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2 changes: 1 addition & 1 deletion package.json
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"name": "@cassiozen/usestatemachine",
"version": "1.0.1",
"version": "2.0.0",
"license": "MIT",
"author": "Cassio Zen",
"main": "dist/index.js",
Expand Down
56 changes: 30 additions & 26 deletions src/index.ts
Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
import { useEffect, useReducer } from "react";
import { UseStateMachine, Machine, $$t } from "./types";
import { UseStateMachine, Machine, $$t, O } from "./types";
import { assertNever, R, useConstant } from "./extras";


const useStateMachineImpl = (definition: Machine.Definition.Impl) => {
const [state, dispatch] = useReducer(createReducer(definition), createInitialState(definition));
const [machineInstant, dispatch] = useReducer(createReducer(definition), createInitialState(definition));

const send = useConstant(() => (sendable: Machine.Sendable.Impl) => dispatch({ type: "SEND", sendable }));

Expand All @@ -13,30 +14,33 @@ const useStateMachineImpl = (definition: Machine.Definition.Impl) => {
};

useEffect(() => {
const entry = R.get(definition.states, state.value)!.effect;
const entry = R.get(definition.states, machineInstant.state)!.effect;
let exit = entry?.({
send,
setContext,
event: state.event,
context: state.context,
event: machineInstant.event,
context: machineInstant.context,
});

return typeof exit === "function"
? () => exit?.({ send, setContext, event: state.event, context: state.context })
? () => exit?.({ send, setContext, event: machineInstant.event, context: machineInstant.context })
: undefined;
// eslint-disable-next-line react-hooks/exhaustive-deps
}, [state.value, state.event]);
}, [machineInstant.state, machineInstant.event]);

return [state, send];
return { ...machineInstant, send };
};

const createInitialState = (definition: Machine.Definition.Impl): Machine.State.Impl => {
type MachineInstant =
O.OmitKey<Machine.Impl, "send">

const createInitialState = (definition: Machine.Definition.Impl): MachineInstant => {
let nextEvents = R.keys(R.concat(
R.fromMaybe(R.get(definition.states, definition.initial)!.on),
R.fromMaybe(definition.on)
))
return {
value: definition.initial,
state: definition.initial,
context: definition.context as Machine.Context.Impl,
event: { type: "$$initial" } as Machine.Event.Impl,
nextEvents: nextEvents,
Expand All @@ -46,56 +50,56 @@ const createInitialState = (definition: Machine.Definition.Impl): Machine.State.

const createReducer = (definition: Machine.Definition.Impl) => {
let log = createLogger(definition);
return (machineState: Machine.State.Impl, internalEvent: InternalEvent): Machine.State.Impl => {
return (machineInstant: MachineInstant, internalEvent: InternalEvent): MachineInstant => {
if (internalEvent.type === "SET_CONTEXT") {
let nextContext = internalEvent.updater(machineState.context);
log("Context update", ["Previous Context", machineState.context], ["Next Context", nextContext]);
let nextContext = internalEvent.updater(machineInstant.context);
log("Context update", ["Previous Context", machineInstant.context], ["Next Context", nextContext]);

return { ...machineState, context: nextContext };
return { ...machineInstant, context: nextContext };
}

if (internalEvent.type === "SEND") {
let sendable = internalEvent.sendable;
let event = typeof sendable === "string" ? { type: sendable } : sendable;
let context = machineState.context;
let stateNode = R.get(definition.states, machineState.value)!;
let context = machineInstant.context;
let stateNode = R.get(definition.states, machineInstant.state)!;
let resolvedTransition =
R.get(R.fromMaybe(stateNode.on), event.type) ?? R.get(R.fromMaybe(definition.on), event.type);

if (!resolvedTransition) {
log(
`Current state doesn't listen to event type "${event.type}".`,
["Current State", machineState],
["Current State", machineInstant],
["Event", event]
);
return machineState;
return machineInstant;
}

let [nextStateValue, didGuardDeny = false] = (() => {
let [nextState, didGuardDeny = false] = (() => {
if (typeof resolvedTransition === "string") return [resolvedTransition];
if (resolvedTransition.guard === undefined) return [resolvedTransition.target];
if (resolvedTransition.guard({ context, event })) return [resolvedTransition.target];
return [resolvedTransition.target, true]
})() as [Machine.StateValue.Impl, true?]
})() as [Machine.State.Impl, true?]

if (didGuardDeny) {
log(
`Transition from "${machineState.value}" to "${nextStateValue}" denied by guard`,
`Transition from "${machineInstant.state}" to "${nextState}" denied by guard`,
["Event", event],
["Context", context]
);
return machineState;
return machineInstant;
}
log(`Transition from "${machineState.value}" to "${nextStateValue}"`, ["Event", event]);
log(`Transition from "${machineInstant.state}" to "${nextState}"`, ["Event", event]);

let resolvedStateNode = R.get(definition.states, nextStateValue)!;
let resolvedStateNode = R.get(definition.states, nextState)!;

let nextEvents = R.keys(R.concat(
R.fromMaybe(resolvedStateNode.on),
R.fromMaybe(definition.on)
));
return {
value: nextStateValue,
state: nextState,
context,
event,
nextEvents,
Expand Down Expand Up @@ -144,4 +148,4 @@ const createLogger = (definition: Machine.Definition.Impl) => (groupLabel: strin
const useStateMachine = useStateMachineImpl as unknown as UseStateMachine;
export default useStateMachine;

export const t = <T extends unknown>() => ({ [$$t]: undefined as T })
export const t = <T>() => ({ [$$t]: undefined as unknown as T })
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