eliminate redundant renews for sort changes

Mentioned in #92.

eval.go

@@ -19,13 +19,13 @@ func (e *setExpr) eval(app *app, args []string) {
 		gOpts.dircounts = !gOpts.dircounts
 	case "dirfirst":
 		gOpts.dirfirst = true
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "nodirfirst":
 		gOpts.dirfirst = false
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "dirfirst!":
 		gOpts.dirfirst = !gOpts.dirfirst
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "globsearch":
 		gOpts.globsearch = true
 	case "noglobsearch":
@@ -55,13 +55,13 @@ func (e *setExpr) eval(app *app, args []string) {
 		gOpts.preview = !gOpts.preview
 	case "reverse":
 		gOpts.reverse = true
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "noreverse":
 		gOpts.reverse = false
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "reverse!":
 		gOpts.reverse = !gOpts.reverse
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "smartcase":
 		gOpts.smartcase = true
 	case "nosmartcase":
@@ -124,7 +124,7 @@ func (e *setExpr) eval(app *app, args []string) {
 			return
 		}
 		gOpts.sortby = e.val
-		app.nav.renew(app.nav.height)
+		app.nav.sort()
 	case "timefmt":
 		gOpts.timefmt = e.val
 	case "ratios":

nav.go

@@ -140,10 +140,19 @@ type dir struct {
 }
 
 func newDir(path string) *dir {
-	return &dir{
-		path: path,
-		fi:   getFilesSorted(path),
+	fi, err := readdir(path)
+	if err != nil {
+		log.Printf("reading directory: %s", err)
 	}
+
+	dir := &dir{
+		path: path,
+		fi:   fi,
+	}
+
+	dir.sort()
+
+	return dir
 }
 
 func (dir *dir) renew(height int) {
@@ -152,11 +161,56 @@ func (dir *dir) renew(height int) {
 		name = dir.fi[dir.ind].Name()
 	}
 
-	dir.fi = getFilesSorted(dir.path)
+	fi, err := readdir(dir.path)
+	if err != nil {
+		log.Printf("reading directory: %s", err)
+	}
+
+	dir.fi = fi
+
+	dir.sort()
 
 	dir.load(dir.ind, dir.pos, height, name)
 }
 
+func (dir *dir) sort() {
+	switch gOpts.sortby {
+	case "natural":
+		sortFilesStable(dir.fi, func(i, j int) bool {
+			return naturalLess(strings.ToLower(dir.fi[i].Name()), strings.ToLower(dir.fi[j].Name()))
+		})
+	case "name":
+		sortFilesStable(dir.fi, func(i, j int) bool {
+			return strings.ToLower(dir.fi[i].Name()) < strings.ToLower(dir.fi[j].Name())
+		})
+	case "size":
+		sortFilesStable(dir.fi, func(i, j int) bool {
+			return dir.fi[i].Size() < dir.fi[j].Size()
+		})
+	case "time":
+		sortFilesStable(dir.fi, func(i, j int) bool {
+			return dir.fi[i].ModTime().Before(dir.fi[j].ModTime())
+		})
+	default:
+		log.Printf("unknown sorting type: %s", gOpts.sortby)
+	}
+
+	if gOpts.reverse {
+		for i, j := 0, len(dir.fi)-1; i < j; i, j = i+1, j-1 {
+			dir.fi[i], dir.fi[j] = dir.fi[j], dir.fi[i]
+		}
+	}
+
+	if gOpts.dirfirst {
+		sortFilesStable(dir.fi, func(i, j int) bool {
+			if dir.fi[i].IsDir() == dir.fi[j].IsDir() {
+				return i < j
+			}
+			return dir.fi[i].IsDir()
+		})
+	}
+}
+
 func (dir *dir) load(ind, pos, height int, name string) {
 	if len(dir.fi) == 0 {
 		dir.ind, dir.pos = 0, 0
@@ -252,6 +306,12 @@ func (nav *nav) renew(height int) {
 	}
 }
 
+func (nav *nav) sort() {
+	for _, d := range nav.dirs {
+		d.sort()
+	}
+}
+
 func (nav *nav) up(dist int) {
 	dir := nav.currDir()