65 lines
2 KiB
C++
65 lines
2 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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//
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// -----------------------------------------------------------------------------
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// File: declare.h
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// -----------------------------------------------------------------------------
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//
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// This file defines the ABSL_DECLARE_FLAG macro, allowing you to declare an
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// `absl::Flag` for use within a translation unit. You should place this
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// declaration within the header file associated with the .cc file that defines
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// and owns the `Flag`.
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#ifndef ABSL_FLAGS_DECLARE_H_
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#define ABSL_FLAGS_DECLARE_H_
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#include "absl/base/config.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace flags_internal {
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// absl::Flag<T> represents a flag of type 'T' created by ABSL_FLAG.
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template <typename T>
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class Flag;
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} // namespace flags_internal
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// Flag
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//
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// Forward declaration of the `absl::Flag` type for use in defining the macro.
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#if defined(_MSC_VER) && !defined(__clang__)
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template <typename T>
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class Flag;
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#else
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template <typename T>
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using Flag = flags_internal::Flag<T>;
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#endif
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ABSL_NAMESPACE_END
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} // namespace absl
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// ABSL_DECLARE_FLAG()
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//
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// This macro is a convenience for declaring use of an `absl::Flag` within a
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// translation unit. This macro should be used within a header file to
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// declare usage of the flag within any .cc file including that header file.
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//
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// The ABSL_DECLARE_FLAG(type, name) macro expands to:
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//
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// extern absl::Flag<type> FLAGS_name;
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#define ABSL_DECLARE_FLAG(type, name) extern ::absl::Flag<type> FLAGS_##name
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#endif // ABSL_FLAGS_DECLARE_H_
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