From e9324d926a9189e222741fce6e676f0944661a72 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Fri, 21 Jun 2019 13:11:42 -0700 Subject: Export of internal Abseil changes. -- 7a6ff16a85beb730c172d5d25cf1b5e1be885c56 by Laramie Leavitt : Internal change. PiperOrigin-RevId: 254454546 -- ff8f9bafaefc26d451f576ea4a06d150aed63f6f by Andy Soffer : Internal changes PiperOrigin-RevId: 254451562 -- deefc5b651b479ce36f0b4ef203e119c0c8936f2 by CJ Johnson : Account for subtracting unsigned values from the size of InlinedVector PiperOrigin-RevId: 254450625 -- 3c677316a27bcadc17e41957c809ca472d5fef14 by Andy Soffer : Add C++17's std::make_from_tuple to absl/utility/utility.h PiperOrigin-RevId: 254411573 -- 4ee3536a918830eeec402a28fc31a62c7c90b940 by CJ Johnson : Adds benchmark for the rest of the InlinedVector public API PiperOrigin-RevId: 254408378 -- e5a21a00700ee83498ff1efbf649169756463ee4 by CJ Johnson : Updates the definition of InlinedVector::shrink_to_fit() to be exception safe and adds exception safety tests for it. PiperOrigin-RevId: 254401387 -- 2ea82e72b86d82d78b4e4712a63a55981b53c64b by Laramie Leavitt : Use absl::InsecureBitGen in place of std::mt19937 in tests absl/random/...distribution_test.cc PiperOrigin-RevId: 254289444 -- fa099e02c413a7ffda732415e8105cad26a90337 by Andy Soffer : Internal changes PiperOrigin-RevId: 254286334 -- ce34b7f36933b30cfa35b9c9a5697a792b5666e4 by Andy Soffer : Internal changes PiperOrigin-RevId: 254273059 -- 6f9c473da7c2090c2e85a37c5f00622e8a912a89 by Jorg Brown : Change absl::container_internal::CompressedTuple to instantiate its internal Storage class with the name of the type it's holding, rather than the name of the Tuple. This is not an externally-visible change, other than less compiler memory is used and less debug information is generated. PiperOrigin-RevId: 254269285 -- 8bd3c186bf2fc0c55d8a2dd6f28a5327502c9fba by Andy Soffer : Adding short-hand IntervalClosed for IntervalClosedClosed and IntervalOpen for IntervalOpenOpen. PiperOrigin-RevId: 254252419 -- ea957f99b6a04fccd42aa05605605f3b44b1ecfd by Abseil Team : Do not directly use __SIZEOF_INT128__. In order to avoid linker errors when building with clang-cl (__fixunsdfti, __udivti3 and __fixunssfti are undefined), this CL uses ABSL_HAVE_INTRINSIC_INT128 which is not defined for clang-cl. PiperOrigin-RevId: 254250739 -- 89ab385cd26b34d64130bce856253aaba96d2345 by Andy Soffer : Internal changes PiperOrigin-RevId: 254242321 -- cffc793d93eca6d6bdf7de733847b6ab4a255ae9 by CJ Johnson : Adds benchmark for InlinedVector::reserve(size_type) PiperOrigin-RevId: 254199226 -- c90c7a9fa3c8f0c9d5114036979548b055ea2f2a by Gennadiy Rozental : Import of CCTZ from GitHub. PiperOrigin-RevId: 254072387 -- c4c388beae016c9570ab54ffa1d52660e4a85b7b by Laramie Leavitt : Internal cleanup. PiperOrigin-RevId: 254062381 -- d3c992e221cc74e5372d0c8fa410170b6a43c062 by Tom Manshreck : Update distributions.h to Abseil standards PiperOrigin-RevId: 254054946 -- d15ad0035c34ef11b14fadc5a4a2d3ec415f5518 by CJ Johnson : Removes functions with only one caller from the implementation details of InlinedVector by manually inlining the definitions PiperOrigin-RevId: 254005427 -- 2f37e807efc3a8ef1f4b539bdd379917d4151520 by Andy Soffer : Initial release of Abseil Random PiperOrigin-RevId: 253999861 -- 24ed1694b6430791d781ed533a8f8ccf6cac5856 by CJ Johnson : Updates the definition of InlinedVector::assign(...)/InlinedVector::operator=(...) to new, exception-safe implementations with exception safety tests to boot PiperOrigin-RevId: 253993691 -- 5613d95f5a7e34a535cfaeadce801441e990843e by CJ Johnson : Adds benchmarks for InlinedVector::shrink_to_fit() PiperOrigin-RevId: 253989647 -- 2a96ddfdac40bbb8cb6a7f1aeab90917067c6e63 by Abseil Team : Initial release of Abseil Random PiperOrigin-RevId: 253927497 -- bf1aff8fc9ffa921ad74643e9525ecf25b0d8dc1 by Andy Soffer : Initial release of Abseil Random PiperOrigin-RevId: 253920512 -- bfc03f4a3dcda3cf3a4b84bdb84cda24e3394f41 by Laramie Leavitt : Internal change. PiperOrigin-RevId: 253886486 -- 05036cfcc078ca7c5f581a00dfb0daed568cbb69 by Eric Fiselier : Don't include `winsock2.h` because it drags in `windows.h` and friends, and they define awful macros like OPAQUE, ERROR, and more. This has the potential to break abseil users. Instead we only forward declare `timeval` and require Windows users include `winsock2.h` themselves. This is both inconsistent and poor QoI, but so including 'windows.h' is bad too. PiperOrigin-RevId: 253852615 GitOrigin-RevId: 7a6ff16a85beb730c172d5d25cf1b5e1be885c56 Change-Id: Icd6aff87da26f29ec8915da856f051129987cef6 --- absl/random/uniform_real_distribution.h | 193 ++++++++++++++++++++++++++++++++ 1 file changed, 193 insertions(+) create mode 100644 absl/random/uniform_real_distribution.h (limited to 'absl/random/uniform_real_distribution.h') diff --git a/absl/random/uniform_real_distribution.h b/absl/random/uniform_real_distribution.h new file mode 100644 index 000000000000..600f915b67af --- /dev/null +++ b/absl/random/uniform_real_distribution.h @@ -0,0 +1,193 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +// ----------------------------------------------------------------------------- +// File: uniform_real_distribution.h +// ----------------------------------------------------------------------------- +// +// This header defines a class for representing a uniform floating-point +// distribution over a half-open interval [a,b). You use this distribution in +// combination with an Abseil random bit generator to produce random values +// according to the rules of the distribution. +// +// `absl::uniform_real_distribution` is a drop-in replacement for the C++11 +// `std::uniform_real_distribution` [rand.dist.uni.real] but is considerably +// faster than the libstdc++ implementation. +// +// Note: the standard-library version may occasionally return `1.0` when +// default-initialized. See https://bugs.llvm.org//show_bug.cgi?id=18767 +// `absl::uniform_real_distribution` does not exhibit this behavior. + +#ifndef ABSL_RANDOM_UNIFORM_REAL_DISTRIBUTION_H_ +#define ABSL_RANDOM_UNIFORM_REAL_DISTRIBUTION_H_ + +#include +#include +#include +#include +#include +#include + +#include "absl/random/internal/distribution_impl.h" +#include "absl/random/internal/fast_uniform_bits.h" +#include "absl/random/internal/iostream_state_saver.h" + +namespace absl { + +// absl::uniform_real_distribution +// +// This distribution produces random floating-point values uniformly distributed +// over the half-open interval [a, b). +// +// Example: +// +// absl::BitGen gen; +// +// // Use the distribution to produce a value between 0.0 (inclusive) +// // and 1.0 (exclusive). +// int value = absl::uniform_real_distribution(0, 1)(gen); +// +template +class uniform_real_distribution { + public: + using result_type = RealType; + + class param_type { + public: + using distribution_type = uniform_real_distribution; + + explicit param_type(result_type lo = 0, result_type hi = 1) + : lo_(lo), hi_(hi), range_(hi - lo) { + // [rand.dist.uni.real] preconditions 2 & 3 + assert(lo <= hi); + // NOTE: For integral types, we can promote the range to an unsigned type, + // which gives full width of the range. However for real (fp) types, this + // is not possible, so value generation cannot use the full range of the + // real type. + assert(range_ <= (std::numeric_limits::max)()); + } + + result_type a() const { return lo_; } + result_type b() const { return hi_; } + + friend bool operator==(const param_type& a, const param_type& b) { + return a.lo_ == b.lo_ && a.hi_ == b.hi_; + } + + friend bool operator!=(const param_type& a, const param_type& b) { + return !(a == b); + } + + private: + friend class uniform_real_distribution; + result_type lo_, hi_, range_; + + static_assert(std::is_floating_point::value, + "Class-template absl::uniform_real_distribution<> must be " + "parameterized using a floating-point type."); + }; + + uniform_real_distribution() : uniform_real_distribution(0) {} + + explicit uniform_real_distribution(result_type lo, result_type hi = 1) + : param_(lo, hi) {} + + explicit uniform_real_distribution(const param_type& param) : param_(param) {} + + // uniform_real_distribution::reset() + // + // Resets the uniform real distribution. Note that this function has no effect + // because the distribution already produces independent values. + void reset() {} + + template + result_type operator()(URBG& gen) { // NOLINT(runtime/references) + return operator()(gen, param_); + } + + template + result_type operator()(URBG& gen, // NOLINT(runtime/references) + const param_type& p); + + result_type a() const { return param_.a(); } + result_type b() const { return param_.b(); } + + param_type param() const { return param_; } + void param(const param_type& params) { param_ = params; } + + result_type(min)() const { return a(); } + result_type(max)() const { return b(); } + + friend bool operator==(const uniform_real_distribution& a, + const uniform_real_distribution& b) { + return a.param_ == b.param_; + } + friend bool operator!=(const uniform_real_distribution& a, + const uniform_real_distribution& b) { + return a.param_ != b.param_; + } + + private: + param_type param_; + random_internal::FastUniformBits fast_u64_; +}; + +// ----------------------------------------------------------------------------- +// Implementation details follow +// ----------------------------------------------------------------------------- +template +template +typename uniform_real_distribution::result_type +uniform_real_distribution::operator()( + URBG& gen, const param_type& p) { // NOLINT(runtime/references) + using random_internal::PositiveValueT; + while (true) { + const result_type sample = random_internal::RandU64ToReal< + result_type>::template Value(fast_u64_(gen)); + const result_type res = p.a() + (sample * p.range_); + if (res < p.b() || p.range_ <= 0 || !std::isfinite(p.range_)) { + return res; + } + // else sample rejected, try again. + } +} + +template +std::basic_ostream& operator<<( + std::basic_ostream& os, // NOLINT(runtime/references) + const uniform_real_distribution& x) { + auto saver = random_internal::make_ostream_state_saver(os); + os.precision(random_internal::stream_precision_helper::kPrecision); + os << x.a() << os.fill() << x.b(); + return os; +} + +template +std::basic_istream& operator>>( + std::basic_istream& is, // NOLINT(runtime/references) + uniform_real_distribution& x) { // NOLINT(runtime/references) + using param_type = typename uniform_real_distribution::param_type; + using result_type = typename uniform_real_distribution::result_type; + auto saver = random_internal::make_istream_state_saver(is); + auto a = random_internal::read_floating_point(is); + if (is.fail()) return is; + auto b = random_internal::read_floating_point(is); + if (!is.fail()) { + x.param(param_type(a, b)); + } + return is; +} +} // namespace absl + +#endif // ABSL_RANDOM_UNIFORM_REAL_DISTRIBUTION_H_ -- cgit 1.4.1