Update vendor/

vendor/github.com/emersion/go-imap/backend/backendutil/flags.go

@@ -0,0 +1,40 @@
+package backendutil
+
+import (
+	"github.com/emersion/go-imap"
+)
+
+// UpdateFlags executes a flag operation on the flag set current.
+func UpdateFlags(current []string, op imap.FlagsOp, flags []string) []string {
+	switch op {
+	case imap.SetFlags:
+		// TODO: keep \Recent if it is present
+		return flags
+	case imap.AddFlags:
+		// Check for duplicates
+		for _, flag := range current {
+			for i, addFlag := range flags {
+				if addFlag == flag {
+					flags = append(flags[:i], flags[i+1:]...)
+					break
+				}
+			}
+		}
+		return append(current, flags...)
+	case imap.RemoveFlags:
+		// Iterate through flags from the last one to the first one, to be able to
+		// delete some of them.
+		for i := len(current) - 1; i >= 0; i-- {
+			flag := current[i]
+
+			for _, removeFlag := range flags {
+				if removeFlag == flag {
+					current = append(current[:i], current[i+1:]...)
+					break
+				}
+			}
+		}
+		return current
+	}
+	return current
+}