# Trait std::slice::SliceIndex

1.28.0 · source ·

    pub unsafe trait SliceIndex<T>: Sealedwhere
        T: ?Sized,{
        type Output: ?Sized;

        // Required methods
        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: *const T) -> *const 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;
    }

Expand description

A helper trait used for indexing operations.

Implementations of this trait have to promise that if the argument to `get_unchecked(_mut)` is a safe reference, then so is the result.

## Required Associated Types§

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#### type Output: ?Sized

The output type returned by methods.

## Required Methods§

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#### fn get(self, slice: &T) -> Option<&Self::Output>

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

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

source

#### fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>

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

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

source

#### unsafe fn get_unchecked(self, slice: *const T) -> *const Self::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.

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#### unsafe fn get_unchecked_mut(self, slice: *mut T) -> *mut Self::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.

source

#### fn index(self, slice: &T) -> &Self::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.

source

#### fn index_mut(self, slice: &mut T) -> &mut Self::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.

## Implementors§

1.73.0 · source§

### impl SliceIndex<str> for (Bound<usize>, Bound<usize>)

Implements substring slicing for arbitrary bounds.

Returns a slice of the given string bounded by the byte indices provided by each bound.

This operation is O(1).

#### Panics

Panics if `begin` or `end` (if it exists and once adjusted for inclusion/exclusion) does not point to the starting byte offset of a character (as defined by `is_char_boundary`), if `begin > end`, or if `end > len`.

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#### type Output = str

1.20.0 (const: unstable) · source§

### impl SliceIndex<str> for Range<usize>

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];

Run
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#### type Output = str

1.20.0 (const: unstable) · source§

### impl SliceIndex<str> for RangeFrom<usize>

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`.

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#### type Output = str

1.20.0 (const: unstable) · source§

### impl SliceIndex<str> for RangeFull

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]`.

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#### type Output = str

1.26.0 (const: unstable) · source§

### impl SliceIndex<str> for RangeInclusive<usize>

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`.

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#### type Output = str

1.20.0 (const: unstable) · source§

### 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`.

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#### type Output = str

1.26.0 (const: unstable) · source§

### impl SliceIndex<str> for RangeToInclusive<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 + 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`.

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#### type Output = str

1.53.0 · source§

### impl<T> SliceIndex<[T]> for (Bound<usize>, Bound<usize>)

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#### type Output = [T]

1.15.0 (const: unstable) · source§

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

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#### type Output = T

1.15.0 (const: unstable) · source§

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

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#### type Output = [T]

1.15.0 (const: unstable) · source§

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

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#### type Output = [T]

1.15.0 (const: unstable) · source§

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

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#### type Output = [T]

1.26.0 (const: unstable) · source§

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

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#### type Output = [T]

1.15.0 (const: unstable) · source§

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

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#### type Output = [T]

1.26.0 (const: unstable) · source§

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

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#### type Output = [T]