36 lines
1.2 KiB
C++
36 lines
1.2 KiB
C++
// Copyright 2018 The Amber 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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// http://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 SRC_CAST_HASH_H_
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#define SRC_CAST_HASH_H_
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#include <cstddef>
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namespace amber {
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/// A hash implementation for types that can trivially be up-cast to a size_t.
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/// For example, use this as a hasher for an enum whose underlying type is
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/// an integer no wider than size_t.
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///
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/// The need for this was a defect in the C++11 library, and has been fixed
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/// in C++14. http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2148
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template <typename T>
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struct CastHash {
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size_t operator()(const T& value) const { return static_cast<size_t>(value); }
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};
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} // namespace amber
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#endif // SRC_CAST_HASH_H_
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