feat(overmind): statemachines best of both worlds

BREAKING CHANGE:
instead of generic single signature, we now have two signatures

Author: christianalfoni

packages/node_modules/overmind/src/statemachine.test.ts

@@ -12,11 +12,11 @@ describe('Statemachine', () => {
     }
 
     const state = statemachine<States, { type: 'TEST'}>({
-      TEST: () => {}
+      FOO: {},
+      BAR: {}
     }).create({
       current: 'FOO'
     })
-
 
     const config = {
       state,
@@ -40,7 +40,8 @@ describe('Statemachine', () => {
     }
 
     const state = statemachine<States, { type: 'TEST' }, BaseState>({
-      TEST: () => {}
+      FOO: {},
+      BAR: {}
     }).create({
       current: 'FOO',
     }, {
@@ -59,7 +60,7 @@ describe('Statemachine', () => {
   })
 
 
-  test('should transition state', () => {
+  test('should transition state using function', () => {
     type States = {
      current: 'FOO'
     } | {
@@ -70,8 +71,8 @@ describe('Statemachine', () => {
       type: 'TOGGLE',
     }
 
-    const state = statemachine<States, Events>({
-      TOGGLE: (state) => ({ current: state.current === 'FOO' ? 'BAR' : 'FOO' })
+    const state = statemachine<States, Events>((_, state) => {
+      return ({ current: state.current === 'FOO' ? 'BAR' : 'FOO' })
     }).create({
       current: 'FOO'
     })
@@ -111,7 +112,12 @@ describe('Statemachine', () => {
     }
 
     const state = statemachine<States, Events>({
-      TOGGLE: () => ({ current: 'BAR' })
+      FOO: {
+        TOGGLE: () => ({ current: 'BAR' })
+      },
+      BAR: {
+        TOGGLE: () => ({ current: 'FOO', foo: 'foo' })
+      }
     }).create({
       current: 'FOO',
       foo: 'bar'
@@ -154,14 +160,12 @@ describe('Statemachine', () => {
       type: 'TOGGLE',
     }
 
-    const state = statemachine<States, Events>({
-      TOGGLE: (state) => {
-        if (state.current === 'FOO') {
-          return { current: 'BAR' }
-        }
-
-        return { current: 'FOO', foo: 'bar'}
+    const state = statemachine<States, Events>((_, state) => {
+      if (state.current === 'FOO') {
+        return { current: 'BAR' }
       }
+
+      return { current: 'FOO', foo: 'bar'}
     }).create({
       current: 'FOO',
       foo: 'bar'
@@ -204,7 +208,12 @@ describe('Statemachine', () => {
     }
 
     const state = statemachine<States, Events>({
-      TOGGLE: () => {}
+      FOO: {
+        TOGGLE: () => {}
+      },
+      BAR: {
+        TOGGLE: () => {}
+      }
     }).create({
       current: 'FOO'
     })
@@ -247,7 +256,10 @@ describe('Statemachine', () => {
     }
 
     const state = statemachine<States, Events>({
-      TOGGLE: () => ({ current: 'BAR' })
+      FOO: {
+        TOGGLE: () => ({ current: 'BAR' })
+      },
+      BAR: {}
     }).create({
       current: 'FOO'
     })
@@ -289,7 +301,12 @@ describe('Statemachine', () => {
     }
 
     const state = statemachine<States, { type: 'TEST'}>({
-      TEST: () => {}
+      FOO: {
+        TEST: () => {}
+      },
+      BAR: {
+        TEST: () => {}
+      }
     }).create({
       current: 'FOO',
       obj: {

packages/node_modules/overmind/src/statemachine.ts

@@ -20,17 +20,25 @@ export type StatemachineTransitions<
   States extends TState,
   Events extends TEvents,
   BaseState extends TBaseState
-> = {
-  [Type in Events['type']]: [BaseState] extends [never]
-    ? ((
-        state: States,
-        payload: Events extends { type: Type } ? Events['data'] : never
-      ) => States | void)
-    : ((
-        state: States & BaseState,
-        payload: Events extends { type: Type } ? Events['data'] : never
-      ) => States | void)
-}
+> =
+  | ([BaseState] extends [never]
+      ? (event: Events, state: States) => States | void
+      : (event: Events, state: States & BaseState) => States | void)
+  | {
+      [State in States['current']]: {
+        [Type in Events['type']]?: [BaseState] extends [never]
+          ? ((
+              state: States extends { current: State } ? States : never,
+              payload: Events extends { type: Type } ? Events['data'] : never
+            ) => States | void)
+          : ((
+              state: States extends { current: State }
+                ? States & BaseState
+                : never,
+              payload: Events extends { type: Type } ? Events['data'] : never
+            ) => States | void)
+      }
+    }
 
 export interface MachineMethods<
   States extends TState,
@@ -147,10 +155,20 @@ export class StateMachine<
     }
 
     const tree = this[PROXY_TREE].master.mutationTree || this[PROXY_TREE]
-    const transition = this[VALUE][TRANSITIONS][type]
 
     tree.enableMutations()
-    const result = transition(this, data)
+
+    let result
+
+    if (typeof this[VALUE][TRANSITIONS] === 'function') {
+      const transition = this[VALUE][TRANSITIONS]
+
+      result = transition({ type, data }, this)
+    } else {
+      const transition = this[VALUE][TRANSITIONS][this[VALUE].current][type]
+
+      result = transition(data, this)
+    }
 
     if (result) {
       this[VALUE][CURRENT_KEYS].forEach((key) => {