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#pragma clang system_header
// 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 <string>
#include <vector>
#include "contrib/libs/apache/arrow_next/cpp/src/arrow/type.h"
#include "contrib/libs/apache/arrow_next/cpp/src/arrow/util/compare.h"
#include "contrib/libs/apache/arrow_next/cpp/src/arrow/util/visibility.h"
namespace arrow20 {
namespace compute {
enum class SortOrder {
/// Arrange values in increasing order
Ascending,
/// Arrange values in decreasing order
Descending,
};
enum class NullPlacement {
/// Place nulls and NaNs before any non-null values.
/// NaNs will come after nulls.
AtStart,
/// Place nulls and NaNs after any non-null values.
/// NaNs will come before nulls.
AtEnd,
};
/// \brief One sort key for PartitionNthIndices (TODO) and SortIndices
class ARROW_EXPORT SortKey : public util::EqualityComparable<SortKey> {
public:
explicit SortKey(FieldRef target, SortOrder order = SortOrder::Ascending)
: target(std::move(target)), order(order) {}
bool Equals(const SortKey& other) const;
std::string ToString() const;
/// A FieldRef targeting the sort column.
FieldRef target;
/// How to order by this sort key.
SortOrder order;
};
class ARROW_EXPORT Ordering : public util::EqualityComparable<Ordering> {
public:
Ordering(std::vector<SortKey> sort_keys,
NullPlacement null_placement = NullPlacement::AtStart)
: sort_keys_(std::move(sort_keys)), null_placement_(null_placement) {}
/// true if data ordered by other is also ordered by this
///
/// For example, if data is ordered by [a, b, c] then it is also ordered
/// by [a, b] but not by [b, c] or [a, b, c, d].
///
/// [a, b].IsSuborderOf([a, b, c]) - true
/// [a, b, c].IsSuborderOf([a, b, c]) - true
/// [b, c].IsSuborderOf([a, b, c]) - false
/// [a, b, c, d].IsSuborderOf([a, b, c]) - false
///
/// The implicit ordering is not a suborder of any other ordering and
/// no other ordering is a suborder of it. The implicit ordering is not a
/// suborder of itself.
///
/// The unordered ordering is a suborder of all other orderings but no
/// other ordering is a suborder of it. The unordered ordering is a suborder
/// of itself.
///
/// The unordered ordering is a suborder of the implicit ordering.
bool IsSuborderOf(const Ordering& other) const;
bool Equals(const Ordering& other) const;
std::string ToString() const;
bool is_implicit() const { return is_implicit_; }
bool is_unordered() const { return !is_implicit_ && sort_keys_.empty(); }
const std::vector<SortKey>& sort_keys() const { return sort_keys_; }
NullPlacement null_placement() const { return null_placement_; }
static const Ordering& Implicit() {
static const Ordering kImplicit(true);
return kImplicit;
}
static const Ordering& Unordered() {
static const Ordering kUnordered(false);
// It is also possible to get an unordered ordering by passing in an empty vector
// using the normal constructor. This is ok and useful when ordering comes from user
// input.
return kUnordered;
}
private:
explicit Ordering(bool is_implicit)
: null_placement_(NullPlacement::AtStart), is_implicit_(is_implicit) {}
/// Column key(s) to order by and how to order by these sort keys.
std::vector<SortKey> sort_keys_;
/// Whether nulls and NaNs are placed at the start or at the end
NullPlacement null_placement_;
bool is_implicit_ = false;
};
} // namespace compute
} // namespace arrow20
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