Replaced pointer to nfaState with nfaState

regex/matching.go

@@ -151,6 +151,11 @@ func pruneIndices(indices []Match) []Match {
 	return toRet
 }
 
+func copyThread(to *nfaState, from nfaState) {
+	to.threadSP = from.threadSP
+	to.threadGroups = from.threadGroups
+}
+
 // Find returns the 0-group of the leftmost match of the regex in the given string.
 // An error value != nil indicates that no match was found.
 func (regex Reg) Find(str string) (Group, error) {
@@ -271,7 +276,7 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 	//	foundPath := false
 	//startIdx := offset
 	//endIdx := offset
-	currentStates := make([]*nfaState, 0)
+	currentStates := make([]nfaState, 0)
 	//	tempStates := make([]*nfaState, 0) // Used to store states that should be used in next loop iteration
 	i := offset // Index in string
 	//startingFrom := i                  // Store starting index
@@ -302,13 +307,15 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 	//}
 
 	start.threadSP = i
-	currentStates = append(currentStates, start)
+	currentStates = append(currentStates, *start)
 	var foundMatch bool
+	var isEmptyAndNoAssertion bool
 	// Main loop
 	for len(currentStates) > 0 {
 		currentState, _ := pop(&currentStates)
 		idx := currentState.threadSP
 		foundMatch = false
+		isEmptyAndNoAssertion = false
 
 		if currentState.threadGroups == nil {
 			currentState.threadGroups = newMatch(numGroups + 1)
@@ -343,44 +350,39 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 		//			continue
 		//		}
 
+		// Alternation - enqueue left then right state, and continue
 		if currentState.isAlternation {
 			rightState := currentState.rightState
-			rightState.threadGroups = currentState.threadGroups
+			copyThread(rightState, currentState)
-			rightState.threadSP = currentState.threadSP
+			currentStates = append(currentStates, *currentState.rightState)
-			currentStates = append(currentStates, currentState.rightState)
 			leftState := currentState.leftState
-			leftState.threadGroups = currentState.threadGroups
+			copyThread(leftState, currentState)
-			leftState.threadSP = currentState.threadSP
+			currentStates = append(currentStates, *currentState.leftState)
-			currentStates = append(currentStates, currentState.leftState)
 			continue
 		}
 
+		// Empty state - enqueue next state, do _not_ increment the SP
 		if currentState.isEmpty && currentState.assert == noneAssert {
-			allMatches := make([]*nfaState, 0)
+			isEmptyAndNoAssertion = true
-			for _, v := range currentState.transitions {
-				allMatches = append(allMatches, v...)
-			}
-			slices.Reverse(allMatches)
-			for _, m := range allMatches {
-				m.threadGroups = currentState.threadGroups
-				m.threadSP = idx
-			}
-			currentStates = append(currentStates, allMatches...)
 		}
 
 		if currentState.contentContains(str, idx) {
 			foundMatch = true
-			allMatches := make([]*nfaState, 0)
+		}
+
+		if isEmptyAndNoAssertion || foundMatch {
+			allMatches := make([]nfaState, 0)
 			for _, v := range currentState.transitions {
-				allMatches = append(allMatches, v...)
+				dereferenced := funcMap(v, func(s *nfaState) nfaState {
+					return *s
+				})
+				allMatches = append(allMatches, dereferenced...)
 			}
 			slices.Reverse(allMatches)
-			for _, m := range allMatches {
+			for i := range allMatches {
-				m.threadGroups = currentState.threadGroups
+				copyThread(&allMatches[i], currentState)
-				if currentState.assert == noneAssert {
+				if foundMatch && currentState.assert == noneAssert {
-					m.threadSP = idx + 1
+					allMatches[i].threadSP += 1
-				} else {
-					m.threadSP = idx
 				}
 			}
 			currentStates = append(currentStates, allMatches...)
@@ -388,8 +390,15 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 
 		if currentState.isLast { // Last state reached
 			if foundMatch {
+				if currentState.assert != noneAssert {
+					currentState.threadGroups[0].EndIdx = idx
+				} else {
 					currentState.threadGroups[0].EndIdx = idx + 1
-				return true, currentState.threadGroups, idx + 1
+				}
+				if idx == currentState.threadGroups[0].StartIdx {
+					idx += 1
+				}
+				return true, currentState.threadGroups, idx
 			} else if currentState.isEmpty && currentState.assert == noneAssert {
 				currentState.threadGroups[0].EndIdx = idx
 				if idx == currentState.threadGroups[0].StartIdx {