Trait collections::str::pattern::DoubleEndedSearcher

pub trait DoubleEndedSearcher<'a>: ReverseSearcher<'a> { }

Unstable (pattern #27721)

: API not fully fleshed out and ready to be stabilized

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 of next_back() in reverse order.
• next() and next_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 from which side it is searched.

Implementors