pub struct Finder<'a>(_);Expand description
A single substring searcher fixed to a particular needle.
The purpose of this type is to permit callers to construct a substring
searcher that can be used to search haystacks without the overhead of
constructing the searcher in the first place. This is a somewhat niche
concern when it’s necessary to re-use the same needle to search multiple
different haystacks with as little overhead as possible. In general, using
ByteSlice::find
or
ByteSlice::find_iter
is good enough, but Finder is useful when you can meaningfully observe
searcher construction time in a profile.
When the std feature is enabled, then this type has an into_owned
version which permits building a Finder that is not connected to the
lifetime of its needle.
Implementations§
source§impl<'a> Finder<'a>
impl<'a> Finder<'a>
sourcepub fn new<B: ?Sized + AsRef<[u8]>>(needle: &'a B) -> Finder<'a>
pub fn new<B: ?Sized + AsRef<[u8]>>(needle: &'a B) -> Finder<'a>
Create a new finder for the given needle.
sourcepub fn into_owned(self) -> Finder<'static>
pub fn into_owned(self) -> Finder<'static>
Convert this finder into its owned variant, such that it no longer borrows the needle.
If this is already an owned finder, then this is a no-op. Otherwise, this copies the needle.
This is only available when the std feature is enabled.
sourcepub fn needle(&self) -> &[u8] ⓘ
pub fn needle(&self) -> &[u8] ⓘ
Returns the needle that this finder searches for.
Note that the lifetime of the needle returned is tied to the lifetime
of the finder, and may be shorter than the 'a lifetime. Namely, a
finder’s needle can be either borrowed or owned, so the lifetime of the
needle returned must necessarily be the shorter of the two.
sourcepub fn find<B: AsRef<[u8]>>(&self, haystack: B) -> Option<usize>
pub fn find<B: AsRef<[u8]>>(&self, haystack: B) -> Option<usize>
Returns the index of the first occurrence of this needle in the given haystack.
The haystack may be any type that can be cheaply converted into a
&[u8]. This includes, but is not limited to, &str and &[u8].
Complexity
This routine is guaranteed to have worst case linear time complexity
with respect to both the needle and the haystack. That is, this runs
in O(needle.len() + haystack.len()) time.
This routine is also guaranteed to have worst case constant space complexity.
Examples
Basic usage:
use bstr::Finder;
let haystack = "foo bar baz";
assert_eq!(Some(0), Finder::new("foo").find(haystack));
assert_eq!(Some(4), Finder::new("bar").find(haystack));
assert_eq!(None, Finder::new("quux").find(haystack));