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reduced typings some more

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Ken
2019-01-31 14:45:33 -08:00
parent 2ecb667b3a
commit 886215cefa
4 changed files with 26 additions and 18 deletions
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19
playground/src/redux-utils/reducer.ts
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@@ -1,13 +1,14 @@
import { Reducer } from 'redux';
import { Draft, produce } from 'immer';
import { GenericActionLookup, GenericActionMapping } from './action';
export type ImmerReducer<T, A> = (state: Draft<T>, action?: A) => T;
export type HandlerMap<T, AT extends string, Lookup extends { [t in AT]: any }> = {
[actionType in AT]?: ImmerReducer<T, Lookup[actionType]>
export type HandlerMap<T, A extends GenericActionMapping<A>> = {
[actionType in keyof A]?: ImmerReducer<T, GenericActionLookup<A>[actionType]>
};
function isHandlerFunction<T, A, AT extends string, Lookup extends { [t in AT]: any }>(
handlerOrMap: HandlerMap<T, AT, Lookup> | ImmerReducer<T, A>
function isHandlerFunction<T, A extends GenericActionMapping<A>>(
handlerOrMap: HandlerMap<T, A> | ImmerReducer<T, A>
): handlerOrMap is ImmerReducer<T, A> {
if (typeof handlerOrMap === 'function') {
return true;
@@ -16,15 +17,15 @@ function isHandlerFunction<T, A, AT extends string, Lookup extends { [t in AT]:
return false;
}
export function createGenericReducer<T, AT extends string, Lookup extends { [t in AT]: any }>(
export function createGenericReducer<T, A extends GenericActionMapping<A>, AM = keyof GenericActionMapping<A>>(
initialState: T,
handlerOrMap: HandlerMap<T, AT, Lookup> | ImmerReducer<T, Lookup[AT]>
handlerOrMap: HandlerMap<T, A> | ImmerReducer<T, GenericActionLookup<A>[AM]>
): Reducer<T> {
return function reducer(state = initialState, action: Lookup[AT]): T {
return function reducer(state = initialState, action: GenericActionLookup<A>[AM]): T {
if (isHandlerFunction(handlerOrMap)) {
return produce(state, draft => handlerOrMap(draft, action as Lookup[AT]));
return produce(state, draft => handlerOrMap(draft, action as GenericActionLookup<A>[AM]));
} else if (handlerOrMap.hasOwnProperty(action.type)) {
const handler = (handlerOrMap as any)[action.type] as ImmerReducer<T, Lookup[AT]>;
const handler = (handlerOrMap as any)[action.type] as ImmerReducer<T, GenericActionLookup<A>[AM]>;
return produce(state, draft => handler(draft, action));
} else {
return state;