feat: add handler map factory

src/__tests__/__snapshots__/create-handler-map.dts.spec.ts.snap

@@ -0,0 +1,5 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`createHandlerMap handle([increment, increase], (state: number) => state + 1) (type) should match snapshot: createHandlerMap handle([increment, increase], (state: number) => state + 1) 1`] = `"import(\\"/Users/brodmann/Projects/@thebrodmann/deox/src/create-handler-map\\").HandlerMap<number, { type: \\"[Counter] increment\\"; } | { type: \\"[Counter] increase\\"; }>"`;
+
+exports[`createHandlerMap handle(increment, (state: number) => state + 1) (type) should match snapshot: createHandlerMap handle(increment, (state: number) => state + 1) 1`] = `"import(\\"/Users/brodmann/Projects/@thebrodmann/deox/src/create-handler-map\\").HandlerMap<number, { type: \\"[Counter] increment\\"; }>"`;

src/__tests__/__snapshots__/create-handler-map.spec.ts.snap

@@ -0,0 +1,14 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`createHandlerMap should belong multiple actions to one handler 1`] = `
+Object {
+  "[Counter] increase": [Function],
+  "[Counter] increment": [Function],
+}
+`;
+
+exports[`createHandlerMap should belong one action to one handler 1`] = `
+Object {
+  "[Counter] increment": [Function],
+}
+`;

src/__tests__/create-handler-map.dts.spec.ts

@@ -0,0 +1,13 @@
+import { createAction } from '../create-action'
+import { createHandlerMap as handle } from '../create-handler-map'
+
+// @dts-jest:group createHandlerMap
+
+const increment = createAction('[Counter] increment')
+const increase = createAction('[Counter] increase')
+
+// @dts-jest:pass:snap
+handle(increment, (state: number) => state + 1)
+
+// @dts-jest:pass:snap
+handle([increment, increase], (state: number) => state + 1)

src/__tests__/create-handler-map.spec.ts

@@ -0,0 +1,19 @@
+import { createAction } from '../create-action'
+import { createHandlerMap as handle } from '../create-handler-map'
+
+describe('createHandlerMap', () => {
+  it('should belong one action to one handler', () => {
+    const increment = createAction('[Counter] increment')
+
+    expect(handle(increment, (state: number) => state + 1)).toMatchSnapshot()
+  })
+
+  it('should belong multiple actions to one handler', () => {
+    const increment = createAction('[Counter] increment')
+    const increase = createAction('[Counter] increase')
+
+    expect(
+      handle([increment, increase], (state: number) => state + 1)
+    ).toMatchSnapshot()
+  })
+})

src/create-handler-map.ts

@@ -0,0 +1,41 @@
+import { ActionCreator } from './create-action'
+import { AnyAction } from './action'
+import { getType } from './get-type'
+
+export type HandlerMap<State, Actions extends AnyAction> = {
+  [key in Actions['type']]: Reducer<State, Actions>
+}
+
+export type CreateHandlerMap<State> = <
+  AC extends ActionCreator<string>,
+  Actions extends AnyAction = AC extends (...args: any[]) => infer T ? T : never
+>(
+  actionCreators: AC | AC[],
+  handler: Reducer<State, Actions>
+) => HandlerMap<State, Actions>
+
+/**
+ * Handler map factory
+ * @description create an action(s) to reducer map
+ * @example
+ * createHandlerMap(increment, (state: number) => state + 1)
+ * @example
+ * createHandlerMap([increment, increase], (state: number) => state + 1)
+ */
+export const createHandlerMap = <
+  AC extends ActionCreator<string>,
+  State,
+  Actions extends AnyAction = AC extends (...args: any[]) => infer T ? T : never
+>(
+  actionCreators: AC | AC[],
+  reducer: Reducer<State, Actions>
+) =>
+  (Array.isArray(actionCreators) ? actionCreators : [actionCreators])
+    .map(getType)
+    .reduce<HandlerMap<State, Actions>>(
+      (acc, type) => {
+        acc[type] = reducer
+        return acc
+      },
+      {} as any
+    )

src/types.d.ts

@@ -0,0 +1 @@
+type Reducer<State, Actions> = (prevState: State, action: Actions) => State

tsconfig.spec.json

@@ -1,6 +1,6 @@
 {
   "extends": "./tsconfig.json",
-  "include": ["./src/**/__tests__/*"],
+  "include": ["./src/**/__tests__/*", "./src/types.d.ts"],
   "compilerOptions": {
     "target": "esnext",
     "esModuleInterop": true