[core] Transition function

.changeset/lemon-needles-play.md

@@ -0,0 +1,23 @@
+---
+'xstate': minor
+---
+
+Added a new `transition` function that takes an actor logic, a snapshot, and an event, and returns a tuple containing the next snapshot and the actions to execute. This function is a pure function and does not execute the actions itself. It can be used like this:
+
+```ts
+import { transition } from 'xstate';
+
+const [nextState, actions] = transition(actorLogic, currentState, event);
+// Execute actions as needed
+```
+
+Added a new `initialTransition` function that takes an actor logic and an optional input, and returns a tuple containing the initial snapshot and the actions to execute from the initial transition. This function is also a pure function and does not execute the actions itself. It can be used like this:
+
+```ts
+import { initialTransition } from 'xstate';
+
+const [initialState, actions] = initialTransition(actorLogic, input);
+// Execute actions as needed
+```
+
+These new functions provide a way to separate the calculation of the next snapshot and actions from the execution of those actions, allowing for more control and flexibility in the transition process.

.vscode/launch.json

@@ -9,6 +9,7 @@
       "args": ["${file}", "--config", "jest.config.js", "--no-cache"],
       "console": "integratedTerminal",
       "internalConsoleOptions": "neverOpen",
+      "runtimeExecutable": "node",
       "windows": {
         "program": "${workspaceFolder}/node_modules/jest/bin/jest"
       }
@@ -27,6 +28,7 @@
       ],
       "console": "integratedTerminal",
       "internalConsoleOptions": "neverOpen",
+      "runtimeExecutable": "node",
       "windows": {
         "program": "${workspaceFolder}/node_modules/jest/bin/jest"
       }

packages/core/src/StateMachine.ts

@@ -46,6 +46,7 @@ import type {
   StateMachineDefinition,
   StateValue,
   TransitionDefinition,
+  UnknownActionObject,
   ResolvedStateMachineTypes,
   StateSchema,
   SnapshotStatus
@@ -293,7 +294,8 @@ export class StateMachine<
     TMeta,
     TConfig
   > {
-    return macrostep(snapshot, event, actorScope).snapshot as typeof snapshot;
+    return macrostep(snapshot, event, actorScope, [])
+      .snapshot as typeof snapshot;
   }
 
   /**
@@ -328,7 +330,7 @@ export class StateMachine<
       TConfig
     >
   > {
-    return macrostep(snapshot, event, actorScope).microstates;
+    return macrostep(snapshot, event, actorScope, []).microstates;
   }
 
   public getTransitionData(
@@ -385,8 +387,9 @@ export class StateMachine<
         preInitial,
         initEvent,
         actorScope,
-        [assign(assignment)],
-        internalQueue
+        [assign(assignment) as unknown as UnknownActionObject],
+        internalQueue,
+        undefined
       ) as SnapshotFrom<this>;
     }
 

packages/core/src/StateNode.ts

@@ -4,6 +4,7 @@ import { NULL_EVENT, STATE_DELIMITER } from './constants.ts';
 import { evaluateGuard } from './guards.ts';
 import { memo } from './memo.ts';
 import {
+  convertAction,
   formatInitialTransition,
   formatTransition,
   formatTransitions,
@@ -30,7 +31,8 @@ import type {
   AnyStateNodeConfig,
   ProvidedActor,
   NonReducibleUnknown,
-  EventDescriptor
+  EventDescriptor,
+  UnknownActionObject
 } from './types.ts';
 import {
   createInvokeId,
@@ -41,21 +43,6 @@ import {
 
 const EMPTY_OBJECT = {};
 
-const toSerializableAction = (action: UnknownAction) => {
-  if (typeof action === 'string') {
-    return { type: action };
-  }
-  if (typeof action === 'function') {
-    if ('resolve' in action) {
-      return { type: (action as any).type };
-    }
-    return {
-      type: action.name
-    };
-  }
-  return action;
-};
-
 interface StateNodeOptions<
   TContext extends MachineContext,
   TEvent extends EventObject
@@ -98,9 +85,9 @@ export class StateNode<
    */
   public history: false | 'shallow' | 'deep';
   /** The action(s) to be executed upon entering the state node. */
-  public entry: UnknownAction[];
+  public entry: UnknownActionObject[];
   /** The action(s) to be executed upon exiting the state node. */
-  public exit: UnknownAction[];
+  public exit: UnknownActionObject[];
   /** The parent state node. */
   public parent?: StateNode<TContext, TEvent>;
   /** The root machine node. */
@@ -209,8 +196,32 @@ export class StateNode<
     this.history =
       this.config.history === true ? 'shallow' : this.config.history || false;
 
-    this.entry = toArray(this.config.entry).slice();
-    this.exit = toArray(this.config.exit).slice();
+    this.entry = toArray(this.config.entry as UnknownAction).map(
+      (action, actionIndex) => {
+        const actionObject = convertAction(
+          action,
+          this,
+          undefined,
+          'entry',
+          0,
+          actionIndex
+        );
+        return actionObject;
+      }
+    );
+    this.exit = toArray(this.config.exit as UnknownAction).map(
+      (action, actionIndex) => {
+        const actionObject = convertAction(
+          action,
+          this,
+          undefined,
+          'exit',
+          0,
+          actionIndex
+        );
+        return actionObject;
+      }
+    );
 
     this.meta = this.config.meta;
     this.output =
@@ -222,8 +233,8 @@ export class StateNode<
   public _initialize() {
     this.transitions = formatTransitions(this);
     if (this.config.always) {
-      this.always = toTransitionConfigArray(this.config.always).map((t) =>
-        formatTransition(this, NULL_EVENT, t)
+      this.always = toTransitionConfigArray(this.config.always).map((t, i) =>
+        formatTransition(this, NULL_EVENT, t, i)
       );
     }
 
@@ -243,13 +254,13 @@ export class StateNode<
         ? {
             target: this.initial.target,
             source: this,
-            actions: this.initial.actions.map(toSerializableAction),
+            actions: this.initial.actions,
             eventType: null as any,
             reenter: false,
             toJSON: () => ({
               target: this.initial!.target!.map((t) => `#${t.id}`),
               source: `#${this.id}`,
-              actions: this.initial!.actions.map(toSerializableAction),
+              actions: this.initial!.actions,
               eventType: null as any
             })
           }
@@ -261,10 +272,10 @@ export class StateNode<
       on: this.on,
       transitions: [...this.transitions.values()].flat().map((t) => ({
         ...t,
-        actions: t.actions.map(toSerializableAction)
+        actions: t.actions
       })),
-      entry: this.entry.map(toSerializableAction),
-      exit: this.exit.map(toSerializableAction),
+      entry: this.entry,
+      exit: this.exit,
       meta: this.meta,
       order: this.order || -1,
       output: this.output,
@@ -375,7 +386,7 @@ export class StateNode<
     event: TEvent
   ): TransitionDefinition<TContext, TEvent>[] | undefined {
     const eventType = event.type;
-    const actions: UnknownAction[] = [];
+    const actions: UnknownActionObject[] = [];
 
     let selectedTransition: TransitionDefinition<TContext, TEvent> | undefined;
 

packages/core/src/actions/assign.ts

@@ -1,7 +1,7 @@
 import isDevelopment from '#is-development';
 import { cloneMachineSnapshot } from '../State.ts';
+import { executingCustomAction } from '../createActor.ts';
 import { Spawner, createSpawner } from '../spawn.ts';
-import { executingCustomAction } from '../stateUtils.ts';
 import type {
   ActionArgs,
   AnyActorScope,
@@ -179,5 +179,9 @@ export function assign<
 
   assign.resolve = resolveAssign;
 
+  assign.toJSON = () => ({
+    ...assign
+  });
+
   return assign;
 }

packages/core/src/actions/cancel.ts

@@ -35,7 +35,7 @@ function resolveCancel(
 
 function executeCancel(actorScope: AnyActorScope, resolvedSendId: string) {
   actorScope.defer(() => {
-    actorScope.system.scheduler.cancel(actorScope.self, resolvedSendId);
+    // actorScope.system.scheduler.cancel(actorScope.self, resolvedSendId);
   });
 }
 
@@ -103,5 +103,9 @@ export function cancel<
   cancel.resolve = resolveCancel;
   cancel.execute = executeCancel;
 
+  cancel.toJSON = () => ({
+    ...cancel
+  });
+
   return cancel;
 }

packages/core/src/actions/emit.ts

@@ -1,5 +1,5 @@
 import isDevelopment from '#is-development';
-import { executingCustomAction } from '../stateUtils.ts';
+import { executingCustomAction } from '../createActor.ts';
 import {
   ActionArgs,
   ActionFunction,
@@ -151,5 +151,9 @@ export function emit<
   emit.resolve = resolveEmit;
   emit.execute = executeEmit;
 
+  emit.toJSON = () => ({
+    ...emit
+  });
+
   return emit;
 }

packages/core/src/actions/enqueueActions.ts

@@ -1,5 +1,6 @@
 import isDevelopment from '#is-development';
 import { Guard, evaluateGuard } from '../guards.ts';
+import { convertAction } from '../stateUtils.ts';
 import {
   Action,
   ActionArgs,
@@ -135,7 +136,16 @@ function resolveEnqueueActions(
   const enqueue: Parameters<typeof collect>[0]['enqueue'] = function enqueue(
     action
   ) {
-    actions.push(action);
+    actions.push(
+      convertAction(
+        action as any,
+        snapshot.machine.root,
+        'enqueue' + Math.random(), // TODO: this should come from state node ID which isn't provided
+        undefined,
+        0,
+        actions.length
+      )
+    );
   };
   enqueue.assign = (...args) => {
     actions.push(assign(...args));
@@ -323,5 +333,9 @@ export function enqueueActions<
   enqueueActions.collect = collect;
   enqueueActions.resolve = resolveEnqueueActions;
 
+  enqueueActions.toJSON = () => ({
+    ...enqueueActions
+  });
+
   return enqueueActions;
 }

packages/core/src/actions/log.ts

@@ -96,5 +96,9 @@ export function log<
   log.resolve = resolveLog;
   log.execute = executeLog;
 
+  log.toJSON = () => ({
+    ...log
+  });
+
   return log;
 }

packages/core/src/actions/raise.ts

@@ -1,5 +1,5 @@
 import isDevelopment from '#is-development';
-import { executingCustomAction } from '../stateUtils.ts';
+import { executingCustomAction } from '../createActor.ts';
 import {
   ActionArgs,
   ActionFunction,
@@ -87,10 +87,10 @@ function executeRaise(
 ) {
   const { event, delay, id } = params;
   if (typeof delay === 'number') {
-    actorScope.defer(() => {
-      const self = actorScope.self;
-      actorScope.system.scheduler.schedule(self, self, event, delay, id);
-    });
+    // actorScope.defer(() => {
+    //   const self = actorScope.self;
+    //   actorScope.system.scheduler.schedule(self, self, event, delay, id);
+    // });
     return;
   }
 }
@@ -165,5 +165,9 @@ export function raise<
   raise.resolve = resolveRaise;
   raise.execute = executeRaise;
 
+  raise.toJSON = () => ({
+    ...raise
+  });
+
   return raise;
 }

packages/core/src/actions/send.ts

@@ -1,7 +1,7 @@
 import isDevelopment from '#is-development';
 import { XSTATE_ERROR } from '../constants.ts';
 import { createErrorActorEvent } from '../eventUtils.ts';
-import { executingCustomAction } from '../stateUtils.ts';
+import { executingCustomAction } from '../createActor.ts';
 import {
   ActionArgs,
   ActionFunction,
@@ -149,13 +149,6 @@ function executeSendTo(
   actorScope.defer(() => {
     const { to, event, delay, id } = params;
     if (typeof delay === 'number') {
-      actorScope.system.scheduler.schedule(
-        actorScope.self,
-        to,
-        event,
-        delay,
-        id
-      );
       return;
     }
     actorScope.system._relay(
@@ -250,7 +243,7 @@ export function sendTo<
     }
   }
 
-  sendTo.type = 'xsnapshot.sendTo';
+  sendTo.type = 'xstate.sendTo';
   sendTo.to = to;
   sendTo.event = eventOrExpr;
   sendTo.id = options?.id;
@@ -260,6 +253,10 @@ export function sendTo<
   sendTo.retryResolve = retryResolveSendTo;
   sendTo.execute = executeSendTo;
 
+  sendTo.toJSON = () => ({
+    ...sendTo
+  });
+
   return sendTo;
 }