8f2828c4b4
ccdbb5941 Export of internal Abseil changes 01f5f81f9 Export of internal Abseil changes 2c92bdc7c Export of internal Abseil changes e7ebf9803 Export of internal Abseil changes 2eba343b5 Export of internal Abseil changes a8b03d90e Export of internal Abseil changes 1d31b5c36 Export of internal Abseil changes da3a87690 Export of internal Abseil changes 8faf20461 Exclude empty directories (#697) 2069dc796 Export of internal Abseil changes 4832bf6bf Added a BUILD file in root to expose license. (#695) af8f994af Export of internal Abseil changes 33caf1097 Export of internal Abseil changes cf1a02e2d Export of internal Abseil changes git-subtree-dir: third_party/abseil_cpp git-subtree-split: ccdbb5941f992fabda7eae3ce72f55efc17c826a
89 lines
3.5 KiB
C++
89 lines
3.5 KiB
C++
//
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// Copyright 2019 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_FLAGS_INTERNAL_REGISTRY_H_
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#define ABSL_FLAGS_INTERNAL_REGISTRY_H_
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#include <functional>
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#include "absl/base/config.h"
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#include "absl/flags/commandlineflag.h"
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#include "absl/flags/internal/commandlineflag.h"
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#include "absl/strings/string_view.h"
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// --------------------------------------------------------------------
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// Global flags registry API.
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace flags_internal {
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// Executes specified visitor for each non-retired flag in the registry.
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// Requires the caller hold the registry lock.
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void ForEachFlagUnlocked(std::function<void(CommandLineFlag&)> visitor);
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// Executes specified visitor for each non-retired flag in the registry. While
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// callback are executed, the registry is locked and can't be changed.
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void ForEachFlag(std::function<void(CommandLineFlag&)> visitor);
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//-----------------------------------------------------------------------------
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bool RegisterCommandLineFlag(CommandLineFlag&);
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//-----------------------------------------------------------------------------
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// Retired registrations:
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//
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// Retired flag registrations are treated specially. A 'retired' flag is
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// provided only for compatibility with automated invocations that still
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// name it. A 'retired' flag:
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// - is not bound to a C++ FLAGS_ reference.
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// - has a type and a value, but that value is intentionally inaccessible.
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// - does not appear in --help messages.
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// - is fully supported by _all_ flag parsing routines.
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// - consumes args normally, and complains about type mismatches in its
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// argument.
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// - emits a complaint but does not die (e.g. LOG(ERROR)) if it is
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// accessed by name through the flags API for parsing or otherwise.
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//
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// The registrations for a flag happen in an unspecified order as the
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// initializers for the namespace-scope objects of a program are run.
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// Any number of weak registrations for a flag can weakly define the flag.
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// One non-weak registration will upgrade the flag from weak to non-weak.
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// Further weak registrations of a non-weak flag are ignored.
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//
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// This mechanism is designed to support moving dead flags into a
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// 'graveyard' library. An example migration:
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//
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// 0: Remove references to this FLAGS_flagname in the C++ codebase.
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// 1: Register as 'retired' in old_lib.
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// 2: Make old_lib depend on graveyard.
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// 3: Add a redundant 'retired' registration to graveyard.
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// 4: Remove the old_lib 'retired' registration.
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// 5: Eventually delete the graveyard registration entirely.
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//
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// Retire flag with name "name" and type indicated by ops.
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bool Retire(const char* name, FlagFastTypeId type_id);
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// Registered a retired flag with name 'flag_name' and type 'T'.
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template <typename T>
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inline bool RetiredFlag(const char* flag_name) {
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return flags_internal::Retire(flag_name, base_internal::FastTypeId<T>());
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}
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} // namespace flags_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_FLAGS_INTERNAL_REGISTRY_H_
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