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Ken
2019-01-31 00:03:02 -08:00
parent e3e977a98d
commit 578ad8221d
9 changed files with 164 additions and 44 deletions
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22
playground/src/reducers/createReducer.ts
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@@ -2,13 +2,23 @@ import { Reducer } from 'redux';
import { ActionTypes, TodoAction } from '../actions';
import { Draft, produce } from 'immer';
export function createReducer<T>(
initialState: T,
handlers: { [actionType in ActionTypes]?: (state: Draft<T>, action: TodoAction) => T }
): Reducer<T> {
export type ImmerReducer<T> = (state: Draft<T>, action: TodoAction) => T;
export type HandlerMap<T> = { [actionType in ActionTypes]?: ImmerReducer<T> };
function isHandlerFunction<T>(handlerOrMap: HandlerMap<T> | ImmerReducer<T>): handlerOrMap is ImmerReducer<T> {
if (typeof handlerOrMap === 'function') {
return true;
}
return false;
}
export function createReducer<T>(initialState: T, handlerOrMap: HandlerMap<T> | ImmerReducer<T>): Reducer<T> {
return function reducer(state = initialState, action: TodoAction): T {
if (handlers.hasOwnProperty(action.type)) {
return produce(state, draft => handlers[action.type](draft, action));
if (isHandlerFunction(handlerOrMap)) {
return produce(state, draft => handlerOrMap(draft, action));
} else if (handlerOrMap.hasOwnProperty(action.type)) {
return produce(state, draft => handlerOrMap[action.type](draft, action));
} else {
return state;
}