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/*
* RNG.h, part of VCMI engine
*
* Authors: listed in file AUTHORS in main folder
*
* License: GNU General Public License v2.0 or later
* Full text of license available in license.txt file, in main folder
*
*/
#pragma once
VCMI_LIB_NAMESPACE_BEGIN
namespace vstd
{
typedef std::function<int64_t()> TRandI64;
typedef std::function<double()> TRand;
class DLL_LINKAGE RNG
{
public:
virtual ~RNG() = default;
virtual TRandI64 getInt64Range(int64_t lower, int64_t upper) = 0;
virtual TRand getDoubleRange(double lower, double upper) = 0;
};
}
namespace RandomGeneratorUtil
{
template<typename Container>
auto nextItem(const Container & container, vstd::RNG & rand) -> decltype(std::begin(container))
{
assert(!container.empty());
return std::next(container.begin(), rand.getInt64Range(0, container.size() - 1)());
}
template<typename Container>
auto nextItem(Container & container, vstd::RNG & rand) -> decltype(std::begin(container))
{
assert(!container.empty());
return std::next(container.begin(), rand.getInt64Range(0, container.size() - 1)());
}
template<typename T>
void randomShuffle(std::vector<T> & container, vstd::RNG & rand)
{
int64_t n = (container.end() - container.begin());
for(int64_t i = n-1; i>0; --i)
{
std::swap(container.begin()[i],container.begin()[rand.getInt64Range(0, i)()]);
}
}
}
VCMI_LIB_NAMESPACE_END
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