refactor: logparser v5 to pkgs

logparser/v5/pipe/group.go

@@ -0,0 +1,60 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package pipe
+
+import (
+	"sort"
+)
+
+// GroupFunc represents a grouping func that returns a grouping key.
+type GroupFunc = func(Record) (key string)
+
+// Group records by a key.
+type Group struct {
+	sum  map[string]Record // metrics per group key
+	keys []string          // unique group keys
+	key  GroupFunc
+}
+
+// GroupBy returns a new Group.
+// It takes a group func that returns a group key.
+// The returned group will group the record using the key.
+func GroupBy(key GroupFunc) *Group {
+	return &Group{
+		sum: make(map[string]Record),
+		key: key,
+	}
+}
+
+// Consume records for grouping.
+func (g *Group) Consume(records Iterator) error {
+	return records.Each(func(r Record) error {
+		k := g.key(r)
+
+		if _, ok := g.sum[k]; !ok {
+			g.keys = append(g.keys, k)
+		}
+
+		g.sum[k] = r.Sum(g.sum[k])
+
+		return nil
+	})
+}
+
+// Each sorts and yields the grouped records.
+func (g *Group) Each(yield func(Record) error) error {
+	sort.Strings(g.keys)
+
+	for _, k := range g.keys {
+		if err := yield(g.sum[k]); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}