More micro-optimizations

utils/index_group_parser.go

@@ -27,11 +27,8 @@ func ParseIndexGroups(spec string) IndexGroups {
 	for _, g := range split {
 		sub := indexGroupsRx.FindStringSubmatch(g)
 		if len(sub) > 0 {
-			i := 0
-			chars := strings.Split(sub[2], "")
-			for _, c := range chars {
-				parsed[c] = sub[1]
-				i++
+			for _, c := range sub[2] {
+				parsed[string(c)] = sub[1]
 			}
 		} else {
 			parsed[g] = g

utils/merge/merge_fs.go

@@ -1,10 +1,13 @@
 package merge
 
 import (
+	"cmp"
 	"errors"
 	"io"
 	"io/fs"
-	"sort"
+	"slices"
+
+	"golang.org/x/exp/maps"
 )
 
 // FS implements a simple merged fs.FS, that can combine a Base FS with an Overlay FS. The semantics are:
@@ -44,33 +47,26 @@ func (m FS) Open(name string) (fs.File, error) {
 }
 
 func (m FS) mergeDirs(name string, info fs.FileInfo, baseDir fs.ReadDirFile, overlayDir fs.ReadDirFile) (fs.File, error) {
-	merged := map[string]fs.DirEntry{}
-
 	baseFiles, err := baseDir.ReadDir(-1)
 	if err != nil {
 		return nil, err
 	}
-	sort.Slice(baseFiles, func(i, j int) bool { return baseFiles[i].Name() < baseFiles[j].Name() })
 
 	overlayFiles, err := overlayDir.ReadDir(-1)
 	if err != nil {
 		overlayFiles = nil
 	}
-	sort.Slice(overlayFiles, func(i, j int) bool { return overlayFiles[i].Name() < overlayFiles[j].Name() })
 
+	merged := map[string]fs.DirEntry{}
 	for _, f := range baseFiles {
 		merged[f.Name()] = f
 	}
 	for _, f := range overlayFiles {
 		merged[f.Name()] = f
 	}
+	entries := maps.Values(merged)
 
-	var entries []fs.DirEntry
-	for _, i := range merged {
-		entries = append(entries, i)
-	}
-
-	sort.Slice(entries, func(i, j int) bool { return entries[i].Name() < entries[j].Name() })
+	slices.SortFunc(entries, func(i, j fs.DirEntry) int { return cmp.Compare(i.Name(), j.Name()) })
 	return &mergedDir{
 		name:    name,
 		info:    info,

utils/str/str.go

@@ -4,16 +4,17 @@ import (
 	"strings"
 )
 
+var utf8ToAscii = strings.NewReplacer(
+	"–", "-",
+	"‐", "-",
+	"“", `"`,
+	"”", `"`,
+	"‘", `'`,
+	"’", `'`,
+)
+
 func Clear(name string) string {
-	r := strings.NewReplacer(
-		"–", "-",
-		"‐", "-",
-		"“", `"`,
-		"”", `"`,
-		"‘", `'`,
-		"’", `'`,
-	)
-	return r.Replace(name)
+	return utf8ToAscii.Replace(name)
 }
 
 func LongestCommonPrefix(list []string) string {