WIP Add indexed condition for browse menu items display

go/engine/engine.go

@@ -114,7 +114,7 @@ func(en *Engine) WriteResult(w io.Writer) error {
 	if err != nil {
 		return err
 	}
-	m, err := en.rs.RenderMenu()
+	m, err := en.rs.RenderMenu(idx)
 	if err != nil {
 		return err
 	}

go/resource/resource.go

@@ -20,7 +20,7 @@ type Resource interface {
 	PutMenu(string, string) error // Add a menu item.
 	SetMenuBrowse(string, string, bool) error // Set menu browser display details.
 	RenderTemplate(sym string, values map[string]string, idx uint16, sizer *Sizer) (string, error) // Render the given data map using the template of the symbol.
-	RenderMenu() (string, error) // Render the current state of menu
+	RenderMenu(idx uint16) (string, error) // Render the current state of menu
 	Render(sym string, values map[string]string, idx uint16, sizer *Sizer) (string, error) // Render full output.
 	FuncFor(sym string) (EntryFunc, error) // Resolve symbol content point for.
 }
@@ -104,7 +104,17 @@ func(m *MenuResource) shiftMenu() (string, string, error) {
 }
 
 // add available browse options.
-func(m *MenuResource) applyPage() error {
+func(m *MenuResource) applyPage(idx uint16) error {
+	l := uint16(len(m.sinkValues))
+	if l == 0 {
+		return nil
+	}
+	if idx == l - 1 {
+		m.canNext = false
+	}
+	if idx == 0 {
+		m.canPrev = false
+	}
 	if m.canNext {
 		err := m.PutMenu(m.next[0], m.next[1])
 		if err != nil {
@@ -123,8 +133,8 @@ func(m *MenuResource) applyPage() error {
 // RenderMenu returns the full current state of the menu as a string.
 //
 // After this has been executed, the state of the menu will be empty.
-func(m *MenuResource) RenderMenu() (string, error) {
+func(m *MenuResource) RenderMenu(idx uint16) (string, error) {
-	err := m.applyPage()
+	err := m.applyPage(idx)
 	if err != nil {
 		return "", err
 	}
@@ -252,7 +262,7 @@ func(m *MenuResource) render(sym string, values map[string]string, idx uint16, s
 			return "", fmt.Errorf("limit exceeded: %v", sizer)
 		}
 	}
-	s, err = m.RenderMenu()
+	s, err = m.RenderMenu(idx)
 	if err != nil {
 		return "", err
 	}

go/resource/state_test.go

@@ -13,7 +13,7 @@ func TestStateResourceInit(t *testing.T) {
 	_ = NewStateResource(&st)
 }
 
-func TestStateBrowse(t *testing.T) {
+func TestStateBrowseNoSink(t *testing.T) {
 	st := state.NewState(0)
 	st.Down("root")
 
@@ -28,7 +28,35 @@ func TestStateBrowse(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	s, err := rs.RenderMenu()
+	s, err := rs.RenderMenu(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect := `1:foo
+2:bar`
+	if s != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, s)
+	}
+}
+
+
+func TestStateBrowseSink(t *testing.T) {
+	st := state.NewState(0)
+	st.Down("root")
+
+	rs := NewStateResource(&st)
+	rs.PutMenu("1", "foo")
+	rs.PutMenu("2", "bar")
+	err := rs.SetMenuBrowse("11", "next", false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = rs.SetMenuBrowse("22", "prev", true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	s, err := rs.RenderMenu(0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -58,7 +86,7 @@ func TestStateBrowse(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	s, err = rs.RenderMenu()
+	s, err = rs.RenderMenu(idx)
 	if err != nil {
 		t.Fatal(err)
 	}

go/vm/runner_test.go

@@ -319,7 +319,7 @@ func TestRunMenu(t *testing.T) {
 		t.Errorf("expected empty remainder, got length %v: %v", l, b)
 	}
 	
-	r, err := rs.RenderMenu()
+	r, err := rs.RenderMenu(0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -351,7 +351,7 @@ func TestRunMenuBrowse(t *testing.T) {
 		t.Errorf("expected empty remainder, got length %v: %v", l, b)
 	}
 	
-	r, err := rs.RenderMenu()
+	r, err := rs.RenderMenu(0)
 	if err != nil {
 		t.Fatal(err)
 	}