Added new assertion that always evaluates to true

nfa.go

@@ -14,10 +14,11 @@ const (
 	EOS
 	WBOUND
 	NONWBOUND
-	PLA // Positive lookahead
-	NLA // Negative lookahead
-	PLB // Positive lookbehind
-	NLB // Negative lookbehind
+	PLA         // Positive lookahead
+	NLA         // Negative lookahead
+	PLB         // Positive lookbehind
+	NLB         // Negative lookbehind
+	ALWAYS_TRUE // An assertion that is always true
 )
 
 type State struct {
@@ -103,6 +104,9 @@ func cloneStateHelper(state *State, cloneMap map[*State]*State) *State {
 // Checks if the given state's assertion is true. Returns true if the given
 // state doesn't have an assertion.
 func (s State) checkAssertion(str []rune, idx int) bool {
+	if s.assert == ALWAYS_TRUE {
+		return true
+	}
 	if s.assert == SOS {
 		return idx == 0
 	}