Fixed assertion matching

regex/compile.go

@@ -987,7 +987,8 @@ func thompson(re []postfixNode) (Reg, error) {
 		if c.nodetype == charclassNode { // A Character class consists of all the nodes in it, alternated
 			// Map the list of nodes to a list of states, each state containing the contents of a specific node
 			states := funcMap(c.nodeContents, func(node postfixNode) *nfaState {
-				s := newState()
+				s := &nfaState{}
+				s.output = append(s.output, s)
 				nodeContents := node.contents
 				if caseInsensitive {
 					nodeContents = slices.Concat(funcMap(nodeContents, func(r rune) []rune {
@@ -1001,7 +1002,7 @@ func thompson(re []postfixNode) (Reg, error) {
 						return n.contents
 					})...)
 				}
-				return &s
+				return s
 			})
 			// Reduce the list of states down to a single state by alternating them
 			toAdd := funcReduce(states, func(s1 *nfaState, s2 *nfaState) *nfaState {
@@ -1046,7 +1047,10 @@ func thompson(re []postfixNode) (Reg, error) {
 			if err != nil {
 				return Reg{}, fmt.Errorf("error applying question operator")
 			}
-			s2 := question(s1)
+			s2, err := question(s1)
+			if err != nil {
+				return Reg{}, err
+			}
 			nfa = append(nfa, s2)
 		case pipeNode:
 			// A pipe operator doesn't actually need either operand to be present. If an operand isn't present,
@@ -1105,7 +1109,11 @@ func thompson(re []postfixNode) (Reg, error) {
 				stateToAdd = concatenate(stateToAdd, s2)
 			} else { // Case 2
 				for i := c.startReps; i < c.endReps; i++ {
-					stateToAdd = concatenate(stateToAdd, question(cloneState(poppedState)))
+					tmp, err := question(cloneState(poppedState))
+					if err != nil {
+						return Reg{}, fmt.Errorf("error processing bounded repetition")
+					}
+					stateToAdd = concatenate(stateToAdd, tmp)
 				}
 			}
 			nfa = append(nfa, stateToAdd)

regex/matching.go

@@ -2,7 +2,6 @@ package regex
 
 import (
 	"fmt"
-	"slices"
 	"sort"
 )
 
@@ -152,7 +151,6 @@ func pruneIndices(indices []Match) []Match {
 }
 
 func copyThread(to *nfaState, from nfaState) {
-	to.threadSP = from.threadSP
 	to.threadGroups = append([]Group{}, from.threadGroups...)
 }
 
@@ -253,6 +251,43 @@ func (regex Reg) FindAllSubmatch(str string) []Match {
 	return indices
 }
 
+func addStateToList(str []rune, idx int, list []nfaState, state nfaState, threadGroups []Group) []nfaState {
+	if stateExists(list, state) {
+		return list
+	}
+	if state.isKleene || state.isQuestion {
+		copyThread(state.splitState, state)
+		list = addStateToList(str, idx, list, *state.splitState, threadGroups)
+		copyThread(state.next, state)
+		list = addStateToList(str, idx, list, *state.next, threadGroups)
+		return list
+	}
+	if state.isAlternation {
+		copyThread(state.next, state)
+		list = addStateToList(str, idx, list, *state.next, threadGroups)
+		copyThread(state.splitState, state)
+		list = addStateToList(str, idx, list, *state.splitState, threadGroups)
+		return list
+	}
+	state.threadGroups = append([]Group{}, threadGroups...)
+	if state.assert != noneAssert {
+		if state.checkAssertion(str, idx) {
+			copyThread(state.next, state)
+			return append(list, addStateToList(str, idx, list, *state.next, state.threadGroups)...)
+		}
+	}
+	if state.groupBegin {
+		state.threadGroups[state.groupNum].StartIdx = idx
+		return append(list, addStateToList(str, idx, list, *state.next, state.threadGroups)...)
+	}
+	if state.groupEnd {
+		state.threadGroups[state.groupNum].EndIdx = idx
+		return append(list, addStateToList(str, idx, list, *state.next, state.threadGroups)...)
+	}
+	return append(list, state)
+
+}
+
 // Helper for FindAllMatches. Returns whether it found a match, the
 // first Match it finds, and how far it got into the string ie. where
 // the next search should start from.
@@ -307,134 +342,113 @@ func findAllSubmatchHelper(start *nfaState, str []rune, offset int, numGroups in
 	//		tempIndices[start.groupNum].startIdx = i
 	//}
 
-	start.threadSP = i
+	start.threadGroups = newMatch(numGroups + 1)
-	currentStates = append(currentStates, *start)
+	start.threadGroups[0].StartIdx = i
-	var foundMatch bool
+	currentStates = addStateToList(str, i, currentStates, *start, start.threadGroups)
-	var isEmptyAndNoAssertion bool
+	var match Match = nil
+	//	var isEmptyAndNoAssertion bool
 	// Main loop
 	for idx := i; idx <= len(str); idx++ {
+		if len(currentStates) == 0 {
+			break
+		}
 		for currentStateIdx := 0; currentStateIdx < len(currentStates); currentStateIdx++ {
 			currentState := currentStates[currentStateIdx]
-			foundMatch = false
-			isEmptyAndNoAssertion = false
 
 			if currentState.threadGroups == nil {
 				currentState.threadGroups = newMatch(numGroups + 1)
 				currentState.threadGroups[0].StartIdx = idx
 			}
 
-			if currentState.groupBegin {
+			if currentState.isLast {
-				currentState.threadGroups[currentState.groupNum].StartIdx = idx
+				currentState.threadGroups[0].EndIdx = idx
-				//		allMatches := make([]nfaState, 0)
+				match = append([]Group{}, currentState.threadGroups...)
-				//		for _, v := range currentState.transitions {
+				break
-				//			dereferenced := funcMap(v, func(s *nfaState) nfaState {
+			} else if !currentState.isAlternation && !currentState.isKleene && !currentState.isQuestion && !currentState.groupBegin && !currentState.groupEnd { // Normal character or assertion
-				//				return *s
+				if currentState.contentContains(str, idx) {
-				//			})
+					nextStates = addStateToList(str, idx+1, nextStates, *currentState.next, currentState.threadGroups)
-				//			allMatches = append(allMatches, dereferenced...)
+				}
-				//		}
-				//		slices.Reverse(allMatches)
-				//		for i := range allMatches {
-				//			copyThread(&allMatches[i], currentState)
-				//		}
-				//		currentStates = append(currentStates, allMatches...)
-			}
-			if currentState.groupEnd {
-				currentState.threadGroups[currentState.groupNum].EndIdx = idx
-				//			allMatches := make([]nfaState, 0)
-				//			for _, v := range currentState.transitions {
-				//				dereferenced := funcMap(v, func(s *nfaState) nfaState {
-				//					return *s
-				//				})
-				//				allMatches = append(allMatches, dereferenced...)
-				//			}
-				//			slices.Reverse(allMatches)
-				//			for i := range allMatches {
-				//				copyThread(&allMatches[i], currentState)
-				//			}
-				//			currentStates = append(currentStates, allMatches...)
 			}
 
-			//		if currentState.isKleene {
+			//			if currentState.groupBegin {
-			//			// Append the next-state (after the kleene), then append the kleene state
+			//				currentState.threadGroups[currentState.groupNum].StartIdx = idx
-			//			allMatches := make([]*nfaState, 0)
-			//			for _, v := range currentState.transitions {
-			//				allMatches = append(allMatches, v...)
 			//			}
-			//			slices.Reverse(allMatches)
+			//			if currentState.groupEnd {
-			//			for _, m := range allMatches {
+			//				currentState.threadGroups[currentState.groupNum].EndIdx = idx
-			//				m.threadGroups = currentState.threadGroups
-			//				m.threadSP = idx
 			//			}
-			//			currentStates = append(currentStates, allMatches...)
-			//
-			//			//	kleeneState := currentState.kleeneState
-			//			//	kleeneState.threadGroups = currentState.threadGroups
-			//			//	kleeneState.threadSP = currentState.threadSP
-			//			//	currentStates = append(currentStates, kleeneState)
-			//			continue
-			//		}
 
 			// Alternation - enqueue left then right state, and continue
-			if currentState.isAlternation {
+			//			if currentState.isAlternation {
-				if currentState.isKleene { // Reverse order of adding things
+			//				if currentState.isKleene { // Reverse order of adding things
-					rightState := currentState.splitState
+			//					rightState := currentState.splitState
-					copyThread(rightState, currentState)
+			//					copyThread(rightState, currentState)
-					currentStates = slices.Insert(currentStates, currentStateIdx+1, *rightState)
+			//					currentStates = slices.Insert(currentStates, currentStateIdx+1, *rightState)
-					leftState := currentState.next
+			//					leftState := currentState.next
-					copyThread(leftState, currentState)
+			//					copyThread(leftState, currentState)
-					currentStates = slices.Insert(currentStates, currentStateIdx+2, *leftState)
+			//					currentStates = slices.Insert(currentStates, currentStateIdx+2, *leftState)
-				} else {
+			//				} else {
-					leftState := currentState.next
+			//					leftState := currentState.next
-					copyThread(leftState, currentState)
+			//					copyThread(leftState, currentState)
-					currentStates = slices.Insert(currentStates, currentStateIdx+1, *leftState)
+			//					currentStates = slices.Insert(currentStates, currentStateIdx+1, *leftState)
-					rightState := currentState.splitState
+			//					rightState := currentState.splitState
-					copyThread(rightState, currentState)
+			//					copyThread(rightState, currentState)
-					currentStates = slices.Insert(currentStates, currentStateIdx+2, *rightState)
+			//					currentStates = slices.Insert(currentStates, currentStateIdx+2, *rightState)
-				}
+			//				}
-				continue
+			//				continue
-			}
+			//			}
 
 			// Empty state - enqueue next state, do _not_ increment the SP
-			if !currentState.isAlternation && currentState.isEmpty && currentState.assert == noneAssert { //&& currentState.groupBegin == false && currentState.groupEnd == false {
+			//			if !currentState.isAlternation && currentState.isEmpty && currentState.assert == noneAssert { //&& currentState.groupBegin == false && currentState.groupEnd == false {
-				isEmptyAndNoAssertion = true
+			//				isEmptyAndNoAssertion = true
-			}
+			//			}
-
+			//
-			if currentState.contentContains(str, idx) {
+			//			if currentState.contentContains(str, idx) {
-				foundMatch = true
+			//				foundMatch = true
-			}
+			//			}
-
+			//
-			if isEmptyAndNoAssertion || foundMatch {
+			//			if isEmptyAndNoAssertion || foundMatch {
-				allMatches := make([]nfaState, 0)
+			//				nextMatch := *(currentState.next)
-				allMatches = append(allMatches, *(currentState.next))
+			//				copyThread(&nextMatch, currentState)
-				slices.Reverse(allMatches)
+			//				if currentState.groupBegin {
-				for i := range allMatches {
+			//					//	if !stateExists(currentStates, nextMatch) {
-					copyThread(&allMatches[i], currentState)
+			//					currentStates = slices.Insert(currentStates, currentStateIdx+1, nextMatch)
-					if foundMatch && currentState.assert == noneAssert {
+			//					//}
-						allMatches[i].threadSP += 1
+			//				} else if currentState.groupEnd {
-					}
+			//					if !stateExists(currentStates, nextMatch) {
-				}
+			//						currentStates = slices.Insert(currentStates, currentStateIdx+1, nextMatch) // append(currentStates, nextMatch)
-				if currentState.groupBegin {
+			//					}
-					currentStates = slices.Insert(currentStates, currentStateIdx+1, allMatches...)
+			//				} else if currentState.assert != noneAssert {
-				} else if currentState.groupEnd {
+			//					if !stateExists(currentStates, nextMatch) {
-					currentStates = append(currentStates, allMatches...)
+			//						currentStates = append(currentStates, nextMatch)
-				} else if currentState.assert != noneAssert {
+			//					}
-					currentStates = append(currentStates, allMatches...)
+			//				} else if currentState.isEmpty && !currentState.groupBegin && !currentState.groupEnd {
-				} else {
+			//					if !stateExists(currentStates, nextMatch) {
-					nextStates = append(nextStates, allMatches...)
+			//						currentStates = append(currentStates, nextMatch)
-				}
+			//					}
-			}
+			//				} else {
-
+			//					if !stateExists(nextStates, nextMatch) {
-			if currentState.isLast && len(nextStates) == 0 { // Last state reached
+			//						nextStates = append(nextStates, nextMatch)
-				currentState.threadGroups[0].EndIdx = idx
+			//					}
-				if idx == currentState.threadGroups[0].StartIdx {
+			//				}
-					idx += 1
+			//			}
-				}
+			//
-				return true, currentState.threadGroups, idx
+			//			if currentState.isLast && len(nextStates) == 0 { // Last state reached
-			}
+			//				currentState.threadGroups[0].EndIdx = idx
+			//				if idx == currentState.threadGroups[0].StartIdx {
+			//					idx += 1
+			//				}
+			//				return true, currentState.threadGroups, idx
+			//			}
 		}
 		currentStates = append([]nfaState{}, nextStates...)
 		nextStates = nil
 	}
+	if match != nil {
+		if offset == match[0].EndIdx {
+			return true, match, match[0].EndIdx + 1
+		}
+		return true, match, match[0].EndIdx
+	}
 	return false, []Group{}, i + 1
 	//		zeroStates := make([]*nfaState, 0)
 	//		// Keep taking zero-states, until there are no more left to take

regex/nfa.go

@@ -47,7 +47,6 @@ type nfaState struct {
 	// The following properties depend on the current match - I should think about resetting them for every match.
 	zeroMatchFound bool    // Whether or not the state has been used for a zero-length match - only relevant for zero states
 	threadGroups   []Group // Assuming that a state is part of a 'thread' in the matching process, this array stores the indices of capturing groups in the current thread. As matches are found for this state, its groups will be copied over.
-	threadSP       int     // The string pointer of the thread - where it is in the input string
 }
 
 // Clones the NFA starting from the given state.
@@ -123,7 +122,6 @@ func resetThreadsHelper(state *nfaState, visitedMap map[*nfaState]bool) {
 	}
 	// Assuming it hasn't been visited
 	state.threadGroups = nil
-	state.threadSP = 0
 	visitedMap[state] = true
 	if state.isAlternation {
 		resetThreadsHelper(state.next, visitedMap)
@@ -331,9 +329,6 @@ func kleene(s1 *nfaState) (*nfaState, error) {
 	toReturn.isAlternation = true
 	toReturn.content = newContents(epsilon)
 	toReturn.splitState = s1
-	for i := range s1.output {
-		s1.output[i].next = toReturn
-	}
 
 	//	toReturn := &nfaState{}
 	//	toReturn.transitions = make(map[int][]*nfaState)
@@ -375,14 +370,20 @@ func alternate(s1 *nfaState, s2 *nfaState) *nfaState {
 	return toReturn
 }
 
-func question(s1 *nfaState) *nfaState { // Use the fact that ab? == a(b|)
+func question(s1 *nfaState) (*nfaState, error) { // Use the fact that ab? == a(b|)
-	s2 := &nfaState{}
+	if s1.isEmpty && s1.assert != noneAssert {
+		return nil, fmt.Errorf("previous token is not quantifiable")
+	}
+	toReturn := &nfaState{}
+	toReturn.isEmpty = true
+	toReturn.isAlternation = true
+	toReturn.isQuestion = true
+	toReturn.content = newContents(epsilon)
+	toReturn.splitState = s1
+	toReturn.output = append([]*nfaState{}, toReturn)
+	toReturn.output = append(toReturn.output, s1.output...)
 	//	s2.transitions = make(map[int][]*nfaState)
-	s2.content = newContents(epsilon)
+	return toReturn, nil
-	s2.output = append(s2.output, s2)
-	s2.isEmpty = true
-	s3 := alternate(s1, s2)
-	return s3
 }
 
 // Creates and returns a new state with the 'default' values.
@@ -408,3 +409,32 @@ func zeroLengthMatchState() nfaState {
 	start.assert = alwaysTrueAssert
 	return start
 }
+
+func (s nfaState) equals(other nfaState) bool {
+	return slices.Equal(s.content, other.content) &&
+		s.isEmpty == other.isEmpty &&
+		s.isLast == other.isLast &&
+		slices.Equal(s.output, other.output) &&
+		s.next == other.next &&
+		s.isKleene == other.isKleene &&
+		s.isQuestion == other.isQuestion &&
+		s.isAlternation == other.isAlternation &&
+		s.splitState == other.splitState &&
+		s.assert == other.assert &&
+		s.allChars == other.allChars &&
+		slices.Equal(s.except, other.except) &&
+		s.lookaroundNFA == other.lookaroundNFA &&
+		s.groupBegin == other.groupBegin &&
+		s.groupEnd == other.groupEnd &&
+		s.groupNum == other.groupNum &&
+		slices.Equal(s.threadGroups, other.threadGroups)
+}
+
+func stateExists(list []nfaState, s nfaState) bool {
+	for i := range list {
+		if list[i].equals(s) {
+			return true
+		}
+	}
+	return false
+}