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Renamed 'State' to 'state' to avoid exposing the insides of the engine

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master
Aadhavan Srinivasan 3 days ago
parent 429d286439
commit d81b2ddaaa
1 changed files with 48 additions and 48 deletions
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96
regex/nfa.go
Unescape Escape View File

@ -22,18 +22,18 @@ const (
alwaysTrueAssert // An assertion that is always true alwaysTrueAssert // An assertion that is always true
) )
type State struct { type state 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 []*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) 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 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 *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 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
@ -44,14 +44,14 @@ type State struct {
} }
// Clones the NFA starting from the given state. // Clones the NFA starting from the given state.
func cloneState(start *State) *State { func cloneState(start *state) *state {
return cloneStateHelper(start, make(map[*State]*State)) return cloneStateHelper(start, make(map[*state]*state))
} }
// Helper function for clone. The map is used to keep track of which states have // Helper function for clone. The map is used to keep track of which states have
// already been copied, and which ones haven't. // already been copied, and which ones haven't.
// This function was created using output from Llama3.1:405B. // This function was created using output from Llama3.1:405B.
func cloneStateHelper(stateToClone *State, cloneMap map[*State]*State) *State { func cloneStateHelper(stateToClone *state, cloneMap map[*state]*state) *state {
// Base case - if the clone exists in our map, return it. // Base case - if the clone exists in our map, return it.
if clone, exists := cloneMap[stateToClone]; exists { if clone, exists := cloneMap[stateToClone]; exists {
return clone 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, // Recursive case - if the clone doesn't exist, create it, add it to the map,
// and recursively call for each of the transition states. // and recursively call for each of the transition states.
clone := &State{ clone := &state{
content: append([]int{}, stateToClone.content...), content: append([]int{}, stateToClone.content...),
isEmpty: stateToClone.isEmpty, isEmpty: stateToClone.isEmpty,
isLast: stateToClone.isLast, isLast: stateToClone.isLast,
output: make([]*State, len(stateToClone.output)), output: make([]*state, len(stateToClone.output)),
transitions: make(map[int][]*State), transitions: make(map[int][]*state),
isKleene: stateToClone.isKleene, isKleene: stateToClone.isKleene,
assert: stateToClone.assert, assert: stateToClone.assert,
zeroMatchFound: stateToClone.zeroMatchFound, zeroMatchFound: stateToClone.zeroMatchFound,
@ -86,7 +86,7 @@ func cloneStateHelper(stateToClone *State, cloneMap map[*State]*State) *State {
} }
} }
for k, v := range stateToClone.transitions { for k, v := range stateToClone.transitions {
clone.transitions[k] = make([]*State, len(v)) clone.transitions[k] = make([]*state, len(v))
for i, s := range v { for i, s := range v {
if s == stateToClone { if s == stateToClone {
clone.transitions[k][i] = clone 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 // Checks if the given state's assertion is true. Returns true if the given
// state doesn't have an assertion. // state doesn't have an assertion.
func (s State) checkAssertion(str []rune, idx int) bool { func (s state) checkAssertion(str []rune, idx int) bool {
if s.assert == alwaysTrueAssert { if s.assert == alwaysTrueAssert {
return true 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 // 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 state) contentContains(str []rune, idx int) bool {
if s.assert != noneAssert { if s.assert != noneAssert {
return s.checkAssertion(str, idx) 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])) return slices.Contains(s.content, int(str[idx]))
} }
func (s State) isLookaround() bool { func (s state) isLookaround() bool {
return s.assert == plaAssert || s.assert == plbAssert || s.assert == nlaAssert || s.assert == nlbAssert 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. // 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. // Also returns the number of matches. Returns -1 if an assertion failed.
func (s State) matchesFor(str []rune, idx int) ([]*State, int) { func (s state) matchesFor(str []rune, idx int) ([]*state, int) {
// Assertions can be viewed as 'checks'. If the check fails, we return // Assertions can be viewed as 'checks'. If the check fails, we return
// an empty array and 0. // an empty array and 0.
// If it passes, we treat it like any other state, and return all the transitions. // If it passes, we treat it like any other state, and return all the transitions.
if s.assert != noneAssert { if s.assert != noneAssert {
if s.checkAssertion(str, idx) == false { if s.checkAssertion(str, idx) == false {
return make([]*State, 0), -1 return make([]*state, 0), -1
} }
} }
listTransitions := s.transitions[int(str[idx])] listTransitions := s.transitions[int(str[idx])]
@ -211,39 +211,39 @@ func (s State) matchesFor(str []rune, idx int) ([]*State, int) {
} }
// verifyLastStatesHelper performs the depth-first recursion needed for verifyLastStates // verifyLastStatesHelper performs the depth-first recursion needed for verifyLastStates
func verifyLastStatesHelper(state *State, visited map[*State]bool) { func verifyLastStatesHelper(st *state, visited map[*state]bool) {
if len(state.transitions) == 0 { if len(st.transitions) == 0 {
state.isLast = true st.isLast = true
return return
} }
// if len(state.transitions) == 1 && len(state.transitions[state.content]) == 1 && state.transitions[state.content][0] == state { // Eg. a* // if len(state.transitions) == 1 && len(state.transitions[state.content]) == 1 && state.transitions[state.content][0] == state { // Eg. a*
if len(state.transitions) == 1 { // Eg. a* if len(st.transitions) == 1 { // Eg. a*
var moreThanOneTrans bool // Dummy variable, check if all the transitions for the current's state's contents have a length of one var moreThanOneTrans bool // Dummy variable, check if all the transitions for the current's state's contents have a length of one
for _, c := range state.content { for _, c := range st.content {
if len(state.transitions[c]) != 1 || state.transitions[c][0] != state { if len(st.transitions[c]) != 1 || st.transitions[c][0] != st {
moreThanOneTrans = true moreThanOneTrans = true
} }
} }
state.isLast = !moreThanOneTrans st.isLast = !moreThanOneTrans
} }
if state.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 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([]*state, 0)
for _, v := range state.transitions { for _, v := range st.transitions {
transitionDests = append(transitionDests, v...) transitionDests = append(transitionDests, v...)
} }
if allEqual(transitionDests...) { if allEqual(transitionDests...) {
state.isLast = true st.isLast = true
return return
} }
} }
if visited[state] == true { if visited[st] == true {
return return
} }
visited[state] = true visited[st] = true
for _, states := range state.transitions { for _, states := range st.transitions {
for i := range states { for i := range states {
if states[i] != state { if states[i] != st {
verifyLastStatesHelper(states[i], visited) verifyLastStatesHelper(states[i], visited)
} }
} }
@ -251,12 +251,12 @@ func verifyLastStatesHelper(state *State, visited map[*State]bool) {
} }
// verifyLastStates enables the 'isLast' flag for the leaf nodes (last states) // verifyLastStates enables the 'isLast' flag for the leaf nodes (last states)
func verifyLastStates(start []*State) { func verifyLastStates(start []*state) {
verifyLastStatesHelper(start[0], make(map[*State]bool)) verifyLastStatesHelper(start[0], make(map[*state]bool))
} }
// Concatenates s1 and s2, returns the start of the concatenation. // Concatenates s1 and s2, returns the start of the concatenation.
func concatenate(s1 *State, s2 *State) *State { func concatenate(s1 *state, s2 *state) *state {
if s1 == nil { if s1 == nil {
return s2 return s2
} }
@ -269,13 +269,13 @@ func concatenate(s1 *State, s2 *State) *State {
return s1 return s1
} }
func kleene(s1 State) (*State, error) { func kleene(s1 state) (*state, error) {
if s1.isEmpty && s1.assert != noneAssert { if s1.isEmpty && s1.assert != noneAssert {
return nil, fmt.Errorf("previous token is not quantifiable") return nil, fmt.Errorf("previous token is not quantifiable")
} }
toReturn := &State{} toReturn := &state{}
toReturn.transitions = make(map[int][]*State) toReturn.transitions = make(map[int][]*state)
toReturn.content = newContents(EPSILON) toReturn.content = newContents(EPSILON)
toReturn.isEmpty = true toReturn.isEmpty = true
toReturn.isKleene = true toReturn.isKleene = true
@ -291,9 +291,9 @@ func kleene(s1 State) (*State, error) {
return toReturn, nil return toReturn, nil
} }
func alternate(s1 *State, s2 *State) *State { func alternate(s1 *state, s2 *state) *state {
toReturn := &State{} toReturn := &state{}
toReturn.transitions = make(map[int][]*State) toReturn.transitions = make(map[int][]*state)
toReturn.output = append(toReturn.output, s1.output...) toReturn.output = append(toReturn.output, s1.output...)
toReturn.output = append(toReturn.output, s2.output...) toReturn.output = append(toReturn.output, s2.output...)
// Unique append is used here (and elsewhere) to ensure that, // Unique append is used here (and elsewhere) to ensure that,
@ -313,9 +313,9 @@ func alternate(s1 *State, s2 *State) *State {
return toReturn return toReturn
} }
func question(s1 *State) *State { // Use the fact that ab? == a(b|) func question(s1 *state) *state { // Use the fact that ab? == a(b|)
s2 := &State{} s2 := &state{}
s2.transitions = make(map[int][]*State) s2.transitions = make(map[int][]*state)
s2.content = newContents(EPSILON) s2.content = newContents(EPSILON)
s2.output = append(s2.output, s2) s2.output = append(s2.output, s2)
s2.isEmpty = true 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. // Creates and returns a new state with the 'default' values.
func newState() State { func newState() state {
ret := State{ ret := state{
output: make([]*State, 0), output: make([]*state, 0),
transitions: make(map[int][]*State), transitions: make(map[int][]*state),
assert: noneAssert, assert: noneAssert,
except: append([]rune{}, 0), except: append([]rune{}, 0),
lookaroundRegex: "", lookaroundRegex: "",
@ -339,7 +339,7 @@ func newState() State {
} }
// Creates and returns a state that _always_ has a zero-length match. // Creates and returns a state that _always_ has a zero-length match.
func zeroLengthMatchState() State { func zeroLengthMatchState() state {
start := newState() start := newState()
start.content = newContents(EPSILON) start.content = newContents(EPSILON)
start.isEmpty = true start.isEmpty = true

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