D7178: [RFC] rust-matchers: add `Matcher` trait and implement `AlwaysMatcher`

[yuja (Yuya Nishihara)]

yuja added a comment.


  > +pub trait Matcher {
  > +    /// Explicitly listed files
  > +    fn file_set(&self) -> HashSet<&HgPath>;
  
  [...]
  
  > +    /// Matcher will match everything and `files_set()` will be empty:
  > +    /// optimization might be possible.
  > +    fn matches_everything(&self) -> bool {
  > +        false
  > +    }
  
  Maybe better to not provide the default implementations since not a few
  matchers will have to reimplement them.
  
  > +impl Matcher for AlwaysMatcher {
  > +    fn file_set(&self) -> HashSet<&HgPath> {
  > +        HashSet::new()
  > +    }
  > +
  > +    fn visit_children_set(
  > +        &self,
  > +        _directory: impl AsRef<HgPath>,
  > +    ) -> VisitChildrenSet {
  > +        VisitChildrenSet::Recursive
  > +    }
  
  Need to implement `matches()` and `matches_everything()`?

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D7178/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D7178

To: Alphare, #hg-reviewers
Cc: yuja, martinvonz, spectral, durin42, kevincox, mercurial-devel