Trait Searcher

unsafe trait Searcher<'a>

A searcher for a string pattern.

This trait provides methods for searching for non-overlapping matches of a pattern starting from the front (left) of a string.

It will be implemented by associated Searcher types of the Pattern trait.

The trait is marked unsafe because the indices returned by the [next()][Searcher::next] methods are required to lie on valid utf8 boundaries in the haystack. This enables consumers of this trait to slice the haystack without additional runtime checks.

Required Methods

fn haystack(self: &Self) -> &'a str

Getter for the underlying string to be searched in

Will always return the same [&str][str].

fn next(self: &mut Self) -> SearchStep

Performs the next search step starting from the front.

  • Returns [Match(a, b)][SearchStep::Match] if haystack[a..b] matches the pattern.
  • Returns [Reject(a, b)][SearchStep::Reject] if haystack[a..b] can not match the pattern, even partially.
  • Returns [Done][SearchStep::Done] if every byte of the haystack has been visited.

The stream of [Match][SearchStep::Match] and [Reject][SearchStep::Reject] values up to a [Done][SearchStep::Done] will contain index ranges that are adjacent, non-overlapping, covering the whole haystack, and laying on utf8 boundaries.

A [Match][SearchStep::Match] result needs to contain the whole matched pattern, however [Reject][SearchStep::Reject] results may be split up into arbitrary many adjacent fragments. Both ranges may have zero length.

As an example, the pattern "aaa" and the haystack "cbaaaaab" might produce the stream [Reject(0, 1), Reject(1, 2), Match(2, 5), Reject(5, 8)]

Provided Methods

fn next_match(self: &mut Self) -> Option<(usize, usize)>

Finds the next [Match][SearchStep::Match] result. See [next()][Searcher::next].

Unlike [next()][Searcher::next], there is no guarantee that the returned ranges of this and [next_reject][Searcher::next_reject] will overlap. This will return (start_match, end_match), where start_match is the index of where the match begins, and end_match is the index after the end of the match.

fn next_reject(self: &mut Self) -> Option<(usize, usize)>

Finds the next [Reject][SearchStep::Reject] result. See [next()][Searcher::next] and [next_match()][Searcher::next_match].

Unlike [next()][Searcher::next], there is no guarantee that the returned ranges of this and [next_match][Searcher::next_match] will overlap.

Implementors