Merge pull request #127 from mum4k/write-atomic-reset

Adding Text Write option that atomically replaces the text content.

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The LineChart widget can display X axis labels in vertical orientation.
 - The LineChart widget allows the user to specify a custom scale for the Y
   axis.
+- The Text widget now has a Write option that atomically replaces the entire
+  text content.
 
 ### Changed
 

widgets/text/text.go

@@ -85,7 +85,11 @@ func New(opts ...Option) (*Text, error) {
 func (t *Text) Reset() {
 	t.mu.Lock()
 	defer t.mu.Unlock()
+	t.reset()
+}
 
+// reset implements Reset, caller must hold t.mu.
+func (t *Text) reset() {
 	t.buff.Reset()
 	t.givenWOpts = nil
 	t.wOptsTracker = attrrange.NewTracker()
@@ -109,8 +113,13 @@ func (t *Text) Write(text string, wOpts ...WriteOption) error {
 		return err
 	}
 
+	opts := newWriteOptions(wOpts...)
+	if opts.replace {
+		t.reset()
+	}
+
 	pos := t.buff.Len()
-	t.givenWOpts = append(t.givenWOpts, newWriteOptions(wOpts...))
+	t.givenWOpts = append(t.givenWOpts, opts)
 	wOptsIdx := len(t.givenWOpts) - 1
 	if err := t.wOptsTracker.Add(pos, pos+len(text), wOptsIdx); err != nil {
 		return err

widgets/text/text_test.go

@@ -133,6 +133,24 @@ func TestTextDraws(t *testing.T) {
 				return ft
 			},
 		},
+		{
+			desc:   "multiple writes replace when requested",
+			canvas: image.Rect(0, 0, 12, 1),
+			writes: func(widget *Text) error {
+				if err := widget.Write("hello", WriteReplace()); err != nil {
+					return err
+				}
+				return widget.Write("world", WriteReplace())
+			},
+			want: func(size image.Point) *faketerm.Terminal {
+				ft := faketerm.MustNew(size)
+				c := testcanvas.MustNew(ft.Area())
+
+				testdraw.MustText(c, "world", image.Point{0, 0})
+				testcanvas.MustApply(c, ft)
+				return ft
+			},
+		},
 		{
 			desc:   "reset clears the content",
 			canvas: image.Rect(0, 0, 12, 1),

widgets/text/write_options.go

@@ -29,6 +29,7 @@ type WriteOption interface {
 // writeOptions stores the provided options.
 type writeOptions struct {
 	cellOpts *cell.Options
+	replace  bool
 }
 
 // newWriteOptions returns new writeOptions instance.
@@ -56,3 +57,11 @@ func WriteCellOpts(opts ...cell.Option) WriteOption {
 		wOpts.cellOpts = cell.NewOptions(opts...)
 	})
 }
+
+// WriteReplace instructs the text widget to replace the entire text content on
+// this write instead of appending.
+func WriteReplace() WriteOption {
+	return writeOption(func(wOpts *writeOptions) {
+		wOpts.replace = true
+	})
+}