Rockingcool/kleingrep
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fixed Kleene Star matching

Browse Source
This commit is contained in:
Aadhavan Srinivasan
2024-10-22 17:07:01 -04:00
parent d191686168
commit bc11777ad5
3 changed files with 31 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
main.go
View File

@@ -102,8 +102,8 @@ func shuntingYard(re string) string {
// Thompson's algorithm. Constructs Finite-State Automaton from given string.
// Returns start state.
func thompson(re string) State {
nfa := make([]State, 0) // Stack of states
func thompson(re string) *State {
nfa := make([]*State, 0) // Stack of states
for _, c := range re {
if isAlphaNum(c) {
state := State{}
@@ -112,7 +112,7 @@ func thompson(re string) State {
state.output = make([]*State, 0)
state.output = append(state.output, &state)
state.isEmpty = false
nfa = append(nfa, state)
nfa = append(nfa, &state)
}
// Must be an operator if it isn't alphanumeric
switch c {
@@ -120,31 +120,31 @@ func thompson(re string) State {
s2 := pop(&nfa)
s1 := pop(&nfa)
for i := range s1.output {
s1.output[i].transitions[s2.content] = append(s1.output[i].transitions[s2.content], &s2)
s1.output[i].transitions[s2.content] = append(s1.output[i].transitions[s2.content], s2)
}
s1.output = s2.output
nfa = append(nfa, s1)
case '*':
s1 := pop(&nfa)
for i := range s1.output {
s1.output[i].transitions[s1.content] = append(s1.output[i].transitions[s1.content], &s1)
s1.output[i].transitions[s1.content] = append(s1.output[i].transitions[s1.content], s1)
}
// Reset output to s1 (in case s1 was a union operator state, which has multiple outputs)
s1.output = nil
s1.output = append(s1.output, &s1)
s1.output = append(s1.output, s1)
nfa = append(nfa, s1)
case '|':
s1 := pop(&nfa)
s2 := pop(&nfa)
s3 := State{}
s3.transitions = make(map[int][]*State)
s3.output = append(s3.output, &s1, &s2)
s3.transitions[s1.content] = append(s3.transitions[s1.content], &s1)
s3.transitions[s2.content] = append(s3.transitions[s2.content], &s2)
s3.output = append(s3.output, s1, s2)
s3.transitions[s1.content] = append(s3.transitions[s1.content], s1)
s3.transitions[s2.content] = append(s3.transitions[s2.content], s2)
s3.content = UNION
s3.isEmpty = true
nfa = append(nfa, s3)
nfa = append(nfa, &s3)
}
}
if len(nfa) != 1 {
@@ -160,13 +160,14 @@ func thompson(re string) State {
func main() {
if len(os.Args) < 3 {
fmt.Println("ERROR: Missing cmdline args")
os.Exit(22)
}
var re string
re = os.Args[1]
re_postfix := shuntingYard(re)
fmt.Println(re_postfix)
start := thompson(re_postfix)
s, e, matched := match(&start, os.Args[2])
s, e, matched := match(start, os.Args[2])
if matched {
fmt.Printf("Matched from %d to %d\n", s, e)
} else {