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      ]); // This is a `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).

Implementations

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

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

Returns true if item is contained in the range.

Examples

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

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,
    Self: Sized,

Feeds a slice of this type into the given Hasher.

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.

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: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

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) -> boolwhere
    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) -> boolwhere
    T: PartialOrd<U>,
    U: PartialOrd<T> + ?Sized,

Returns true if item is contained in the range.

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)

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)

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

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

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

Returns a shared reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

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

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

Returns a mutable reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

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

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

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)

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<&<RangeTo<usize> as SliceIndex<str>>::Output>

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

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)

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

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

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

Returns a shared reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

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)

Returns a mutable reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

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

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

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)

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

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

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

impl<T> OneSidedRange<T> for RangeTo<T>where
    RangeTo<T>: RangeBounds<T>,

impl<Idx> StructuralEq for RangeTo<Idx>

impl<Idx> StructuralPartialEq for RangeTo<Idx>