完善Source和Sink

stream/ring_buffer.go

@@ -0,0 +1,77 @@
+package stream
+
+type RingBuffer interface {
+	IsEmpty() bool
+
+	IsFull() bool
+
+	Push(value interface{})
+
+	Pop() interface{}
+
+	Head() interface{}
+
+	Tail() interface{}
+
+	Size() int
+}
+
+func NewRingBuffer(capacity int) RingBuffer {
+	r := &ringBuffer{
+		data: make([]interface{}, capacity),
+		head: 0,
+		tail: 0,
+		size: 0,
+	}
+
+	return r
+}
+
+type ringBuffer struct {
+	data []interface{}
+	head int
+	tail int
+	size int
+}
+
+func (r *ringBuffer) IsEmpty() bool {
+	return r.size == 0
+}
+
+func (r *ringBuffer) IsFull() bool {
+	return r.size == cap(r.data)
+}
+
+func (r *ringBuffer) Push(value interface{}) {
+	if r.IsFull() {
+		r.Pop()
+	}
+
+	r.data[r.tail] = value
+	r.tail = (r.tail + 1) % cap(r.data)
+
+	r.size++
+}
+
+func (r *ringBuffer) Pop() interface{} {
+	if r.IsEmpty() {
+		return nil
+	}
+
+	element := r.data[r.head]
+	r.head = (r.head + 1) % cap(r.data)
+	r.size--
+	return element
+}
+
+func (r *ringBuffer) Head() interface{} {
+	return r.data[r.head]
+}
+
+func (r *ringBuffer) Tail() interface{} {
+	return r.data[r.tail]
+}
+
+func (r *ringBuffer) Size() int {
+	return r.size
+}