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Use the RNG output directly in basic_random_generator when its results are uniform uint32_t or uint64_t. Fixes #174.

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Peter Dimov
2025-06-28 19:39:43 +03:00
parent 575469e5f6
commit 95855404d2
1 changed files with 33 additions and 6 deletions
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39
include/boost/uuid/basic_random_generator.hpp
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@@ -56,14 +56,9 @@ public:
{
UniformRandomNumberGenerator& gen = p_? *p_: g_;
std::uniform_int_distribution<std::uint32_t> dist;
result_type u;
detail::store_native_u32( u.data + 0, dist( gen ) );
detail::store_native_u32( u.data + 4, dist( gen ) );
detail::store_native_u32( u.data + 8, dist( gen ) );
detail::store_native_u32( u.data + 12, dist( gen ) );
fill_data( gen, u );
// set variant
// must be 0b10xxxxxx
@@ -80,6 +75,38 @@ public:
private:
template<class URNG> static void fill_data_impl( URNG& gen, uuid& u, std::false_type, std::false_type )
{
std::uniform_int_distribution<std::uint32_t> dist;
detail::store_little_u32( u.data + 0, dist( gen ) );
detail::store_little_u32( u.data + 4, dist( gen ) );
detail::store_little_u32( u.data + 8, dist( gen ) );
detail::store_little_u32( u.data + 12, dist( gen ) );
}
template<class URNG> static void fill_data_impl( URNG& gen, uuid& u, std::true_type, std::false_type )
{
detail::store_little_u32( u.data + 0, static_cast<std::uint32_t>( gen() ) );
detail::store_little_u32( u.data + 4, static_cast<std::uint32_t>( gen() ) );
detail::store_little_u32( u.data + 8, static_cast<std::uint32_t>( gen() ) );
detail::store_little_u32( u.data + 12, static_cast<std::uint32_t>( gen() ) );
}
template<class URNG> static void fill_data_impl( URNG& gen, uuid& u, std::false_type, std::true_type )
{
detail::store_little_u64( u.data + 0, static_cast<std::uint64_t>( gen() ) );
detail::store_little_u64( u.data + 8, static_cast<std::uint64_t>( gen() ) );
}
template<class URNG> static void fill_data( URNG& gen, uuid& u )
{
fill_data_impl( gen, u,
std::integral_constant<bool, (URNG::min)() == 0 && (URNG::max)() == static_cast<std::uint32_t>( -1 )>(),
std::integral_constant<bool, (URNG::min)() == 0 && (URNG::max)() == static_cast<std::uint64_t>( -1 )>()
);
}
// Detect whether UniformRandomNumberGenerator has a seed() method which indicates that
// it is a PseudoRandomNumberGenerator and needs a seed to initialize it. This allows
// basic_random_generator to take any type of UniformRandomNumberGenerator and still