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Added field to denote all characters which an 'allChars' node _shouldn't_ match (useful for invertinc character classes

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This commit is contained in:
Aadhavan Srinivasan
2024-11-20 09:39:24 -05:00
parent c694c47be7
commit 708a9e1303
1 changed files with 12 additions and 4 deletions
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16
nfa.go
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@@ -23,7 +23,8 @@ type State struct {
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
zeroMatchFound bool // Whether or not the state has been used for a zero-length match - only relevant for zero states zeroMatchFound bool // Whether or not the state has been used for a zero-length match - only relevant for zero states
isDot bool // Whether or not the state represents 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.
} }
// Clones the NFA starting from the given state. // Clones the NFA starting from the given state.
@@ -50,6 +51,8 @@ func cloneStateHelper(state *State, cloneMap map[*State]*State) *State {
isKleene: state.isKleene, isKleene: state.isKleene,
assert: state.assert, assert: state.assert,
zeroMatchFound: state.zeroMatchFound, zeroMatchFound: state.zeroMatchFound,
allChars: state.allChars,
except: append([]rune{}, state.except...),
} }
cloneMap[state] = clone cloneMap[state] = clone
for i, s := range state.output { for i, s := range state.output {
@@ -95,8 +98,8 @@ func (s State) contentContains(str []rune, idx int) bool {
if s.assert != NONE { if s.assert != NONE {
return s.checkAssertion(str, idx) return s.checkAssertion(str, idx)
} }
if s.isDot { if s.allChars {
return !slices.Contains(notDotChars, str[idx]) return !slices.Contains(slices.Concat(notDotChars, s.except), str[idx]) // Return true only if the index isn't a 'notDotChar', or isn't one of the exception characters for the current node.
} }
// Default - s.assert must be NONE // Default - s.assert must be NONE
return slices.Contains(s.content, int(str[idx])) return slices.Contains(s.content, int(str[idx]))
@@ -122,7 +125,12 @@ func (s State) matchesFor(str []rune, idx int) ([]*State, int) {
} }
listTransitions := s.transitions[int(str[idx])] listTransitions := s.transitions[int(str[idx])]
for _, dest := range s.transitions[int(ANY_CHAR)] { for _, dest := range s.transitions[int(ANY_CHAR)] {
listTransitions = append(listTransitions, dest) if !slices.Contains(slices.Concat(notDotChars, dest.except), str[idx]) {
// Add an allChar state to the list of matches if:
// a. The current character isn't a 'notDotChars' character. In single line mode, this includes newline. In multiline mode, it doesn't.
// b. The current character isn't the state's exception list.
listTransitions = append(listTransitions, dest)
}
} }
numTransitions := len(listTransitions) numTransitions := len(listTransitions)
return listTransitions, numTransitions return listTransitions, numTransitions