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/* ************************************************************** * C++ Mathematical Expression Toolkit Library * * * * ExprTk Loop Timeout RTC * * Author: Arash Partow (1999-2024) * * URL: https://www.partow.net/programming/exprtk/index.html * * * * Copyright notice: * * Free use of the Mathematical Expression Toolkit Library is * * permitted under the guidelines and in accordance with the * * most current version of the MIT License. * * https://www.opensource.org/licenses/MIT * * SPDX-License-Identifier: MIT * * * ************************************************************** */ #include #include #include #include "exprtk.hpp" struct timeout_rtc_handler final : public exprtk::loop_runtime_check { timeout_rtc_handler() : exprtk::loop_runtime_check() {} class timeout_exception final : public std::runtime_error { public: timeout_exception(const std::string& what = "") : std::runtime_error(what) {} }; using time_point_t = std::chrono::time_point; void set_timeout_time(const time_point_t& timeout_tp) { timeout_tp_ = timeout_tp; } bool check() override { static constexpr std::size_t max_iters_per_check = 100000; if (++iterations_ >= max_iters_per_check) { if (std::chrono::steady_clock::now() >= timeout_tp_) { return false; } iterations_ = 0; } return true; } void handle_runtime_violation(const violation_context&) override { throw timeout_exception("Loop run-time timeout violation."); } std::size_t iterations_ = 0; time_point_t timeout_tp_; }; struct vector_access_rtc final : public exprtk::vector_access_runtime_check { bool handle_runtime_violation(violation_context&) override { throw std::runtime_error("Runtime vector access violation."); return false; } }; template void loop_timeout_rtc() { typedef exprtk::expression expression_t; typedef exprtk::parser parser_t; typedef exprtk::loop_runtime_check loop_runtime_check_t; const std::string sieve_of_eratosthenes_program = " var sieve[10^8] := [false]; " " var m := trunc(sqrt(sieve[])); " " " " sieve[0] := true; " " sieve[1] := true; " " " " for (var i := 0; i <= m; i += 1) " " { " " if (false == sieve[i]) " " { " " for (var j := i^2; j < sieve[]; j += i) " " { " " sieve[j] := true; " " } " " } " " }; " " " " var prime_count := sieve[] - sum(sieve); " " " " prime_count == 5761455; "; timeout_rtc_handler loop_runtime_check; loop_runtime_check.loop_set = loop_runtime_check_t::e_all_loops; loop_runtime_check.max_loop_iterations = static_cast(10e8 * std::log10(std::log10(10e8))); // O(n) = nlog(log(n)) vector_access_rtc vec_rtc; expression_t expression; parser_t parser; parser.register_loop_runtime_check(loop_runtime_check); parser.register_vector_access_runtime_check(vec_rtc); parser.compile(sieve_of_eratosthenes_program,expression); const auto max_duration = std::chrono::seconds(1); const auto timeout_tp = std::chrono::steady_clock::now() + max_duration; loop_runtime_check.set_timeout_time(timeout_tp); try { expression.value(); } catch (timeout_rtc_handler::timeout_exception& /*toe*/) { printf("Timeout Exception\n"); } catch (std::runtime_error& rte) { printf("Exception: %s\n",rte.what()); } parser.clear_loop_runtime_check(); } int main() { loop_timeout_rtc(); return 0; }