mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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// SPDX-License-Identifier: GPL-3.0
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#pragma once
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#include <boost/random/mersenne_twister.hpp>
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#include <cstdint>
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namespace solidity::phaser
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{
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/**
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* A class that provides functions for generating random numbers good enough for simulation purposes.
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*
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* The functions share a common instance of the generator which can be reset with a known seed
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* to deterministically generate a given sequence of numbers. Initially the generator is seeded with
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* a value from @a generateSeed() which is different on each run.
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*
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* The numbers are not cryptographically secure so do not use this for anything that requires
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* them to be truly unpredictable.
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*/
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class SimulationRNG
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{
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public:
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static bool bernoulliTrial(double _successProbability);
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static size_t uniformInt(size_t _min, size_t _max);
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static size_t binomialInt(size_t _numTrials, double _successProbability);
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/// Resets generator to a known state given by the @a seed. Given the same seed, a fixed
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/// sequence of calls to the members generating random values is guaranteed to produce the
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/// same results.
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static void reset(uint32_t seed) { s_generator = boost::random::mt19937(seed); }
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/// Generates a seed that's different on each run of the program.
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/// Does **not** use the generator and is not affected by @a reset().
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static uint32_t generateSeed();
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private:
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thread_local static boost::random::mt19937 s_generator;
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};
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}
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