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

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This commit is contained in:
Aadhavan Srinivasan
2025-01-30 10:31:02 -05:00
parent d81b2ddaaa
commit 93474c5159
3 changed files with 74 additions and 74 deletions
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94
regex/nfa.go
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@@ -22,36 +22,36 @@ const (
alwaysTrueAssert // An assertion that is always true
)
type state struct {
content stateContents // Contents of current state
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)
output []*state // 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)
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
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.
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
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
groupEnd bool // Whether or not the node ends a capturing group
groupNum int // Which capturing group the node starts / ends
type nfaState struct {
content stateContents // Contents of current state
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)
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][]*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
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
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
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
groupBegin bool // Whether or not the node starts a capturing group
groupEnd bool // Whether or not the node ends a capturing group
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 {
return cloneStateHelper(start, make(map[*state]*state))
func cloneState(start *nfaState) *nfaState {
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)),
transitions: make(map[int][]*state),
output: make([]*nfaState, len(stateToClone.output)),
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) {
verifyLastStatesHelper(start[0], make(map[*state]bool))
func verifyLastStates(start []*nfaState) {
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.transitions = make(map[int][]*state)
toReturn := &nfaState{}
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 {
toReturn := &state{}
toReturn.transitions = make(map[int][]*state)
func alternate(s1 *nfaState, s2 *nfaState) *nfaState {
toReturn := &nfaState{}
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|)
s2 := &state{}
s2.transitions = make(map[int][]*state)
func question(s1 *nfaState) *nfaState { // Use the fact that ab? == a(b|)
s2 := &nfaState{}
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 {
ret := state{
output: make([]*state, 0),
transitions: make(map[int][]*state),
func newState() nfaState {
ret := nfaState{
output: make([]*nfaState, 0),
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