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No more segfault during regex parsing #451

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merged 2 commits into from
Nov 4, 2024
Merged

No more segfault during regex parsing #451

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ecc240f
no more segfault
koniksedy Oct 30, 2024
f706d86
replace function call with trim
koniksedy Oct 31, 2024
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54 changes: 1 addition & 53 deletions src/re2parser.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -252,7 +252,7 @@ namespace {
}
}
}
RegexParser::renumber_states(output_nfa, prog_size, explicit_nfa);
*output_nfa = Nfa(explicit_nfa).trim();
}

private: // private methods
Expand Down Expand Up @@ -440,58 +440,6 @@ namespace {
}
}

/**
* Renumbers the states of the input_nfa to be from <0, numberOfStates>
* @param program_size Size of the RE2 prog
* @param input_nfa Nfa which states should be renumbered
* @return Same Nfa as input_nfa but with states from interval <0, numberOfStates>
*/
static Nfa renumber_states(Nfa* output_nfa,
size_t program_size,
Nfa &input_nfa) {
std::vector<mata::nfa::State> renumbered_states(program_size, mata::nfa::Limits::max_state);
Nfa& renumbered_explicit_nfa = *output_nfa;
for (mata::nfa::State state{ 0 }; state < program_size; state++) {
const auto& transition_list = input_nfa.delta.state_post(state);
// If the transition list is empty, the state is not used
if (transition_list.empty()) {
continue;
} else {
// addNewState returns next unused state of the new NFA, so we map it to the original state
renumbered_states[state] = renumbered_explicit_nfa.add_state();
}
}

for (auto state: input_nfa.final) {
if (static_cast<int>(renumbered_states[state]) == -1) {
renumbered_states[state] = renumbered_explicit_nfa.add_state();
}
renumbered_explicit_nfa.final.insert(renumbered_states[state]);
}

for (mata::nfa::State state{ 0 }; state < program_size; state++) {
const auto& transition_list = input_nfa.delta.state_post(state);
for (const auto& transition: transition_list) {
for (auto stateTo: transition.targets) {
if (renumbered_states[stateTo] == mata::nfa::Limits::max_state) {
renumbered_states[stateTo] = renumbered_explicit_nfa.add_state();
}
assert(renumbered_states[state] <= renumbered_explicit_nfa.num_of_states());
assert(renumbered_states[stateTo] <= renumbered_explicit_nfa.num_of_states());
renumbered_explicit_nfa.delta.add(renumbered_states[state], transition.symbol,
renumbered_states[stateTo]);
}
}
}


for (auto state: input_nfa.initial) {
renumbered_explicit_nfa.initial.insert(renumbered_states[state]);
}

return renumbered_explicit_nfa;
}

/**
* Gets all states that are mapped to the state (i.e., states that are within epsilon transitions chain)
* @param prog RE2 prog corresponding to the parsed regex
Expand Down
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