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100 lines
2.8 KiB
C++
100 lines
2.8 KiB
C++
/*
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* CRandomGenerator.h, part of VCMI engine
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*
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* Authors: listed in file AUTHORS in main folder
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*
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* License: GNU General Public License v2.0 or later
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* Full text of license available in license.txt file, in main folder
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*
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*/
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#pragma once
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#include <vstd/RNG.h>
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#include "serializer/Serializeable.h"
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VCMI_LIB_NAMESPACE_BEGIN
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/// Generator to use for all randomization in game
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/// minstd_rand is selected due to following reasons:
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/// 1. Its randomization quality is below mt_19937 however this is unlikely to be noticeable in game
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/// 2. It has very low state size, leading to low overhead in size of saved games (due to large number of random generator instances in game)
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using TGenerator = std::minstd_rand;
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using TIntDist = std::uniform_int_distribution<int>;
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using TInt64Dist = std::uniform_int_distribution<int64_t>;
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using TRealDist = std::uniform_real_distribution<double>;
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/// The random generator randomly generates integers and real numbers("doubles") between
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/// a given range. This is a header only class and mainly a wrapper for
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/// convenient usage of the standard random API. An instance of this RNG is not thread safe.
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class DLL_LINKAGE CRandomGenerator final : public vstd::RNG, boost::noncopyable, public Serializeable
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{
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public:
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/// Seeds the generator by default with the product of the current time in milliseconds and the
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/// current thread ID.
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CRandomGenerator();
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/// Seeds the generator with provided initial seed
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explicit CRandomGenerator(int seed);
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void setSeed(int seed);
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/// Resets the seed to the product of the current time in milliseconds and the
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/// current thread ID.
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void resetSeed();
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/// Generates an integer between 0 and upper.
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/// requires: 0 <= upper
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int nextInt(int upper) override;
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int64_t nextInt64(int64_t upper) override;
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/// requires: lower <= upper
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int nextInt(int lower, int upper) override;
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int64_t nextInt64(int64_t lower, int64_t upper) override;
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/// Generates an integer between 0 and the maximum value it can hold.
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int nextInt() override;
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///
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int nextBinomialInt(int coinsCount, double coinChance) override;
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/// Generates a double between 0 and upper.
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/// requires: 0 <= upper
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double nextDouble(double upper) override;
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/// requires: lower <= upper
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double nextDouble(double lower, double upper) override;
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/// Gets a globally accessible RNG which will be constructed once per thread. For the
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/// seed a combination of the thread ID and current time in milliseconds will be used.
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static CRandomGenerator & getDefault();
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private:
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TGenerator rand;
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public:
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template <typename Handler>
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void serialize(Handler & h)
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{
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if(h.saving)
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{
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std::ostringstream stream;
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stream << rand;
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std::string str = stream.str();
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h & str;
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}
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else
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{
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std::string str;
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h & str;
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std::istringstream stream(str);
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stream >> rand;
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}
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}
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};
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VCMI_LIB_NAMESPACE_END
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