Struct core::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: PartialOrd<Idx>> RangeTo<Idx>

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

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<Idx: Copy> Copy for RangeTo<Idx>

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

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

Returns true if item is contained in the range.

impl<Idx: PartialEq> PartialEq<RangeTo<Idx>> for RangeTo<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<Idx: Eq> Eq for RangeTo<Idx>

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

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

Returns a copy of the value.

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

Performs copy-assignment from source.

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.

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. Calling this method with an out-of-bounds index is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html

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. Calling this method with an out-of-bounds index is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html

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.

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 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<&Self::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 Self::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) -> &Self::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. Calling this method with an out-of-bounds index is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html

unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::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. Calling this method with an out-of-bounds index is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html

fn index(self, slice: &str) -> &Self::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 Self::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<Idx: Hash> Hash for RangeTo<Idx>

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

Feeds this value into the given [Hasher].

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

Feeds a slice of this type into the given [Hasher].

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

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

Formats the value using the given formatter.