diff rust/hg-core/src/matchers.rs @ 48311:6d69e83e6b6e

rhg: more efficient `HgPath::join`

This commit makes `HgPath::join` slightly more efficient
by avoiding one copy.

It also avoids a particularly inefficient (quadratic) use of
`HgPath::join` by using a new mutating function `HgPathBuf::push` instead.

The name for `HgPathBuf::push` is chosen by analogy to `PathBuf::push`.

Differential Revision: https://phab.mercurial-scm.org/D11721

--- a/rust/hg-core/src/matchers.rs	Tue Nov 09 15:25:38 2021 +0100
+++ b/rust/hg-core/src/matchers.rs	Tue Oct 26 19:47:30 2021 +0100
@@ -391,8 +391,7 @@
         } = ignore_pattern;
         match syntax {
             PatternSyntax::RootGlob | PatternSyntax::Glob => {
-                let mut root = vec![];
-
+                let mut root = HgPathBuf::new();
                 for p in pattern.split(|c| *c == b'/') {
                     if p.iter().any(|c| match *c {
                         b'[' | b'{' | b'*' | b'?' => true,
@@ -400,11 +399,9 @@
                     }) {
                         break;
                     }
-                    root.push(HgPathBuf::from_bytes(p));
+                    root.push(HgPathBuf::from_bytes(p).as_ref());
                 }
-                let buf =
-                    root.iter().fold(HgPathBuf::new(), |acc, r| acc.join(r));
-                roots.push(buf);
+                roots.push(root);
             }
             PatternSyntax::Path | PatternSyntax::RelPath => {
                 let pat = HgPath::new(if pattern == b"." {