Filters.

filters.go

@@ -0,0 +1,66 @@
+package telebot
+
+// Filter is some thing that does filtering for
+// incoming updates.
+//
+// Return false if you wish to sieve the update out.
+type Filter interface {
+	Filter(*Update) bool
+}
+
+// FilterFunc is basically a lightweight version of Filter.
+type FilterFunc func(*Update) bool
+
+func NewChain(parent Poller) *Chain {
+	c := &Chain{}
+	c.Poller = parent
+	c.Filter = func(upd *Update) bool {
+		for _, filter := range c.Filters {
+			switch f := filter.(type) {
+			case Filter:
+				if !f.Filter(upd) {
+					return false
+				}
+
+			case FilterFunc:
+				if !f(upd) {
+					return false
+				}
+
+			case func(*Update) bool:
+				if !f(upd) {
+					return false
+				}
+			}
+
+		}
+
+		return true
+	}
+
+	return c
+}
+
+// Chain is a chain of middle
+type Chain struct {
+	MiddlewarePoller
+
+	// (Filter | FilterFunc | func(*Update) bool)
+	Filters []interface{}
+}
+
+// Add accepts either Filter interface or FilterFunc
+func (c *Chain) Add(filter interface{}) {
+	switch filter.(type) {
+	case Filter:
+		break
+	case FilterFunc:
+		break
+	case func(*Update) bool:
+		break
+	default:
+		panic("telebot: unsupported filter type")
+	}
+
+	c.Filters = append(c.Filters, filter)
+}