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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/traits.h"
#include <cstdint>
#include <type_traits>
#include "gtest/gtest.h"
namespace {
using absl::random_internal::is_widening_convertible;
// CheckWideningConvertsToSelf<T1, T2, ...>()
//
// For each type T, checks:
// - T IS widening-convertible to itself.
//
template <typename T>
void CheckWideningConvertsToSelf() {
static_assert(is_widening_convertible<T, T>::value,
"Type is not convertible to self!");
}
template <typename T, typename Next, typename... Args>
void CheckWideningConvertsToSelf() {
CheckWideningConvertsToSelf<T>();
CheckWideningConvertsToSelf<Next, Args...>();
}
// CheckNotWideningConvertibleWithSigned<T1, T2, ...>()
//
// For each unsigned-type T, checks that:
// - T is NOT widening-convertible to Signed(T)
// - Signed(T) is NOT widening-convertible to T
//
template <typename T>
void CheckNotWideningConvertibleWithSigned() {
using signed_t = typename std::make_signed<T>::type;
static_assert(!is_widening_convertible<T, signed_t>::value,
"Unsigned type is convertible to same-sized signed-type!");
static_assert(!is_widening_convertible<signed_t, T>::value,
"Signed type is convertible to same-sized unsigned-type!");
}
template <typename T, typename Next, typename... Args>
void CheckNotWideningConvertibleWithSigned() {
CheckNotWideningConvertibleWithSigned<T>();
CheckWideningConvertsToSelf<Next, Args...>();
}
// CheckWideningConvertsToLargerType<T1, T2, ...>()
//
// For each successive unsigned-types {Ti, Ti+1}, checks that:
// - Ti IS widening-convertible to Ti+1
// - Ti IS widening-convertible to Signed(Ti+1)
// - Signed(Ti) is NOT widening-convertible to Ti
// - Signed(Ti) IS widening-convertible to Ti+1
template <typename T, typename Higher>
void CheckWideningConvertsToLargerTypes() {
using signed_t = typename std::make_signed<T>::type;
using higher_t = Higher;
using signed_higher_t = typename std::make_signed<Higher>::type;
static_assert(is_widening_convertible<T, higher_t>::value,
"Type not embeddable into larger type!");
static_assert(is_widening_convertible<T, signed_higher_t>::value,
"Type not embeddable into larger signed type!");
static_assert(!is_widening_convertible<signed_t, higher_t>::value,
"Signed type is embeddable into larger unsigned type!");
static_assert(is_widening_convertible<signed_t, signed_higher_t>::value,
"Signed type not embeddable into larger signed type!");
}
template <typename T, typename Higher, typename Next, typename... Args>
void CheckWideningConvertsToLargerTypes() {
CheckWideningConvertsToLargerTypes<T, Higher>();
CheckWideningConvertsToLargerTypes<Higher, Next, Args...>();
}
// CheckWideningConvertsTo<T, U, [expect]>
//
// Checks that T DOES widening-convert to U.
// If "expect" is false, then asserts that T does NOT widening-convert to U.
template <typename T, typename U, bool expect = true>
void CheckWideningConvertsTo() {
static_assert(is_widening_convertible<T, U>::value == expect,
"Unexpected result for is_widening_convertible<T, U>!");
}
TEST(TraitsTest, IsWideningConvertibleTest) {
constexpr bool kInvalid = false;
CheckWideningConvertsToSelf<uint8_t, uint16_t, uint32_t, uint64_t, int8_t,
int16_t, int32_t, int64_t, float, double>();
CheckNotWideningConvertibleWithSigned<uint8_t, uint16_t, uint32_t,
uint64_t>();
CheckWideningConvertsToLargerTypes<uint8_t, uint16_t, uint32_t, uint64_t>();
CheckWideningConvertsTo<float, double>();
CheckWideningConvertsTo<uint16_t, float>();
CheckWideningConvertsTo<uint32_t, double>();
CheckWideningConvertsTo<uint64_t, double, kInvalid>();
CheckWideningConvertsTo<double, float, kInvalid>();
CheckWideningConvertsTo<bool, int>();
CheckWideningConvertsTo<bool, float>();
}
} // namespace
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