newedit/listing: Add basic selection movement support.

newedit/listing/listing.go

@@ -14,6 +14,8 @@
 package listing
 
 import (
+	"sync"
+
 	"github.com/elves/elvish/edit/tty"
 	"github.com/elves/elvish/edit/ui"
 	"github.com/elves/elvish/newedit/types"
@@ -23,7 +25,8 @@ import (
 // Mode represents a listing mode, implementing the types.Mode interface.
 type Mode struct {
 	StartConfig
-	states
+	state      State
+	stateMutex sync.Mutex
 }
 
 // StartConfig is the configuration for starting the listing mode.
@@ -37,14 +40,6 @@ type StartConfig struct {
 	// StartFiltering bool
 }
 
-type states struct {
-	filtering bool
-	filter    string
-	items     Items
-	first     int
-	selected  int
-}
-
 // Items is an interface for accessing items to show in the listing mode.
 type Items interface {
 	Len() int
@@ -75,11 +70,14 @@ func (m *Mode) ModeRenderFlag() types.ModeRenderFlag {
 	return 0
 }
 
+// HandleEvent handles key events and ignores other types of events.
 func (m *Mode) HandleEvent(e tty.Event, st *types.State) types.HandlerAction {
 	switch e := e.(type) {
 	case tty.KeyEvent:
 		if m.KeyHandler == nil {
-			return defaultHandler(ui.Key(e), st)
+			m.stateMutex.Lock()
+			defer m.stateMutex.Unlock()
+			return defaultHandler(ui.Key(e), st, &m.state)
 		}
 		return m.KeyHandler(ui.Key(e))
 	default:
@@ -87,15 +85,31 @@ func (m *Mode) HandleEvent(e tty.Event, st *types.State) types.HandlerAction {
 	}
 }
 
-func defaultHandler(k ui.Key, st *types.State) types.HandlerAction {
+func defaultHandler(k ui.Key, st *types.State, mst *State) types.HandlerAction {
 	switch k {
-	case ui.Key{'[', ui.Ctrl}:
+	case ui.K('[', ui.Ctrl):
 		// TODO(xiaq): Go back to previous mode instead of the initial mode.
 		st.SetMode(nil)
+	case ui.K(ui.Down):
+		mst.Down()
+	case ui.K(ui.Up):
+		mst.Up()
+	case ui.K(ui.Tab):
+		mst.DownCycle()
+	case ui.K(ui.Tab, ui.Shift):
+		mst.UpCycle()
 	}
 	return 0
 }
 
+// MutateStates mutates the states using the given function, guarding the
+// mutation with the mutex.
+func (m *Mode) MutateStates(f func(*State)) {
+	m.stateMutex.Lock()
+	defer m.stateMutex.Unlock()
+	f(&m.state)
+}
+
 // The number of lines the listing mode keeps between the current selected item
 // and the top and bottom edges of the window, unless the available height is
 // too small or if the selected item is near the top or bottom of the list.
@@ -106,29 +120,34 @@ var (
 	styleForLastLine = "underlined"
 )
 
+// List renders the listing.
 func (m *Mode) List(maxHeight int) ui.Renderer {
-	if m.items == nil {
+	m.stateMutex.Lock()
+	defer m.stateMutex.Unlock()
+	st := &m.state
+
+	if st.items == nil {
 		// This is the first time List is called, get initial items.
-		m.items = m.ItemsGetter(m.filter)
+		st.items = m.ItemsGetter(st.filter)
 	}
-	n := m.items.Len()
+	n := st.items.Len()
 	if n == 0 {
 		// No result.
 		return ui.NewStringRenderer("(no result)")
 	}
 
-	newFirst, firstCrop := findWindow(m.items, m.first, m.selected, maxHeight)
-	m.first = newFirst
+	newFirst, firstCrop := findWindow(st.items, st.first, st.selected, maxHeight)
+	st.first = newFirst
 
 	var allLines []styled.Text
 	upper := n
 	lastCropped := false
-	for i := m.first; i < n; i++ {
-		lines := m.items.Show(i).SplitByRune('\n')
-		if i == m.first && firstCrop > 0 {
+	for i := st.first; i < n; i++ {
+		lines := st.items.Show(i).SplitByRune('\n')
+		if i == st.first && firstCrop > 0 {
 			lines = lines[firstCrop:]
 		}
-		if i == m.selected {
+		if i == st.selected {
 			for i := range lines {
 				lines[i] = styled.Transform(lines[i], styleForSelected)
 			}
@@ -147,8 +166,8 @@ func (m *Mode) List(maxHeight int) ui.Renderer {
 	}
 
 	rd := NewStyledTextsRenderer(allLines)
-	if m.first > 0 || firstCrop > 0 || upper < n || lastCropped {
-		rd = ui.NewRendererWithVerticalScrollbar(rd, n, m.first, upper)
+	if st.first > 0 || firstCrop > 0 || upper < n || lastCropped {
+		rd = ui.NewRendererWithVerticalScrollbar(rd, n, st.first, upper)
 	}
 	return rd
 }

newedit/listing/listing_test.go

@@ -75,8 +75,8 @@ func TestList_Normal(t *testing.T) {
 	m := Mode{}
 	m.Start(StartConfig{ItemsGetter: func(string) Items { return fakeItems{10} }})
 
-	m.selected = 3
-	m.first = 1
+	m.state.selected = 3
+	m.state.first = 1
 
 	renderer := m.List(6)
 
@@ -114,7 +114,7 @@ func TestList_Crop(t *testing.T) {
 			styled.Unstyled("1a\n1b"), styled.Unstyled("2a\n2b"))
 	}})
 
-	m.selected = 1
+	m.state.selected = 1
 	renderer := m.List(4)
 
 	wantBase := NewStyledTextsRenderer([]styled.Text{

newedit/listing/state.go

@@ -0,0 +1,44 @@
+package listing
+
+// State keeps the state of the listing mode.
+type State struct {
+	filtering bool
+	filter    string
+	items     Items
+	first     int
+	selected  int
+}
+
+// Up moves the selection up.
+func (st *State) Up() {
+	if st.selected > 0 {
+		st.selected--
+	}
+}
+
+// UpCycle moves the selection up, wrapping to the last item if the currently
+// selected item is the first item.
+func (st *State) UpCycle() {
+	if st.selected > 0 {
+		st.selected--
+	} else {
+		st.selected = st.items.Len() - 1
+	}
+}
+
+// Down moves the selection down.
+func (st *State) Down() {
+	if st.selected < st.items.Len()-1 {
+		st.selected++
+	}
+}
+
+// DownCycle moves the selection down, wrapping to the first item if the
+// currently selected item is the last item.
+func (st *State) DownCycle() {
+	if st.selected < st.items.Len()-1 {
+		st.selected++
+	} else {
+		st.selected = 0
+	}
+}