Sort By Access Time and Change Time (#226)

- Add access time and change time as sort by types. This is
  powered by github.com/djherbis/times.
- Fall back to modification time if access time and change time
  cannot be determined.
- Add `sa` and `sc` as default bindings for sort by access time and
  sort by change time respectively.
- Add access time and change time to info types allowing them to be
  displayed by the file list in the ui

docstring.go

@@ -177,6 +177,8 @@ The following additional keybindings are provided by default:
     map sn :set sortby natural; set info
     map ss :set sortby size; set info size
     map st :set sortby time; set info time
+    map sa :set sortby atime; set info atime
+    map sc :set sortby ctime; set info ctime
     map gh cd ~
 
 The following keybindings to applications are provided by default:

eval.go

@@ -238,10 +238,6 @@ func (e *setExpr) eval(app *app, args []string) {
 	case "shell":
 		gOpts.shell = e.val
 	case "sortby":
-		if e.val != "natural" && e.val != "name" && e.val != "size" && e.val != "time" {
-			app.ui.echoerr("sortby: value should either be 'natural', 'name', 'size' or 'time'")
-			return
-		}
 		switch e.val {
 		case "natural":
 			gOpts.sortType.method = naturalSort
@@ -251,6 +247,13 @@ func (e *setExpr) eval(app *app, args []string) {
 			gOpts.sortType.method = sizeSort
 		case "time":
 			gOpts.sortType.method = timeSort
+		case "ctime":
+			gOpts.sortType.method = ctimeSort
+		case "atime":
+			gOpts.sortType.method = atimeSort
+		default:
+			app.ui.echoerr("sortby: value should either be 'natural', 'name', 'size', 'time', 'atime' or 'ctime'")
+			return
 		}
 		app.nav.sort()
 		app.ui.sort()
@@ -281,8 +284,10 @@ func (e *setExpr) eval(app *app, args []string) {
 	case "info":
 		toks := strings.Split(e.val, ":")
 		for _, s := range toks {
-			if s != "" && s != "size" && s != "time" {
-				app.ui.echoerr("info: should consist of 'size' or 'time' separated with colon")
+			switch s {
+			case "", "size", "time", "atime", "ctime":
+			default:
+				app.ui.echoerr("info: should consist of 'size', 'time', 'atime' or 'ctime' separated with colon")
 				return
 			}
 		}

go.mod

@@ -5,4 +5,5 @@ go 1.12
 require (
 	github.com/mattn/go-runewidth v0.0.4
 	github.com/nsf/termbox-go v0.0.0-20190325093121-288510b9734e
+	gopkg.in/djherbis/times.v1 v1.2.0
 )

go.sum

@@ -2,3 +2,5 @@ github.com/mattn/go-runewidth v0.0.4 h1:2BvfKmzob6Bmd4YsL0zygOqfdFnK7GR4QL06Do4/
 github.com/mattn/go-runewidth v0.0.4/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/nsf/termbox-go v0.0.0-20190325093121-288510b9734e h1:Vbib8wJAaMEF9jusI/kMSYMr/LtRzM7+F9MJgt/nH8k=
 github.com/nsf/termbox-go v0.0.0-20190325093121-288510b9734e/go.mod h1:IuKpRQcYE1Tfu+oAQqaLisqDeXgjyyltCfsaoYN18NQ=
+gopkg.in/djherbis/times.v1 v1.2.0 h1:UCvDKl1L/fmBygl2Y7hubXCnY7t4Yj46ZrBFNUipFbM=
+gopkg.in/djherbis/times.v1 v1.2.0/go.mod h1:AQlg6unIsrsCEdQYhTzERy542dz6SFdQFZFv6mUY0P8=

nav.go

@@ -13,6 +13,8 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	times "gopkg.in/djherbis/times.v1"
 )
 
 type linkState byte
@@ -25,9 +27,11 @@ const (
 
 type file struct {
 	os.FileInfo
-	linkState linkState
-	path      string
-	dirCount  int
+	linkState  linkState
+	path       string
+	dirCount   int
+	accessTime time.Time
+	changeTime time.Time
 }
 
 func readdir(path string) ([]*file, error) {
@@ -62,11 +66,24 @@ func readdir(path string) ([]*file, error) {
 			}
 		}
 
+		ts := times.Get(lstat)
+		at := ts.AccessTime()
+		var ct time.Time
+		// from times docs: ChangeTime() panics unless HasChangeTime() is true
+		if ts.HasChangeTime() {
+			ct = ts.ChangeTime()
+		} else {
+			// fall back to ModTime if ChangeTime cannot be determined
+			ct = lstat.ModTime()
+		}
+
 		files = append(files, &file{
-			FileInfo:  lstat,
-			linkState: linkState,
-			path:      fpath,
-			dirCount:  -1,
+			FileInfo:   lstat,
+			linkState:  linkState,
+			path:       fpath,
+			dirCount:   -1,
+			accessTime: at,
+			changeTime: ct,
 		})
 	}
 
@@ -124,6 +141,14 @@ func (dir *dir) sort() {
 		sort.SliceStable(dir.files, func(i, j int) bool {
 			return dir.files[i].ModTime().Before(dir.files[j].ModTime())
 		})
+	case atimeSort:
+		sort.SliceStable(dir.files, func(i, j int) bool {
+			return dir.files[i].accessTime.Before(dir.files[j].accessTime)
+		})
+	case ctimeSort:
+		sort.SliceStable(dir.files, func(i, j int) bool {
+			return dir.files[i].changeTime.Before(dir.files[j].changeTime)
+		})
 	}
 
 	if gOpts.sortType.option&reverseSort != 0 {

opts.go

@@ -9,6 +9,8 @@ const (
 	nameSort
 	sizeSort
 	timeSort
+	atimeSort
+	ctimeSort
 )
 
 type sortOption byte
@@ -153,6 +155,8 @@ func init() {
 	gOpts.keys["sn"] = &listExpr{[]expr{&setExpr{"sortby", "natural"}, &setExpr{"info", ""}}}
 	gOpts.keys["ss"] = &listExpr{[]expr{&setExpr{"sortby", "size"}, &setExpr{"info", "size"}}}
 	gOpts.keys["st"] = &listExpr{[]expr{&setExpr{"sortby", "time"}, &setExpr{"info", "time"}}}
+	gOpts.keys["sa"] = &listExpr{[]expr{&setExpr{"sortby", "atime"}, &setExpr{"info", "atime"}}}
+	gOpts.keys["sc"] = &listExpr{[]expr{&setExpr{"sortby", "ctime"}, &setExpr{"info", "ctime"}}}
 	gOpts.keys["gh"] = &callExpr{"cd", []string{"~"}, 1}
 
 	gOpts.cmdkeys = make(map[string]expr)

ui.go

@@ -231,6 +231,10 @@ func fileInfo(f *file, d *dir) string {
 			}
 		case "time":
 			info = fmt.Sprintf("%s %12s", info, f.ModTime().Format("Jan _2 15:04"))
+		case "atime":
+			info = fmt.Sprintf("%s %12s", info, f.accessTime.Format("Jan _2 15:04"))
+		case "ctime":
+			info = fmt.Sprintf("%s %12s", info, f.changeTime.Format("Jan _2 15:04"))
 		default:
 			log.Printf("unknown info type: %s", s)
 		}