Renamed 'state' to 'nfaState' because 'state' by itself means nothing

regex/compile.go

@@ -14,7 +14,7 @@ var notDotChars []rune
 // the startState of the NFA representation of the regex, and the number of capturing
 // groups in the regex.
 type Reg struct {
-	start     *State
+	start     *nfaState
 	numGroups int
 }
 
@@ -799,8 +799,8 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 // Thompson's algorithm. Constructs Finite-State Automaton from given string.
 // Returns start state and number of groups in regex.
 func thompson(re []postfixNode) (Reg, error) {
-	nfa := make([]*State, 0) // Stack of states
+	nfa := make([]*nfaState, 0) // Stack of states
-	numGroups := 0           // Number of capturing groups
+	numGroups := 0              // Number of capturing groups
 
 	// If thompson() receives an empty regex, then whatever was given to shuntingYard()
 	// was parsed away. This doesn't mean that the regex itself is empty.
@@ -815,8 +815,8 @@ func thompson(re []postfixNode) (Reg, error) {
 
 	for _, c := range re {
 		if c.nodetype == characterNode || c.nodetype == assertionNode {
-			stateToAdd := State{}
+			stateToAdd := nfaState{}
-			stateToAdd.transitions = make(map[int][]*State)
+			stateToAdd.transitions = make(map[int][]*nfaState)
 			if c.allChars {
 				stateToAdd.allChars = true
 				if len(c.except) != 0 {
@@ -862,7 +862,7 @@ func thompson(re []postfixNode) (Reg, error) {
 				})...)
 			}
 			stateToAdd.content = stateContents(append([]int(stateToAdd.content), []int(rune2Contents(runesToAdd))...))
-			stateToAdd.output = make([]*State, 0)
+			stateToAdd.output = make([]*nfaState, 0)
 			stateToAdd.output = append(stateToAdd.output, &stateToAdd)
 			stateToAdd.isEmpty = false
 			if c.nodetype == assertionNode {
@@ -918,13 +918,13 @@ func thompson(re []postfixNode) (Reg, error) {
 			nfa = append(nfa, &stateToAdd)
 		}
 		if c.nodetype == lparenNode || c.nodetype == rparenNode {
-			s := &State{}
+			s := &nfaState{}
 			s.assert = noneAssert
 			s.content = newContents(EPSILON)
 			s.isEmpty = true
-			s.output = make([]*State, 0)
+			s.output = make([]*nfaState, 0)
 			s.output = append(s.output, s)
-			s.transitions = make(map[int][]*State)
+			s.transitions = make(map[int][]*nfaState)
 			// LPAREN nodes are just added normally
 			if c.nodetype == lparenNode {
 				numGroups++
@@ -971,7 +971,7 @@ 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) *State {
+			states := funcMap(c.nodeContents, func(node postfixNode) *nfaState {
 				s := newState()
 				nodeContents := node.contents
 				if caseInsensitive {
@@ -989,7 +989,7 @@ func thompson(re []postfixNode) (Reg, error) {
 				return &s
 			})
 			// Reduce the list of states down to a single state by alternating them
-			toAdd := funcReduce(states, func(s1 *State, s2 *State) *State {
+			toAdd := funcReduce(states, func(s1 *nfaState, s2 *nfaState) *nfaState {
 				return alternate(s1, s2)
 			})
 			nfa = append(nfa, toAdd)
@@ -1066,7 +1066,7 @@ func thompson(re []postfixNode) (Reg, error) {
 				return Reg{}, fmt.Errorf("numeric specifier - start greater than end")
 			}
 			poppedState := mustPop(&nfa)
-			var stateToAdd *State = nil
+			var stateToAdd *nfaState = nil
 			// Take advantage of the following facts:
 			// a{5} == aaaaa
 			// a{3,5} == aaaa?a?

regex/matching.go

@@ -61,7 +61,7 @@ func (g Group) isValid() bool {
 // given slice. It returns the resulting states. If any of the resulting states is a 0-state,
 // the second ret val is true.
 // If a state begins or ends a capturing group, its 'thread' is updated to contain the correct index.
-func takeZeroState(states []*State, numGroups int, idx int) (rtv []*State, isZero bool) {
+func takeZeroState(states []*nfaState, numGroups int, idx int) (rtv []*nfaState, isZero bool) {
 	for _, state := range states {
 		if len(state.transitions[EPSILON]) > 0 {
 			for _, s := range state.transitions[EPSILON] {
@@ -93,9 +93,9 @@ func takeZeroState(states []*State, numGroups int, idx int) (rtv []*State, isZer
 // from any of the given states, given the string and our position in it.
 // It uses the same algorithm to find zero-states as the one inside the loop,
 // so I should probably put it in a function.
-func zeroMatchPossible(str []rune, idx int, numGroups int, states ...*State) bool {
+func zeroMatchPossible(str []rune, idx int, numGroups int, states ...*nfaState) bool {
 	zeroStates, isZero := takeZeroState(states, numGroups, idx)
-	tempstates := make([]*State, 0, len(zeroStates)+len(states))
+	tempstates := make([]*nfaState, 0, len(zeroStates)+len(states))
 	tempstates = append(tempstates, states...)
 	tempstates = append(tempstates, zeroStates...)
 	num_appended := 0 // number of unique states addded to tempstates
@@ -204,7 +204,7 @@ func FindAllMatches(regex Reg, str string) []Match {
 // the next search should start from.
 //
 //	Might return duplicates or overlapping indices, so care must be taken to prune the resulting array.
-func findAllMatchesHelper(start *State, str []rune, offset int, numGroups int) (bool, Match, int) {
+func findAllMatchesHelper(start *nfaState, str []rune, offset int, numGroups int) (bool, Match, int) {
 	// Base case - exit if offset exceeds string's length
 	if offset > len(str) {
 		// The second value here shouldn't be used, because we should exit when the third return value is > than len(str)
@@ -221,10 +221,10 @@ func findAllMatchesHelper(start *State, str []rune, offset int, numGroups int) (
 	foundPath := false
 	startIdx := offset
 	endIdx := offset
-	currentStates := make([]*State, 0)
+	currentStates := make([]*nfaState, 0)
-	tempStates := make([]*State, 0) // Used to store states that should be used in next loop iteration
+	tempStates := make([]*nfaState, 0) // Used to store states that should be used in next loop iteration
-	i := offset                     // Index in string
+	i := offset                        // Index in string
-	startingFrom := i               // Store starting index
+	startingFrom := i                  // Store starting index
 
 	// If the first state is an assertion, makes sure the assertion
 	// is true before we do _anything_ else.
@@ -257,7 +257,7 @@ func findAllMatchesHelper(start *State, str []rune, offset int, numGroups int) (
 	for i < len(str) {
 		foundPath = false
 
-		zeroStates := make([]*State, 0)
+		zeroStates := make([]*nfaState, 0)
 		// Keep taking zero-states, until there are no more left to take
 		// Objective: If any of our current states have transitions to 0-states, replace them with the 0-state. Do this until there are no more transitions to 0-states, or there are no more unique 0-states to take.
 		zeroStates, isZero := takeZeroState(currentStates, numGroups, i)
@@ -275,11 +275,11 @@ func findAllMatchesHelper(start *State, str []rune, offset int, numGroups int) (
 		tempStates = nil
 
 		// Take any transitions corresponding to current character
-		numStatesMatched := 0         // The number of states which had at least 1 match for this round
+		numStatesMatched := 0            // The number of states which had at least 1 match for this round
-		assertionFailed := false      // Whether or not an assertion failed for this round
+		assertionFailed := false         // Whether or not an assertion failed for this round
-		lastStateInList := false      // Whether or not a last state was in our list of states
+		lastStateInList := false         // Whether or not a last state was in our list of states
-		var lastStatePtr *State = nil // Pointer to the last-state, if it was found
+		var lastStatePtr *nfaState = nil // Pointer to the last-state, if it was found
-		lastLookaroundInList := false // Whether or not a last state (that is a lookaround) was in our list of states
+		lastLookaroundInList := false    // Whether or not a last state (that is a lookaround) was in our list of states
 		for _, state := range currentStates {
 			matches, numMatches := state.matchesFor(str, i)
 			if numMatches > 0 {
@@ -364,7 +364,7 @@ func findAllMatchesHelper(start *State, str []rune, offset int, numGroups int) (
 			}
 			return false, []Group{}, startIdx
 		}
-		currentStates = make([]*State, len(tempStates))
+		currentStates = make([]*nfaState, len(tempStates))
 		copy(currentStates, tempStates)
 		tempStates = nil
 

regex/nfa.go

@@ -22,36 +22,36 @@ const (
 	alwaysTrueAssert // An assertion that is always true
 )
 
-type state struct {
+type nfaState struct {
-	content                    stateContents    // Contents of current state
+	content                    stateContents       // Contents of current state
-	isEmpty                    bool             // If it is empty - Union operator and Kleene star states will be empty
+	isEmpty                    bool                // If it is empty - Union operator and Kleene star states will be empty
-	isLast                     bool             // If it is the last state (acept state)
+	isLast                     bool                // If it is the last state (acept state)
-	output                     []*state         // The outputs of the current state ie. the 'outward arrows'. A union operator state will have more than one of these.
+	output                     []*nfaState         // The outputs of the current state ie. the 'outward arrows'. A union operator state will have more than one of these.
-	transitions                map[int][]*state // Transitions to different states (maps a character (int representation) to a _list of states. This is useful if one character can lead multiple states eg. ab|aa)
+	transitions                map[int][]*nfaState // Transitions to different states (maps a character (int representation) to a _list of states. This is useful if one character can lead multiple states eg. ab|aa)
-	isKleene                   bool             // Identifies whether current node is a 0-state representing Kleene star
+	isKleene                   bool                // Identifies whether current node is a 0-state representing Kleene star
-	assert                     assertType       // Type of assertion of current node - NONE means that the node doesn't assert anything
+	assert                     assertType          // Type of assertion of current node - NONE means that the node doesn't assert anything
-	allChars                   bool             // Whether or not the state represents all characters (eg. a 'dot' metacharacter). A 'dot' node doesn't store any contents directly, as it would take up too much space
+	allChars                   bool                // Whether or not the state represents all characters (eg. a 'dot' metacharacter). A 'dot' node doesn't store any contents directly, as it would take up too much space
-	except                     []rune           // Only valid if allChars is true - match all characters _except_ the ones in this block. Useful for inverting character classes.
+	except                     []rune              // Only valid if allChars is true - match all characters _except_ the ones in this block. Useful for inverting character classes.
-	lookaroundRegex            string           // Only for lookaround states - Contents of the regex that the lookaround state holds
+	lookaroundRegex            string              // Only for lookaround states - Contents of the regex that the lookaround state holds
-	lookaroundNFA              *state           // Holds the NFA of the lookaroundRegex - if it exists
+	lookaroundNFA              *nfaState           // Holds the NFA of the lookaroundRegex - if it exists
-	lookaroundNumCaptureGroups int              // Number of capturing groups in lookaround regex if current node is a lookaround
+	lookaroundNumCaptureGroups int                 // Number of capturing groups in lookaround regex if current node is a lookaround
-	groupBegin                 bool             // Whether or not the node starts a capturing group
+	groupBegin                 bool                // Whether or not the node starts a capturing group
-	groupEnd                   bool             // Whether or not the node ends a capturing group
+	groupEnd                   bool                // Whether or not the node ends a capturing group
-	groupNum                   int              // Which capturing group the node starts / ends
+	groupNum                   int                 // Which capturing group the node starts / ends
 	// 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.
 }
 
 // Clones the NFA starting from the given state.
-func cloneState(start *state) *state {
+func cloneState(start *nfaState) *nfaState {
-	return cloneStateHelper(start, make(map[*state]*state))
+	return cloneStateHelper(start, make(map[*nfaState]*nfaState))
 }
 
 // Helper function for clone. The map is used to keep track of which states have
 // already been copied, and which ones haven't.
 // This function was created using output from Llama3.1:405B.
-func cloneStateHelper(stateToClone *state, cloneMap map[*state]*state) *state {
+func cloneStateHelper(stateToClone *nfaState, cloneMap map[*nfaState]*nfaState) *nfaState {
 	// Base case - if the clone exists in our map, return it.
 	if clone, exists := cloneMap[stateToClone]; exists {
 		return clone
@@ -61,12 +61,12 @@ func cloneStateHelper(stateToClone *state, cloneMap map[*state]*state) *state {
 	}
 	// Recursive case - if the clone doesn't exist, create it, add it to the map,
 	// and recursively call for each of the transition states.
-	clone := &state{
+	clone := &nfaState{
 		content:         append([]int{}, stateToClone.content...),
 		isEmpty:         stateToClone.isEmpty,
 		isLast:          stateToClone.isLast,
-		output:          make([]*state, len(stateToClone.output)),
+		output:          make([]*nfaState, len(stateToClone.output)),
-		transitions:     make(map[int][]*state),
+		transitions:     make(map[int][]*nfaState),
 		isKleene:        stateToClone.isKleene,
 		assert:          stateToClone.assert,
 		zeroMatchFound:  stateToClone.zeroMatchFound,
@@ -86,7 +86,7 @@ func cloneStateHelper(stateToClone *state, cloneMap map[*state]*state) *state {
 		}
 	}
 	for k, v := range stateToClone.transitions {
-		clone.transitions[k] = make([]*state, len(v))
+		clone.transitions[k] = make([]*nfaState, len(v))
 		for i, s := range v {
 			if s == stateToClone {
 				clone.transitions[k][i] = clone
@@ -104,7 +104,7 @@ func cloneStateHelper(stateToClone *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 {
+func (s nfaState) checkAssertion(str []rune, idx int) bool {
 	if s.assert == alwaysTrueAssert {
 		return true
 	}
@@ -171,7 +171,7 @@ func (s state) checkAssertion(str []rune, idx int) bool {
 }
 
 // Returns true if the contents of 's' contain the value at the given index of the given string
-func (s state) contentContains(str []rune, idx int) bool {
+func (s nfaState) contentContains(str []rune, idx int) bool {
 	if s.assert != noneAssert {
 		return s.checkAssertion(str, idx)
 	}
@@ -182,19 +182,19 @@ func (s state) contentContains(str []rune, idx int) bool {
 	return slices.Contains(s.content, int(str[idx]))
 }
 
-func (s state) isLookaround() bool {
+func (s nfaState) isLookaround() bool {
 	return s.assert == plaAssert || s.assert == plbAssert || s.assert == nlaAssert || s.assert == nlbAssert
 }
 
 // Returns the matches for the character at the given index of the given string.
 // Also returns the number of matches. Returns -1 if an assertion failed.
-func (s state) matchesFor(str []rune, idx int) ([]*state, int) {
+func (s nfaState) matchesFor(str []rune, idx int) ([]*nfaState, int) {
 	// Assertions can be viewed as 'checks'. If the check fails, we return
 	// an empty array and 0.
 	// If it passes, we treat it like any other state, and return all the transitions.
 	if s.assert != noneAssert {
 		if s.checkAssertion(str, idx) == false {
-			return make([]*state, 0), -1
+			return make([]*nfaState, 0), -1
 		}
 	}
 	listTransitions := s.transitions[int(str[idx])]
@@ -211,7 +211,7 @@ func (s state) matchesFor(str []rune, idx int) ([]*state, int) {
 }
 
 // verifyLastStatesHelper performs the depth-first recursion needed for verifyLastStates
-func verifyLastStatesHelper(st *state, visited map[*state]bool) {
+func verifyLastStatesHelper(st *nfaState, visited map[*nfaState]bool) {
 	if len(st.transitions) == 0 {
 		st.isLast = true
 		return
@@ -228,7 +228,7 @@ func verifyLastStatesHelper(st *state, visited map[*state]bool) {
 	}
 
 	if st.isKleene { // A State representing a Kleene Star has transitions going out, which loop back to it. If all those transitions point to the same (single) state, then it must be a last state
-		transitionDests := make([]*state, 0)
+		transitionDests := make([]*nfaState, 0)
 		for _, v := range st.transitions {
 			transitionDests = append(transitionDests, v...)
 		}
@@ -251,12 +251,12 @@ func verifyLastStatesHelper(st *state, visited map[*state]bool) {
 }
 
 // verifyLastStates enables the 'isLast' flag for the leaf nodes (last states)
-func verifyLastStates(start []*state) {
+func verifyLastStates(start []*nfaState) {
-	verifyLastStatesHelper(start[0], make(map[*state]bool))
+	verifyLastStatesHelper(start[0], make(map[*nfaState]bool))
 }
 
 // Concatenates s1 and s2, returns the start of the concatenation.
-func concatenate(s1 *state, s2 *state) *state {
+func concatenate(s1 *nfaState, s2 *nfaState) *nfaState {
 	if s1 == nil {
 		return s2
 	}
@@ -269,13 +269,13 @@ func concatenate(s1 *state, s2 *state) *state {
 	return s1
 }
 
-func kleene(s1 state) (*state, error) {
+func kleene(s1 nfaState) (*nfaState, error) {
 	if s1.isEmpty && s1.assert != noneAssert {
 		return nil, fmt.Errorf("previous token is not quantifiable")
 	}
 
-	toReturn := &state{}
+	toReturn := &nfaState{}
-	toReturn.transitions = make(map[int][]*state)
+	toReturn.transitions = make(map[int][]*nfaState)
 	toReturn.content = newContents(EPSILON)
 	toReturn.isEmpty = true
 	toReturn.isKleene = true
@@ -291,9 +291,9 @@ func kleene(s1 state) (*state, error) {
 	return toReturn, nil
 }
 
-func alternate(s1 *state, s2 *state) *state {
+func alternate(s1 *nfaState, s2 *nfaState) *nfaState {
-	toReturn := &state{}
+	toReturn := &nfaState{}
-	toReturn.transitions = make(map[int][]*state)
+	toReturn.transitions = make(map[int][]*nfaState)
 	toReturn.output = append(toReturn.output, s1.output...)
 	toReturn.output = append(toReturn.output, s2.output...)
 	// Unique append is used here (and elsewhere) to ensure that,
@@ -313,9 +313,9 @@ func alternate(s1 *state, s2 *state) *state {
 	return toReturn
 }
 
-func question(s1 *state) *state { // Use the fact that ab? == a(b|)
+func question(s1 *nfaState) *nfaState { // Use the fact that ab? == a(b|)
-	s2 := &state{}
+	s2 := &nfaState{}
-	s2.transitions = make(map[int][]*state)
+	s2.transitions = make(map[int][]*nfaState)
 	s2.content = newContents(EPSILON)
 	s2.output = append(s2.output, s2)
 	s2.isEmpty = true
@@ -324,10 +324,10 @@ func question(s1 *state) *state { // Use the fact that ab? == a(b|)
 }
 
 // Creates and returns a new state with the 'default' values.
-func newState() state {
+func newState() nfaState {
-	ret := state{
+	ret := nfaState{
-		output:          make([]*state, 0),
+		output:          make([]*nfaState, 0),
-		transitions:     make(map[int][]*state),
+		transitions:     make(map[int][]*nfaState),
 		assert:          noneAssert,
 		except:          append([]rune{}, 0),
 		lookaroundRegex: "",
@@ -339,7 +339,7 @@ func newState() state {
 }
 
 // Creates and returns a state that _always_ has a zero-length match.
-func zeroLengthMatchState() state {
+func zeroLengthMatchState() nfaState {
 	start := newState()
 	start.content = newContents(EPSILON)
 	start.isEmpty = true