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LibRegex: Make infinite repetitions short-circuit on empty matches

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This makes (addmittedly weird) patterns like `(a*)*` work correctly
without going into an infinite fork loop.
This commit is contained in:
Ali Mohammad Pur 2021-09-06 02:38:47 +04:30 • committed by Ali Mohammad Pur
parent f8570bd773
commit abbe9da255
4 changed files with 131 additions and 69 deletions
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15
Tests/LibRegex/Regex.cpp
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@ -852,6 +852,21 @@ TEST_CASE(extremely_long_fork_chain)
EXPECT_EQ(result.success, true);
}
TEST_CASE(theoretically_infinite_loop)
{
Array patterns {
"(a*)*"sv, // Infinitely matching empty substrings, the outer loop should short-circuit.
"(a*?)*"sv, // Infinitely matching empty substrings, the outer loop should short-circuit.
"(a*)*?"sv, // Should match exactly nothing.
"(?:)*?"sv, // Should not generate an infinite fork loop.
};
for (auto& pattern : patterns) {
Regex<ECMA262> re(pattern);
auto result = re.match("");
EXPECT_EQ(result.success, true);
}
}
static auto g_lots_of_a_s = String::repeated('a', 10'000'000);
BENCHMARK_CASE(fork_performance)