chromium/third_party/abseil-cpp/absl/strings/internal/pow10_helper.cc

// Copyright 2018 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/strings/internal/pow10_helper.h"

#include <cmath>

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace strings_internal {

namespace {

// The exact value of 1e23 falls precisely halfway between two representable
// doubles. Furthermore, the rounding rules we prefer (break ties by rounding
// to the nearest even) dictate in this case that the number should be rounded
// down, but this is not completely specified for floating-point literals in
// C++. (It just says to use the default rounding mode of the standard
// library.) We ensure the result we want by using a number that has an
// unambiguous correctly rounded answer.
constexpr double k1e23 = …;

constexpr double kPowersOfTen[] = …;

}  // namespace

double Pow10(int exp) { … }

}  // namespace strings_internal
ABSL_NAMESPACE_END
}  // namespace absl