DefaultMap.js 1.4 KB

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  1. "use strict";
  2. /**
  3. * Copyright 2023 Google LLC.
  4. * Copyright (c) Microsoft Corporation.
  5. *
  6. * Licensed under the Apache License, Version 2.0 (the "License");
  7. * you may not use this file except in compliance with the License.
  8. * You may obtain a copy of the License at
  9. *
  10. * http://www.apache.org/licenses/LICENSE-2.0
  11. *
  12. * Unless required by applicable law or agreed to in writing, software
  13. * distributed under the License is distributed on an "AS IS" BASIS,
  14. * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15. * See the License for the specific language governing permissions and
  16. * limitations under the License.
  17. */
  18. Object.defineProperty(exports, "__esModule", { value: true });
  19. exports.DefaultMap = void 0;
  20. /**
  21. * A subclass of Map whose functionality is almost the same as its parent
  22. * except for the fact that DefaultMap never returns undefined. It provides a
  23. * default value for keys that do not exist.
  24. */
  25. class DefaultMap extends Map {
  26. /** The default value to return whenever a key is not present in the map. */
  27. #getDefaultValue;
  28. constructor(getDefaultValue, entries) {
  29. super(entries);
  30. this.#getDefaultValue = getDefaultValue;
  31. }
  32. get(key) {
  33. if (!this.has(key)) {
  34. this.set(key, this.#getDefaultValue(key));
  35. }
  36. return super.get(key);
  37. }
  38. }
  39. exports.DefaultMap = DefaultMap;
  40. //# sourceMappingURL=DefaultMap.js.map