alloc::slice::SliceIndex - Rust
Description: API documentation for the Rust `SliceIndex` trait in crate `alloc`.
Keywords: rust, rustlang, rust-lang, SliceIndex

# 1.28.0[−][src]Trait alloc::slice::SliceIndex

    pub trait SliceIndex<T>: Sealed where
        T: ?Sized, {
        type Output: ?Sized;
        fn get(self, slice: &T) -> Option<&Self::Output>;
        fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>;
        unsafe fn get_unchecked(self, slice: &T) -> &Self::Output;
        unsafe fn get_unchecked_mut(self, slice: &mut T) -> &mut Self::Output;
        fn index(self, slice: &T) -> &Self::Output;
        fn index_mut(self, slice: &mut T) -> &mut Self::Output;
    }

A helper trait used for indexing operations.

## Associated Types

### `type Output: ?Sized`

The output type returned by methods.

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## Required methods

### `fn get(self, slice: &T) -> 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 T) -> 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: &T) -> &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 T) -> &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: &T) -> &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 T) -> &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.

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## Implementations on Foreign Types

### `impl SliceIndex<str> for RangeInclusive<usize>`[src]

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

Returns a slice of the given string from the byte range [`begin`, `end`]. Equivalent to `&self [begin .. end + 1]` or `&mut self[begin .. end + 1]`, except if `end` has the maximum value for `usize`.

This operation is `O(1)`.

# Panics

Panics if `begin` does not point to the starting byte offset of a character (as defined by `is_char_boundary`), if `end` does not point to the ending byte offset of a character (`end + 1` is either a starting byte offset or equal to `len`), if `begin > end`, or if `end >= len`.

#### `type Output = str`

#### `fn get(
self,
slice: &str
) -> Option<&<RangeInclusive<usize> as SliceIndex<str>>::Output>`[src]

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

#### `fn get_mut(
self,
slice: &mut str
) -> Option<&mut <RangeInclusive<usize> as SliceIndex<str>>::Output>`[src]

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

####
ⓘImportant traits for RangeInclusive<A>

### Important traits for RangeInclusive<A>

`impl<A> Iterator for RangeInclusive<A> where
A: Step, type Item = A;`
`unsafe fn get_unchecked(
self,
slice: &str
) -> &<RangeInclusive<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for RangeInclusive<A>

### Important traits for RangeInclusive<A>

`impl<A> Iterator for RangeInclusive<A> where
A: Step, type Item = A;`
`unsafe fn get_unchecked_mut(
self,
slice: &mut str
) -> &mut <RangeInclusive<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for RangeInclusive<A>

### Important traits for RangeInclusive<A>

`impl<A> Iterator for RangeInclusive<A> where
A: Step, type Item = A;`
`fn index(
self,
slice: &str
) -> &<RangeInclusive<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for RangeInclusive<A>

### Important traits for RangeInclusive<A>

`impl<A> Iterator for RangeInclusive<A> where
A: Step, type Item = A;`
`fn index_mut(
self,
slice: &mut str
) -> &mut <RangeInclusive<usize> as SliceIndex<str>>::Output`[src]

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

### `impl<T> SliceIndex<[T]> for RangeToInclusive<usize>`[src]

#### `type Output = [T]`

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

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

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

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

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

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

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

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

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

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

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

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

### `impl SliceIndex<str> for RangeToInclusive<usize>`[src]

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 + 1]`, except if `end` has the maximum value for `usize`.

This operation is `O(1)`.

# Panics

Panics if `end` does not point to the ending byte offset of a character (`end + 1` is either a starting byte offset as defined by `is_char_boundary`, or equal to `len`), or if `end >= len`.

#### `type Output = str`

#### `fn get(
self,
slice: &str
) -> Option<&<RangeToInclusive<usize> as SliceIndex<str>>::Output>`[src]

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

#### `fn get_mut(
self,
slice: &mut str
) -> Option<&mut <RangeToInclusive<usize> as SliceIndex<str>>::Output>`[src]

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

#### `unsafe fn get_unchecked(
self,
slice: &str
) -> &<RangeToInclusive<usize> as SliceIndex<str>>::Output`[src]

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

#### `unsafe fn get_unchecked_mut(
self,
slice: &mut str
) -> &mut <RangeToInclusive<usize> as SliceIndex<str>>::Output`[src]

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

#### `fn index(
self,
slice: &str
) -> &<RangeToInclusive<usize> as SliceIndex<str>>::Output`[src]

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

#### `fn index_mut(
self,
slice: &mut str
) -> &mut <RangeToInclusive<usize> as SliceIndex<str>>::Output`[src]

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

### `impl<T> SliceIndex<[T]> for Range<usize>`[src]

#### `type Output = [T]`

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<T> SliceIndex<[T]> for RangeFull`[src]

#### `type Output = [T]`

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<T> SliceIndex<[T]> for RangeTo<usize>`[src]

#### `type Output = [T]`

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<T> SliceIndex<[T]> for RangeFrom<usize>`[src]

#### `type Output = [T]`

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

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

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

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

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

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

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

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

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

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

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

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

### `impl SliceIndex<str> for RangeFrom<usize>`[src]

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

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

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

#### `type Output = str`

#### `fn get(
self,
slice: &str
) -> Option<&<RangeFrom<usize> as SliceIndex<str>>::Output>`[src]

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

#### `fn get_mut(
self,
slice: &mut str
) -> Option<&mut <RangeFrom<usize> as SliceIndex<str>>::Output>`[src]

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

####
ⓘImportant traits for RangeFrom<A>

### Important traits for RangeFrom<A>

`impl<A> Iterator for RangeFrom<A> where
A: Step, type Item = A;`
`unsafe fn get_unchecked(
self,
slice: &str
) -> &<RangeFrom<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for RangeFrom<A>

### Important traits for RangeFrom<A>

`impl<A> Iterator for RangeFrom<A> where
A: Step, type Item = A;`
`unsafe fn get_unchecked_mut(
self,
slice: &mut str
) -> &mut <RangeFrom<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for RangeFrom<A>

### Important traits for RangeFrom<A>

`impl<A> Iterator for RangeFrom<A> where
A: Step, type Item = A;`
`fn index(self, slice: &str) -> &<RangeFrom<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for RangeFrom<A>

### Important traits for RangeFrom<A>

`impl<A> Iterator for RangeFrom<A> where
A: Step, type Item = A;`
`fn index_mut(
self,
slice: &mut str
) -> &mut <RangeFrom<usize> as SliceIndex<str>>::Output`[src]

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

### `impl SliceIndex<str> for RangeTo<usize>`[src]

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`

#### `fn get(
self,
slice: &str
) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>`[src]

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

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

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

#### `unsafe fn get_unchecked(
self,
slice: &str
) -> &<RangeTo<usize> as SliceIndex<str>>::Output`[src]

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

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

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

#### `fn index(self, slice: &str) -> &<RangeTo<usize> as SliceIndex<str>>::Output`[src]

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

#### `fn index_mut(
self,
slice: &mut str
) -> &mut <RangeTo<usize> as SliceIndex<str>>::Output`[src]

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

### `impl SliceIndex<str> for RangeFull`[src]

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

Returns a slice of the whole string, i.e., returns `&self` or `&mut self`. Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`. Unlike other indexing operations, this can never panic.

This operation is `O(1)`.

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

Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`.

#### `type Output = str`

#### `fn get(self, slice: &str) -> Option<&<RangeFull as SliceIndex<str>>::Output>`[src]

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

#### `fn get_mut(
self,
slice: &mut str
) -> Option<&mut <RangeFull as SliceIndex<str>>::Output>`[src]

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

#### `unsafe fn get_unchecked(
self,
slice: &str
) -> &<RangeFull as SliceIndex<str>>::Output`[src]

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

#### `unsafe fn get_unchecked_mut(
self,
slice: &mut str
) -> &mut <RangeFull as SliceIndex<str>>::Output`[src]

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

#### `fn index(self, slice: &str) -> &<RangeFull as SliceIndex<str>>::Output`[src]

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

#### `fn index_mut(
self,
slice: &mut str
) -> &mut <RangeFull as SliceIndex<str>>::Output`[src]

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

### `impl SliceIndex<str> for Range<usize>`[src]

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

Returns a slice of the given string from the byte range [`begin`, `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 `begin` or `end` does not point to the starting byte offset of a character (as defined by `is_char_boundary`), if `begin > end`, or if `end > len`.

# Examples

    let s = "Löwe 老虎 Léopard";
    assert_eq!(&s[0 .. 1], "L");

    assert_eq!(&s[1 .. 9], "öwe 老");

    // these will panic:
    // byte 2 lies within `ö`:
    // &s[2 ..3];

    // byte 8 lies within `老`
    // &s[1 .. 8];

    // byte 100 is outside the string
    // &s[3 .. 100];

#### `type Output = str`

#### `fn get(self, slice: &str) -> Option<&<Range<usize> as SliceIndex<str>>::Output>`[src]

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

#### `fn get_mut(
self,
slice: &mut str
) -> Option<&mut <Range<usize> as SliceIndex<str>>::Output>`[src]

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

####
ⓘImportant traits for Range<A>

### Important traits for Range<A>

`impl<A> Iterator for Range<A> where
A: Step, type Item = A;`
`unsafe fn get_unchecked(
self,
slice: &str
) -> &<Range<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for Range<A>

### Important traits for Range<A>

`impl<A> Iterator for Range<A> where
A: Step, type Item = A;`
`unsafe fn get_unchecked_mut(
self,
slice: &mut str
) -> &mut <Range<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for Range<A>

### Important traits for Range<A>

`impl<A> Iterator for Range<A> where
A: Step, type Item = A;`
`fn index(self, slice: &str) -> &<Range<usize> as SliceIndex<str>>::Output`[src]

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

####
ⓘImportant traits for Range<A>

### Important traits for Range<A>

`impl<A> Iterator for Range<A> where
A: Step, type Item = A;`
`fn index_mut(
self,
slice: &mut str
) -> &mut <Range<usize> as SliceIndex<str>>::Output`[src]

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

### `impl<T> SliceIndex<[T]> for RangeInclusive<usize>`[src]

#### `type Output = [T]`

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<T> SliceIndex<[T]> for usize`[src]

#### `type Output = T`

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

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

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

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

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

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

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

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

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

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

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

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