import quincy 17.2.0

[ceph.git] / ceph / src / arrow / cpp / src / arrow / util / compare.h

diff --git a/ceph/src/arrow/cpp/src/arrow/util/compare.h b/ceph/src/arrow/cpp/src/arrow/util/compare.h
new file mode 100644 (file)
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+++ b/ceph/src/arrow/cpp/src/arrow/util/compare.h
@@ -0,0 +1,62 @@
+// 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);
+    }
+  };
+
+  bool operator==(const T& other) const { return cast().Equals(other); }
+  bool operator!=(const T& other) const { return !(cast() == other); }
+
+ private:
+  const T& cast() const { return static_cast<const T&>(*this); }
+};
+
+}  // namespace util
+}  // namespace arrow