Add debouncer

debouncer/debouncer.go

@@ -0,0 +1,53 @@
+package debouncer
+
+import "time"
+
+type Debouncer struct {
+	input <-chan bool
+	C     <-chan bool
+}
+
+func New(ch <-chan bool) *Debouncer {
+	output := make(chan bool)
+	var currentState bool
+	var lastState bool
+	falseTimer := time.NewTimer(0)
+	falseTimer.Stop()
+	go func() {
+		for {
+			select {
+			case <-falseTimer.C:
+				if !currentState && lastState {
+					output <- false
+					lastState = false
+				} else {
+					falseTimer.Reset(200 * time.Millisecond)
+				}
+			case v, ok := <-ch:
+				if !ok {
+					falseTimer.Reset(200 * time.Millisecond)
+					<-falseTimer.C
+					output <- false
+					close(output)
+					return
+				}
+				if v {
+					if !lastState {
+						output <- true
+						lastState = true
+						falseTimer.Reset(200 * time.Millisecond)
+					}
+
+					currentState = true
+				} else {
+					falseTimer.Reset(200 * time.Millisecond)
+
+					currentState = false
+				}
+			}
+		}
+	}()
+	d := &Debouncer{input: ch, C: output}
+
+	return d
+}

debouncer/debouncer_test.go

@@ -0,0 +1,89 @@
+package debouncer_test
+
+import (
+	"testing"
+	"time"
+
+	"git.t-juice.club/torjus/ghettoptt/debouncer"
+)
+
+func TestDebouncer(t *testing.T) {
+	t.Run("Simple", func(t *testing.T) {
+		ch := make(chan bool)
+		d := debouncer.New(ch)
+
+		go func() {
+			ch <- true
+			close(ch)
+		}()
+
+		if v := <-d.C; v != true {
+			t.Errorf("Expected true, got %v", v)
+		}
+	})
+	t.Run("TrueTrueTrueFalse", func(t *testing.T) {
+		ch := make(chan bool)
+		d := debouncer.New(ch)
+		go func() {
+			ch <- true
+			ch <- true
+			ch <- true
+			ch <- false
+			close(ch)
+		}()
+		if v := <-d.C; v != true {
+			t.Errorf("Expected true, got %v", v)
+		}
+		if v := <-d.C; v != false {
+			t.Errorf("Expected false, got %v", v)
+		}
+	})
+	t.Run("Debounce", func(t *testing.T) {
+		ch := make(chan bool)
+		d := debouncer.New(ch)
+		go func() {
+			ch <- true
+			time.Sleep(10 * time.Millisecond)
+			ch <- false
+			time.Sleep(1 * time.Millisecond)
+			ch <- true
+			time.Sleep(1 * time.Millisecond)
+			ch <- false
+			time.Sleep(10 * time.Millisecond)
+			close(ch)
+		}()
+		if v := <-d.C; v != true {
+			t.Errorf("Expected first value to be true, got %v", v)
+		}
+		if v := <-d.C; v != false {
+			t.Errorf("Expected second value to be false, got %v", v)
+		}
+
+		if v, ok := <-d.C; ok {
+			t.Errorf("Expected closed channel, got %v", v)
+		}
+	})
+	t.Run("DebounceDelay", func(t *testing.T) {
+		ch := make(chan bool)
+		d := debouncer.New(ch)
+		go func() {
+			ch <- true
+			ch <- false
+			close(ch)
+		}()
+		start := time.Now()
+		if v := <-d.C; v != true {
+			t.Errorf("Expected first value to be true, got %v", v)
+		}
+		if v, ok := <-d.C; v != false || !ok {
+			if ok {
+				t.Errorf("Expected second value to be false, got %v", v)
+			} else {
+				t.Error("Unexpected closed channel")
+			}
+		}
+		if duration := time.Since(start); duration < 200*time.Millisecond {
+			t.Errorf("Got false too soon: %s", duration)
+		}
+	})
+}