diff options
Diffstat (limited to 'absl/random/internal/uniform_helper.h')
-rw-r--r-- | absl/random/internal/uniform_helper.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/absl/random/internal/uniform_helper.h b/absl/random/internal/uniform_helper.h index 663107cb3a63..5b2afecb89e6 100644 --- a/absl/random/internal/uniform_helper.h +++ b/absl/random/internal/uniform_helper.h @@ -19,10 +19,13 @@ #include <limits> #include <type_traits> +#include "absl/base/config.h" #include "absl/meta/type_traits.h" +#include "absl/random/internal/traits.h" namespace absl { ABSL_NAMESPACE_BEGIN + template <typename IntType> class uniform_int_distribution; @@ -58,6 +61,26 @@ struct IntervalOpenOpenTag : public random_internal::TagTypeCompare<IntervalOpenOpenTag> {}; namespace random_internal { + +// In the absence of an explicitly provided return-type, the template +// "uniform_inferred_return_t<A, B>" is used to derive a suitable type, based on +// the data-types of the endpoint-arguments {A lo, B hi}. +// +// Given endpoints {A lo, B hi}, one of {A, B} will be chosen as the +// return-type, if one type can be implicitly converted into the other, in a +// lossless way. The template "is_widening_convertible" implements the +// compile-time logic for deciding if such a conversion is possible. +// +// If no such conversion between {A, B} exists, then the overload for +// absl::Uniform() will be discarded, and the call will be ill-formed. +// Return-type for absl::Uniform() when the return-type is inferred. +template <typename A, typename B> +using uniform_inferred_return_t = + absl::enable_if_t<absl::disjunction<is_widening_convertible<A, B>, + is_widening_convertible<B, A>>::value, + typename std::conditional< + is_widening_convertible<A, B>::value, B, A>::type>; + // The functions // uniform_lower_bound(tag, a, b) // and @@ -149,12 +172,19 @@ uniform_upper_bound(Tag, FloatType, FloatType b) { return std::nextafter(b, (std::numeric_limits<FloatType>::max)()); } +// UniformDistribution selects either absl::uniform_int_distribution +// or absl::uniform_real_distribution depending on the NumType parameter. template <typename NumType> using UniformDistribution = typename std::conditional<std::is_integral<NumType>::value, absl::uniform_int_distribution<NumType>, absl::uniform_real_distribution<NumType>>::type; +// UniformDistributionWrapper is used as the underlying distribution type +// by the absl::Uniform template function. It selects the proper Abseil +// uniform distribution and provides constructor overloads that match the +// expected parameter order as well as adjusting distribtuion bounds based +// on the tag. template <typename NumType> struct UniformDistributionWrapper : public UniformDistribution<NumType> { template <typename TagType> |