fix: add Diagram and avail source state in the event

fsm.go

@@ -4,6 +4,12 @@ import (
 	"golang.org/x/exp/constraints"
 )
 
+type Diagram interface {
+	// Visualize outputs a visualization of a Fsm in the desired format.
+	// If the type is not given it defaults to Graphviz
+	Visualize(t VisualizeType) (string, error)
+}
+
 type IFsm[E constraints.Ordered, S constraints.Ordered] interface {
 	// Clone the Fsm.
 	Clone() IFsm[E, S]
@@ -50,6 +56,8 @@ type IFsm[E constraints.Ordered, S constraints.Ordered] interface {
 	ContainsAllEvent(events ...E) bool
 	// AvailEvents returns a list of available transform event in src state.
 	AvailEvents(srcState S) []E
+	// AvailSourceStates returns a list of available source state in the event.
+	AvailSourceStates(event E) []S
 	// SortedTriggerSource return a list of sorted trigger source
 	SortedTriggerSource() []TriggerSource[E, S]
 	// SortedStates return a list of sorted states.
@@ -60,6 +68,7 @@ type IFsm[E constraints.Ordered, S constraints.Ordered] interface {
 	EventName(event E) string
 	// StateName returns a state name.
 	StateName(state S) string
+	Diagram
 }
 
 type ErrorTranslator interface {

fsm_safe.go

@@ -77,3 +77,6 @@ func (f *SafeFsm[E, S]) MatchCurrentAllOccur(event ...E) bool {
 func (f *SafeFsm[E, S]) CurrentAvailEvents() []E {
 	return f.Transition.AvailEvents(f.current)
 }
+func (f *SafeFsm[E, S]) Visualize(t VisualizeType) (string, error) {
+	return Visualize[E, S](t, f)
+}

fsm_test.go

@@ -111,12 +111,12 @@ func test_Fsm_State(t *testing.T, newFsm func(initState string, ts *Transition[s
 	}
 }
 
-func Test_Fsm_AvailEvents(t *testing.T) {
-	test_Fsm_AvailEvents(t, NewSafeFsm[string, string])
-	test_Fsm_AvailEvents(t, NewFsm[string, string])
+func Test_Fsm_Avail(t *testing.T) {
+	test_Fsm_Avail(t, NewSafeFsm[string, string])
+	test_Fsm_Avail(t, NewFsm[string, string])
 }
 
-func test_Fsm_AvailEvents(t *testing.T, newFsm func(initState string, ts *Transition[string, string]) IFsm[string, string]) {
+func test_Fsm_Avail(t *testing.T, newFsm func(initState string, ts *Transition[string, string]) IFsm[string, string]) {
 	fsm := newFsm(
 		"closed",
 		NewTransition([]Transform[string, string]{
@@ -133,6 +133,10 @@ func test_Fsm_AvailEvents(t *testing.T, newFsm func(initState string, ts *Transi
 	if !slices.Equal(sortedEvents, []string{"close", "middle", "open"}) {
 		t.Error("expected sort event [close, middle, open] event with current state")
 	}
+	availSourceStates := fsm.AvailSourceStates("open")
+	if !slices.Contains(availSourceStates, "closed") {
+		t.Error("expected avail source state [closed] with the event")
+	}
 
 	if !fsm.MatchCurrentAllOccur("middle", "open") {
 		t.Error("expected contain all [middle, open] event with current state")

fsm_transition.go

@@ -15,20 +15,20 @@ var (
 	ErrNonExistEvent      = errors.New("fsm: event does not exist")
 )
 
-// Transform represents an event when initializing the FSM.
+// Transform represents an event when initializing the Fsm.
 //
 // The event can have one or more source states that is valid for performing
-// the transition. If the FSM is in one of the source states it will end up in
+// the transition. If the Fsm is in one of the source states it will end up in
 // the specified destination state.
 type Transform[E constraints.Ordered, S constraints.Ordered] struct {
 	// Name the event.
 	Name string
 	// Event is the event used when calling for the transform.
 	Event E
-	// Src is a slice of source states that the FSM must be in to perform a
+	// Src is a slice of source states that the Fsm must be in to perform a
 	// state transform.
 	Src []S
-	// Dst is the destination state that the FSM will be in if the transform
+	// Dst is the destination state that the Fsm will be in if the transform
 	// succeeds.
 	Dst S
 }
@@ -192,6 +192,17 @@ func (t *Transition[E, S]) AvailEvents(srcState S) []E {
 	return maps.Keys(events)
 }
 
+// AvailSourceStates returns a list of available source state in the event.
+func (t *Transition[E, S]) AvailSourceStates(event E) []S {
+	srcs := make([]S, 0, 8)
+	for ts := range t.mapping {
+		if ts.event == event {
+			srcs = append(srcs, ts.src)
+		}
+	}
+	return srcs
+}
+
 // SortedTriggerSource return a list of sorted trigger source
 func (t *Transition[E, S]) SortedTriggerSource() []TriggerSource[E, S] {
 	triggerSources := maps.Keys(t.mapping)

fsm_unsafe.go

@@ -57,3 +57,6 @@ func (f *Fsm[E, S]) MatchCurrentAllOccur(event ...E) bool {
 func (f *Fsm[E, S]) CurrentAvailEvents() []E {
 	return f.Transition.AvailEvents(f.current)
 }
+func (f *Fsm[E, S]) Visualize(t VisualizeType) (string, error) {
+	return Visualize[E, S](t, f)
+}

visualizer._mermaid.go

@@ -19,7 +19,7 @@ const (
 	StateDiagram MermaidType = "stateDiagram"
 )
 
-// VisualizeMermaid outputs a visualization of a FSM in Mermaid format as specified by the graphType.
+// VisualizeMermaid outputs a visualization of a Fsm in Mermaid format as specified by the graphType.
 func VisualizeMermaid[E constraints.Ordered, S constraints.Ordered](t MermaidType, fsm Visualizer[E, S]) (string, error) {
 	switch t {
 	case FlowChart:
@@ -52,7 +52,7 @@ func visualizeMermaidStateDiagram[E constraints.Ordered, S constraints.Ordered](
 	return buf.String(), nil
 }
 
-// visualizeMermaidFlowChart outputs a visualization of a FSM in Mermaid format (including highlighting of current state).
+// visualizeMermaidFlowChart outputs a visualization of a Fsm in Mermaid format (including highlighting of current state).
 func visualizeMermaidFlowChart[E constraints.Ordered, S constraints.Ordered](fsm Visualizer[E, S]) (string, error) {
 	v := newVisualizeMermaidFlowChartBuilder(fsm).
 		writeFlowChartGraphType().

visualizer.go

@@ -4,7 +4,7 @@ import (
 	"golang.org/x/exp/constraints"
 )
 
-// Visualize outputs a visualization of a FSM in the desired format.
+// Visualize outputs a visualization of a Fsm in the desired format.
 type Visualizer[E constraints.Ordered, S constraints.Ordered] interface {
 	Current() S
 	Name() string
@@ -30,7 +30,7 @@ const (
 	MermaidFlowChart VisualizeType = "mermaid-flow-chart"
 )
 
-// Visualize outputs a visualization of a FSM in the desired format.
+// Visualize outputs a visualization of a Fsm in the desired format.
 // If the type is not given it defaults to Graphviz
 func Visualize[E constraints.Ordered, S constraints.Ordered](t VisualizeType, fsm Visualizer[E, S]) (string, error) {
 	switch t {

visualizer_graphviz.go

@@ -8,7 +8,7 @@ import (
 	"golang.org/x/exp/constraints"
 )
 
-// VisualizeGraphviz outputs a visualization of a FSM in Graphviz format.
+// VisualizeGraphviz outputs a visualization of a Fsm in Graphviz format.
 func VisualizeGraphviz[E constraints.Ordered, S constraints.Ordered](fsm Visualizer[E, S]) (string, error) {
 	v := newVisualizeGraphvizBuilder(fsm).
 		writeHeaderLine().

visualizer_graphviz_test.go

@@ -7,15 +7,15 @@ import (
 )
 
 func Test_Graphviz(t *testing.T) {
-	fsmUnderTest := NewSafeFsm(
+	fsmUnderTest := NewFsm(
 		"closed",
 		NewTransition([]Transform[string, string]{
 			{Event: "open", Src: []string{"closed"}, Dst: "open"},
 			{Event: "close", Src: []string{"open"}, Dst: "closed"},
 			{Event: "part-close", Src: []string{"intermediate"}, Dst: "closed"},
 		}),
 	)
-	got, err := VisualizeGraphviz[string, string](fsmUnderTest)
+	got, err := fsmUnderTest.Visualize(Graphviz)
 	if err != nil {
 		panic(err)
 	}
@@ -54,7 +54,8 @@ func Test_Graphviz_CustomName(t *testing.T) {
 			}).
 			Build(),
 	)
-	got, err := VisualizeGraphviz[string, string](fsmUnderTest)
+
+	got, err := fsmUnderTest.Visualize(Graphviz)
 	if err != nil {
 		panic(err)
 	}