indicator: add KLineLoader interface

pkg/indicator/inf.go

@@ -16,6 +16,12 @@ type KLinePusher interface {
 	PushK(k types.KLine)
 }
 
+// KLineLoader provides an interface for API user to load history klines to the indicator.
+// The indicator implements its own way to calculate the values from the given history kline array.
+type KLineLoader interface {
+	LoadK(allKLines []types.KLine)
+}
+
 type KLineCalculateUpdater interface {
 	CalculateAndUpdate(allKLines []types.KLine)
 }