Struct Two
pub struct Two(/* private fields */);
dep_memchr
only.Expand description
Finds all occurrences of two bytes in a haystack.
That is, this reports matches of one of two possible bytes. For example,
searching for a
or b
in afoobar
would report matches at offsets 0
,
4
and 5
.
Implementations§
§impl Two
impl Two
pub fn new(needle1: u8, needle2: u8) -> Option<Two> ⓘ
pub fn new(needle1: u8, needle2: u8) -> Option<Two> ⓘ
Create a new searcher that finds occurrences of the needle bytes given.
This particular searcher is specialized to use SSE2 vector instructions that typically make it quite fast.
If SSE2 is unavailable in the current environment, then None
is
returned.
pub unsafe fn new_unchecked(needle1: u8, needle2: u8) -> Two
pub unsafe fn new_unchecked(needle1: u8, needle2: u8) -> Two
Create a new finder specific to SSE2 vectors and routines without checking that SSE2 is available.
§Safety
Callers must guarantee that it is safe to execute sse2
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
pub fn is_available() -> bool
Returns true when this implementation is available in the current environment.
When this is true, it is guaranteed that Two::new
will return
a Some
value. Similarly, when it is false, it is guaranteed that
Two::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> ⓘ
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> ⓘ
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 unsafe fn find_raw(
&self,
start: *const u8,
end: *const u8,
) -> Option<*const u8> ⓘ
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
andend
must be valid for reads. - Both
start
andend
must point to an initialized value. - Both
start
andend
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
andend
must be derived from a pointer to the same object. - The distance between
start
andend
must not overflowisize
. - 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> ⓘ
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
andend
must be valid for reads. - Both
start
andend
must point to an initialized value. - Both
start
andend
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
andend
must be derived from a pointer to the same object. - The distance between
start
andend
must not overflowisize
. - 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.
Trait Implementations§
Auto Trait Implementations§
impl Freeze for Two
impl RefUnwindSafe for Two
impl Send for Two
impl Sync for Two
impl Unpin for Two
impl UnwindSafe for Two
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