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// 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.
#include "absl/random/internal/uniform_helper.h"
#include <cmath>
#include <cstdint>
#include <random>
#include "gtest/gtest.h"
namespace {
using absl::IntervalClosedClosedTag;
using absl::IntervalClosedOpenTag;
using absl::IntervalOpenClosedTag;
using absl::IntervalOpenOpenTag;
using absl::random_internal::uniform_inferred_return_t;
using absl::random_internal::uniform_lower_bound;
using absl::random_internal::uniform_upper_bound;
class UniformHelperTest : public testing::Test {};
TEST_F(UniformHelperTest, UniformBoundFunctionsGeneral) {
constexpr IntervalClosedClosedTag IntervalClosedClosed;
constexpr IntervalClosedOpenTag IntervalClosedOpen;
constexpr IntervalOpenClosedTag IntervalOpenClosed;
constexpr IntervalOpenOpenTag IntervalOpenOpen;
// absl::uniform_int_distribution natively assumes IntervalClosedClosed
// absl::uniform_real_distribution natively assumes IntervalClosedOpen
EXPECT_EQ(uniform_lower_bound(IntervalOpenClosed, 0, 100), 1);
EXPECT_EQ(uniform_lower_bound(IntervalOpenOpen, 0, 100), 1);
EXPECT_GT(uniform_lower_bound<float>(IntervalOpenClosed, 0, 1.0), 0);
EXPECT_GT(uniform_lower_bound<float>(IntervalOpenOpen, 0, 1.0), 0);
EXPECT_GT(uniform_lower_bound<double>(IntervalOpenClosed, 0, 1.0), 0);
EXPECT_GT(uniform_lower_bound<double>(IntervalOpenOpen, 0, 1.0), 0);
EXPECT_EQ(uniform_lower_bound(IntervalClosedClosed, 0, 100), 0);
EXPECT_EQ(uniform_lower_bound(IntervalClosedOpen, 0, 100), 0);
EXPECT_EQ(uniform_lower_bound<float>(IntervalClosedClosed, 0, 1.0), 0);
EXPECT_EQ(uniform_lower_bound<float>(IntervalClosedOpen, 0, 1.0), 0);
EXPECT_EQ(uniform_lower_bound<double>(IntervalClosedClosed, 0, 1.0), 0);
EXPECT_EQ(uniform_lower_bound<double>(IntervalClosedOpen, 0, 1.0), 0);
EXPECT_EQ(uniform_upper_bound(IntervalOpenOpen, 0, 100), 99);
EXPECT_EQ(uniform_upper_bound(IntervalClosedOpen, 0, 100), 99);
EXPECT_EQ(uniform_upper_bound<float>(IntervalOpenOpen, 0, 1.0), 1.0);
EXPECT_EQ(uniform_upper_bound<float>(IntervalClosedOpen, 0, 1.0), 1.0);
EXPECT_EQ(uniform_upper_bound<double>(IntervalOpenOpen, 0, 1.0), 1.0);
EXPECT_EQ(uniform_upper_bound<double>(IntervalClosedOpen, 0, 1.0), 1.0);
EXPECT_EQ(uniform_upper_bound(IntervalOpenClosed, 0, 100), 100);
EXPECT_EQ(uniform_upper_bound(IntervalClosedClosed, 0, 100), 100);
EXPECT_GT(uniform_upper_bound<float>(IntervalOpenClosed, 0, 1.0), 1.0);
EXPECT_GT(uniform_upper_bound<float>(IntervalClosedClosed, 0, 1.0), 1.0);
EXPECT_GT(uniform_upper_bound<double>(IntervalOpenClosed, 0, 1.0), 1.0);
EXPECT_GT(uniform_upper_bound<double>(IntervalClosedClosed, 0, 1.0), 1.0);
// Negative value tests
EXPECT_EQ(uniform_lower_bound(IntervalOpenClosed, -100, -1), -99);
EXPECT_EQ(uniform_lower_bound(IntervalOpenOpen, -100, -1), -99);
EXPECT_GT(uniform_lower_bound<float>(IntervalOpenClosed, -2.0, -1.0), -2.0);
EXPECT_GT(uniform_lower_bound<float>(IntervalOpenOpen, -2.0, -1.0), -2.0);
EXPECT_GT(uniform_lower_bound<double>(IntervalOpenClosed, -2.0, -1.0), -2.0);
EXPECT_GT(uniform_lower_bound<double>(IntervalOpenOpen, -2.0, -1.0), -2.0);
EXPECT_EQ(uniform_lower_bound(IntervalClosedClosed, -100, -1), -100);
EXPECT_EQ(uniform_lower_bound(IntervalClosedOpen, -100, -1), -100);
EXPECT_EQ(uniform_lower_bound<float>(IntervalClosedClosed, -2.0, -1.0), -2.0);
EXPECT_EQ(uniform_lower_bound<float>(IntervalClosedOpen, -2.0, -1.0), -2.0);
EXPECT_EQ(uniform_lower_bound<double>(IntervalClosedClosed, -2.0, -1.0),
-2.0);
EXPECT_EQ(uniform_lower_bound<double>(IntervalClosedOpen, -2.0, -1.0), -2.0);
EXPECT_EQ(uniform_upper_bound(IntervalOpenOpen, -100, -1), -2);
EXPECT_EQ(uniform_upper_bound(IntervalClosedOpen, -100, -1), -2);
EXPECT_EQ(uniform_upper_bound<float>(IntervalOpenOpen, -2.0, -1.0), -1.0);
EXPECT_EQ(uniform_upper_bound<float>(IntervalClosedOpen, -2.0, -1.0), -1.0);
EXPECT_EQ(uniform_upper_bound<double>(IntervalOpenOpen, -2.0, -1.0), -1.0);
EXPECT_EQ(uniform_upper_bound<double>(IntervalClosedOpen, -2.0, -1.0), -1.0);
EXPECT_EQ(uniform_upper_bound(IntervalOpenClosed, -100, -1), -1);
EXPECT_EQ(uniform_upper_bound(IntervalClosedClosed, -100, -1), -1);
EXPECT_GT(uniform_upper_bound<float>(IntervalOpenClosed, -2.0, -1.0), -1.0);
EXPECT_GT(uniform_upper_bound<float>(IntervalClosedClosed, -2.0, -1.0), -1.0);
EXPECT_GT(uniform_upper_bound<double>(IntervalOpenClosed, -2.0, -1.0), -1.0);
EXPECT_GT(uniform_upper_bound<double>(IntervalClosedClosed, -2.0, -1.0),
-1.0);
EXPECT_GT(uniform_lower_bound(IntervalOpenClosed, 1.0, 2.0), 1.0);
EXPECT_LT(uniform_lower_bound(IntervalOpenClosed, 1.0, +0.0), 1.0);
EXPECT_LT(uniform_lower_bound(IntervalOpenClosed, 1.0, -0.0), 1.0);
EXPECT_LT(uniform_lower_bound(IntervalOpenClosed, 1.0, -1.0), 1.0);
}
TEST_F(UniformHelperTest, UniformBoundFunctionsIntBounds) {
// Verifies the saturating nature of uniform_lower_bound and
// uniform_upper_bound
constexpr IntervalOpenOpenTag IntervalOpenOpen;
// uint max.
constexpr auto m = (std::numeric_limits<uint64_t>::max)();
EXPECT_EQ(1, uniform_lower_bound(IntervalOpenOpen, 0u, 0u));
EXPECT_EQ(m, uniform_lower_bound(IntervalOpenOpen, m, m));
EXPECT_EQ(m, uniform_lower_bound(IntervalOpenOpen, m - 1, m - 1));
EXPECT_EQ(0, uniform_upper_bound(IntervalOpenOpen, 0u, 0u));
EXPECT_EQ(m - 1, uniform_upper_bound(IntervalOpenOpen, m, m));
// int min/max
constexpr auto l = (std::numeric_limits<int64_t>::min)();
constexpr auto r = (std::numeric_limits<int64_t>::max)();
EXPECT_EQ(1, uniform_lower_bound(IntervalOpenOpen, 0, 0));
EXPECT_EQ(l + 1, uniform_lower_bound(IntervalOpenOpen, l, l));
EXPECT_EQ(r, uniform_lower_bound(IntervalOpenOpen, r - 1, r - 1));
EXPECT_EQ(r, uniform_lower_bound(IntervalOpenOpen, r, r));
EXPECT_EQ(-1, uniform_upper_bound(IntervalOpenOpen, 0, 0));
EXPECT_EQ(l, uniform_upper_bound(IntervalOpenOpen, l, l));
EXPECT_EQ(r - 1, uniform_upper_bound(IntervalOpenOpen, r, r));
}
TEST_F(UniformHelperTest, UniformBoundFunctionsRealBounds) {
// absl::uniform_real_distribution natively assumes IntervalClosedOpen;
// use the inverse here so each bound has to change.
constexpr IntervalOpenClosedTag IntervalOpenClosed;
// Edge cases: the next value toward itself is itself.
EXPECT_EQ(1.0, uniform_lower_bound(IntervalOpenClosed, 1.0, 1.0));
EXPECT_EQ(1.0f, uniform_lower_bound(IntervalOpenClosed, 1.0f, 1.0f));
// rightmost and leftmost finite values.
constexpr auto r = (std::numeric_limits<double>::max)();
const auto re = std::nexttoward(r, 0.0);
constexpr auto l = -r;
const auto le = std::nexttoward(l, 0.0);
EXPECT_EQ(l, uniform_lower_bound(IntervalOpenClosed, l, l)); // (l,l)
EXPECT_EQ(r, uniform_lower_bound(IntervalOpenClosed, r, r)); // (r,r)
EXPECT_EQ(le, uniform_lower_bound(IntervalOpenClosed, l, r)); // (l,r)
EXPECT_EQ(le, uniform_lower_bound(IntervalOpenClosed, l, 0.0)); // (l, 0)
EXPECT_EQ(le, uniform_lower_bound(IntervalOpenClosed, l, le)); // (l, le)
EXPECT_EQ(r, uniform_lower_bound(IntervalOpenClosed, re, r)); // (re, r)
EXPECT_EQ(le, uniform_upper_bound(IntervalOpenClosed, l, l)); // (l,l)
EXPECT_EQ(r, uniform_upper_bound(IntervalOpenClosed, r, r)); // (r,r)
EXPECT_EQ(r, uniform_upper_bound(IntervalOpenClosed, l, r)); // (l,r)
EXPECT_EQ(r, uniform_upper_bound(IntervalOpenClosed, l, re)); // (l,re)
EXPECT_EQ(r, uniform_upper_bound(IntervalOpenClosed, 0.0, r)); // (0, r)
EXPECT_EQ(r, uniform_upper_bound(IntervalOpenClosed, re, r)); // (re, r)
EXPECT_EQ(r, uniform_upper_bound(IntervalOpenClosed, le, re)); // (le, re)
const double e = std::nextafter(1.0, 2.0); // 1 + epsilon
const double f = std::nextafter(1.0, 0.0); // 1 - epsilon
// (1.0, 1.0 + epsilon)
EXPECT_EQ(e, uniform_lower_bound(IntervalOpenClosed, 1.0, e));
EXPECT_EQ(std::nextafter(e, 2.0),
uniform_upper_bound(IntervalOpenClosed, 1.0, e));
// (1.0-epsilon, 1.0)
EXPECT_EQ(1.0, uniform_lower_bound(IntervalOpenClosed, f, 1.0));
EXPECT_EQ(e, uniform_upper_bound(IntervalOpenClosed, f, 1.0));
// denorm cases.
const double g = std::numeric_limits<double>::denorm_min();
const double h = std::nextafter(g, 1.0);
// (0, denorm_min)
EXPECT_EQ(g, uniform_lower_bound(IntervalOpenClosed, 0.0, g));
EXPECT_EQ(h, uniform_upper_bound(IntervalOpenClosed, 0.0, g));
// (denorm_min, 1.0)
EXPECT_EQ(h, uniform_lower_bound(IntervalOpenClosed, g, 1.0));
EXPECT_EQ(e, uniform_upper_bound(IntervalOpenClosed, g, 1.0));
// Edge cases: invalid bounds.
EXPECT_EQ(f, uniform_lower_bound(IntervalOpenClosed, 1.0, -1.0));
}
struct Invalid {};
template <typename A, typename B>
auto InferredUniformReturnT(int) -> uniform_inferred_return_t<A, B>;
template <typename, typename>
Invalid InferredUniformReturnT(...);
// Given types <A, B, Expect>, CheckArgsInferType() verifies that
//
// uniform_inferred_return_t<A, B> and
// uniform_inferred_return_t<B, A>
//
// returns the type "Expect".
//
// This interface can also be used to assert that a given inferred return types
// are invalid. Writing:
//
// CheckArgsInferType<float, int, Invalid>()
//
// will assert that this overload does not exist.
template <typename A, typename B, typename Expect>
void CheckArgsInferType() {
static_assert(
absl::conjunction<
std::is_same<Expect, decltype(InferredUniformReturnT<A, B>(0))>,
std::is_same<Expect,
decltype(InferredUniformReturnT<B, A>(0))>>::value,
"");
}
TEST_F(UniformHelperTest, UniformTypeInference) {
// Infers common types.
CheckArgsInferType<uint16_t, uint16_t, uint16_t>();
CheckArgsInferType<uint32_t, uint32_t, uint32_t>();
CheckArgsInferType<uint64_t, uint64_t, uint64_t>();
CheckArgsInferType<int16_t, int16_t, int16_t>();
CheckArgsInferType<int32_t, int32_t, int32_t>();
CheckArgsInferType<int64_t, int64_t, int64_t>();
CheckArgsInferType<float, float, float>();
CheckArgsInferType<double, double, double>();
// Properly promotes uint16_t.
CheckArgsInferType<uint16_t, uint32_t, uint32_t>();
CheckArgsInferType<uint16_t, uint64_t, uint64_t>();
CheckArgsInferType<uint16_t, int32_t, int32_t>();
CheckArgsInferType<uint16_t, int64_t, int64_t>();
CheckArgsInferType<uint16_t, float, float>();
CheckArgsInferType<uint16_t, double, double>();
// Properly promotes int16_t.
CheckArgsInferType<int16_t, int32_t, int32_t>();
CheckArgsInferType<int16_t, int64_t, int64_t>();
CheckArgsInferType<int16_t, float, float>();
CheckArgsInferType<int16_t, double, double>();
// Invalid (u)int16_t-pairings do not compile.
// See "CheckArgsInferType" comments above, for how this is achieved.
CheckArgsInferType<uint16_t, int16_t, Invalid>();
CheckArgsInferType<int16_t, uint32_t, Invalid>();
CheckArgsInferType<int16_t, uint64_t, Invalid>();
// Properly promotes uint32_t.
CheckArgsInferType<uint32_t, uint64_t, uint64_t>();
CheckArgsInferType<uint32_t, int64_t, int64_t>();
CheckArgsInferType<uint32_t, double, double>();
// Properly promotes int32_t.
CheckArgsInferType<int32_t, int64_t, int64_t>();
CheckArgsInferType<int32_t, double, double>();
// Invalid (u)int32_t-pairings do not compile.
CheckArgsInferType<uint32_t, int32_t, Invalid>();
CheckArgsInferType<int32_t, uint64_t, Invalid>();
CheckArgsInferType<int32_t, float, Invalid>();
CheckArgsInferType<uint32_t, float, Invalid>();
// Invalid (u)int64_t-pairings do not compile.
CheckArgsInferType<uint64_t, int64_t, Invalid>();
CheckArgsInferType<int64_t, float, Invalid>();
CheckArgsInferType<int64_t, double, Invalid>();
// Properly promotes float.
CheckArgsInferType<float, double, double>();
}
} // namespace
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