Started implementing Thompson's algorithm for matching, because the old one was completely backtracking (so it would enter infinite loops on something like '(a*)*' )

The git diff claims that a ton of code was changed, but most of it was just indentation changes.

regex/matching.go

@@ -277,6 +277,7 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 	//startIdx := offset
 	//endIdx := offset
 	currentStates := make([]nfaState, 0)
+	nextStates := 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
@@ -311,9 +312,9 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 	var foundMatch bool
 	var isEmptyAndNoAssertion bool
 	// Main loop
-	for len(currentStates) > 0 {
-		currentState, _ := pop(&currentStates)
-		idx := currentState.threadSP
+	for idx := i; idx <= len(str); idx++ {
+		for currentStateIdx := 0; currentStateIdx < len(currentStates); currentStateIdx++ {
+			currentState := currentStates[currentStateIdx]
 			foundMatch = false
 			isEmptyAndNoAssertion = false
 
@@ -352,12 +353,12 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 
 			// Alternation - enqueue left then right state, and continue
 			if currentState.isAlternation {
-			rightState := currentState.rightState
-			copyThread(rightState, currentState)
-			currentStates = append(currentStates, *currentState.rightState)
 				leftState := currentState.leftState
 				copyThread(leftState, currentState)
 				currentStates = append(currentStates, *currentState.leftState)
+				rightState := currentState.rightState
+				copyThread(rightState, currentState)
+				currentStates = append(currentStates, *currentState.rightState)
 				continue
 			}
 
@@ -385,7 +386,7 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 						allMatches[i].threadSP += 1
 					}
 				}
-			currentStates = append(currentStates, allMatches...)
+				nextStates = append(nextStates, allMatches...)
 			}
 
 			if currentState.isLast { // Last state reached
@@ -409,6 +410,9 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 
 			}
 		}
+		copy(currentStates, nextStates)
+		nextStates = nil
+	}
 	return false, []Group{}, i + 1
 	//		zeroStates := make([]*nfaState, 0)
 	//		// Keep taking zero-states, until there are no more left to take