feat: kill the program and restore terminal state

* Add Kill() to force kill the program from the outside
* Prevent renderer channel from being closed multiple times

standard_renderer.go

@@ -32,6 +32,7 @@ type standardRenderer struct {
 	lastRender        string
 	linesRendered     int
 	useANSICompressor bool
+	once              sync.Once
 
 	// essentially whether or not we're using the full size of the terminal
 	altScreenActive bool
@@ -72,7 +73,9 @@ func (r *standardRenderer) start() {
 func (r *standardRenderer) stop() {
 	r.flush()
 	clearLine(r.out)
-	close(r.done)
+	r.once.Do(func() {
+		close(r.done)
+	})
 
 	if r.useANSICompressor {
 		if w, ok := r.out.(io.WriteCloser); ok {
@@ -84,7 +87,9 @@ func (r *standardRenderer) stop() {
 // kill halts the renderer. The final frame will not be rendered.
 func (r *standardRenderer) kill() {
 	clearLine(r.out)
-	close(r.done)
+	r.once.Do(func() {
+		close(r.done)
+	})
 }
 
 // listen waits for ticks on the ticker, or a signal to stop the renderer.

tea.go

@@ -97,6 +97,8 @@ type Program struct {
 	// is on by default.
 	CatchPanics bool
 
+	killc chan bool
+
 	console console.Console
 
 	// Stores the original reference to stdin for cases where input is not a
@@ -248,6 +250,7 @@ func NewProgram(model Model, opts ...ProgramOption) *Program {
 		input:        os.Stdin,
 		msgs:         make(chan Msg),
 		CatchPanics:  true,
+		killc:        make(chan bool, 1),
 	}
 
 	// Apply all options to the program.
@@ -486,6 +489,8 @@ func (p *Program) StartReturningModel() (Model, error) {
 	// Handle updates and draw.
 	for {
 		select {
+		case <-p.killc:
+			return nil, nil
 		case err := <-errs:
 			cancelContext()
 			waitForGoroutines(cancelReader.Cancel())
@@ -577,13 +582,25 @@ func (p *Program) Quit() {
 	p.Send(Quit())
 }
 
+// Kill stops the program immediately and restores the former terminal state.
+// The final render that you would normally see when quitting will be skipped.
+//
+// This method is currently provisional. The method signature may alter
+// slightly, or it may be removed in a future version of this package.
+func (p *Program) Kill() {
+	p.killc <- true
+	p.shutdown(true)
+}
+
 // shutdown performs operations to free up resources and restore the terminal
 // to its original state.
 func (p *Program) shutdown(kill bool) {
-	if kill {
-		p.renderer.kill()
-	} else {
-		p.renderer.stop()
+	if p.renderer != nil {
+		if kill {
+			p.renderer.kill()
+		} else {
+			p.renderer.stop()
+		}
 	}
 	p.ExitAltScreen()
 	p.DisableMouseCellMotion()