Ring2 impl Drop, At

container2/ring2/ring2.go

@@ -5,14 +5,17 @@ type Ring2[T any] struct {
 	r, w uint64
 }
 
+// NewRing2 creates a new ring with the given capacity.
 func NewRing2[T any](size uint64) *Ring2[T] {
 	return &Ring2[T]{data: make([]T, size)}
 }
 
+// Len returns the number of elements in the ring.
 func (r *Ring2[T]) Len() uint64 {
 	return r.w - r.r
 }
 
+// Write writes data to the ring. If the ring is full, ok is false.
 func (r *Ring2[T]) Write(data T) (ok bool) {
 	if r.w-r.r >= uint64(len(r.data)) {
 		return false
@@ -22,6 +25,7 @@ func (r *Ring2[T]) Write(data T) (ok bool) {
 	return true
 }
 
+// Read reads the next element from the ring. If the ring is empty, ok is false.
 func (r *Ring2[T]) Read() (data T, ok bool) {
 	if r.w == r.r {
 		return
@@ -31,14 +35,27 @@ func (r *Ring2[T]) Read() (data T, ok bool) {
 	return data, true
 }
 
+// Reset resets the ring to empty.
 func (r *Ring2[T]) Reset() {
 	r.r, r.w = 0, 0
 }
 
+// Cap returns the capacity of the ring.
 func (r *Ring2[T]) Cap() uint64 {
 	return uint64(len(r.data))
 }
 
+// Free returns the number of elements that can be written to the ring.
 func (r *Ring2[T]) Free() uint64 {
 	return r.Cap() - r.Len()
 }
+
+// At returns the element at index i, where i is relative to the read index.
+func (r *Ring2[T]) At(i uint64) T {
+	return r.data[(r.r+i)%r.Cap()]
+}
+
+// Drop drops the first n elements from the ring.
+func (r *Ring2[T]) Drop(n uint64) {
+	r.r += n
+}

container2/ring2/ring2_test.go

@@ -109,3 +109,81 @@ func TestRing2(t *testing.T) {
 		t.Errorf("expected read to fail")
 	}
 }
+
+func TestRing2At(t *testing.T) {
+	r := ring2.NewRing2[uint64](3)
+	r.Write(1)
+	r.Write(2)
+	r.Write(3)
+	r.Read()
+	r.Read()
+	r.Write(4)
+	r.Write(5)
+
+	if r.At(0) != 3 {
+		t.Errorf("expected data 3, got %d", r.At(0))
+	}
+
+	if r.At(1) != 4 {
+		t.Errorf("expected data 4, got %d", r.At(1))
+	}
+
+	if r.At(2) != 5 {
+		t.Errorf("expected data 5, got %d", r.At(2))
+	}
+}
+
+func TestRing2Drop(t *testing.T) {
+	r := ring2.NewRing2[uint64](3)
+	r.Write(1)
+	r.Write(2)
+	r.Write(3)
+	r.Read()
+	r.Read()
+	r.Write(4)
+	r.Write(5)
+	r.Drop(2)
+
+	if r.Len() != 1 {
+		t.Errorf("expected len 1, got %d", r.Len())
+	}
+
+	if r.Free() != 2 {
+		t.Errorf("expected free 2, got %d", r.Free())
+	}
+
+	if r.At(0) != 5 {
+		t.Errorf("expected data 5, got %d", r.At(0))
+	}
+
+	r.Reset()
+
+	if r.Len() != 0 {
+		t.Errorf("expected len 0, got %d", r.Len())
+	}
+
+	if r.Free() != 3 {
+		t.Errorf("expected free 3, got %d", r.Free())
+	}
+
+	r.Write(100)
+	r.Write(200)
+	r.Write(300)
+	r.Drop(1)
+
+	if r.Len() != 2 {
+		t.Errorf("expected len 2, got %d", r.Len())
+	}
+
+	if r.Free() != 1 {
+		t.Errorf("expected free 1, got %d", r.Free())
+	}
+
+	if r.At(0) != 200 {
+		t.Errorf("expected data 200, got %d", r.At(0))
+	}
+
+	if r.At(1) != 300 {
+		t.Errorf("expected data 300, got %d", r.At(1))
+	}
+}