@angular-redux/store/src/components/selectors.ts

Angular 2 bindings for Redux

import { getIn } from '../utils/get-in';
import { Observable } from 'rxjs/Observable';

export type Comparator = (x: any, y: any) => boolean;
export type Transformer<RootState, V> = (store$: Observable<RootState>) => Observable<V>
export type PropertySelector = string | number | symbol;
export type PathSelector = (string | number)[];
export type FunctionSelector<RootState, S> = ((s: RootState) => S);
export type Selector<RootState, S> = PropertySelector |
  PathSelector |
  FunctionSelector<RootState, S>;

/** @hidden */
export const sniffSelectorType = <RootState, S>(selector?: Selector<RootState, S>) =>
  !selector ?
    'nil' :
    Array.isArray(selector) ?
      'path' :
      typeof selector === 'function' ?
        'function' :
        'property';

/** @hidden */
export const resolver = <RootState, S>(selector?: Selector<RootState, S>) => ({
  property: state => state[selector as PropertySelector],
  path: state => getIn(state, selector as PathSelector),
  function: selector as FunctionSelector<RootState, S>,
  nil: state => state,
});

/** @hidden */
export const resolveToFunctionSelector = <RootState, S>(selector?: Selector<RootState, S>) =>
  resolver(selector)[sniffSelectorType(selector)];