Struct memchr::arch::x86_64::avx2::memchr::One

pub struct One { /* private fields */ }

Finds all occurrences of a single byte in a haystack.

Implementations

impl One

pub fn new(needle: u8) -> Option<One>

Create a new searcher that finds occurrences of the needle byte given.

This particular searcher is specialized to use AVX2 vector instructions that typically make it quite fast. (SSE2 is used for haystacks that are too short to accommodate an AVX2 vector.)

If either SSE2 or AVX2 is unavailable in the current environment, then None is returned.

pub unsafe fn new_unchecked(needle: u8) -> One

Available on target features sse2 and avx2 only.

Create a new finder specific to AVX2 vectors and routines without checking that either SSE2 or AVX2 is available.

Safety

Callers must guarantee that it is safe to execute both sse2 and avx2 instructions in the current environment.

Note that it is a common misconception that if one compiles for an x86_64 target, then they therefore automatically have access to SSE2 instructions. While this is almost always the case, it isn’t true in 100% of cases.

pub fn is_available() -> bool

Returns true when this implementation is available in the current environment.

When this is true, it is guaranteed that One::new will return a Some value. Similarly, when it is false, it is guaranteed that One::new will return a None value.

Note also that for the lifetime of a single program, if this returns true then it will always return true.

pub fn find(&self, haystack: &[u8]) -> Option<usize>

Return the first occurrence of one of the needle bytes in the given haystack. If no such occurrence exists, then None is returned.

The occurrence is reported as an offset into haystack. Its maximum value is haystack.len() - 1.

pub fn rfind(&self, haystack: &[u8]) -> Option<usize>

Return the last occurrence of one of the needle bytes in the given haystack. If no such occurrence exists, then None is returned.

The occurrence is reported as an offset into haystack. Its maximum value is haystack.len() - 1.

pub fn count(&self, haystack: &[u8]) -> usize

Counts all occurrences of this byte in the given haystack.

pub unsafe fn find_raw( &self, start: *const u8, end: *const u8 ) -> Option<*const u8>

Like find, but accepts and returns raw pointers.

When a match is found, the pointer returned is guaranteed to be >= start and < end.

This routine is useful if you’re already using raw pointers and would like to avoid converting back to a slice before executing a search.

Safety

• Both start and end must be valid for reads.
• Both start and end must point to an initialized value.
• Both start and end must point to the same allocated object and must either be in bounds or at most one byte past the end of the allocated object.
• Both start and end must be derived from a pointer to the same object.
• The distance between start and end must not overflow isize.
• The distance being in bounds must not rely on “wrapping around” the address space.

Note that callers may pass a pair of pointers such that start >= end. In that case, None will always be returned.

pub unsafe fn rfind_raw( &self, start: *const u8, end: *const u8 ) -> Option<*const u8>

Like rfind, but accepts and returns raw pointers.

When a match is found, the pointer returned is guaranteed to be >= start and < end.

This routine is useful if you’re already using raw pointers and would like to avoid converting back to a slice before executing a search.

Safety

• Both start and end must be valid for reads.
• Both start and end must point to an initialized value.
• Both start and end must point to the same allocated object and must either be in bounds or at most one byte past the end of the allocated object.
• Both start and end must be derived from a pointer to the same object.
• The distance between start and end must not overflow isize.
• The distance being in bounds must not rely on “wrapping around” the address space.

Note that callers may pass a pair of pointers such that start >= end. In that case, None will always be returned.

pub unsafe fn count_raw(&self, start: *const u8, end: *const u8) -> usize

Counts all occurrences of this byte in the given haystack represented by raw pointers.

This routine is useful if you’re already using raw pointers and would like to avoid converting back to a slice before executing a search.

Safety

• Both start and end must be valid for reads.
• Both start and end must point to an initialized value.
• Both start and end must point to the same allocated object and must either be in bounds or at most one byte past the end of the allocated object.
• Both start and end must be derived from a pointer to the same object.
• The distance between start and end must not overflow isize.
• The distance being in bounds must not rely on “wrapping around” the address space.

Note that callers may pass a pair of pointers such that start >= end. In that case, 0 will always be returned.

pub fn iter<'a, 'h>(&'a self, haystack: &'h [u8]) -> OneIter<'a, 'h>

Returns an iterator over all occurrences of the needle byte in the given haystack.

The iterator returned implements DoubleEndedIterator. This means it can also be used to find occurrences in reverse order.

Trait Implementations

impl Clone for One

fn clone(&self) -> One

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for One

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for One