1 files changed, 39 insertions, 0 deletions
diff --git a/feed/nodeop.go b/feed/nodeop.go
new file mode 100644
index 0000000..8bfa0a0
--- /dev/null
+++ b/feed/nodeop.go
@@ -0,0 +1,39 @@
+package feed
+
+//go:generate stringer -linecomment -type=NodeOp
+
+import (
+  "encoding/json"
+  "fmt"
+)
+
+// Node boolean operator.
+type NodeOp byte
+
+const (
+  OrOp NodeOp = iota  // OR
+  AndOp               // AND
+)
+
+// Unmarshal DataVersion from JSON.
+func (me *NodeOp) UnmarshalJSON(b []byte) error {
+  // decode string, check for error
+  var s string
+  if err := json.Unmarshal(b, &s); err != nil {
+    return err
+  }
+
+  // check value
+  switch s {
+  case "AND":
+    *me = AndOp
+  case "OR":
+    *me = OrOp
+  default:
+    // return error
+    return fmt.Errorf("unknown operator: %s", s)
+  }
+
+  // return success
+  return nil
+}