Added function to determine if a state is a lookaround

nfa.go

@@ -98,7 +98,7 @@ func (s State) checkAssertion(str []rune, idx int) bool {
 	if s.assert == NONWBOUND {
 		return !isWordBoundary(str, idx)
 	}
-	if s.assert == PLA || s.assert == PLB || s.assert == NLA || s.assert == NLB { // Lookaround
+	if s.isLookaround() {
 		// The process here is simple:
 		// 		1. Compile the regex stored in the state's contents.
 		// 		2. Run it on the test string.
@@ -143,6 +143,10 @@ func (s State) contentContains(str []rune, idx int) bool {
 	return slices.Contains(s.content, int(str[idx]))
 }
 
+func (s State) isLookaround() bool {
+	return s.assert == PLA || s.assert == PLB || s.assert == NLA || s.assert == NLB
+}
+
 // Returns the matches for the character at the given index of the given string.
 // Also returns the number of matches. Returns -1 if an assertion failed.
 func (s State) matchesFor(str []rune, idx int) ([]*State, int) {