add root.equals and todo.equals

pttodo/todo.go

@@ -43,3 +43,37 @@ func (todo *Todo) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	alt := (*Alt)(todo)
 	return unmarshal(alt)
 }
+
+func (todo Todo) Equals(other Todo) bool {
+	if !equalTodoSlices(todo.Subtasks, other.Subtasks) {
+		return false
+	}
+	if todo.TS != other.TS {
+		return false
+	}
+	if todo.Tags != other.Tags {
+		return false
+	}
+	if todo.Schedule != other.Schedule {
+		return false
+	}
+	if todo.Details != other.Details {
+		return false
+	}
+	if todo.Todo != other.Todo {
+		return false
+	}
+	return true
+}
+
+func equalTodoSlices(a, b []Todo) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if !a[i].Equals(b[i]) {
+			return false
+		}
+	}
+	return true
+}