solidity/tools/yulPhaser/SimulationRNG.h
Kamil Śliwak 8f55ead48d yul-phaser: Switch from uint32_t to size_t in SimulationRNG
- Also pass the appriopriate type internally to the distribution instead of relying on the default (which is uint32_t)
2020-06-04 17:19:42 +02:00

58 lines
2.0 KiB
C++

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