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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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.
#pragma once
#include <memory>
#include <type_traits>
#include <utility>
#include "arrow/util/macros.h"
namespace arrow {
namespace util {
/// CRTP helper for declaring equality comparison. Defines operator== and operator!=
template <typename T>
class EqualityComparable {
public:
~EqualityComparable() {
static_assert(
std::is_same<decltype(std::declval<const T>().Equals(std::declval<const T>())),
bool>::value,
"EqualityComparable depends on the method T::Equals(const T&) const");
}
template <typename... Extra>
bool Equals(const std::shared_ptr<T>& other, Extra&&... extra) const {
if (other == NULLPTR) {
return false;
}
return cast().Equals(*other, std::forward<Extra>(extra)...);
}
struct PtrsEqual {
bool operator()(const std::shared_ptr<T>& l, const std::shared_ptr<T>& r) const {
return l->Equals(*r);
}
};
friend bool operator==(T const& a, T const& b) { return a.Equals(b); }
friend bool operator!=(T const& a, T const& b) { return !(a == b); }
private:
const T& cast() const { return static_cast<const T&>(*this); }
};
} // namespace util
} // namespace arrow
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