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124 lines
3.4 KiB
C++
124 lines
3.4 KiB
C++
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/*
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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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typedef std::mt19937 TGenerator;
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typedef std::uniform_int_distribution<int> TIntDist;
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typedef std::uniform_real_distribution<double> TRealDist;
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typedef std::function<int()> TRandI;
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typedef std::function<double()> TRand;
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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 : boost::noncopyable
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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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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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/// Generate several integer numbers within the same range.
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/// e.g.: auto a = gen.getIntRange(0,10); a(); a(); a();
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/// requires: lower <= upper
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TRandI getIntRange(int lower, int upper);
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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);
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/// requires: lower <= upper
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int nextInt(int lower, int upper);
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/// Generates an integer between 0 and the maximum value it can hold.
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int nextInt();
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/// Generate several double/real numbers within the same range.
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/// e.g.: auto a = gen.getDoubleRange(4.5,10.2); a(); a(); a();
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/// requires: lower <= upper
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TRand getDoubleRange(double lower, double upper);
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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);
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/// requires: lower <= upper
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double nextDouble(double lower, double upper);
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/// Generates a double between 0.0 and 1.0.
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double nextDouble();
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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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/// Provide method so that this RNG can be used with legacy std:: API
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TGenerator & getStdGenerator();
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private:
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TGenerator rand;
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static boost::thread_specific_ptr<CRandomGenerator> defaultRand;
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public:
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template <typename Handler>
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void serialize(Handler & h, const int version)
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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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namespace RandomGeneratorUtil
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{
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template<typename Container>
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auto nextItem(const Container & container, CRandomGenerator & rand) -> decltype(std::begin(container))
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{
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assert(!container.empty());
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return std::next(container.begin(), rand.nextInt(container.size() - 1));
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}
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template<typename Container>
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auto nextItem(Container & container, CRandomGenerator & rand) -> decltype(std::begin(container))
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{
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assert(!container.empty());
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return std::next(container.begin(), rand.nextInt(container.size() - 1));
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}
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template<typename T>
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void randomShuffle(std::vector<T>& container, CRandomGenerator & rand)
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{
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int n = (container.end() - container.begin());
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for (int i = n-1; i>0; --i)
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{
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std::swap (container.begin()[i],container.begin()[rand.nextInt(i+1)]);
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}
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}
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}
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