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