Code coverage report for src/operator/filter.ts

Statements: 100% (28 / 28)      Branches: 100% (6 / 6)      Functions: 100% (7 / 7)      Lines: 100% (22 / 22)      Ignored: none     

All files » src/operator/ » filter.ts
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import {Operator} from '../Operator';
import {Subscriber} from '../Subscriber';
import {tryCatch} from '../util/tryCatch';
import {errorObject} from '../util/errorObject';
import {Observable} from '../Observable';
 
/**
 * Similar to the well-known `Array.prototype.filter` method, this operator filters values down to a set
 * allowed by a `select` function
 *
 * @param {Function} select a function that is used to select the resulting values
 *  if it returns `true`, the value is emitted, if `false` the value is not passed to the resulting observable
 * @param {any} [thisArg] an optional argument to determine the value of `this` in the `select` function
 * @returns {Observable} an observable of values allowed by the select function
 */
export function filter<T>(select: (value: T, index: number) => boolean, thisArg?: any): Observable<T> {
  return this.lift(new FilterOperator(select, thisArg));
}
 
class FilterOperator<T> implements Operator<T, T> {
  constructor(private select: (value: T, index: number) => boolean, private thisArg?: any) {
  }
 
  call(subscriber: Subscriber<T>): Subscriber<T> {
    return new FilterSubscriber(subscriber, this.select, this.thisArg);
  }
}
 
class FilterSubscriber<T> extends Subscriber<T> {
 
  count: number = 0;
 
  constructor(destination: Subscriber<T>, private select: (value: T, index: number) => boolean, private thisArg: any) {
    super(destination);
    this.select = select;
  }
 
  protected _next(x: T) {
    const result = tryCatch(this.select).call(this.thisArg || this, x, this.count++);
    if (result === errorObject) {
      this.destination.error(errorObject.e);
    } else if (Boolean(result)) {
      this.destination.next(x);
    }
  }
}