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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 17:44:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 17:44:55 +0000 |
commit | 5068d34c08f951a7ea6257d305a1627b09a95817 (patch) | |
tree | 08213e2be853396a3b07ce15dbe222644dcd9a89 /src/third-party/scnlib/include/scn/util/expected.h | |
parent | Initial commit. (diff) | |
download | lnav-5068d34c08f951a7ea6257d305a1627b09a95817.tar.xz lnav-5068d34c08f951a7ea6257d305a1627b09a95817.zip |
Adding upstream version 0.11.1.upstream/0.11.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/third-party/scnlib/include/scn/util/expected.h')
-rw-r--r-- | src/third-party/scnlib/include/scn/util/expected.h | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/src/third-party/scnlib/include/scn/util/expected.h b/src/third-party/scnlib/include/scn/util/expected.h new file mode 100644 index 0000000..f7c9a82 --- /dev/null +++ b/src/third-party/scnlib/include/scn/util/expected.h @@ -0,0 +1,158 @@ +// Copyright 2017 Elias Kosunen +// +// 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. +// +// This file is a part of scnlib: +// https://github.com/eliaskosunen/scnlib + +#ifndef SCN_UTIL_EXPECTED_H +#define SCN_UTIL_EXPECTED_H + +#include "memory.h" + +namespace scn { + SCN_BEGIN_NAMESPACE + + /** + * expected-like type. + * For situations where there can be a value in case of success or an error + * code. + */ + template <typename T, typename Error, typename Enable> + class expected; + + /** + * expected-like type for default-constructible success values. + * Not optimized for space-efficiency (both members are stored + * simultaneously). + * `error` is used as the error value and discriminant flag. + */ + template <typename T, typename Error> + class expected<T, + Error, + typename std::enable_if< + std::is_default_constructible<T>::value>::type> { + public: + using success_type = T; + using error_type = Error; + + constexpr expected() = default; + constexpr expected(success_type s) : m_s(s) {} + constexpr expected(error_type e) : m_e(e) {} + + SCN_NODISCARD constexpr bool has_value() const noexcept + { + return m_e == Error{}; + } + constexpr explicit operator bool() const noexcept + { + return has_value(); + } + constexpr bool operator!() const noexcept + { + return !operator bool(); + } + + SCN_CONSTEXPR14 success_type& value() & noexcept + { + return m_s; + } + constexpr success_type value() const& noexcept + { + return m_s; + } + SCN_CONSTEXPR14 success_type value() && noexcept + { + return SCN_MOVE(m_s); + } + + SCN_CONSTEXPR14 error_type& error() noexcept + { + return m_e; + } + constexpr error_type error() const noexcept + { + return m_e; + } + + private: + success_type m_s{}; + error_type m_e{error_type::success_tag()}; + }; + + /** + * expected-like type for non-default-constructible success values. + * Not optimized for space-efficiency. + * `error` is used as the error value and discriminant flag. + */ + template <typename T, typename Error> + class expected<T, + Error, + typename std::enable_if< + !std::is_default_constructible<T>::value>::type> { + public: + using success_type = T; + using success_storage = detail::erased_storage<T>; + using error_type = Error; + + expected(success_type s) : m_s(SCN_MOVE(s)) {} + constexpr expected(error_type e) : m_e(e) {} + + SCN_NODISCARD constexpr bool has_value() const noexcept + { + return m_e == Error{}; + } + constexpr explicit operator bool() const noexcept + { + return has_value(); + } + constexpr bool operator!() const noexcept + { + return !operator bool(); + } + + SCN_CONSTEXPR14 success_type& value() noexcept + { + return *m_s; + } + constexpr const success_type& value() const noexcept + { + return *m_s; + } + + SCN_CONSTEXPR14 error_type& error() noexcept + { + return m_e; + } + constexpr error_type error() const noexcept + { + return m_e; + } + + private: + success_storage m_s{}; + error_type m_e{error_type::success_tag()}; + }; + + template <typename T, + typename U = typename std::remove_cv< + typename std::remove_reference<T>::type>::type> + expected<U> make_expected(T&& val) + { + return expected<U>(std::forward<T>(val)); + } + + SCN_END_NAMESPACE +} // namespace scn + +#endif |