evgenyfedorenko

import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs';
import * as fromRoot from './reducers/';
import { Increment, Decrement, Reset } from './actions/counter.actions';
import { StoreService, select } from './store.service';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
})

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export function createSelector(...args: any[]) {
  const selectors = args.slice(0, args.length - 1);
  const projector = args[args.length - 1];

  return function (state: any) {
    const args = selectors.map(fn => fn(state));

    return projector.apply(null, args);
  };
}

evgenyfedorenko

export function select<T, Props, K>(selector: (state: T, props?: Props) => any) {
  return function selectOperator(source$: Observable<T>): Observable<K> {
    let mapped$: Observable<any>;

    mapped$ = source$.pipe(
      map(source => selector(source))
    );

    return mapped$.pipe(distinctUntilChanged());
  };

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function reduceState(stateActionPair = { state: undefined }, [action, reducer]) {
  const { state } = stateActionPair;
  return { state: reducer(state, action), action };
}

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function reducerFactory(reducers) {
  return function combination(state, action) {
    const nextState: any = {};
    const reducerKeys = Object.keys(reducers);
    for (let i = 0; i < reducerKeys.length; i++) {
      const key = reducerKeys[i];
      const reducer: any = reducers[key];
      nextState[key] = reducer(state[key], action);
    }
    return nextState;

evgenyfedorenko

  ...  
  actions$: BehaviorSubject<Action>;
  state$: BehaviorSubject<any>;

  constructor() {
    this.actions$ = new BehaviorSubject({ type: 'INIT' });
    const actionsOnQueue$: Observable<Action> = this.actions$.pipe(observeOn(queueScheduler));
    const reducer$: Observable<
      ActionReducer<any, any>
    > = new BehaviorSubject(reducerFactory(reducers));

evgenyfedorenko

import { Injectable } from '@angular/core';
import {
  BehaviorSubject,
  Observable,
  queueScheduler,
} from 'rxjs';
import { observeOn, scan, withLatestFrom, map, distinctUntilChanged } from 'rxjs/operators';
import { reducers } from './reducers';

export interface Action {

evgenyfedorenko

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evgenyfedorenko

...

@Component({
  selector: 'transaction',
  templateUrl: './transaction.html',
  styleUrls: ['./transaction.scss'],
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class TransactionComponent implements OnChanges {