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, 4];
assert_eq!(arr[ ..  ], [0,1,2,3,4]);
assert_eq!(arr[ .. 3], [0,1,2    ]);  // RangeTo
assert_eq!(arr[ ..=3], [0,1,2,3  ]);
assert_eq!(arr[1..  ], [  1,2,3,4]);
assert_eq!(arr[1.. 3], [  1,2    ]);
assert_eq!(arr[1..=3], [  1,2,3  ]);

Fields

end: Idx

The upper bound of the range (exclusive).

Methods

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

pub fn contains<U>(&self, item: &U) -> bool where
    Idx: PartialOrd<U>,
    U: PartialOrd<Idx> + ?Sized, 

Returns true if item is contained in the range.

Examples

use std::f32;

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

assert!( (..1.0).contains(&0.5));
assert!(!(..1.0).contains(&f32::NAN));
assert!(!(..f32::NAN).contains(&0.5));

Trait Implementations

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

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

Start index bound.

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

End index bound.

fn contains<U>(&self, item: &U) -> bool where
    T: PartialOrd<U>,
    U: PartialOrd<T> + ?Sized, 

Returns true if item is contained in the range.

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

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

Start index bound.

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

End index bound.

fn contains<U>(&self, item: &U) -> bool where
    T: PartialOrd<U>,
    U: PartialOrd<T> + ?Sized, 

Returns true if item is contained in the range.

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

fn hash<__HIdx>(&self, state: &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> Eq for RangeTo<Idx> where
    Idx: Eq, 

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

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

Formats the value using the given formatter.

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

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

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

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

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

This method tests for !=.

impl SliceIndex<str> for RangeTo<usize>

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

Returns a slice of the given string from the byte range [0, end). Equivalent to &self[0 .. end] or &mut self[0 .. end].

This operation is O(1).

Prior to 1.20.0, these indexing operations were still supported by direct implementation of Index and IndexMut.

Panics

Panics if end does not point to the starting byte offset of a character (as defined by is_char_boundary), or if end > len.

type Output = str

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_index_methods #0)

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_index_methods #0)

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_index_methods #0)

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_index_methods #0)

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_index_methods #0)

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_index_methods #0)

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]

The output type returned by methods.

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

🔬 This is a nightly-only experimental API. (slice_index_methods #0)

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_index_methods #0)

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

Important traits for &'_ [u8]

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

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

🔬 This is a nightly-only experimental API. (slice_index_methods #0)

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

Important traits for &'_ [u8]

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

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

🔬 This is a nightly-only experimental API. (slice_index_methods #0)

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

Important traits for &'_ [u8]

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

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

🔬 This is a nightly-only experimental API. (slice_index_methods #0)

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

Important traits for &'_ [u8]

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

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

🔬 This is a nightly-only experimental API. (slice_index_methods #0)

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

impl IndexMut<RangeTo<usize>> for String

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

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

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.