T where
    T: ?Sized, 

Shared references can be copied, but mutable references cannot!

impl<'_, T> Debug for &'_ mut T where
    T: Debug + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Debug for &'_ T where
    T: Debug + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Deref for &'_ mut T where
    T: ?Sized, 

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<'_, T> Deref for &'_ T where
    T: ?Sized, 

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<'_, T> !DerefMut for &'_ T where
    T: ?Sized, 

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'_, T> DerefMut for &'_ mut T where
    T: ?Sized, 

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<'a, T, U> DispatchFromDyn<&'a U> for &'a T where
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'a, T, U> DispatchFromDyn<&'a mut U> for &'a mut T where
    T: Unsize<U> + ?Sized,
    U: ?Sized, 

impl<'_, T> Display for &'_ mut T where
    T: Display + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Display for &'_ T where
    T: Display + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'a, I> DoubleEndedIterator for &'a mut I where
    I: DoubleEndedIterator + ?Sized, 

fn next_back(&mut self) -> Option<<I as Iterator>::Item>

Removes and returns an element from the end of the iterator.

fn advance_back_by(&mut self, n: usize) -> Result<(), usize>

🔬 This is a nightly-only experimental API. (iter_advance_by #77404)

recently added

Advances the iterator from the back by n elements.

fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item>

Returns the nth element from the end of the iterator.

fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

This is the reverse version of Iterator::try_fold(): it takes elements starting from the back of the iterator.

fn rfold<B, F>(self, init: B, f: F) -> B where
    F: FnMut(B, Self::Item) -> B, 

An iterator method that reduces the iterator's elements to a single, final value, starting from the back.

fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator from the back that satisfies a predicate.

impl<'_, A> Eq for &'_ A where
    A: Eq + ?Sized, 

impl<'_, A> Eq for &'_ mut A where
    A: Eq + ?Sized, 

impl<'_, I> ExactSizeIterator for &'_ mut I where
    I: ExactSizeIterator + ?Sized, 

fn len(&self) -> usize

Returns the exact length of the iterator.

fn is_empty(&self) -> bool

🔬 This is a nightly-only experimental API. (exact_size_is_empty #35428)

Returns true if the iterator is empty.

impl<'_, A, F> Fn<A> for &'_ F where
    F: Fn<A> + ?Sized, 

extern "rust-call" fn call(&self, args: A) -> <F as FnOnce<A>>::Output

🔬 This is a nightly-only experimental API. (fn_traits #29625)

Performs the call operation.

impl<'_, A, F> FnMut<A> for &'_ mut F where
    F: FnMut<A> + ?Sized, 

extern "rust-call" fn call_mut(&mut self, args: A) -> <F as FnOnce<A>>::Output

🔬 This is a nightly-only experimental API. (fn_traits #29625)

Performs the call operation.

impl<'_, A, F> FnMut<A> for &'_ F where
    F: Fn<A> + ?Sized, 

extern "rust-call" fn call_mut(&mut self, args: A) -> <F as FnOnce<A>>::Output

🔬 This is a nightly-only experimental API. (fn_traits #29625)

Performs the call operation.

impl<'_, A, F> FnOnce<A> for &'_ mut F where
    F: FnMut<A> + ?Sized, 

type Output = <F as FnOnce<A>>::Output

The returned type after the call operator is used.

extern "rust-call" fn call_once(self, args: A) -> <F as FnOnce<A>>::Output

🔬 This is a nightly-only experimental API. (fn_traits #29625)

Performs the call operation.

impl<'_, A, F> FnOnce<A> for &'_ F where
    F: Fn<A> + ?Sized, 

type Output = <F as FnOnce<A>>::Output

The returned type after the call operator is used.

extern "rust-call" fn call_once(self, args: A) -> <F as FnOnce<A>>::Output

🔬 This is a nightly-only experimental API. (fn_traits #29625)

Performs the call operation.

impl<'_, I> FusedIterator for &'_ mut I where
    I: FusedIterator + ?Sized, 

impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 

type Output = <F as Future>::Output

The type of value produced on completion.

fn poll(
    self: Pin<&mut &'_ mut F>,
    cx: &mut Context<'_>
) -> Poll<<&'_ mut F as Future>::Output>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.

impl<'_, G, R> Generator<R> for &'_ mut G where
    G: Unpin + Generator<R> + ?Sized, 

type Yield = <G as Generator<R>>::Yield

🔬 This is a nightly-only experimental API. (generator_trait #43122)

The type of value this generator yields.

type Return = <G as Generator<R>>::Return

🔬 This is a nightly-only experimental API. (generator_trait #43122)

The type of value this generator returns.

fn resume(
    self: Pin<&mut &'_ mut G>,
    arg: R
) -> GeneratorState<<&'_ mut G as Generator<R>>::Yield, <&'_ mut G as Generator<R>>::Return>

🔬 This is a nightly-only experimental API. (generator_trait #43122)

Resumes the execution of this generator.

impl<'_, T> Hash for &'_ mut T where
    T: Hash + ?Sized, 

fn hash<H>(&self, state: &mut H) where
    H: Hasher, 

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<'_, T> Hash for &'_ T where
    T: Hash + ?Sized, 

fn hash<H>(&self, state: &mut H) where
    H: Hasher, 

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<'_, H> Hasher for &'_ mut H where
    H: Hasher + ?Sized, 

fn finish(&self) -> u64

Returns the hash value for the values written so far.

fn write(&mut self, bytes: &[u8])

Writes some data into this Hasher.

fn write_u8(&mut self, i: u8)

Writes a single u8 into this hasher.

fn write_u16(&mut self, i: u16)

Writes a single u16 into this hasher.

fn write_u32(&mut self, i: u32)

Writes a single u32 into this hasher.

fn write_u64(&mut self, i: u64)

Writes a single u64 into this hasher.

fn write_u128(&mut self, i: u128)

Writes a single u128 into this hasher.

fn write_usize(&mut self, i: usize)

Writes a single usize into this hasher.

fn write_i8(&mut self, i: i8)

Writes a single i8 into this hasher.

fn write_i16(&mut self, i: i16)

Writes a single i16 into this hasher.

fn write_i32(&mut self, i: i32)

Writes a single i32 into this hasher.

fn write_i64(&mut self, i: i64)

Writes a single i64 into this hasher.

fn write_i128(&mut self, i: i128)

Writes a single i128 into this hasher.

fn write_isize(&mut self, i: isize)

Writes a single isize into this hasher.

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 

type Item = <I as Iterator>::Item

The type of the elements being iterated over.

fn next(&mut self) -> Option<<I as Iterator>::Item>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn advance_by(&mut self, n: usize) -> Result<(), usize>

🔬 This is a nightly-only experimental API. (iter_advance_by #77404)

recently added

Advances the iterator by n elements.

fn nth(&mut self, n: usize) -> Option<<&'_ mut I as Iterator>::Item>

Returns the nth element of the iterator.

fn count(self) -> usize

Consumes the iterator, counting the number of iterations and returning it.

fn last(self) -> Option<Self::Item>

Consumes the iterator, returning the last element.

fn step_by(self, step: usize) -> StepBy<Self>

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
    U: IntoIterator<Item = Self::Item>, 

Takes two iterators and creates a new iterator over both in sequence.

fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
    U: IntoIterator, 

'Zips up' two iterators into a single iterator of pairs.

fn map<B, F>(self, f: F) -> Map<Self, F> where
    F: FnMut(Self::Item) -> B, 

Takes a closure and creates an iterator which calls that closure on each element.

fn for_each<F>(self, f: F) where
    F: FnMut(Self::Item), 

Calls a closure on each element of an iterator.

fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator which uses a closure to determine if an element should be yielded.

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
    F: FnMut(Self::Item) -> Option<B>, 

Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self>

Creates an iterator which gives the current iteration count as well as the next value.

fn peekable(self) -> Peekable<Self>

Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that skips elements based on a predicate.

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that yields elements based on a predicate.

fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> where
    P: FnMut(Self::Item) -> Option<B>, 

🔬 This is a nightly-only experimental API. (iter_map_while #68537)

recently added

Creates an iterator that both yields elements based on a predicate and maps.

fn skip(self, n: usize) -> Skip<Self>

Creates an iterator that skips the first n elements.

fn take(self, n: usize) -> Take<Self>

Creates an iterator that yields its first n elements.

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
    F: FnMut(&mut St, Self::Item) -> Option<B>, 

An iterator adaptor similar to fold that holds internal state and produces a new iterator.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
    F: FnMut(Self::Item) -> U,
    U: IntoIterator, 

Creates an iterator that works like map, but flattens nested structure.

fn flatten(self) -> Flatten<Self> where
    Self::Item: IntoIterator, 

Creates an iterator that flattens nested structure.

fn fuse(self) -> Fuse<Self>

Creates an iterator which ends after the first None.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item), 

Does something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self

Borrows an iterator, rather than consuming it.

#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]fn collect<B>(self) -> B where
    B: FromIterator<Self::Item>, 

Transforms an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B) where
    B: Default + Extend<Self::Item>,
    F: FnMut(&Self::Item) -> bool, 

Consumes an iterator, creating two collections from it.

fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
    P: FnMut(&T) -> bool,
    Self: DoubleEndedIterator<Item = &'a mut T>,
    T: 'a, 

🔬 This is a nightly-only experimental API. (iter_partition_in_place #62543)

new API

Reorders the elements of this iterator in-place according to the given predicate, such that all those that return true precede all those that return false. Returns the number of true elements found.

fn is_partitioned<P>(self, predicate: P) -> bool where
    P: FnMut(Self::Item) -> bool, 

🔬 This is a nightly-only experimental API. (iter_is_partitioned #62544)

new API

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

fn try_for_each<F, R>(&mut self, f: F) -> R where
    F: FnMut(Self::Item) -> R,
    R: Try<Ok = ()>, 

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

fn fold<B, F>(self, init: B, f: F) -> B where
    F: FnMut(B, Self::Item) -> B, 

An iterator method that applies a function, producing a single, final value.

fn fold_first<F>(self, f: F) -> Option<Self::Item> where
    F: FnMut(Self::Item, Self::Item) -> Self::Item, 

🔬 This is a nightly-only experimental API. (iterator_fold_self #68125)

The same as fold(), but uses the first element in the iterator as the initial value, folding every subsequent element into it. If the iterator is empty, return None; otherwise, return the result of the fold.

fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(Self::Item) -> bool, 

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool where
    F: FnMut(Self::Item) -> bool, 

Tests if any element of the iterator matches a predicate.

fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator that satisfies a predicate.

fn find_map<B, F>(&mut self, f: F) -> Option<B> where
    F: FnMut(Self::Item) -> Option<B>, 

Applies function to the elements of iterator and returns the first non-none result.

fn try_find<F, R>(
    &mut self,
    f: F
) -> Result<Option<Self::Item>, <R as Try>::Error> where
    F: FnMut(&Self::Item) -> R,
    R: Try<Ok = bool>, 

🔬 This is a nightly-only experimental API. (try_find #63178)

new API

Applies function to the elements of iterator and returns the first true result or the first error.

fn position<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool, 

Searches for an element in an iterator, returning its index.

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool,
    Self: ExactSizeIterator + DoubleEndedIterator, 

Searches for an element in an iterator from the right, returning its index.

fn max(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the maximum element of an iterator.

fn min(self) -> Option<Self::Item> where
    Self::Item: Ord, 

Returns the minimum element of an iterator.

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the maximum value from the specified function.

fn max_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the maximum value with respect to the specified comparison function.

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
    B: Ord,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the minimum value from the specified function.

fn min_by<F>(self, compare: F) -> Option<Self::Item> where
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the minimum value with respect to the specified comparison function.

fn rev(self) -> Rev<Self> where
    Self: DoubleEndedIterator, 

Reverses an iterator's direction.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
    FromA: Default + Extend<A>,
    FromB: Default + Extend<B>,
    Self: Iterator<Item = (A, B)>, 

Converts an iterator of pairs into a pair of containers.

fn copied<'a, T>(self) -> Copied<Self> where
    Self: Iterator<Item = &'a T>,
    T: 'a + Copy, 

Creates an iterator which copies all of its elements.

fn cloned<'a, T>(self) -> Cloned<Self> where
    Self: Iterator<Item = &'a T>,
    T: 'a + Clone, 

Creates an iterator which clones all of its elements.

fn cycle(self) -> Cycle<Self> where
    Self: Clone, 

Repeats an iterator endlessly.

fn sum<S>(self) -> S where
    S: Sum<Self::Item>, 

Sums the elements of an iterator.

fn product<P>(self) -> P where
    P: Product<Self::Item>, 

Iterates over the entire iterator, multiplying all the elements

fn cmp<I>(self, other: I) -> Ordering where
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord, 

Lexicographically compares the elements of this Iterator with those of another.

fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
    I: IntoIterator, 

🔬 This is a nightly-only experimental API. (iter_order_by #64295)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Lexicographically compares the elements of this Iterator with those of another.

fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
    I: IntoIterator, 

🔬 This is a nightly-only experimental API. (iter_order_by #64295)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn eq<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are equal to those of another.

fn eq_by<I, F>(self, other: I, eq: F) -> bool where
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
    I: IntoIterator, 

🔬 This is a nightly-only experimental API. (iter_order_by #64295)

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function.

fn ne<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are unequal to those of another.

fn lt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically less than those of another.

fn le<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

fn gt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically greater than those of another.

fn ge<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>, 

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

fn is_sorted(self) -> bool where
    Self::Item: PartialOrd<Self::Item>, 

🔬 This is a nightly-only experimental API. (is_sorted #53485)

new API

Checks if the elements of this iterator are sorted.

fn is_sorted_by<F>(self, compare: F) -> bool where
    F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>, 

🔬 This is a nightly-only experimental API. (is_sorted #53485)

new API

Checks if the elements of this iterator are sorted using the given comparator function.

fn is_sorted_by_key<F, K>(self, f: F) -> bool where
    F: FnMut(Self::Item) -> K,
    K: PartialOrd<K>, 

🔬 This is a nightly-only experimental API. (is_sorted #53485)

new API

Checks if the elements of this iterator are sorted using the given key extraction function.

impl<'_, T> LowerExp for &'_ mut T where
    T: LowerExp + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> LowerExp for &'_ T where
    T: LowerExp + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> LowerHex for &'_ T where
    T: LowerHex + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> LowerHex for &'_ mut T where
    T: LowerHex + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Octal for &'_ mut T where
    T: Octal + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Octal for &'_ T where
    T: Octal + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, A> Ord for &'_ mut A where
    A: Ord + ?Sized, 

fn cmp(&self, other: &&'_ mut A) -> Ordering

This method returns an Ordering between self and other.

#[must_use]fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp #44095)

Restrict a value to a certain interval.

impl<'_, A> Ord for &'_ A where
    A: Ord + ?Sized, 

fn cmp(&self, other: &&'_ A) -> Ordering

This method returns an Ordering between self and other.

#[must_use]fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp #44095)

Restrict a value to a certain interval.

impl<'_, '_, A, B> PartialEq<&'_ B> for &'_ mut A where
    A: PartialEq<B> + ?Sized,
    B: ?Sized, 

fn eq(&self, other: &&B) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&B) -> bool

This method tests for !=.

impl<'_, '_, A, B> PartialEq<&'_ B> for &'_ A where
    A: PartialEq<B> + ?Sized,
    B: ?Sized, 

fn eq(&self, other: &&B) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&B) -> bool

This method tests for !=.

impl<'_, '_, A, B> PartialEq<&'_ mut B> for &'_ mut A where
    A: PartialEq<B> + ?Sized,
    B: ?Sized, 

fn eq(&self, other: &&mut B) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&mut B) -> bool

This method tests for !=.

impl<'_, '_, A, B> PartialEq<&'_ mut B> for &'_ A where
    A: PartialEq<B> + ?Sized,
    B: ?Sized, 

fn eq(&self, other: &&mut B) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&mut B) -> bool

This method tests for !=.

impl<'_, '_, A, B> PartialOrd<&'_ B> for &'_ A where
    A: PartialOrd<B> + ?Sized,
    B: ?Sized, 

fn partial_cmp(&self, other: &&B) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &&B) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &&B) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &&B) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &&B) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'_, '_, A, B> PartialOrd<&'_ mut B> for &'_ mut A where
    A: PartialOrd<B> + ?Sized,
    B: ?Sized, 

fn partial_cmp(&self, other: &&mut B) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &&mut B) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &&mut B) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &&mut B) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &&mut B) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'_, T> Pointer for &'_ T where
    T: ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> Pointer for &'_ mut T where
    T: ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<R: Read + ?Sized, '_> Read for &'_ mut R

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector #69941)

Determines if this Reader has an efficient read_vectored implementation.

unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer #42788)

Determines if this Reader can work with buffers of uninitialized memory.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Read all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Read the exact number of bytes required to fill buf.

fn by_ref(&mut self) -> &mut Self where
    Self: Sized, 

Creates a "by reference" adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self> where
    Self: Sized, 

Transforms this Read instance to an Iterator over its bytes.

fn chain<R: Read>(self, next: R) -> Chain<Self, R> where
    Self: Sized, 

Creates an adaptor which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self> where
    Self: Sized, 

Creates an adaptor which will read at most limit bytes from it.

impl<S: Seek + ?Sized, '_> Seek for &'_ mut S

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

fn stream_len(&mut self) -> Result<u64>

🔬 This is a nightly-only experimental API. (seek_convenience #59359)

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64>

🔬 This is a nightly-only experimental API. (seek_convenience #59359)

Returns the current seek position from the start of the stream.

impl<'_, T> Send for &'_ T where
    T: Sync + ?Sized, 

impl<'_, T> Send for &'_ mut T where
    T: Send + ?Sized, 

impl<T: ToSocketAddrs + ?Sized, '_> ToSocketAddrs for &'_ T

type Iter = T::Iter

Returned iterator over socket addresses which this type may correspond to.

fn to_socket_addrs(&self) -> Result<T::Iter>

Converts this object to an iterator of resolved SocketAddrs.

impl<'_, I> TrustedLen for &'_ mut I where
    I: TrustedLen + ?Sized, 

impl<'a, T> Unpin for &'a mut T where
    T: 'a + ?Sized, 

impl<'a, T> Unpin for &'a T where
    T: 'a + ?Sized, 

impl<T: ?Sized, '_> !UnwindSafe for &'_ mut T

impl<T: RefUnwindSafe + ?Sized, '_> UnwindSafe for &'_ T

impl<'_, T> UpperExp for &'_ mut T where
    T: UpperExp + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> UpperExp for &'_ T where
    T: UpperExp + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> UpperHex for &'_ T where
    T: UpperHex + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, T> UpperHex for &'_ mut T where
    T: UpperHex + ?Sized, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'_, W> Write for &'_ mut W where
    W: Write + ?Sized, 

fn write_str(&mut self, s: &str) -> Result<(), Error>

Writes a string slice into this writer, returning whether the write succeeded.

fn write_char(&mut self, c: char) -> Result<(), Error>

Writes a char into this writer, returning whether the write succeeded.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Glue for usage of the write! macro with implementors of this trait.

impl<W: Write + ?Sized, '_> Write for &'_ mut W

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector #69941)

Determines if this Writeer has an efficient write_vectored implementation.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>

🔬 This is a nightly-only experimental API. (write_all_vectored #70436)

Attempts to write multiple buffers into this writer.

fn by_ref(&mut self) -> &mut Self where
    Self: Sized, 

Creates a "by reference" adaptor for this instance of Write.