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Diffstat (limited to 'third_party/abseil_cpp/absl/time/internal/cctz/include/cctz/zone_info_source.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/time/internal/cctz/include/cctz/zone_info_source.h | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/include/cctz/zone_info_source.h b/third_party/abseil_cpp/absl/time/internal/cctz/include/cctz/zone_info_source.h new file mode 100644 index 0000000000..012eb4ec30 --- /dev/null +++ b/third_party/abseil_cpp/absl/time/internal/cctz/include/cctz/zone_info_source.h @@ -0,0 +1,102 @@ +// Copyright 2016 Google Inc. All Rights Reserved. +// +// 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. + +#ifndef ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_ +#define ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_ + +#include <cstddef> +#include <functional> +#include <memory> +#include <string> + +#include "absl/base/config.h" + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace time_internal { +namespace cctz { + +// A stdio-like interface for providing zoneinfo data for a particular zone. +class ZoneInfoSource { + public: + virtual ~ZoneInfoSource(); + + virtual std::size_t Read(void* ptr, std::size_t size) = 0; // like fread() + virtual int Skip(std::size_t offset) = 0; // like fseek() + + // Until the zoneinfo data supports versioning information, we provide + // a way for a ZoneInfoSource to indicate it out-of-band. The default + // implementation returns an empty string. + virtual std::string Version() const; +}; + +} // namespace cctz +} // namespace time_internal +ABSL_NAMESPACE_END +} // namespace absl + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace time_internal { +namespace cctz_extension { + +// A function-pointer type for a factory that returns a ZoneInfoSource +// given the name of a time zone and a fallback factory. Returns null +// when the data for the named zone cannot be found. +using ZoneInfoSourceFactory = + std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource> (*)( + const std::string&, + const std::function<std::unique_ptr< + absl::time_internal::cctz::ZoneInfoSource>(const std::string&)>&); + +// The user can control the mapping of zone names to zoneinfo data by +// providing a definition for cctz_extension::zone_info_source_factory. +// For example, given functions my_factory() and my_other_factory() that +// can return a ZoneInfoSource for a named zone, we could inject them into +// cctz::load_time_zone() with: +// +// namespace cctz_extension { +// namespace { +// std::unique_ptr<cctz::ZoneInfoSource> CustomFactory( +// const std::string& name, +// const std::function<std::unique_ptr<cctz::ZoneInfoSource>( +// const std::string& name)>& fallback_factory) { +// if (auto zip = my_factory(name)) return zip; +// if (auto zip = fallback_factory(name)) return zip; +// if (auto zip = my_other_factory(name)) return zip; +// return nullptr; +// } +// } // namespace +// ZoneInfoSourceFactory zone_info_source_factory = CustomFactory; +// } // namespace cctz_extension +// +// This might be used, say, to use zoneinfo data embedded in the program, +// or read from a (possibly compressed) file archive, or both. +// +// cctz_extension::zone_info_source_factory() will be called: +// (1) from the same thread as the cctz::load_time_zone() call, +// (2) only once for any zone name, and +// (3) serially (i.e., no concurrent execution). +// +// The fallback factory obtains zoneinfo data by reading files in ${TZDIR}, +// and it is used automatically when no zone_info_source_factory definition +// is linked into the program. +extern ZoneInfoSourceFactory zone_info_source_factory; + +} // namespace cctz_extension +} // namespace time_internal +ABSL_NAMESPACE_END +} // namespace absl + +#endif // ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_ |