FEmptyNode.m 836 B

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  1. /*
  2. * Copyright 2017 Google
  3. *
  4. * Licensed under the Apache License, Version 2.0 (the "License");
  5. * you may not use this file except in compliance with the License.
  6. * You may obtain a copy of the License at
  7. *
  8. * http://www.apache.org/licenses/LICENSE-2.0
  9. *
  10. * Unless required by applicable law or agreed to in writing, software
  11. * distributed under the License is distributed on an "AS IS" BASIS,
  12. * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13. * See the License for the specific language governing permissions and
  14. * limitations under the License.
  15. */
  16. #import "FEmptyNode.h"
  17. #import "FChildrenNode.h"
  18. @implementation FEmptyNode
  19. + (id<FNode>) emptyNode {
  20. static FChildrenNode* empty = nil;
  21. if (empty == nil) {
  22. empty = [[FChildrenNode alloc] init];
  23. }
  24. return empty;
  25. }
  26. @end