51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
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//
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// Copyright 2020 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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#ifndef ABSL_BASE_INTERNAL_FAST_TYPE_ID_H_
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#define ABSL_BASE_INTERNAL_FAST_TYPE_ID_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 base_internal {
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template <typename Type>
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struct FastTypeTag {
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constexpr static char dummy_var = 0;
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};
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#ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL
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template <typename Type>
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constexpr char FastTypeTag<Type>::dummy_var;
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#endif
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// FastTypeId<Type>() evaluates at compile/link-time to a unique pointer for the
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// passed-in type. These are meant to be good match for keys into maps or
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// straight up comparisons.
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using FastTypeIdType = const void*;
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template <typename Type>
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constexpr inline FastTypeIdType FastTypeId() {
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return &FastTypeTag<Type>::dummy_var;
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}
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} // namespace base_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_BASE_INTERNAL_FAST_TYPE_ID_H_
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