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  1. import { OperatorFunction, ObservableInput, ObservedValueOf, SubjectLike } from '../types';
  2. import { Observable } from '../Observable';
  3. /**
  4. * An object used to configure {@link connect} operator.
  5. */
  6. export interface ConnectConfig<T> {
  7. /**
  8. * A factory function used to create the Subject through which the source
  9. * is multicast. By default, this creates a {@link Subject}.
  10. */
  11. connector: () => SubjectLike<T>;
  12. }
  13. /**
  14. * Creates an observable by multicasting the source within a function that
  15. * allows the developer to define the usage of the multicast prior to connection.
  16. *
  17. * This is particularly useful if the observable source you wish to multicast could
  18. * be synchronous or asynchronous. This sets it apart from {@link share}, which, in the
  19. * case of totally synchronous sources will fail to share a single subscription with
  20. * multiple consumers, as by the time the subscription to the result of {@link share}
  21. * has returned, if the source is synchronous its internal reference count will jump from
  22. * 0 to 1 back to 0 and reset.
  23. *
  24. * To use `connect`, you provide a `selector` function that will give you
  25. * a multicast observable that is not yet connected. You then use that multicast observable
  26. * to create a resulting observable that, when subscribed, will set up your multicast. This is
  27. * generally, but not always, accomplished with {@link merge}.
  28. *
  29. * Note that using a {@link takeUntil} inside of `connect`'s `selector` _might_ mean you were looking
  30. * to use the {@link takeWhile} operator instead.
  31. *
  32. * When you subscribe to the result of `connect`, the `selector` function will be called. After
  33. * the `selector` function returns, the observable it returns will be subscribed to, _then_ the
  34. * multicast will be connected to the source.
  35. *
  36. * ## Example
  37. *
  38. * Sharing a totally synchronous observable
  39. *
  40. * ```ts
  41. * import { of, tap, connect, merge, map, filter } from 'rxjs';
  42. *
  43. * const source$ = of(1, 2, 3, 4, 5).pipe(
  44. * tap({
  45. * subscribe: () => console.log('subscription started'),
  46. * next: n => console.log(`source emitted ${ n }`)
  47. * })
  48. * );
  49. *
  50. * source$.pipe(
  51. * // Notice in here we're merging 3 subscriptions to `shared$`.
  52. * connect(shared$ => merge(
  53. * shared$.pipe(map(n => `all ${ n }`)),
  54. * shared$.pipe(filter(n => n % 2 === 0), map(n => `even ${ n }`)),
  55. * shared$.pipe(filter(n => n % 2 === 1), map(n => `odd ${ n }`))
  56. * ))
  57. * )
  58. * .subscribe(console.log);
  59. *
  60. * // Expected output: (notice only one subscription)
  61. * 'subscription started'
  62. * 'source emitted 1'
  63. * 'all 1'
  64. * 'odd 1'
  65. * 'source emitted 2'
  66. * 'all 2'
  67. * 'even 2'
  68. * 'source emitted 3'
  69. * 'all 3'
  70. * 'odd 3'
  71. * 'source emitted 4'
  72. * 'all 4'
  73. * 'even 4'
  74. * 'source emitted 5'
  75. * 'all 5'
  76. * 'odd 5'
  77. * ```
  78. *
  79. * @param selector A function used to set up the multicast. Gives you a multicast observable
  80. * that is not yet connected. With that, you're expected to create and return
  81. * and Observable, that when subscribed to, will utilize the multicast observable.
  82. * After this function is executed -- and its return value subscribed to -- the
  83. * operator will subscribe to the source, and the connection will be made.
  84. * @param config The configuration object for `connect`.
  85. */
  86. export declare function connect<T, O extends ObservableInput<unknown>>(selector: (shared: Observable<T>) => O, config?: ConnectConfig<T>): OperatorFunction<T, ObservedValueOf<O>>;
  87. //# sourceMappingURL=connect.d.ts.map