Add menu browse display conditional on state

go/resource/resource.go

@@ -18,7 +18,6 @@ type Resource interface {
 	GetTemplate(sym string, sizer *Sizer) (string, error) // Get the template for a given symbol.
 	GetCode(sym string) ([]byte, error) // Get the bytecode for the given symbol.
 	PutMenu(string, string) error // Add a menu item.
-	ShiftMenu() (string, string, error) // Remove and return the first menu item in list.
 	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
@@ -30,6 +29,8 @@ type MenuResource struct {
 	menu [][2]string
 	next [2]string
 	prev [2]string
+	canNext bool
+	canPrev bool
 	sinkValues []string
 	codeFunc CodeFunc
 	templateFunc TemplateFunc
@@ -68,12 +69,22 @@ func(m *MenuResource) SetMenuBrowse(selector string, title string, back bool) er
 	entry := [2]string{selector, title}
 	if back {
 		m.prev = entry
+		m.canPrev = true
 	} else {
 		m.next = entry
+		m.canNext = true
 	}
 	return nil
 }
 
+//func(m *MenuResource) putNext() error {
+//	return m.PutMenu(m.next[0], m.next[1])
+//}
+//
+//func(m *MenuResource) putPrevious() error {
+//	return m.PutMenu(m.prev[0], m.prev[1])
+//}
+
 // PutMenu adds a menu option to the menu rendering.
 func(m *MenuResource) PutMenu(selector string, title string) error {
 	m.menu = append(m.menu, [2]string{selector, title})
@@ -81,10 +92,9 @@ func(m *MenuResource) PutMenu(selector string, title string) error {
 	return nil
 }
 
-// PutMenu removes and returns the first of remaining menu options.
+// removes and returns the first of remaining menu options.
-//
+// fails if menu is empty.
-// Fails if menu is empty.
+func(m *MenuResource) shiftMenu() (string, string, error) {
-func(m *MenuResource) ShiftMenu() (string, string, error) {
 	if len(m.menu) == 0 {
 		return "", "", fmt.Errorf("menu is empty")
 	}
@@ -93,14 +103,36 @@ func(m *MenuResource) ShiftMenu() (string, string, error) {
 	return r[0], r[1], nil
 }
 
+// add available browse options.
+func(m *MenuResource) applyPage() error {
+	if m.canNext {
+		err := m.PutMenu(m.next[0], m.next[1])
+		if err != nil {
+			return err
+		}
+	}
+	if m.canPrev {
+		err := m.PutMenu(m.prev[0], m.prev[1])
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // 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) {
+	err := m.applyPage()
+	if err != nil {
+		return "", err
+	}
+
 	r := ""
 	for true {
 		l := len(r)
-		choice, title, err := m.ShiftMenu()
+		choice, title, err := m.shiftMenu()
 		if err != nil {
 			break
 		}

go/resource/state.go

@@ -20,10 +20,25 @@ func NewStateResource(st *state.State) *StateResource {
 	}
 }
 
-func(s *StateResource) WithState(st *state.State) *StateResource {
+func(sr *StateResource) WithState(st *state.State) *StateResource {
-	if s.st != nil {
+	if sr.st != nil {
 		panic("state already set")
 	}
-	s.st = st
+	sr.st = st
-	return s
+	return sr
+}
+
+func(sr *StateResource) SetMenuBrowse(selector string, title string, back bool) error {
+	var err error
+	next, prev := sr.st.Sides()
+
+	if back {
+		if prev {
+			err = sr.Resource.SetMenuBrowse(selector, title, true)
+		}
+	} else if next {
+		err = sr.Resource.SetMenuBrowse(selector, title, false)
+
+	}
+	return err
 }

go/resource/state_test.go

@@ -12,3 +12,62 @@ func TestStateResourceInit(t *testing.T) {
 	_ = ToStateResource(rs).WithState(&st)
 	_ = NewStateResource(&st)
 }
+
+func TestStateBrowse(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()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect := `1:foo
+2:bar
+11:next`
+	if s != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, s)
+	}
+
+	idx, err := st.Next()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if idx != 1 {
+		t.Fatalf("expected idx 1, got %v", idx)
+	}
+	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()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect = `1:foo
+2:bar
+11:next
+22:prev`
+	if s != expect {
+		t.Fatalf("expected:\n\t%s\ngot:\n\t%s\n", expect, s)
+	}
+}

go/state/state.go

@@ -204,7 +204,7 @@ func(st State) WithOutputSize(outputSize uint32) State {
 }
 
 // Where returns the current active rendering symbol.
-func(st State) Where() (string, uint16) {
+func(st *State) Where() (string, uint16) {
 	if len(st.execPath) == 0 {
 		return "", 0
 	}
@@ -213,11 +213,13 @@ func(st State) Where() (string, uint16) {
 }
 
 // Next moves to the next sink page index.
-func(st State) Next() (uint16, error) {
+func(st *State) Next() (uint16, error) {
 	if len(st.execPath) == 0 {
 		return 0, fmt.Errorf("state root node not yet defined")
 	}
 	st.sizeIdx += 1
+	s, idx := st.Where()
+	log.Printf("next page for %s: %v", s, idx)
 	return st.sizeIdx, nil
 }
 
@@ -232,6 +234,8 @@ func(st *State) Previous() (uint16, error) {
 		return 0, fmt.Errorf("already at first index")
 	}
 	st.sizeIdx -= 1
+	s, idx := st.Where()
+	log.Printf("previous page for %s: %v", s, idx)
 	return st.sizeIdx, nil
 }
 
@@ -243,6 +247,7 @@ func(st *State) Sides() (bool, bool) {
 		return false, false
 	}
 	next := true
+	log.Printf("sides %v", st.sizeIdx)
 	if st.sizeIdx == 0 {
 		return next, false	
 	}