rust-matchers: improve `Matcher` trait ergonomics
`VisitChildrenSet` has no need to own the set, this will save allocations.
The `file_set` return type change is motivated by both ergonomics and... being
able to compile code.
The `AlwaysMatcher` does not store a `file_set`, which requires it to return an
owned `HashSet`, which in turn would change our return type to `Cow<&HgPath>`
(lifetimes omitted). This is both un-ergonomic and troublesome for more
complex lifetime issues (especially with the upcoming `FileMatcher` in the
following patch).
Differential Revision: https://phab.mercurial-scm.org/D7525
--- a/rust/hg-core/src/matchers.rs Fri Nov 29 17:19:34 2019 +0100
+++ b/rust/hg-core/src/matchers.rs Fri Nov 29 18:33:56 2019 +0100
@@ -10,21 +10,21 @@
use crate::utils::hg_path::{HgPath, HgPathBuf};
use std::collections::HashSet;
-pub enum VisitChildrenSet {
+pub enum VisitChildrenSet<'a> {
/// Don't visit anything
Empty,
/// Only visit this directory
This,
/// Visit this directory and these subdirectories
/// TODO Should we implement a `NonEmptyHashSet`?
- Set(HashSet<HgPathBuf>),
+ Set(HashSet<&'a HgPath>),
/// Visit this directory and all subdirectories
Recursive,
}
pub trait Matcher {
/// Explicitly listed files
- fn file_set(&self) -> HashSet<&HgPath>;
+ fn file_set(&self) -> Option<&HashSet<&HgPath>>;
/// Returns whether `filename` is in `file_set`
fn exact_match(&self, filename: impl AsRef<HgPath>) -> bool;
/// Returns whether `filename` is matched by this matcher
@@ -82,8 +82,8 @@
pub struct AlwaysMatcher;
impl Matcher for AlwaysMatcher {
- fn file_set(&self) -> HashSet<&HgPath> {
- HashSet::new()
+ fn file_set(&self) -> Option<&HashSet<&HgPath>> {
+ None
}
fn exact_match(&self, _filename: impl AsRef<HgPath>) -> bool {
false