diff options
author | Abseil Team <absl-team@google.com> | 2020-05-26 10:57:33 -0700 |
---|---|---|
committer | Derek Mauro <dmauro@google.com> | 2020-05-26 14:45:38 -0400 |
commit | 33caf1097ecce4fe892567462fa8821d477854b4 (patch) | |
tree | 27eecef4f8c5638857b134ea117c3bd20a980b96 /absl/random/internal/uniform_helper.h | |
parent | cf1a02e2dc5a1bc9d095f4c996306de448ca200f (diff) |
Export of internal Abseil changes
--
7d0468a6610ed85586d5c87fd65de8dac5118923 by Derek Mauro <dmauro@google.com>:
Import of CCTZ from GitHub.
PiperOrigin-RevId: 313226473
--
1131ef6d116f5ce7d46537a82f300ea06dcaaa53 by Gennadiy Rozental <rogeeff@google.com>:
Migrate internal interface to use mutable references.
PiperOrigin-RevId: 312931131
--
96225212a9f5fbd0b38c71fe65539164992c7c3b by Laramie Leavitt <lar@google.com>:
Remove random/internal/distributions.h
This file was something of an historical artifact. All of the related
code has either been removed or migraged, and so the only remaining type
belongs with uniform_helper.h, as it is used to infer the return type
of the absl::Uniform method in a few cases.
PiperOrigin-RevId: 312878173
--
6dcbd5be58ad425e08740ff64088373ee7fe4a72 by Mark Barolak <mbar@google.com>:
Release the StrFormat test case for Cords to open source.
PiperOrigin-RevId: 312707974
--
34484d18dfb63a0a7ad6e2aaeb570e33592968be by Abseil Team <absl-team@google.com>:
Let Cord::Cord(string&&), Cord::operator=(string&&),
Cord::Append(string&&), and Cord::Prepend(string&&) steal string data
and embed it into the Cord as a single external chunk, instead of
copying it into flat chunks (at most 4083-byte each).
Stealing string data is faster, but it creates a long chunk, which leads
to a higher more memory usage if its subcords are created and outlive
the whole Cord.
These functions revert to copying the data if any of the following
conditions holds:
- string size is at most kMaxBytesToCopy (511), to avoid the overhead
of an external chunk for short strings;
- less than half of string capacity is used, to avoid pinning to much
unused memory.
PiperOrigin-RevId: 312683785
GitOrigin-RevId: 7d0468a6610ed85586d5c87fd65de8dac5118923
Change-Id: If79b5a1dfe6d53a8ddddbc7da84338f11fc4cfa3
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 663107cb..5b2afecb 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> |