Trait tracing_core::stdlib::str::pattern::DoubleEndedSearcher
source · pub trait DoubleEndedSearcher<'a>: ReverseSearcher<'a> { }
🔬This is a nightly-only experimental API. (
pattern
#27721)Expand description
A marker trait to express that a ReverseSearcher
can be used for a DoubleEndedIterator
implementation.
For this, the impl of Searcher
and ReverseSearcher
need
to follow these conditions:
- All results of
next()
need to be identical to the results ofnext_back()
in reverse order. next()
andnext_back()
need to behave as the two ends of a range of values, that is they can not “walk past each other”.
§Examples
char::Searcher
is a DoubleEndedSearcher
because searching for a
char
only requires looking at one at a time, which behaves the same
from both ends.
(&str)::Searcher
is not a DoubleEndedSearcher
because
the pattern "aa"
in the haystack "aaa"
matches as either
"[aa]a"
or "a[aa]"
, depending on which side it is searched.