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Started implementing backreferences (octal values should now be prefaced with \0)

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Aadhavan Srinivasan
2025-02-11 16:14:48 -05:00
parent 073f231b89
commit 8327450dd2
5 changed files with 156 additions and 39 deletions
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11
regex/nfa.go
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@@ -45,8 +45,10 @@ type nfaState struct {
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.
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.
isBackreference bool // Whether or not current node is backreference
referredGroup int // If current node is a backreference, the node that it points to
threadBackref int // If current node is a backreference, how many characters to look forward into the referred group
}
// Clones the NFA starting from the given state.
@@ -76,7 +78,6 @@ func cloneStateHelper(stateToClone *nfaState, cloneMap map[*nfaState]*nfaState)
isQuestion: stateToClone.isQuestion,
isAlternation: stateToClone.isAlternation,
assert: stateToClone.assert,
zeroMatchFound: stateToClone.zeroMatchFound,
allChars: stateToClone.allChars,
except: append([]rune{}, stateToClone.except...),
lookaroundRegex: stateToClone.lookaroundRegex,
@@ -122,6 +123,7 @@ func resetThreadsHelper(state *nfaState, visitedMap map[*nfaState]bool) {
}
// Assuming it hasn't been visited
state.threadGroups = nil
state.threadBackref = 0
visitedMap[state] = true
if state.isAlternation {
resetThreadsHelper(state.next, visitedMap)
@@ -428,7 +430,8 @@ func (s nfaState) equals(other nfaState) bool {
s.groupBegin == other.groupBegin &&
s.groupEnd == other.groupEnd &&
s.groupNum == other.groupNum &&
slices.Equal(s.threadGroups, other.threadGroups)
slices.Equal(s.threadGroups, other.threadGroups) &&
s.threadBackref == other.threadBackref
}
func stateExists(list []nfaState, s nfaState) bool {