| // Copyright 2023 The Pigweed 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. |
| #pragma once |
| |
| #include <cstddef> |
| |
| #include "pw_polyfill/language_feature_macros.h" |
| |
| namespace pw { |
| namespace internal { |
| |
| // This function is not intended for use by end-users. |
| // |
| // This function does nothing, but attempting to call it in a constexpr |
| // context will result in a compilation error. |
| // |
| // If it appears in an error like the following: |
| // |
| // ``` |
| // error: call to consteval function 'pw::operator""_b' is not a constant |
| // expression |
| // ... |
| // note: non-constexpr function 'ByteLiteralIsTooLarge' cannot be used in a |
| // constant expression |
| // ``` |
| // |
| // Then a byte-literal with a value exceeding 255 has been written. |
| // For example, ``255_b`` is okay, but ``256_b`` will result in an error. |
| inline void ByteLiteralIsTooLarge() {} |
| |
| } // namespace internal |
| |
| /// Returns a ``std::byte`` when used as a ``_b`` suffix. |
| /// |
| /// This is useful for writing byte literals, particularly in tests. |
| /// To use, add ``using ::pw::operator""_b;`` and then use like ``5_b`` |
| /// in order to create a ``std::byte`` with the contents ``5``. |
| /// |
| /// This should not be used in header files, as it requires a ``using`` |
| /// declaration that will be publicly exported at whatever level it is |
| /// used. |
| PW_CONSTEVAL std::byte operator"" _b(unsigned long long value) { |
| if (value > 255) { |
| internal::ByteLiteralIsTooLarge(); |
| } |
| return std::byte(value); |
| } |
| |
| } // namespace pw |
