Allow one state to map to multiple states with the same transition eg. ab|aa

main.go

@@ -106,7 +106,7 @@ func thompson(re string) State {
 	for _, c := range re {
 		if isAlphaNum(c) {
 			state := State{}
-			state.transitions = make(map[int]*State)
+			state.transitions = make(map[int][]*State)
 			state.content = int(c)
 			state.output = make([]*State, 0)
 			state.output = append(state.output, &state)
@@ -119,14 +119,14 @@ func thompson(re string) State {
 			s2 := pop(&nfa)
 			s1 := pop(&nfa)
 			for i := range s1.output {
-				s1.output[i].transitions[s2.content] = &s2
+				s1.output[i].transitions[s2.content] = append(s1.output[i].transitions[s2.content], &s2)
 			}
 			s1.output = s2.output
 			nfa = append(nfa, s1)
 		case '*':
 			s1 := pop(&nfa)
 			for i := range s1.output {
-				s1.output[i].transitions[s1.content] = &s1
+				s1.output[i].transitions[s1.content] = append(s1.output[i].transitions[s1.content], &s1)
 			}
 			// Reset output to s1 (in case s1 was a union operator state, which has multiple outputs)
 			s1.output = nil
@@ -136,10 +136,10 @@ func thompson(re string) State {
 			s1 := pop(&nfa)
 			s2 := pop(&nfa)
 			s3 := State{}
-			s3.transitions = make(map[int]*State)
+			s3.transitions = make(map[int][]*State)
 			s3.output = append(s3.output, &s1, &s2)
-			s3.transitions[s1.content] = &s1
-			s3.transitions[s2.content] = &s2
+			s3.transitions[s1.content] = append(s3.transitions[s1.content], &s1)
+			s3.transitions[s2.content] = append(s3.transitions[s2.content], &s2)
 			s3.content = UNION
 			s3.isEmpty = true
 
@@ -159,12 +159,11 @@ func thompson(re string) State {
 func main() {
 	var re string
 	//	fmt.Scanln(&re)
-	re = "a(b|c)*d"
+	re = "abab|abbb"
 	re_postfix := shuntingYard(re)
 	fmt.Println(re_postfix)
 	start := thompson(re_postfix)
-
-	assert(len(start.transitions) == 1)
-	assert(len(start.transitions[UNION].transitions) == 2)
-
+	UNUSED(start)
 }
+
+func UNUSED[T any](val T) {}