From ce156c4405049ef33e35fb685f22bda32a0858ef Mon Sep 17 00:00:00 2001
From: Aadhavan Srinivasan <aadhavan@twomorecents.org>
Date: Wed, 23 Oct 2024 14:42:35 -0400
Subject: [PATCH] Fixed kleene star matching at end of string - failed test a*
 and ppppppppaaaaaaaa

---
 matching.go | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/matching.go b/matching.go
index e248927..63c206a 100644
--- a/matching.go
+++ b/matching.go
@@ -34,6 +34,7 @@ func matchHelper(start *State, str string, indices []matchIndex, offset int) []m
 		return indices
 	}
 
+	foundPath := false
 	startIdx := 0
 	endIdx := 0
 	currentStates := make([]*State, 0)
@@ -47,12 +48,13 @@ func matchHelper(start *State, str string, indices []matchIndex, offset int) []m
 		startIdx = i
 		i++ // Advance to next character (if we aren't at a 0-state, which doesn't match anything), so that we can check for transitions. If we advance at a 0-state, we will never get a chance to match the first character
 	}
-	// TODO - If start state is kleene star, try to match the next state
-
+	startingFrom := i
 	currentStates = append(currentStates, start)
 
 	// Main loop
 	for i < len(str) {
+		foundPath = false
+
 		zeroStates := make([]*State, 0)
 		// Keep taking zero-states, until there are no more left to take
 		zeroStates, isZero := takeZeroState(currentStates)
@@ -69,16 +71,23 @@ func matchHelper(start *State, str string, indices []matchIndex, offset int) []m
 		for _, state := range currentStates {
 			if len(state.transitions[int(str[i])]) > 0 {
 				tempStates = append(tempStates, state.transitions[int(str[i])]...)
+				foundPath = true
 			} else {
 				// This enables the 'greedy' behavior - last-state status is only checked if we can't match anything else
 				if state.isLast {
 					endIdx = i
 					indices = append(indices, matchIndex{startIdx + offset, endIdx + offset})
 				}
-				// Recursion - match with rest of string
-				return matchHelper(start, str[i:], indices, offset+i)
 			}
 		}
+
+		if foundPath == false {
+			// Recursion - match with rest of string if we have nowhere to go. If we haven't moved in the string, increment the counter by 1 to ensure we don't keep trying the same string over and over
+			if i == startingFrom {
+				i++
+			}
+			return matchHelper(start, str[i:], indices, offset+i)
+		}
 		currentStates = make([]*State, len(tempStates))
 		copy(currentStates, tempStates)
 		tempStates = nil