Store all states visited in a single run of 'addStateToList()' in a slice

regex/matching.go

@@ -251,38 +251,40 @@ func (regex Reg) FindAllSubmatch(str string) []Match {
 	return indices
 }
 
-func addStateToList(str []rune, idx int, list []nfaState, state nfaState, threadGroups []Group) []nfaState {
-	if stateExists(list, state) {
+func addStateToList(str []rune, idx int, list []nfaState, state nfaState, threadGroups []Group, visited []nfaState) []nfaState {
+	if stateExists(list, state) || stateExists(visited, state) {
 		return list
 	}
+	visited = append(visited, state)
+
 	if state.isKleene || state.isQuestion {
 		copyThread(state.splitState, state)
-		list = addStateToList(str, idx, list, *state.splitState, threadGroups)
+		list = addStateToList(str, idx, list, *state.splitState, threadGroups, visited)
 		copyThread(state.next, state)
-		list = addStateToList(str, idx, list, *state.next, threadGroups)
+		list = addStateToList(str, idx, list, *state.next, threadGroups, visited)
 		return list
 	}
 	if state.isAlternation {
 		copyThread(state.next, state)
-		list = addStateToList(str, idx, list, *state.next, threadGroups)
+		list = addStateToList(str, idx, list, *state.next, threadGroups, visited)
 		copyThread(state.splitState, state)
-		list = addStateToList(str, idx, list, *state.splitState, threadGroups)
+		list = addStateToList(str, idx, list, *state.splitState, threadGroups, visited)
 		return list
 	}
 	state.threadGroups = append([]Group{}, threadGroups...)
 	if state.assert != noneAssert {
 		if state.checkAssertion(str, idx) {
 			copyThread(state.next, state)
-			return append(list, addStateToList(str, idx, list, *state.next, state.threadGroups)...)
+			return addStateToList(str, idx, list, *state.next, state.threadGroups, visited)
 		}
 	}
 	if state.groupBegin {
 		state.threadGroups[state.groupNum].StartIdx = idx
-		return append(list, addStateToList(str, idx, list, *state.next, state.threadGroups)...)
+		return addStateToList(str, idx, list, *state.next, state.threadGroups, visited)
 	}
 	if state.groupEnd {
 		state.threadGroups[state.groupNum].EndIdx = idx
-		return append(list, addStateToList(str, idx, list, *state.next, state.threadGroups)...)
+		return addStateToList(str, idx, list, *state.next, state.threadGroups, visited)
 	}
 	return append(list, state)
 
@@ -344,7 +346,7 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 
 	start.threadGroups = newMatch(numGroups + 1)
 	start.threadGroups[0].StartIdx = i
-	currentStates = addStateToList(str, i, currentStates, *start, start.threadGroups)
+	currentStates = addStateToList(str, i, currentStates, *start, start.threadGroups, nil)
 	var match Match = nil
 	//	var isEmptyAndNoAssertion bool
 	// Main loop
@@ -366,7 +368,7 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 				break
 			} else if !currentState.isAlternation && !currentState.isKleene && !currentState.isQuestion && !currentState.groupBegin && !currentState.groupEnd { // Normal character or assertion
 				if currentState.contentContains(str, idx) {
-					nextStates = addStateToList(str, idx+1, nextStates, *currentState.next, currentState.threadGroups)
+					nextStates = addStateToList(str, idx+1, nextStates, *currentState.next, currentState.threadGroups, nil)
 				}
 			}