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Harden Search::Do state transitions to avoid crashes #5

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Merged
WJiangzhi merged 1 commit into from
Mar 3, 2026
Merged

Harden Search::Do state transitions to avoid crashes #5

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15 changes: 14 additions & 1 deletion ZACLib/ZACLib.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -218,10 +218,23 @@ namespace ZACLib {

std::vector<Search::Match> Search::Do(const ZAC_SV& input) const {
std::vector<Match> result;
if (trie.empty()) return result;

int state = 0;
for (size_t i = 0; i < input.size(); ++i) {
const auto c = static_cast<unsigned char>(input[i]);
state = trie[state].next[c];

// Allow matching even when Build() has not been called yet.
// In that case transitions can still be -1, so we fall back to
// the fail chain and finally the root instead of indexing trie[-1].
while (state != 0 && trie[state].next[c] == -1) {
state = trie[state].fail;
}
if (trie[state].next[c] != -1) {
state = trie[state].next[c];
} else {
state = 0;
}
Comment on lines +230 to +237
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@gemini-code-assist gemini-code-assist Bot Mar 3, 2026

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medium

The logic to handle state transitions is correct and successfully hardens the function against crashes. However, the implementation can be made more concise. The current while loop followed by an if-else block can be simplified into a more standard pattern for Aho-Corasick state transitions. This improves readability and maintainability.

            while (trie[state].next[c] == -1 && state != 0) {
                state = trie[state].fail;
            }
            state = trie[state].next[c];
            if (state == -1) {
                state = 0;
            }


if (trie[state].output_id != Node::kInvalidOutput) {
result.push_back(
Expand Down