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Use stateContents type to allow a state to store multiple characters

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This commit is contained in:
Aadhavan Srinivasan
2024-10-28 17:38:43 -04:00
parent 4f2f14212c
commit 3778869567
1 changed files with 35 additions and 17 deletions
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52
nfa.go
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@@ -3,7 +3,7 @@ package main
const EPSILON int = 0
type State struct {
content int // 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
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.
@@ -22,17 +22,25 @@ func verifyLastStatesHelper(state *State, visited map[*State]bool) {
state.isLast = true
return
}
if len(state.transitions) == 1 && len(state.transitions[state.content]) == 1 && state.transitions[state.content][0] == state { // Eg. a*
state.isLast = true
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 { // Eg. a*
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 {
if len(state.transitions[c]) != 1 || state.transitions[c][0] != state {
moreThanOneTrans = true
}
}
state.isLast = !moreThanOneTrans
}
if len(state.transitions) == 1 && state.isKleene { // A State representing a Kleene Star has a transition going out, which loops back to it. If that is the only transition (and it contains only one state), then it must be a last-state
for _, v := range state.transitions { // Should only loop once
if len(v) == 1 {
state.isLast = true
return
}
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
transitionDests := make([]*State, 0)
for _, v := range state.transitions {
transitionDests = append(transitionDests, v...)
}
if allEqual(transitionDests...) {
state.isLast = true
return
}
}
if visited[state] == true {
@@ -55,7 +63,9 @@ func verifyLastStates(start []*State) {
func concatenate(s1 *State, s2 *State) *State {
for i := range s1.output {
s1.output[i].transitions[s2.content], _ = unique_append(s1.output[i].transitions[s2.content], s2)
for _, c := range s2.content { // Create transitions for every element in s2's content to s2'
s1.output[i].transitions[c], _ = unique_append(s1.output[i].transitions[c], s2)
}
}
s1.output = s2.output
return s1
@@ -64,14 +74,18 @@ func concatenate(s1 *State, s2 *State) *State {
func kleene(s1 State) *State {
toReturn := &State{}
toReturn.transitions = make(map[int][]*State)
toReturn.content = EPSILON
toReturn.content = newContents(EPSILON)
toReturn.isEmpty = true
toReturn.isKleene = true
toReturn.output = append(toReturn.output, toReturn)
for i := range s1.output {
s1.output[i].transitions[toReturn.content], _ = unique_append(s1.output[i].transitions[toReturn.content], toReturn)
for _, c := range toReturn.content {
s1.output[i].transitions[c], _ = unique_append(s1.output[i].transitions[c], toReturn)
}
}
for _, c := range s1.content {
toReturn.transitions[c], _ = unique_append(toReturn.transitions[c], &s1)
}
toReturn.transitions[s1.content], _ = unique_append(toReturn.transitions[s1.content], &s1)
return toReturn
}
@@ -85,9 +99,13 @@ func alternate(s1 *State, s2 *State) *State {
// For example, given the transition 'a', the state 's1' can only be mentioned once.
// This would lead to multiple instances of the same set of match indices, since both
// 's1' states would be considered to match.
toReturn.transitions[s1.content], _ = unique_append(toReturn.transitions[s1.content], s1)
toReturn.transitions[s2.content], _ = unique_append(toReturn.transitions[s2.content], s2)
toReturn.content = EPSILON
for _, c := range s1.content {
toReturn.transitions[c], _ = unique_append(toReturn.transitions[c], s1)
}
for _, c := range s2.content {
toReturn.transitions[c], _ = unique_append(toReturn.transitions[c], s2)
}
toReturn.content = newContents(EPSILON)
toReturn.isEmpty = true
return toReturn