1 | /*
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2 | * This file and its definitions are needed just so that ESDoc sees these
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3 | * JSDoc documentation comments. Originally they were meant for some TypeScript
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4 | * interfaces, but TypeScript strips away JSDoc comments near interfaces. Hence,
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5 | * we need these bogus classes, which are not stripped away. This file on the
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6 | * other hand, is not included in the release bundle.
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7 | */
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8 | import { Observer, TeardownLogic } from './internal/types';
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9 | import { Observable } from './internal/Observable';
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10 | import './internal/observable/dom/MiscJSDoc';
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11 |
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12 | /**
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13 | * We need this JSDoc comment for affecting ESDoc.
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14 | * @extends {Ignored}
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15 | * @hide true
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16 | */
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17 | export class ObservableDoc {
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18 | /**
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19 | * Creates a new Observable, that will execute the specified function when an
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20 | * {@link Observer} subscribes to it.
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21 | *
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22 | * <span class="informal">Create custom Observable, that does whatever you like.</span>
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23 | *
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24 | * ![](create.png)
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25 | *
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26 | * `create` converts an `onSubscription` function to an actual Observable.
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27 | * Whenever someone subscribes to that Observable, the function will be called
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28 | * with an {@link Observer} instance as a first and only parameter. `onSubscription` should
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29 | * then invoke the Observers `next`, `error` and `complete` methods.
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30 | *
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31 | * Calling `next` with a value will emit that value to the observer. Calling `complete`
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32 | * means that Observable finished emitting and will not do anything else.
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33 | * Calling `error` means that something went wrong - value passed to `error` method should
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34 | * provide details on what exactly happened.
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35 | *
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36 | * A well-formed Observable can emit as many values as it needs via `next` method,
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37 | * but `complete` and `error` methods can be called only once and nothing else can be called
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38 | * thereafter. If you try to invoke `next`, `complete` or `error` methods after created
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39 | * Observable already completed or ended with an error, these calls will be ignored to
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40 | * preserve so called *Observable Contract*. Note that you are not required to call
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41 | * `complete` at any point - it is perfectly fine to create an Observable that never ends,
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42 | * depending on your needs.
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43 | *
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44 | * `onSubscription` can optionally return either a function or an object with
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45 | * `unsubscribe` method. In both cases function or method will be called when
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46 | * subscription to Observable is being cancelled and should be used to clean up all
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47 | * resources. So, for example, if you are using `setTimeout` in your custom
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48 | * Observable, when someone unsubscribes, you can clear planned timeout, so that
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49 | * it does not fire needlessly and browser (or other environment) does not waste
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50 | * computing power on timing event that no one will listen to anyways.
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51 | *
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52 | * Most of the times you should not need to use `create`, because existing
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53 | * operators allow you to create an Observable for most of the use cases.
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54 | * That being said, `create` is low-level mechanism allowing you to create
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55 | * any Observable, if you have very specific needs.
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56 | *
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57 | * **TypeScript signature issue**
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58 | *
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59 | * Because Observable extends class which already has defined static `create` function,
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60 | * but with different type signature, it was impossible to assign proper signature to
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61 | * `Observable.create`. Because of that, it has very general type `Function` and thus
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62 | * function passed to `create` will not be type checked, unless you explicitly state
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63 | * what signature it should have.
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64 | *
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65 | * When using TypeScript we recommend to declare type signature of function passed to
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66 | * `create` as `(observer: Observer) => TeardownLogic`, where {@link Observer}
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67 | * and {@link TeardownLogic} are interfaces provided by the library.
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68 | *
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69 | * @example <caption>Emit three numbers, then complete.</caption>
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70 | * var observable = Rx.Observable.create(function (observer) {
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71 | * observer.next(1);
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72 | * observer.next(2);
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73 | * observer.next(3);
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74 | * observer.complete();
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75 | * });
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76 | * observable.subscribe(
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77 | * value => console.log(value),
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78 | * err => {},
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79 | * () => console.log('this is the end')
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80 | * );
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81 | *
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82 | * // Logs
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83 | * // 1
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84 | * // 2
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85 | * // 3
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86 | * // "this is the end"
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87 | *
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88 | *
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89 | * @example <caption>Emit an error</caption>
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90 | * const observable = Rx.Observable.create((observer) => {
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91 | * observer.error('something went really wrong...');
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92 | * });
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93 | *
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94 | * observable.subscribe(
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95 | * value => console.log(value), // will never be called
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96 | * err => console.log(err),
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97 | * () => console.log('complete') // will never be called
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98 | * );
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99 | *
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100 | * // Logs
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101 | * // "something went really wrong..."
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102 | *
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103 | *
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104 | * @example <caption>Return unsubscribe function</caption>
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105 | *
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106 | * const observable = Rx.Observable.create(observer => {
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107 | * const id = setTimeout(() => observer.next('...'), 5000); // emit value after 5s
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108 | *
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109 | * return () => { clearTimeout(id); console.log('cleared!'); };
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110 | * });
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111 | *
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112 | * const subscription = observable.subscribe(value => console.log(value));
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113 | *
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114 | * setTimeout(() => subscription.unsubscribe(), 3000); // cancel subscription after 3s
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115 | *
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116 | * // Logs:
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117 | * // "cleared!" after 3s
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118 | *
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119 | * // Never logs "..."
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120 | *
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121 | *
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122 | * @see {@link empty}
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123 | * @see {@link never}
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124 | * @see {@link of}
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125 | * @see {@link throw}
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126 | *
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127 | * @param {function(observer: Observer): TeardownLogic} onSubscription A
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128 | * function that accepts an Observer, and invokes its `next`,
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129 | * `error`, and `complete` methods as appropriate, and optionally returns some
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130 | * logic for cleaning up resources.
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131 | * @return {Observable} An Observable that, whenever subscribed, will execute the
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132 | * specified function.
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133 | * @static true
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134 | * @name create
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135 | * @owner Observable
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136 | * @nocollapse
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137 | */
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138 | static create<T>(onSubscription: <R>(observer: Observer<R>) => TeardownLogic): Observable<T> {
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139 | return new Observable<T>(onSubscription);
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140 | }
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141 | }
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142 |
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143 | /**
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144 | * An interface for a consumer of push-based notifications delivered by an
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145 | * {@link Observable}.
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146 | *
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147 | * ```ts
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148 | * interface Observer<T> {
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149 | * closed?: boolean;
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150 | * next: (value: T) => void;
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151 | * error: (err: any) => void;
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152 | * complete: () => void;
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153 | * }
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154 | * ```
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155 | *
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156 | * An object conforming to the Observer interface is usually
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157 | * given to the `observable.subscribe(observer)` method, and the Observable will
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158 | * call the Observer's `next(value)` method to provide notifications. A
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159 | * well-behaved Observable will call an Observer's `complete()` method exactly
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160 | * once or the Observer's `error(err)` method exactly once, as the last
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161 | * notification delivered.
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162 | *
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163 | * @interface
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164 | * @name Observer
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165 | * @noimport true
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166 | */
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167 | export class ObserverDoc<T> {
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168 | /**
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169 | * An optional flag to indicate whether this Observer, when used as a
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170 | * subscriber, has already been unsubscribed from its Observable.
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171 | * @type {boolean}
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172 | */
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173 | closed: boolean = false;
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174 | /**
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175 | * The callback to receive notifications of type `next` from the Observable,
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176 | * with a value. The Observable may call this method 0 or more times.
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177 | * @param {T} value The `next` value.
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178 | * @return {void}
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179 | */
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180 | next(value: T): void {
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181 | return void 0;
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182 | }
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183 | /**
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184 | * The callback to receive notifications of type `error` from the Observable,
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185 | * with an attached {@link Error}. Notifies the Observer that the Observable
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186 | * has experienced an error condition.
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187 | * @param {any} err The `error` exception.
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188 | * @return {void}
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189 | */
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190 | error(err: any): void {
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191 | return void 0;
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192 | }
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193 | /**
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194 | * The callback to receive a valueless notification of type `complete` from
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195 | * the Observable. Notifies the Observer that the Observable has finished
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196 | * sending push-based notifications.
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197 | * @return {void}
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198 | */
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199 | complete(): void {
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200 | return void 0;
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201 | }
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202 | }
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203 |
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204 | /**
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205 | * `SubscribableOrPromise` interface describes values that behave like either
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206 | * Observables or Promises. Every operator that accepts arguments annotated
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207 | * with this interface, can be also used with parameters that are not necessarily
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208 | * RxJS Observables.
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209 | *
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210 | * Following types of values might be passed to operators expecting this interface:
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211 | *
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212 | * ## Observable
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213 | *
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214 | * RxJS {@link Observable} instance.
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215 | *
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216 | * ## Observable-like (Subscribable)
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217 | *
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218 | * This might be any object that has `Symbol.observable` method. This method,
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219 | * when called, should return object with `subscribe` method on it, which should
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220 | * behave the same as RxJS `Observable.subscribe`.
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221 | *
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222 | * `Symbol.observable` is part of https://github.com/tc39/proposal-observable proposal.
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223 | * Since currently it is not supported natively, and every symbol is equal only to itself,
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224 | * you should use https://github.com/blesh/symbol-observable polyfill, when implementing
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225 | * custom Observable-likes.
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226 | *
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227 | * **TypeScript Subscribable interface issue**
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228 | *
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229 | * Although TypeScript interface claims that Subscribable is an object that has `subscribe`
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230 | * method declared directly on it, passing custom objects that have `subscribe`
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231 | * method but not `Symbol.observable` method will fail at runtime. Conversely, passing
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232 | * objects with `Symbol.observable` but without `subscribe` will fail at compile time
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233 | * (if you use TypeScript).
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234 | *
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235 | * TypeScript has problem supporting interfaces with methods defined as symbol
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236 | * properties. To get around that, you should implement `subscribe` directly on
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237 | * passed object, and make `Symbol.observable` method simply return `this`. That way
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238 | * everything will work as expected, and compiler will not complain. If you really
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239 | * do not want to put `subscribe` directly on your object, you will have to type cast
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240 | * it to `any`, before passing it to an operator.
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241 | *
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242 | * When this issue is resolved, Subscribable interface will only permit Observable-like
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243 | * objects with `Symbol.observable` defined, no matter if they themselves implement
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244 | * `subscribe` method or not.
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245 | *
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246 | * ## ES6 Promise
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247 | *
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248 | * Promise can be interpreted as Observable that emits value and completes
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249 | * when it is resolved or errors when it is rejected.
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250 | *
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251 | * ## Promise-like (Thenable)
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252 | *
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253 | * Promises passed to operators do not have to be native ES6 Promises.
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254 | * They can be implementations from popular Promise libraries, polyfills
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255 | * or even custom ones. They just need to have `then` method that works
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256 | * as the same as ES6 Promise `then`.
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257 | *
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258 | * @example <caption>Use merge and then map with non-RxJS observable</caption>
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259 | * const nonRxJSObservable = {
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260 | * subscribe(observer) {
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261 | * observer.next(1000);
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262 | * observer.complete();
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263 | * },
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264 | * [Symbol.observable]() {
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265 | * return this;
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266 | * }
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267 | * };
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268 | *
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269 | * Rx.Observable.merge(nonRxJSObservable)
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270 | * .map(value => "This value is " + value)
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271 | * .subscribe(result => console.log(result)); // Logs "This value is 1000"
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272 | *
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273 | *
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274 | * @example <caption>Use combineLatest with ES6 Promise</caption>
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275 | * Rx.Observable.combineLatest(Promise.resolve(5), Promise.resolve(10), Promise.resolve(15))
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276 | * .subscribe(
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277 | * value => console.log(value),
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278 | * err => {},
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279 | * () => console.log('the end!')
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280 | * );
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281 | * // Logs
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282 | * // [5, 10, 15]
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283 | * // "the end!"
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284 | *
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285 | *
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286 | * @interface
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287 | * @name SubscribableOrPromise
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288 | * @noimport true
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289 | */
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290 | export class SubscribableOrPromiseDoc<T> {
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291 |
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292 | }
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293 |
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294 | /**
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295 | * `ObservableInput` interface describes all values that are either an
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296 | * {@link SubscribableOrPromise} or some kind of collection of values that
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297 | * can be transformed to Observable emitting that values. Every operator that
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298 | * accepts arguments annotated with this interface, can be also used with
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299 | * parameters that are not necessarily RxJS Observables.
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300 | *
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301 | * `ObservableInput` extends {@link SubscribableOrPromise} with following types:
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302 | *
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303 | * ## Array
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304 | *
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305 | * Arrays can be interpreted as observables that emit all values in array one by one,
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306 | * from left to right, and then complete immediately.
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307 | *
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308 | * ## Array-like
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309 | *
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310 | * Arrays passed to operators do not have to be built-in JavaScript Arrays. They
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311 | * can be also, for example, `arguments` property available inside every function,
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312 | * [DOM NodeList](https://developer.mozilla.org/pl/docs/Web/API/NodeList),
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313 | * or, actually, any object that has `length` property (which is a number)
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314 | * and stores values under non-negative (zero and up) integers.
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315 | *
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316 | * ## ES6 Iterable
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317 | *
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318 | * Operators will accept both built-in and custom ES6 Iterables, by treating them as
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319 | * observables that emit all its values in order of iteration and then complete
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320 | * when iteration ends. Note that contrary to arrays, Iterables do not have to
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321 | * necessarily be finite, so creating Observables that never complete is possible as well.
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322 | *
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323 | * Note that you can make iterator an instance of Iterable by having it return itself
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324 | * in `Symbol.iterator` method. It means that every operator accepting Iterables accepts,
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325 | * though indirectly, iterators themselves as well. All native ES6 iterators are instances
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326 | * of Iterable by default, so you do not have to implement their `Symbol.iterator` method
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327 | * yourself.
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328 | *
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329 | * **TypeScript Iterable interface issue**
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330 | *
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331 | * TypeScript `ObservableInput` interface actually lacks type signature for Iterables,
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332 | * because of issues it caused in some projects (see [this issue](https://github.com/ReactiveX/rxjs/issues/2306)).
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333 | * If you want to use Iterable as argument for operator, cast it to `any` first.
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334 | * Remember of course that, because of casting, you have to yourself ensure that passed
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335 | * argument really implements said interface.
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336 | *
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337 | *
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338 | * @example <caption>Use merge with arrays</caption>
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339 | * Rx.Observable.merge([1, 2], [4], [5, 6])
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340 | * .subscribe(
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341 | * value => console.log(value),
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342 | * err => {},
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343 | * () => console.log('ta dam!')
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344 | * );
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345 | *
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346 | * // Logs
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347 | * // 1
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348 | * // 2
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349 | * // 3
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350 | * // 4
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351 | * // 5
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352 | * // 6
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353 | * // "ta dam!"
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354 | *
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355 | *
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356 | * @example <caption>Use merge with array-like</caption>
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357 | * Rx.Observable.merge({0: 1, 1: 2, length: 2}, {0: 3, length: 1})
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358 | * .subscribe(
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359 | * value => console.log(value),
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360 | * err => {},
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361 | * () => console.log('nice, huh?')
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362 | * );
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363 | *
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364 | * // Logs
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365 | * // 1
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366 | * // 2
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367 | * // 3
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368 | * // "nice, huh?"
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369 | *
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370 | * @example <caption>Use merge with an Iterable (Map)</caption>
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371 | * const firstMap = new Map([[1, 'a'], [2, 'b']]);
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372 | * const secondMap = new Map([[3, 'c'], [4, 'd']]);
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373 | *
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374 | * Rx.Observable.merge(
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375 | * firstMap, // pass Iterable
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376 | * secondMap.values() // pass iterator, which is itself an Iterable
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377 | * ).subscribe(
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378 | * value => console.log(value),
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379 | * err => {},
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380 | * () => console.log('yup!')
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381 | * );
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382 | *
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383 | * // Logs
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384 | * // [1, "a"]
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385 | * // [2, "b"]
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386 | * // "c"
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387 | * // "d"
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388 | * // "yup!"
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389 | *
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390 | * @example <caption>Use from with generator (returning infinite iterator)</caption>
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391 | * // infinite stream of incrementing numbers
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392 | * const infinite = function* () {
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393 | * let i = 0;
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394 | *
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395 | * while (true) {
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396 | * yield i++;
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397 | * }
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398 | * };
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399 | *
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400 | * Rx.Observable.from(infinite())
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401 | * .take(3) // only take 3, cause this is infinite
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402 | * .subscribe(
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403 | * value => console.log(value),
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404 | * err => {},
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405 | * () => console.log('ta dam!')
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406 | * );
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407 | *
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408 | * // Logs
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409 | * // 0
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410 | * // 1
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411 | * // 2
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412 | * // "ta dam!"
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413 | *
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414 | * @interface
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415 | * @name ObservableInput
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416 | * @noimport true
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417 | */
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418 | export class ObservableInputDoc<T> {
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419 |
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420 | }
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421 |
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422 | /**
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423 | *
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424 | * This interface describes what should be returned by function passed to Observable
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425 | * constructor or static {@link create} function. Value of that interface will be used
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426 | * to cancel subscription for given Observable.
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427 | *
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428 | * `TeardownLogic` can be:
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429 | *
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430 | * ## Function
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431 | *
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432 | * Function that takes no parameters. When consumer of created Observable calls `unsubscribe`,
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433 | * that function will be called
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434 | *
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435 | * ## AnonymousSubscription
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436 | *
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437 | * `AnonymousSubscription` is simply an object with `unsubscribe` method on it. That method
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438 | * will work the same as function
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439 | *
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440 | * ## void
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441 | *
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442 | * If created Observable does not have any resources to clean up, function does not have to
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443 | * return anything.
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444 | *
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445 | * @interface
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446 | * @name TeardownLogic
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447 | * @noimport true
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448 | */
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449 | export class TeardownLogicDoc {
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450 |
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451 | }
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