More progress on backreference implementation

regex/matching.go

@@ -228,45 +228,25 @@ func (re Reg) FindAllStringSubmatch(str string) [][]string {
 	return rtv
 }
 
-// Second parameter is the 'new index'
+func addStateToList(str []rune, idx int, list []nfaState, state nfaState, threadGroups []Group, visited []nfaState, preferLongest bool) []nfaState {
-func addStateToList(str []rune, idx int, list []nfaState, state nfaState, threadGroups []Group, visited []nfaState, preferLongest bool) ([]nfaState, int) {
 	if stateExists(list, state) || stateExists(visited, state) {
-		return list, idx
+		return list
 	}
 	visited = append(visited, state)
 
-	if state.isBackreference {
-		if threadGroups[state.referredGroup].IsValid() {
-			groupLength := threadGroups[state.referredGroup].EndIdx - threadGroups[state.referredGroup].StartIdx
-			if state.threadBackref == groupLength {
-				state.threadBackref = 0
-				copyThread(state.next, state)
-				return addStateToList(str, idx+groupLength, list, *state.next, threadGroups, visited, preferLongest)
-			}
-			idxInReferredGroup := threadGroups[state.referredGroup].StartIdx + state.threadBackref
-			if idxInReferredGroup < len(str) && idx+state.threadBackref < len(str) && str[idxInReferredGroup] == str[idx+state.threadBackref] {
-				state.threadBackref += 1
-				return addStateToList(str, idx, list, state, threadGroups, visited, preferLongest)
-			} else {
-				return list, idx
-			}
-		} else {
-			return list, idx
-		}
-	}
 	if state.isKleene || state.isQuestion {
 		copyThread(state.splitState, state)
-		list, newIdx := addStateToList(str, idx, list, *state.splitState, threadGroups, visited, preferLongest)
+		list := addStateToList(str, idx, list, *state.splitState, threadGroups, visited, preferLongest)
 		copyThread(state.next, state)
-		list, newIdx = addStateToList(str, newIdx, list, *state.next, threadGroups, visited, preferLongest)
+		list = addStateToList(str, idx, list, *state.next, threadGroups, visited, preferLongest)
-		return list, newIdx
+		return list
 	}
 	if state.isAlternation {
 		copyThread(state.next, state)
-		list, newIdx := addStateToList(str, idx, list, *state.next, threadGroups, visited, preferLongest)
+		list := addStateToList(str, idx, list, *state.next, threadGroups, visited, preferLongest)
 		copyThread(state.splitState, state)
-		list, newIdx = addStateToList(str, newIdx, list, *state.splitState, threadGroups, visited, preferLongest)
+		list = addStateToList(str, idx, list, *state.splitState, threadGroups, visited, preferLongest)
-		return list, newIdx
+		return list
 	}
 	state.threadGroups = append([]Group{}, threadGroups...)
 	if state.assert != noneAssert {
@@ -285,7 +265,7 @@ func addStateToList(str []rune, idx int, list []nfaState, state nfaState, thread
 		copyThread(state.next, state)
 		return addStateToList(str, idx, list, *state.next, state.threadGroups, visited, preferLongest)
 	}
-	return append(list, state), idx
+	return append(list, state)
 
 }
 
@@ -315,7 +295,7 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 
 	start.threadGroups = newMatch(numGroups + 1)
 	start.threadGroups[0].StartIdx = i
-	currentStates, _ = addStateToList(str, i, currentStates, *start, start.threadGroups, nil, preferLongest) // We can't go forward at the beginning, so I discard the second retval
+	currentStates = addStateToList(str, i, currentStates, *start, start.threadGroups, nil, preferLongest)
 	var match Match = nil
 	for idx := i; idx <= len(str); idx++ {
 		if len(currentStates) == 0 {
@@ -335,14 +315,26 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 				if !preferLongest {
 					break
 				}
-			} else if !currentState.isAlternation && !currentState.isKleene && !currentState.isQuestion && !currentState.groupBegin && !currentState.groupEnd && currentState.assert == noneAssert { // Normal character
+			} else if !currentState.isAlternation && !currentState.isKleene && !currentState.isQuestion && !currentState.isBackreference && !currentState.groupBegin && !currentState.groupEnd && currentState.assert == noneAssert { // Normal character
 				if currentState.contentContains(str, idx, preferLongest) {
-					var newIdx int
+					nextStates = addStateToList(str, idx+1, nextStates, *currentState.next, currentState.threadGroups, nil, preferLongest)
-					nextStates, newIdx = addStateToList(str, idx+1, nextStates, *currentState.next, currentState.threadGroups, nil, preferLongest)
+				}
-					idx = newIdx - 1
+			} else if currentState.isBackreference {
+				groupLength := currentState.threadGroups[currentState.referredGroup].EndIdx - currentState.threadGroups[currentState.referredGroup].StartIdx
+				if currentState.threadBackref == groupLength {
+					currentState.threadBackref = 0
+					copyThread(currentState.next, currentState)
+					currentStates = addStateToList(str, idx, currentStates, *currentState.next, currentState.threadGroups, nil, preferLongest)
+				} else {
+					idxInReferredGroup := currentState.threadGroups[currentState.referredGroup].StartIdx + currentState.threadBackref
+					if idxInReferredGroup < len(str) && idx < len(str) && str[idxInReferredGroup] == str[idx] {
+						currentState.threadBackref += 1
+						nextStates = append(nextStates, currentState)
 					}
 				}
 			}
+
+		}
 		currentStates = append([]nfaState{}, nextStates...)
 		nextStates = nil
 	}