feat: westworldwithwoman. add elsa

chapter-2-state-driven-agent-design/westworldwithwoman/state_visit_bathroom.go

@@ -0,0 +1,47 @@
+package westworldwithwoman
+
+import (
+	"fmt"
+	"sync"
+)
+
+// visitBathroom is a "blip" state: it interrupts whatever Elsa was
+// doing, does its one bit of business, and immediately hands control
+// straight back to whatever she was doing before - it never leads
+// anywhere new on its own.
+type visitBathroom struct{}
+
+var (
+	visitBathroomInstance *visitBathroom
+	visitBathroomOnce     sync.Once
+)
+
+// VisitBathroom is the Go stand-in for "VisitBathroom::Instance()".
+func VisitBathroom() *visitBathroom {
+	visitBathroomOnce.Do(func() {
+		visitBathroomInstance = &visitBathroom{}
+	})
+	return visitBathroomInstance
+}
+
+var _ State[Elsa] = (*visitBathroom)(nil)
+
+// Enter announces the trip to the bathroom.
+func (s *visitBathroom) Enter(e *Elsa) {
+	fmt.Printf("\n%s: Walkin' to the can. Need to powda mah pretty li'l nose", GetNameOfEntity(e.ID()))
+}
+
+// Execute is the entire "blip": do the business, then immediately
+// revert to whatever state was active before VisitBathroom
+// interrupted it. RevertToPreviousState runs the normal ChangeState
+// dance (Exit here, Enter there), so nothing extra is needed.
+func (s *visitBathroom) Execute(e *Elsa) {
+	fmt.Printf("\n%s: Ahhhhhh! Sweet relief!", GetNameOfEntity(e.ID()))
+	e.FSM().RevertToPreviousState()
+}
+
+// Exit announces leaving the bathroom - this runs automatically as
+// part of the RevertToPreviousState call above.
+func (s *visitBathroom) Exit(e *Elsa) {
+	fmt.Printf("\n%s: Leavin' the john", GetNameOfEntity(e.ID()))
+}