88 lines
3.0 KiB
C++
88 lines
3.0 KiB
C++
// Copyright 2023 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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// Common code shared between absl/hash/hash_test.cc and
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// absl/hash/hash_instantiated_test.cc.
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#ifndef ABSL_HASH_INTERNAL_HASH_TEST_H_
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#define ABSL_HASH_INTERNAL_HASH_TEST_H_
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#include <type_traits>
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#include <utility>
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#include "absl/base/config.h"
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#include "absl/hash/hash.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace hash_test_internal {
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// Utility wrapper of T for the purposes of testing the `AbslHash` type erasure
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// mechanism. `TypeErasedValue<T>` can be constructed with a `T`, and can
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// be compared and hashed. However, all hashing goes through the hashing
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// type-erasure framework.
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template <typename T>
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class TypeErasedValue {
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public:
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TypeErasedValue() = default;
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TypeErasedValue(const TypeErasedValue&) = default;
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TypeErasedValue(TypeErasedValue&&) = default;
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explicit TypeErasedValue(const T& n) : n_(n) {}
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template <typename H>
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friend H AbslHashValue(H hash_state, const TypeErasedValue& v) {
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v.HashValue(absl::HashState::Create(&hash_state));
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return hash_state;
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}
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void HashValue(absl::HashState state) const {
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absl::HashState::combine(std::move(state), n_);
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}
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bool operator==(const TypeErasedValue& rhs) const { return n_ == rhs.n_; }
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bool operator!=(const TypeErasedValue& rhs) const { return !(*this == rhs); }
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private:
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T n_;
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};
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// A TypeErasedValue refinement, for containers. It exposes the wrapped
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// `value_type` and is constructible from an initializer list.
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template <typename T>
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class TypeErasedContainer : public TypeErasedValue<T> {
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public:
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using value_type = typename T::value_type;
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TypeErasedContainer() = default;
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TypeErasedContainer(const TypeErasedContainer&) = default;
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TypeErasedContainer(TypeErasedContainer&&) = default;
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explicit TypeErasedContainer(const T& n) : TypeErasedValue<T>(n) {}
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TypeErasedContainer(std::initializer_list<value_type> init_list)
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: TypeErasedContainer(T(init_list.begin(), init_list.end())) {}
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// one-argument constructor of value type T, to appease older toolchains that
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// get confused by one-element initializer lists in some contexts
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explicit TypeErasedContainer(const value_type& v)
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: TypeErasedContainer(T(&v, &v + 1)) {}
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};
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// Helper trait to verify if T is hashable. We use absl::Hash's poison status to
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// detect it.
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template <typename T>
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using is_hashable = std::is_default_constructible<absl::Hash<T>>;
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} // namespace hash_test_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_HASH_INTERNAL_HASH_TEST_H_
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