Struct std::ops::RangeTo

pub struct RangeTo<Idx> {
    pub end: Idx,
}

A range only bounded exclusively above (..end).

The RangeTo ..end contains all values with x < end. It cannot serve as an Iterator because it doesn't have a starting point.

Examples

The ..end syntax is a RangeTo:

assert_eq!((..5), std::ops::RangeTo { end: 5 });

It does not have an IntoIterator implementation, so you can't use it in a for loop directly. This won't compile:

// error[E0277]: the trait bound `std::ops::RangeTo<{integer}>:
// std::iter::Iterator` is not satisfied
for i in ..5 {
    // ...
}

When used as a slicing index, RangeTo produces a slice of all array elements before the index indicated by end.

let arr = [0, 1, 2, 3];
assert_eq!(arr[ .. ], [0,1,2,3]);
assert_eq!(arr[ ..3], [0,1,2  ]);  // RangeTo
assert_eq!(arr[1.. ], [  1,2,3]);
assert_eq!(arr[1..3], [  1,2  ]);

Fields

end: Idx

The upper bound of the range (exclusive).

Methods

impl<Idx> RangeTo<Idx> where     Idx: PartialOrd<Idx>,

pub fn contains(&self, item: Idx) -> bool

🔬 This is a nightly-only experimental API. (range_contains #32311)

recently added as per RFC

Returns true if item is contained in the range.

Examples

#![feature(range_contains)]

assert!( (..5).contains(-1_000_000_000));
assert!( (..5).contains(4));
assert!(!(..5).contains(5));

Trait Implementations

impl<Idx> Copy for RangeTo<Idx> where     Idx: Copy,

impl<Idx> Debug for RangeTo<Idx> where     Idx: Debug,

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

Formats the value using the given formatter.

impl Index<RangeTo<usize>> for str

Implements substring slicing with syntax &self[.. end].

Returns a slice of the string from the beginning to byte offset end.

Equivalent to &self[0 .. end].

type Output = str

The returned type after indexing.

fn index(&self, index: RangeTo<usize>) -> &str

Performs the indexing (container[index]) operation.

impl<Idx> Hash for RangeTo<Idx> where     Idx: Hash,

fn hash<__HIdx>(&self, __arg_0: &mut __HIdx) where     __HIdx: 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<Idx> PartialEq<RangeTo<Idx>> for RangeTo<Idx> where     Idx: PartialEq<Idx>,

fn eq(&self, __arg_0: &RangeTo<Idx>) -> bool

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

fn ne(&self, __arg_0: &RangeTo<Idx>) -> bool

This method tests for !=.

impl SliceIndex<str> for RangeTo<usize>

type Output = str

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

The output type returned by methods.

fn get(     self,     slice: &str ) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(     self,     slice: &mut str ) -> Option<&mut <RangeTo<usize> as SliceIndex<str>>::Output>

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(     self,     slice: &str ) -> &<RangeTo<usize> as SliceIndex<str>>::Output

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a shared reference to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(     self,     slice: &mut str ) -> &mut <RangeTo<usize> as SliceIndex<str>>::Output

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a mutable reference to the output at this location, without performing any bounds checking.

fn index(self, slice: &str) -> &<RangeTo<usize> as SliceIndex<str>>::Output

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(     self,     slice: &mut str ) -> &mut <RangeTo<usize> as SliceIndex<str>>::Output

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeTo<usize>

type Output = [T]

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a mutable reference to the output at this location, if in bounds.

Important traits for &'a [u8]

impl<'a> Read for &'a [u8]impl<'a> Write for &'a mut [u8]

unsafe fn get_unchecked(self, slice: &[T]) -> &[T]

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a shared reference to the output at this location, without performing any bounds checking.

Important traits for &'a [u8]

impl<'a> Read for &'a [u8]impl<'a> Write for &'a mut [u8]

unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T]

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a mutable reference to the output at this location, without performing any bounds checking.

Important traits for &'a [u8]

impl<'a> Read for &'a [u8]impl<'a> Write for &'a mut [u8]

fn index(self, slice: &[T]) -> &[T]

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a shared reference to the output at this location, panicking if out of bounds.

Important traits for &'a [u8]

impl<'a> Read for &'a [u8]impl<'a> Write for &'a mut [u8]

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬 This is a nightly-only experimental API. (slice_get_slice #35729)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<Idx> Clone for RangeTo<Idx> where     Idx: Clone,

fn clone(&self) -> RangeTo<Idx>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl IndexMut<RangeTo<usize>> for str

Implements mutable substring slicing with syntax &mut self[.. end].

Returns a mutable slice of the string from the beginning to byte offset end.

Equivalent to &mut self[0 .. end].

fn index_mut(&mut self, index: RangeTo<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<Idx> Eq for RangeTo<Idx> where     Idx: Eq,

impl<T> RangeBounds<T> for RangeTo<T>

fn start(&self) -> Bound<&T>

🔬 This is a nightly-only experimental API. (collections_range #30877)

might be replaced with Into<_> and a type containing two Bound values

Start index bound.

fn end(&self) -> Bound<&T>

🔬 This is a nightly-only experimental API. (collections_range #30877)

might be replaced with Into<_> and a type containing two Bound values

End index bound.

impl<'a, T> RangeBounds<T> for RangeTo<&'a T>

fn start(&self) -> Bound<&T>

🔬 This is a nightly-only experimental API. (collections_range #30877)

might be replaced with Into<_> and a type containing two Bound values

Start index bound.

fn end(&self) -> Bound<&T>

🔬 This is a nightly-only experimental API. (collections_range #30877)

might be replaced with Into<_> and a type containing two Bound values

End index bound.

impl Index<RangeTo<usize>> for String

type Output = str

The returned type after indexing.

fn index(&self, index: RangeTo<usize>) -> &str

Performs the indexing (container[index]) operation.

impl IndexMut<RangeTo<usize>> for String

fn index_mut(&mut self, index: RangeTo<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.