Finish ring buffer

ring/ring.go

@@ -1,6 +1,8 @@
 package ring
 
-import "golang.org/x/exp/constraints"
+import (
+	"golang.org/x/exp/constraints"
+)
 
 type Buffer[T any] struct {
 	Data  []T
@@ -9,13 +11,13 @@ type Buffer[T any] struct {
 	Cap   int64
 }
 
-func (b *Buffer[T]) Append(x ...T) {
+func (b *Buffer[T]) Write(x ...T) {
 
 	inLen := int64(len(x))
 
 	for len(x) > 0 {
 
-		copied := copy(b.Data[b.Head():], x)
+		copied := copy(b.Data[b.WriteHead():], x)
 		x = x[copied:]
 
 		if b.Len == b.Cap {
@@ -26,33 +28,54 @@ func (b *Buffer[T]) Append(x ...T) {
 	}
 }
 
-func (b *Buffer[T]) Head() int64 {
+//WriteHead is the absolute position within the buffer where new writes will happen
+func (b *Buffer[T]) WriteHead() int64 {
 	return (b.Start + b.Len) % b.Cap
 }
 
+//Clear resets Len and Start to zero but elements within Data aren't touched.
+//This gives you empty Views and new writes/inserts will overwrite old data
+func (b *Buffer[T]) Clear() {
+	b.Len = 0
+	b.Start = 0
+}
+
+func (b *Buffer[T]) IsFull() bool {
+	return b.Len == b.Cap
+}
+
+//Insert inserts the given elements starting at the provided index.
+//
+//Note: Insert is a no-op if the buffer is full or doesn't have enough place for the elements
 func (b *Buffer[T]) Insert(index uint64, x ...T) {
 
 	delta := int64(len(x))
 	newLen := b.Len + delta
-	if newLen <= b.Cap {
-
-		copy(b.Data[b.Start+int64(index)+delta:], b.Data[index:])
-		copy(b.Data[index:], x)
-
-		b.Len = newLen
+	if newLen > b.Cap {
 		return
 	}
+
+	copy(b.Data[b.Start+int64(index)+delta:], b.Data[index:])
+	copy(b.Data[index:], x)
+	b.Len = newLen
 }
 
-func (b *Buffer[T]) Delete(delStartIndex, elementsToDel uint64, x ...T) {
+//DeleteN removes 'n' elements starting at the provided index.
+//
+//Note DeleteN is a no-op if Len==0 or if buffer is full with start>0
+func (b *Buffer[T]) DeleteN(delStartIndex, n uint64) {
 
 	if b.Len == 0 {
 		return
 	}
 
-	copy(b.Data[uint64(b.Start)+delStartIndex:], b.Data[uint64(b.Start)+delStartIndex+elementsToDel:])
+	if b.Len == b.Cap && b.Start > 0 {
+		return
+	}
 
-	// p.cmdBufLen--
+	relStartIndex := b.Start + int64(delStartIndex)
+	copy(b.Data[relStartIndex:], b.Data[relStartIndex+int64(n):])
+	b.Len = clamp(b.Len-int64(n), 0, b.Cap)
 }
 
 func clamp[T constraints.Ordered](x, min, max T) T {
@@ -69,17 +92,17 @@ func clamp[T constraints.Ordered](x, min, max T) T {
 }
 
 // Views returns two slices that have 'Len' elements in total between them.
-// The first slice is from Start till min(Start+Len, Cap). If Start+Len<=Cap then the first slice contains all the data and the second is nil.
+// The first slice is from Start till min(Start+Len, Cap). If Start+Len<=Cap then the first slice contains all the data and the second is empty.
 // If Start+Len>Cap then the first slice contains the data from Start till Cap, and the second slice contains data from Zero till Start+Len-Cap (basically the remaining elements to reach Len in total)
 //
 // This function does NOT copy. Any changes on the returned slices will reflect on the buffer Data
 func (b *Buffer[T]) Views() (v1, v2 []T) {
 
 	if b.Start+b.Len <= b.Cap {
-		return b.Data[b.Start : b.Start+b.Len], nil
+		return b.Data[b.Start : b.Start+b.Len], []T{}
 	}
 
-	v1 = b.Data[b.Start:b.Cap]
+	v1 = b.Data[b.Start:]
 	v2 = b.Data[:b.Start+b.Len-b.Cap]
 	return
 }

ring/ring_test.go

@@ -10,7 +10,7 @@ func TestRing(t *testing.T) {
 
 	// Basics
 	b := ring.NewBuffer[rune](4)
-	b.Append('a', 'b', 'c', 'd')
+	b.Write('a', 'b', 'c', 'd')
 	CheckArr(t, []rune{'a', 'b', 'c', 'd'}, b.Data)
 
 	v1, v2 := b.Views()
@@ -19,7 +19,7 @@ func TestRing(t *testing.T) {
 	Check(t, 0, b.Start)
 	Check(t, 4, b.Len)
 
-	b.Append('e', 'f')
+	b.Write('e', 'f')
 	Check(t, 2, b.Start)
 	CheckArr(t, []rune{'e', 'f', 'c', 'd'}, b.Data)
 
@@ -27,7 +27,7 @@ func TestRing(t *testing.T) {
 	CheckArr(t, []rune{'c', 'd'}, v1)
 	CheckArr(t, []rune{'e', 'f'}, v2)
 
-	b.Append('g')
+	b.Write('g')
 	Check(t, 3, b.Start)
 
 	v1, v2 = b.Views()
@@ -35,26 +35,58 @@ func TestRing(t *testing.T) {
 	CheckArr(t, []rune{'d'}, v1)
 	CheckArr(t, []rune{'e', 'f', 'g'}, v2)
 
+	b = ring.NewBuffer[rune](4)
+	b.Write('a', 'b', 'c', 'd', 'e')
+	Check(t, 1, b.Start)
+
 	// Input over 2x bigger than buffer
 	b = ring.NewBuffer[rune](4)
-	b.Append('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i')
+	b.Write('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i')
 	CheckArr(t, []rune{'i', 'f', 'g', 'h'}, b.Data)
 
 	// Input starting in the middle and having to loop back
 	b2 := ring.NewBuffer[int](4)
-	b2.Append(1, 2, 3)
+	b2.Write(1, 2, 3)
 
-	b2.Append(4, 5)
+	b2.Write(4, 5)
 	CheckArr(t, []int{5, 2, 3, 4}, b2.Data)
 
-	b2.Append(6)
+	b2.Write(6)
 	CheckArr(t, []int{5, 6, 3, 4}, b2.Data)
 
-	b2.Append(7)
+	b2.Write(7)
 	CheckArr(t, []int{5, 6, 7, 4}, b2.Data)
 
-	b2.Append(8)
+	b2.Write(8)
 	CheckArr(t, []int{5, 6, 7, 8}, b2.Data)
+
+	// Insert
+	b2 = ring.NewBuffer[int](4)
+	b2.Write(1, 2)
+
+	b2.Insert(0, 3)
+	CheckArr(t, []int{3, 1, 2, 0}, b2.Data)
+
+	b2.Insert(3, 4)
+	CheckArr(t, []int{3, 1, 2, 4}, b2.Data)
+
+	b2.Insert(2, 5, 6)
+	CheckArr(t, []int{3, 1, 2, 4}, b2.Data)
+
+	// Delete
+	b2 = ring.NewBuffer[int](4)
+	b2.Write(1, 2, 3, 4)
+
+	b2.DeleteN(0, 4)
+	Check(t, 0, b2.Start)
+	Check(t, 0, b2.Len)
+	CheckArr(t, []int{1, 2, 3, 4}, b2.Data)
+
+	b2.Write(5, 6, 7, 8)
+	Check(t, 4, b2.Len)
+	b2.DeleteN(2, 1)
+	Check(t, 3, b2.Len)
+	CheckArr(t, []int{5, 6, 8, 8}, b2.Data)
 }
 
 func Check[T comparable](t *testing.T, expected, got T) {