add 'period' option for periodic refresh

Related #73

app.go

@@ -9,6 +9,7 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+	"time"
 )
 
 type cmdItem struct {
@@ -19,6 +20,7 @@ type cmdItem struct {
 type app struct {
 	ui            *ui
 	nav           *nav
+	ticker        *time.Ticker
 	quitChan      chan bool
 	cmd           *exec.Cmd
 	cmdIn         io.WriteCloser
@@ -34,6 +36,7 @@ func newApp() *app {
 	return &app{
 		ui:       ui,
 		nav:      nav,
+		ticker:   new(time.Ticker),
 		quitChan: make(chan bool, 1),
 	}
 }
@@ -132,6 +135,10 @@ func (app *app) loop() {
 		case e := <-serverChan:
 			e.eval(app, nil)
 			app.ui.draw(app.nav)
+		case <-app.ticker.C:
+			app.nav.renew()
+			app.ui.loadFile(app.nav)
+			app.ui.draw(app.nav)
 		}
 	}
 }

complete.go

@@ -82,6 +82,7 @@ var (
 		"wrapscan",
 		"nowrapscan",
 		"wrapscan!",
+		"period",
 		"scrolloff",
 		"tabstop",
 		"filesep",

doc.go

@@ -91,6 +91,7 @@ The following options can be used to customize the behavior of lf:
     reverse     boolean  (default off)
     smartcase   boolean  (default on)
     wrapscan    boolean  (default on)
+    period      integer  (default 0)
     scrolloff   integer  (default 0)
     tabstop     integer  (default 8)
     filesep     string   (default "\n")

docstring.go

@@ -95,6 +95,7 @@ The following options can be used to customize the behavior of lf:
     reverse     boolean  (default off)
     smartcase   boolean  (default on)
     wrapscan    boolean  (default on)
+    period      integer  (default 0)
     scrolloff   integer  (default 0)
     tabstop     integer  (default 8)
     filesep     string   (default "\n")

eval.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"time"
 	"unicode"
 	"unicode/utf8"
 )
@@ -96,6 +97,23 @@ func (e *setExpr) eval(app *app, args []string) {
 		gOpts.wrapscan = false
 	case "wrapscan!":
 		gOpts.wrapscan = !gOpts.wrapscan
+	case "period":
+		n, err := strconv.Atoi(e.val)
+		if err != nil {
+			app.ui.printf("period: %s", err)
+			return
+		}
+		if n < 0 {
+			app.ui.print("period: value should be a non-negative number")
+			return
+		}
+		gOpts.period = n
+		if n == 0 {
+			app.ticker.Stop()
+		} else {
+			app.ticker.Stop()
+			app.ticker = time.NewTicker(time.Duration(gOpts.period) * time.Second)
+		}
 	case "scrolloff":
 		n, err := strconv.Atoi(e.val)
 		if err != nil {

opts.go

@@ -32,6 +32,7 @@ var gOpts struct {
 	preview    bool
 	smartcase  bool
 	wrapscan   bool
+	period     int
 	scrolloff  int
 	tabstop    int
 	filesep    string
@@ -56,6 +57,7 @@ func init() {
 	gOpts.preview = true
 	gOpts.smartcase = true
 	gOpts.wrapscan = true
+	gOpts.period = 0
 	gOpts.scrolloff = 0
 	gOpts.tabstop = 8
 	gOpts.filesep = "\n"