Added new state fields to tell if a state is a question or alternation

regex/nfa.go

@@ -31,6 +31,8 @@ type nfaState struct {
 	output                     []*nfaState         // The outputs of the current state ie. the 'outward arrows'. A union operator state will have more than one of these.
 	transitions                map[int][]*nfaState // Transitions to different states (maps a character (int representation) to a _list of states. This is useful if one character can lead multiple states eg. ab|aa)
 	isKleene                   bool                // Identifies whether current node is a 0-state representing Kleene star
+	isQuestion                 bool                // Identifies whether current node is a 0-state representing the question operator
+	isAlternation              bool                // Identifies whether current node is a 0-state representing an alternation
 	assert                     assertType          // Type of assertion of current node - NONE means that the node doesn't assert anything
 	allChars                   bool                // Whether or not the state represents all characters (eg. a 'dot' metacharacter). A 'dot' node doesn't store any contents directly, as it would take up too much space
 	except                     []rune              // Only valid if allChars is true - match all characters _except_ the ones in this block. Useful for inverting character classes.
@@ -70,6 +72,8 @@ func cloneStateHelper(stateToClone *nfaState, cloneMap map[*nfaState]*nfaState)
 		output:          make([]*nfaState, len(stateToClone.output)),
 		transitions:     make(map[int][]*nfaState),
 		isKleene:        stateToClone.isKleene,
+		isQuestion:      stateToClone.isQuestion,
+		isAlternation:   stateToClone.isAlternation,
 		assert:          stateToClone.assert,
 		zeroMatchFound:  stateToClone.zeroMatchFound,
 		allChars:        stateToClone.allChars,
@@ -341,6 +345,7 @@ func alternate(s1 *nfaState, s2 *nfaState) *nfaState {
 	}
 	toReturn.content = newContents(epsilon)
 	toReturn.isEmpty = true
+	toReturn.isAlternation = true
 
 	return toReturn
 }
@@ -351,6 +356,7 @@ func question(s1 *nfaState) *nfaState { // Use the fact that ab? == a(b|)
 	s2.content = newContents(epsilon)
 	s2.output = append(s2.output, s2)
 	s2.isEmpty = true
+	s2.isQuestion = true
 	s3 := alternate(s1, s2)
 	return s3
 }