314 lines
11 KiB
C++
314 lines
11 KiB
C++
// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements. See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership. The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License. You may obtain a copy of the License at
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//
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// http://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,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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#pragma once
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#include <cstdint>
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#include <memory>
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#include <string>
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#include <type_traits>
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#include <utility>
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#include <variant>
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#include <vector>
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#include "arrow/array/data.h"
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#include "arrow/device_allocation_type_set.h"
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#include "arrow/scalar.h"
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#include "arrow/type.h"
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#include "arrow/type_traits.h"
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#include "arrow/util/checked_cast.h"
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#include "arrow/util/macros.h"
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#include "arrow/util/visibility.h"
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namespace arrow {
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class Array;
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class ChunkedArray;
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class RecordBatch;
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class Table;
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/// \class Datum
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/// \brief Variant type for various Arrow C++ data structures
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struct ARROW_EXPORT Datum {
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/// \brief The kind of datum stored
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enum Kind { NONE, SCALAR, ARRAY, CHUNKED_ARRAY, RECORD_BATCH, TABLE };
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/// \brief A placeholder type to represent empty datum
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struct Empty {};
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/// \brief Datums variants may have a length. This special value indicate that the
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/// current variant does not have a length.
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static constexpr int64_t kUnknownLength = -1;
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/// \brief Storage of the actual datum.
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///
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/// Note: For arrays, ArrayData is stored instead of Array for easier processing
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std::variant<Empty, std::shared_ptr<Scalar>, std::shared_ptr<ArrayData>,
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std::shared_ptr<ChunkedArray>, std::shared_ptr<RecordBatch>,
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std::shared_ptr<Table>>
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value;
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/// \brief Empty datum, to be populated elsewhere
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Datum() = default;
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Datum(const Datum& other) = default;
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Datum& operator=(const Datum& other) = default;
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Datum(Datum&& other) = default;
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Datum& operator=(Datum&& other) = default;
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/// \brief Construct from a Scalar
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Datum(std::shared_ptr<Scalar> value) // NOLINT implicit conversion
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: value(std::move(value)) {}
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/// \brief Construct from an ArrayData
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Datum(std::shared_ptr<ArrayData> value) // NOLINT implicit conversion
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: value(std::move(value)) {}
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/// \brief Construct from an ArrayData
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Datum(ArrayData arg) // NOLINT implicit conversion
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: value(std::make_shared<ArrayData>(std::move(arg))) {}
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/// \brief Construct from an Array
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Datum(const Array& value); // NOLINT implicit conversion
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/// \brief Construct from an Array
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Datum(const std::shared_ptr<Array>& value); // NOLINT implicit conversion
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/// \brief Construct from a ChunkedArray
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Datum(std::shared_ptr<ChunkedArray> value); // NOLINT implicit conversion
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/// \brief Construct from a RecordBatch
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Datum(std::shared_ptr<RecordBatch> value); // NOLINT implicit conversion
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/// \brief Construct from a Table
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Datum(std::shared_ptr<Table> value); // NOLINT implicit conversion
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/// \brief Construct from a ChunkedArray.
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///
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/// This can be expensive, prefer the shared_ptr<ChunkedArray> constructor
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explicit Datum(const ChunkedArray& value);
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/// \brief Construct from a RecordBatch.
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///
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/// This can be expensive, prefer the shared_ptr<RecordBatch> constructor
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explicit Datum(const RecordBatch& value);
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/// \brief Construct from a Table.
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///
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/// This can be expensive, prefer the shared_ptr<Table> constructor
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explicit Datum(const Table& value);
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/// \brief Cast from concrete subtypes of Array or Scalar to Datum
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template <typename T, bool IsArray = std::is_base_of_v<Array, T>,
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bool IsScalar = std::is_base_of_v<Scalar, T>,
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typename = enable_if_t<IsArray || IsScalar>>
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Datum(std::shared_ptr<T> value) // NOLINT implicit conversion
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: Datum(std::shared_ptr<typename std::conditional<IsArray, Array, Scalar>::type>(
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std::move(value))) {}
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/// \brief Cast from concrete subtypes of Array or Scalar to Datum
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template <typename T, typename TV = typename std::remove_reference_t<T>,
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bool IsArray = std::is_base_of_v<Array, T>,
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bool IsScalar = std::is_base_of_v<Scalar, T>,
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typename = enable_if_t<IsArray || IsScalar>>
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Datum(T&& value) // NOLINT implicit conversion
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: Datum(std::make_shared<TV>(std::forward<T>(value))) {}
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/// \brief Copy from concrete subtypes of Scalar.
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///
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/// The concrete scalar type must be copyable (not all of them are).
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template <typename T, typename = enable_if_t<std::is_base_of_v<Scalar, T>>>
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Datum(const T& value) // NOLINT implicit conversion
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: Datum(std::make_shared<T>(value)) {}
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// Convenience constructors
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/// \brief Convenience constructor storing a bool scalar.
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explicit Datum(bool value);
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/// \brief Convenience constructor storing an int8 scalar.
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explicit Datum(int8_t value);
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/// \brief Convenience constructor storing a uint8 scalar.
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explicit Datum(uint8_t value);
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/// \brief Convenience constructor storing an int16 scalar.
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explicit Datum(int16_t value);
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/// \brief Convenience constructor storing a uint16 scalar.
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explicit Datum(uint16_t value);
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/// \brief Convenience constructor storing an int32 scalar.
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explicit Datum(int32_t value);
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/// \brief Convenience constructor storing a uint32 scalar.
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explicit Datum(uint32_t value);
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/// \brief Convenience constructor storing an int64 scalar.
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explicit Datum(int64_t value);
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/// \brief Convenience constructor storing a uint64 scalar.
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explicit Datum(uint64_t value);
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/// \brief Convenience constructor storing a float scalar.
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explicit Datum(float value);
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/// \brief Convenience constructor storing a double scalar.
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explicit Datum(double value);
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/// \brief Convenience constructor storing a string scalar.
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explicit Datum(std::string value);
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/// \brief Convenience constructor storing a string scalar.
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explicit Datum(const char* value);
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/// \brief Convenience constructor for a DurationScalar from std::chrono::duration
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template <template <typename, typename> class StdDuration, typename Rep,
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typename Period,
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typename = decltype(DurationScalar{StdDuration<Rep, Period>{}})>
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explicit Datum(StdDuration<Rep, Period> d) : Datum{DurationScalar(d)} {}
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/// \brief The kind of data stored in Datum
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Datum::Kind kind() const {
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switch (this->value.index()) {
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case 0:
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return Datum::NONE;
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case 1:
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return Datum::SCALAR;
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case 2:
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return Datum::ARRAY;
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case 3:
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return Datum::CHUNKED_ARRAY;
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case 4:
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return Datum::RECORD_BATCH;
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case 5:
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return Datum::TABLE;
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default:
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return Datum::NONE;
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}
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}
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/// \brief Retrieve the stored array as ArrayData
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///
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/// Use make_array() if an Array is desired (which is more expensive).
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/// \throws std::bad_variant_access if the datum is not an array
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const std::shared_ptr<ArrayData>& array() const {
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return std::get<std::shared_ptr<ArrayData>>(this->value);
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}
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/// \brief The sum of bytes in each buffer referenced by the datum
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/// Note: Scalars report a size of 0
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/// \see arrow::util::TotalBufferSize for caveats
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int64_t TotalBufferSize() const;
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/// \brief Get the stored ArrayData in mutable form
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///
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/// For internal use primarily. Keep in mind a shared_ptr<Datum> may have multiple
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/// owners.
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ArrayData* mutable_array() const { return this->array().get(); }
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/// \brief Retrieve the stored array as Array
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/// \throws std::bad_variant_access if the datum is not an array
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std::shared_ptr<Array> make_array() const;
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/// \brief Retrieve the chunked array stored
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/// \throws std::bad_variant_access if the datum is not a chunked array
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const std::shared_ptr<ChunkedArray>& chunked_array() const {
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return std::get<std::shared_ptr<ChunkedArray>>(this->value);
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}
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/// \brief Retrieve the record batch stored
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/// \throws std::bad_variant_access if the datum is not a record batch
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const std::shared_ptr<RecordBatch>& record_batch() const {
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return std::get<std::shared_ptr<RecordBatch>>(this->value);
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}
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/// \brief Retrieve the table stored
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/// \throws std::bad_variant_access if the datum is not a table
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const std::shared_ptr<Table>& table() const {
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return std::get<std::shared_ptr<Table>>(this->value);
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}
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/// \brief Retrieve the scalar stored
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/// \throws std::bad_variant_access if the datum is not a scalar
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const std::shared_ptr<Scalar>& scalar() const {
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return std::get<std::shared_ptr<Scalar>>(this->value);
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}
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/// \brief Retrieve the datum as its concrete array type
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/// \throws std::bad_variant_access if the datum is not an array
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/// \tparam ExactType the expected array type, may cause undefined behavior if it is not
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/// the type of the stored array
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template <typename ExactType>
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std::shared_ptr<ExactType> array_as() const {
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return internal::checked_pointer_cast<ExactType>(this->make_array());
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}
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/// \brief Retrieve the datum as its concrete scalar type
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/// \throws std::bad_variant_access if the datum is not a scalar
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/// \tparam ExactType the expected scalar type, may cause undefined behavior if it is
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/// not the type of the stored scalar
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template <typename ExactType>
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const ExactType& scalar_as() const {
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return internal::checked_cast<const ExactType&>(*this->scalar());
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}
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/// \brief True if Datum contains an array
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bool is_array() const { return this->kind() == Datum::ARRAY; }
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/// \brief True if Datum contains a chunked array
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bool is_chunked_array() const { return this->kind() == Datum::CHUNKED_ARRAY; }
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/// \brief True if Datum contains an array or a chunked array
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bool is_arraylike() const {
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return this->kind() == Datum::ARRAY || this->kind() == Datum::CHUNKED_ARRAY;
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}
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/// \brief True if Datum contains a scalar
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bool is_scalar() const { return this->kind() == Datum::SCALAR; }
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/// \brief True if Datum contains a scalar or array-like data
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bool is_value() const { return this->is_arraylike() || this->is_scalar(); }
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/// \brief Return the null count.
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///
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/// Only valid for scalar and array-like data.
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int64_t null_count() const;
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/// \brief The value type of the variant, if any
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///
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/// \return nullptr if no type
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const std::shared_ptr<DataType>& type() const;
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/// \brief The schema of the variant, if any
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///
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/// \return nullptr if no schema
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const std::shared_ptr<Schema>& schema() const;
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/// \brief The value length of the variant, if any
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///
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/// \return kUnknownLength if no type
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int64_t length() const;
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/// \brief The array chunks of the variant, if any
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///
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/// \return empty if not arraylike
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ArrayVector chunks() const;
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DeviceAllocationTypeSet device_types() const;
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/// \brief True if the two data are equal
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bool Equals(const Datum& other) const;
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bool operator==(const Datum& other) const { return Equals(other); }
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bool operator!=(const Datum& other) const { return !Equals(other); }
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std::string ToString() const;
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};
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ARROW_EXPORT void PrintTo(const Datum&, std::ostream*);
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ARROW_EXPORT std::string ToString(Datum::Kind kind);
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} // namespace arrow
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