team-10/env/Lib/site-packages/pyarrow/include/arrow/array/data.h
2025-08-02 07:34:44 +02:00

750 lines
28 KiB
C++

// 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 <atomic> // IWYU pragma: export
#include <cassert>
#include <cstdint>
#include <memory>
#include <utility>
#include <vector>
#include "arrow/array/statistics.h"
#include "arrow/buffer.h"
#include "arrow/result.h"
#include "arrow/type.h"
#include "arrow/type_fwd.h"
#include "arrow/util/bit_util.h"
#include "arrow/util/macros.h"
#include "arrow/util/span.h"
#include "arrow/util/visibility.h"
namespace arrow {
namespace internal {
// ----------------------------------------------------------------------
// Null handling for types without a validity bitmap and the dictionary type
ARROW_EXPORT bool IsNullSparseUnion(const ArrayData& data, int64_t i);
ARROW_EXPORT bool IsNullDenseUnion(const ArrayData& data, int64_t i);
ARROW_EXPORT bool IsNullRunEndEncoded(const ArrayData& data, int64_t i);
ARROW_EXPORT bool UnionMayHaveLogicalNulls(const ArrayData& data);
ARROW_EXPORT bool RunEndEncodedMayHaveLogicalNulls(const ArrayData& data);
ARROW_EXPORT bool DictionaryMayHaveLogicalNulls(const ArrayData& data);
} // namespace internal
// When slicing, we do not know the null count of the sliced range without
// doing some computation. To avoid doing this eagerly, we set the null count
// to -1 (any negative number will do). When Array::null_count is called the
// first time, the null count will be computed. See ARROW-33
constexpr int64_t kUnknownNullCount = -1;
// ----------------------------------------------------------------------
// Generic array data container
/// \class ArrayData
/// \brief Mutable container for generic Arrow array data
///
/// This data structure is a self-contained representation of the memory and
/// metadata inside an Arrow array data structure (called vectors in Java). The
/// Array class and its concrete subclasses provide strongly-typed accessors
/// with support for the visitor pattern and other affordances.
///
/// This class is designed for easy internal data manipulation, analytical data
/// processing, and data transport to and from IPC messages.
///
/// This class is also useful in an analytics setting where memory may be
/// efficiently reused. For example, computing the Abs of a numeric array
/// should return null iff the input is null: therefore, an Abs function can
/// reuse the validity bitmap (a Buffer) of its input as the validity bitmap
/// of its output.
///
/// This class is meant mostly for immutable data access. Any mutable access
/// (either to ArrayData members or to the contents of its Buffers) should take
/// into account the fact that ArrayData instances are typically wrapped in a
/// shared_ptr and can therefore have multiple owners at any given time.
/// Therefore, mutable access is discouraged except when initially populating
/// the ArrayData.
struct ARROW_EXPORT ArrayData {
ArrayData() = default;
ArrayData(std::shared_ptr<DataType> type, int64_t length,
int64_t null_count = kUnknownNullCount, int64_t offset = 0)
: type(std::move(type)), length(length), null_count(null_count), offset(offset) {}
ArrayData(std::shared_ptr<DataType> type, int64_t length,
std::vector<std::shared_ptr<Buffer>> buffers,
int64_t null_count = kUnknownNullCount, int64_t offset = 0)
: ArrayData(std::move(type), length, null_count, offset) {
this->buffers = std::move(buffers);
#ifndef NDEBUG
// in debug mode, call the `device_type` function to trigger
// the DCHECKs that validate all the buffers are on the same device
ARROW_UNUSED(this->device_type());
#endif
}
ArrayData(std::shared_ptr<DataType> type, int64_t length,
std::vector<std::shared_ptr<Buffer>> buffers,
std::vector<std::shared_ptr<ArrayData>> child_data,
int64_t null_count = kUnknownNullCount, int64_t offset = 0)
: ArrayData(std::move(type), length, null_count, offset) {
this->buffers = std::move(buffers);
this->child_data = std::move(child_data);
#ifndef NDEBUG
// in debug mode, call the `device_type` function to trigger
// the DCHECKs that validate all the buffers (including children)
// are on the same device
ARROW_UNUSED(this->device_type());
#endif
}
static std::shared_ptr<ArrayData> Make(std::shared_ptr<DataType> type, int64_t length,
std::vector<std::shared_ptr<Buffer>> buffers,
int64_t null_count = kUnknownNullCount,
int64_t offset = 0);
static std::shared_ptr<ArrayData> Make(
std::shared_ptr<DataType> type, int64_t length,
std::vector<std::shared_ptr<Buffer>> buffers,
std::vector<std::shared_ptr<ArrayData>> child_data,
int64_t null_count = kUnknownNullCount, int64_t offset = 0);
static std::shared_ptr<ArrayData> Make(
std::shared_ptr<DataType> type, int64_t length,
std::vector<std::shared_ptr<Buffer>> buffers,
std::vector<std::shared_ptr<ArrayData>> child_data,
std::shared_ptr<ArrayData> dictionary, int64_t null_count = kUnknownNullCount,
int64_t offset = 0);
static std::shared_ptr<ArrayData> Make(std::shared_ptr<DataType> type, int64_t length,
int64_t null_count = kUnknownNullCount,
int64_t offset = 0);
// Move constructor
ArrayData(ArrayData&& other) noexcept
: type(std::move(other.type)),
length(other.length),
null_count(other.null_count.load()),
offset(other.offset),
buffers(std::move(other.buffers)),
child_data(std::move(other.child_data)),
dictionary(std::move(other.dictionary)),
statistics(std::move(other.statistics)) {}
// Copy constructor
ArrayData(const ArrayData& other) noexcept
: type(other.type),
length(other.length),
null_count(other.null_count.load()),
offset(other.offset),
buffers(other.buffers),
child_data(other.child_data),
dictionary(other.dictionary),
statistics(other.statistics) {}
// Move assignment
ArrayData& operator=(ArrayData&& other) {
type = std::move(other.type);
length = other.length;
SetNullCount(other.null_count);
offset = other.offset;
buffers = std::move(other.buffers);
child_data = std::move(other.child_data);
dictionary = std::move(other.dictionary);
statistics = std::move(other.statistics);
return *this;
}
// Copy assignment
ArrayData& operator=(const ArrayData& other) {
type = other.type;
length = other.length;
SetNullCount(other.null_count);
offset = other.offset;
buffers = other.buffers;
child_data = other.child_data;
dictionary = other.dictionary;
statistics = other.statistics;
return *this;
}
/// \brief Return a shallow copy of this ArrayData
std::shared_ptr<ArrayData> Copy() const { return std::make_shared<ArrayData>(*this); }
/// \brief Deep copy this ArrayData to destination memory manager
///
/// Returns a new ArrayData object with buffers and all child buffers
/// copied to the destination memory manager. This includes dictionaries
/// if applicable.
Result<std::shared_ptr<ArrayData>> CopyTo(
const std::shared_ptr<MemoryManager>& to) const;
/// \brief View or copy this ArrayData to destination memory manager
///
/// Tries to view the buffer contents on the given memory manager's device
/// if possible (to avoid a copy) but falls back to copying if a no-copy view
/// isn't supported.
Result<std::shared_ptr<ArrayData>> ViewOrCopyTo(
const std::shared_ptr<MemoryManager>& to) const;
/// \brief Return the null-ness of a given array element
///
/// Calling `IsNull(i)` is the same as `!IsValid(i)`.
bool IsNull(int64_t i) const { return !IsValid(i); }
/// \brief Return the validity of a given array element
///
/// For most data types, this will simply query the validity bitmap.
/// For union and run-end-encoded arrays, the underlying child data is
/// queried instead.
/// For dictionary arrays, this reflects the validity of the dictionary
/// index, but the corresponding dictionary value might still be null.
/// For null arrays, this always returns false.
bool IsValid(int64_t i) const {
if (buffers[0] != NULLPTR) {
return bit_util::GetBit(buffers[0]->data(), i + offset);
}
const auto type = this->type->id();
if (type == Type::SPARSE_UNION) {
return !internal::IsNullSparseUnion(*this, i);
}
if (type == Type::DENSE_UNION) {
return !internal::IsNullDenseUnion(*this, i);
}
if (type == Type::RUN_END_ENCODED) {
return !internal::IsNullRunEndEncoded(*this, i);
}
return null_count.load() != length;
}
/// \brief Access a buffer's data as a typed C pointer
///
/// \param i the buffer index
/// \param absolute_offset the offset into the buffer
///
/// If `absolute_offset` is non-zero, the type `T` must match the
/// layout of buffer number `i` for the array's data type; otherwise
/// offset computation would be incorrect.
///
/// If the given buffer is bit-packed (such as a validity bitmap, or
/// the data buffer of a boolean array), then `absolute_offset` must be
/// zero for correct results, and any bit offset must be applied manually
/// by the caller.
template <typename T>
inline const T* GetValues(int i, int64_t absolute_offset) const {
if (buffers[i]) {
return reinterpret_cast<const T*>(buffers[i]->data()) + absolute_offset;
} else {
return NULLPTR;
}
}
/// \brief Access a buffer's data as a typed C pointer
///
/// \param i the buffer index
///
/// This method uses the array's offset to index into buffer number `i`.
///
/// Calling this method on a bit-packed buffer (such as a validity bitmap, or
/// the data buffer of a boolean array) will lead to incorrect results.
/// You should instead call `GetValues(i, 0)` and apply the bit offset manually.
template <typename T>
inline const T* GetValues(int i) const {
return GetValues<T>(i, offset);
}
/// \brief Access a buffer's data as a typed C pointer
///
/// \param i the buffer index
/// \param absolute_offset the offset into the buffer
///
/// Like `GetValues(i, absolute_offset)`, but returns nullptr if the given buffer
/// is not a CPU buffer.
template <typename T>
inline const T* GetValuesSafe(int i, int64_t absolute_offset) const {
if (buffers[i] && buffers[i]->is_cpu()) {
return reinterpret_cast<const T*>(buffers[i]->data()) + absolute_offset;
} else {
return NULLPTR;
}
}
/// \brief Access a buffer's data as a typed C pointer
///
/// \param i the buffer index
///
/// Like `GetValues(i)`, but returns nullptr if the given buffer is not a CPU buffer.
template <typename T>
inline const T* GetValuesSafe(int i) const {
return GetValuesSafe<T>(i, offset);
}
/// \brief Access a buffer's data as a mutable typed C pointer
///
/// \param i the buffer index
/// \param absolute_offset the offset into the buffer
///
/// Like `GetValues(i, absolute_offset)`, but allows mutating buffer contents.
/// This should only be used when initially populating the ArrayData, before
/// it is attached to a Array instance.
template <typename T>
inline T* GetMutableValues(int i, int64_t absolute_offset) {
if (buffers[i]) {
return reinterpret_cast<T*>(buffers[i]->mutable_data()) + absolute_offset;
} else {
return NULLPTR;
}
}
/// \brief Access a buffer's data as a mutable typed C pointer
///
/// \param i the buffer index
///
/// Like `GetValues(i)`, but allows mutating buffer contents.
/// This should only be used when initially populating the ArrayData, before
/// it is attached to a Array instance.
template <typename T>
inline T* GetMutableValues(int i) {
return GetMutableValues<T>(i, offset);
}
/// \brief Construct a zero-copy slice of the data with the given offset and length
///
/// This method applies the given slice to this ArrayData, taking into account
/// its existing offset and length.
/// If the given `length` is too large, the slice length is clamped so as not
/// to go past the offset end.
/// If the given `often` is too large, or if either `offset` or `length` is negative,
/// behavior is undefined.
///
/// The associated ArrayStatistics is always discarded in a sliced
/// ArrayData, even if the slice is trivially equal to the original ArrayData.
/// If you want to reuse the statistics from the original ArrayData, you must
/// explicitly reattach them.
std::shared_ptr<ArrayData> Slice(int64_t offset, int64_t length) const;
/// \brief Construct a zero-copy slice of the data with the given offset and length
///
/// Like `Slice(offset, length)`, but returns an error if the requested slice
/// falls out of bounds.
/// Unlike Slice, `length` isn't clamped to the available buffer size.
Result<std::shared_ptr<ArrayData>> SliceSafe(int64_t offset, int64_t length) const;
/// \brief Set the cached physical null count
///
/// \param v the number of nulls in the ArrayData
///
/// This should only be used when initially populating the ArrayData, if
/// it possible to compute the null count without visiting the entire validity
/// bitmap. In most cases, relying on `GetNullCount` is sufficient.
void SetNullCount(int64_t v) { null_count.store(v); }
/// \brief Return the physical null count
///
/// This method returns the number of array elements for which `IsValid` would
/// return false.
///
/// A cached value is returned if already available, otherwise it is first
/// computed and stored.
/// How it is is computed depends on the data type, see `IsValid` for details.
///
/// Note that this method is typically much faster than calling `IsValid`
/// for all elements. Therefore, it helps avoid per-element validity bitmap
/// lookups in the common cases where the array contains zero or only nulls.
int64_t GetNullCount() const;
/// \brief Return true if the array may have nulls in its validity bitmap
///
/// This method returns true if the data has a validity bitmap, and the physical
/// null count is either known to be non-zero or not yet known.
///
/// Unlike `MayHaveLogicalNulls`, this does not check for the presence of nulls
/// in child data for data types such as unions and run-end encoded types.
///
/// \see HasValidityBitmap
/// \see MayHaveLogicalNulls
bool MayHaveNulls() const {
// If an ArrayData is slightly malformed it may have kUnknownNullCount set
// but no buffer
return null_count.load() != 0 && buffers[0] != NULLPTR;
}
/// \brief Return true if the array has a validity bitmap
bool HasValidityBitmap() const { return buffers[0] != NULLPTR; }
/// \brief Return true if the array may have logical nulls
///
/// Unlike `MayHaveNulls`, this method checks for null child values
/// for types without a validity bitmap, such as unions and run-end encoded
/// types, and for null dictionary values for dictionary types.
///
/// This implies that `MayHaveLogicalNulls` may return true for arrays that
/// don't have a top-level validity bitmap. It is therefore necessary
/// to call `HasValidityBitmap` before accessing a top-level validity bitmap.
///
/// Code that previously used MayHaveNulls and then dealt with the validity
/// bitmap directly can be fixed to handle all types correctly without
/// performance degradation when handling most types by adopting
/// HasValidityBitmap and MayHaveLogicalNulls.
///
/// Before:
///
/// uint8_t* validity = array.MayHaveNulls() ? array.buffers[0].data : NULLPTR;
/// for (int64_t i = 0; i < array.length; ++i) {
/// if (validity && !bit_util::GetBit(validity, i)) {
/// continue; // skip a NULL
/// }
/// ...
/// }
///
/// After:
///
/// bool all_valid = !array.MayHaveLogicalNulls();
/// uint8_t* validity = array.HasValidityBitmap() ? array.buffers[0].data : NULLPTR;
/// for (int64_t i = 0; i < array.length; ++i) {
/// bool is_valid = all_valid ||
/// (validity && bit_util::GetBit(validity, i)) ||
/// array.IsValid(i);
/// if (!is_valid) {
/// continue; // skip a NULL
/// }
/// ...
/// }
bool MayHaveLogicalNulls() const {
if (buffers[0] != NULLPTR) {
return null_count.load() != 0;
}
const auto t = type->id();
if (t == Type::SPARSE_UNION || t == Type::DENSE_UNION) {
return internal::UnionMayHaveLogicalNulls(*this);
}
if (t == Type::RUN_END_ENCODED) {
return internal::RunEndEncodedMayHaveLogicalNulls(*this);
}
if (t == Type::DICTIONARY) {
return internal::DictionaryMayHaveLogicalNulls(*this);
}
return null_count.load() != 0;
}
/// \brief Compute the logical null count for arrays of all types
///
/// If the array has a validity bitmap, this function behaves the same as
/// GetNullCount. For arrays that have no validity bitmap but whose values
/// may be logically null (such as union arrays and run-end encoded arrays),
/// this function recomputes the null count every time it is called.
///
/// \see GetNullCount
int64_t ComputeLogicalNullCount() const;
/// \brief Return the device_type of the underlying buffers and children
///
/// If there are no buffers in this ArrayData object, it just returns
/// DeviceAllocationType::kCPU as a default. We also assume that all buffers
/// should be allocated on the same device type and perform DCHECKs to confirm
/// this in debug mode.
///
/// \return DeviceAllocationType
DeviceAllocationType device_type() const;
std::shared_ptr<DataType> type;
int64_t length = 0;
mutable std::atomic<int64_t> null_count{0};
// The logical start point into the physical buffers (in values, not bytes).
// Note that, for child data, this must be *added* to the child data's own offset.
int64_t offset = 0;
std::vector<std::shared_ptr<Buffer>> buffers;
std::vector<std::shared_ptr<ArrayData>> child_data;
// The dictionary for this Array, if any. Only used for dictionary type
std::shared_ptr<ArrayData> dictionary;
// The statistics for this Array.
std::shared_ptr<ArrayStatistics> statistics;
};
/// \brief A non-owning Buffer reference
struct ARROW_EXPORT BufferSpan {
// It is the user of this class's responsibility to ensure that
// buffers that were const originally are not written to
// accidentally.
uint8_t* data = NULLPTR;
int64_t size = 0;
// Pointer back to buffer that owns this memory
const std::shared_ptr<Buffer>* owner = NULLPTR;
template <typename T>
const T* data_as() const {
return reinterpret_cast<const T*>(data);
}
template <typename T>
T* mutable_data_as() {
return reinterpret_cast<T*>(data);
}
};
/// \brief EXPERIMENTAL: A non-owning array data container
///
/// Unlike ArrayData, this class doesn't own its referenced data type nor data buffers.
/// It is cheaply copyable and can therefore be suitable for use cases where
/// shared_ptr overhead is not acceptable. However, care should be taken to
/// keep alive the referenced objects and memory while the ArraySpan object is in use.
/// For this reason, this should not be exposed in most public APIs (apart from
/// compute kernel interfaces).
struct ARROW_EXPORT ArraySpan {
const DataType* type = NULLPTR;
int64_t length = 0;
mutable int64_t null_count = kUnknownNullCount;
int64_t offset = 0;
BufferSpan buffers[3];
ArraySpan() = default;
explicit ArraySpan(const DataType* type, int64_t length) : type(type), length(length) {}
ArraySpan(const ArrayData& data) { // NOLINT implicit conversion
SetMembers(data);
}
explicit ArraySpan(const Scalar& data) { FillFromScalar(data); }
/// If dictionary-encoded, put dictionary in the first entry
std::vector<ArraySpan> child_data;
/// \brief Populate ArraySpan to look like an array of length 1 pointing at
/// the data members of a Scalar value
void FillFromScalar(const Scalar& value);
void SetMembers(const ArrayData& data);
void SetBuffer(int index, const std::shared_ptr<Buffer>& buffer) {
this->buffers[index].data = const_cast<uint8_t*>(buffer->data());
this->buffers[index].size = buffer->size();
this->buffers[index].owner = &buffer;
}
const ArraySpan& dictionary() const { return child_data[0]; }
/// \brief Return the number of buffers (out of 3) that are used to
/// constitute this array
int num_buffers() const;
// Access a buffer's data as a typed C pointer
template <typename T>
inline T* GetValues(int i, int64_t absolute_offset) {
return reinterpret_cast<T*>(buffers[i].data) + absolute_offset;
}
template <typename T>
inline T* GetValues(int i) {
return GetValues<T>(i, this->offset);
}
// Access a buffer's data as a typed C pointer
template <typename T>
inline const T* GetValues(int i, int64_t absolute_offset) const {
return reinterpret_cast<const T*>(buffers[i].data) + absolute_offset;
}
template <typename T>
inline const T* GetValues(int i) const {
return GetValues<T>(i, this->offset);
}
/// \brief Access a buffer's data as a span
///
/// \param i The buffer index
/// \param length The required length (in number of typed values) of the requested span
/// \pre i > 0
/// \pre length <= the length of the buffer (in number of values) that's expected for
/// this array type
/// \return A span<const T> of the requested length
template <typename T>
util::span<const T> GetSpan(int i, int64_t length) const {
const int64_t buffer_length = buffers[i].size / static_cast<int64_t>(sizeof(T));
assert(i > 0 && length + offset <= buffer_length);
ARROW_UNUSED(buffer_length);
return util::span<const T>(buffers[i].data_as<T>() + this->offset, length);
}
/// \brief Access a buffer's data as a span
///
/// \param i The buffer index
/// \param length The required length (in number of typed values) of the requested span
/// \pre i > 0
/// \pre length <= the length of the buffer (in number of values) that's expected for
/// this array type
/// \return A span<T> of the requested length
template <typename T>
util::span<T> GetSpan(int i, int64_t length) {
const int64_t buffer_length = buffers[i].size / static_cast<int64_t>(sizeof(T));
assert(i > 0 && length + offset <= buffer_length);
ARROW_UNUSED(buffer_length);
return util::span<T>(buffers[i].mutable_data_as<T>() + this->offset, length);
}
inline bool IsNull(int64_t i) const { return !IsValid(i); }
inline bool IsValid(int64_t i) const {
if (this->buffers[0].data != NULLPTR) {
return bit_util::GetBit(this->buffers[0].data, i + this->offset);
} else {
const auto type = this->type->id();
if (type == Type::SPARSE_UNION) {
return !IsNullSparseUnion(i);
}
if (type == Type::DENSE_UNION) {
return !IsNullDenseUnion(i);
}
if (type == Type::RUN_END_ENCODED) {
return !IsNullRunEndEncoded(i);
}
return this->null_count != this->length;
}
}
std::shared_ptr<ArrayData> ToArrayData() const;
std::shared_ptr<Array> ToArray() const;
std::shared_ptr<Buffer> GetBuffer(int index) const {
const BufferSpan& buf = this->buffers[index];
if (buf.owner) {
return *buf.owner;
} else if (buf.data != NULLPTR) {
// Buffer points to some memory without an owning buffer
return std::make_shared<Buffer>(buf.data, buf.size);
} else {
return NULLPTR;
}
}
void SetSlice(int64_t offset, int64_t length) {
this->offset = offset;
this->length = length;
if (this->type->id() == Type::NA) {
this->null_count = this->length;
} else if (this->MayHaveNulls()) {
this->null_count = kUnknownNullCount;
} else {
this->null_count = 0;
}
}
/// \brief Return physical null count, or compute and set it if it's not known
int64_t GetNullCount() const;
/// \brief Return true if the array has a validity bitmap and the physical null
/// count is known to be non-zero or not yet known
///
/// Note that this is not the same as MayHaveLogicalNulls, which also checks
/// for the presence of nulls in child data for types like unions and run-end
/// encoded types.
///
/// \see HasValidityBitmap
/// \see MayHaveLogicalNulls
bool MayHaveNulls() const {
// If an ArrayData is slightly malformed it may have kUnknownNullCount set
// but no buffer
return null_count != 0 && buffers[0].data != NULLPTR;
}
/// \brief Return true if the array has a validity bitmap
bool HasValidityBitmap() const { return buffers[0].data != NULLPTR; }
/// \brief Return true if the validity bitmap may have 0's in it, or if the
/// child arrays (in the case of types without a validity bitmap) may have
/// nulls, or if the dictionary of dictionay array may have nulls.
///
/// \see ArrayData::MayHaveLogicalNulls
bool MayHaveLogicalNulls() const {
if (buffers[0].data != NULLPTR) {
return null_count != 0;
}
const auto t = type->id();
if (t == Type::SPARSE_UNION || t == Type::DENSE_UNION) {
return UnionMayHaveLogicalNulls();
}
if (t == Type::RUN_END_ENCODED) {
return RunEndEncodedMayHaveLogicalNulls();
}
if (t == Type::DICTIONARY) {
return DictionaryMayHaveLogicalNulls();
}
return null_count != 0;
}
/// \brief Compute the logical null count for arrays of all types including
/// those that do not have a validity bitmap like union and run-end encoded
/// arrays
///
/// If the array has a validity bitmap, this function behaves the same as
/// GetNullCount. For types that have no validity bitmap, this function will
/// recompute the logical null count every time it is called.
///
/// \see GetNullCount
int64_t ComputeLogicalNullCount() const;
/// Some DataTypes (StringView, BinaryView) may have an arbitrary number of variadic
/// buffers. Since ArraySpan only has 3 buffers, we pack the variadic buffers into
/// buffers[2]; IE buffers[2].data points to the first shared_ptr<Buffer> of the
/// variadic set and buffers[2].size is the number of variadic buffers times
/// sizeof(shared_ptr<Buffer>).
///
/// \see HasVariadicBuffers
util::span<const std::shared_ptr<Buffer>> GetVariadicBuffers() const;
bool HasVariadicBuffers() const;
private:
ARROW_FRIEND_EXPORT friend bool internal::IsNullRunEndEncoded(const ArrayData& data,
int64_t i);
bool IsNullSparseUnion(int64_t i) const;
bool IsNullDenseUnion(int64_t i) const;
/// \brief Return true if the value at logical index i is null
///
/// This function uses binary-search, so it has a O(log N) cost.
/// Iterating over the whole array and calling IsNull is O(N log N), so
/// for better performance it is recommended to use a
/// ree_util::RunEndEncodedArraySpan to iterate run by run instead.
bool IsNullRunEndEncoded(int64_t i) const;
bool UnionMayHaveLogicalNulls() const;
bool RunEndEncodedMayHaveLogicalNulls() const;
bool DictionaryMayHaveLogicalNulls() const;
};
namespace internal {
void FillZeroLengthArray(const DataType* type, ArraySpan* span);
/// Construct a zero-copy view of this ArrayData with the given type.
///
/// This method checks if the types are layout-compatible.
/// Nested types are traversed in depth-first order. Data buffers must have
/// the same item sizes, even though the logical types may be different.
/// An error is returned if the types are not layout-compatible.
ARROW_EXPORT
Result<std::shared_ptr<ArrayData>> GetArrayView(const std::shared_ptr<ArrayData>& data,
const std::shared_ptr<DataType>& type);
} // namespace internal
} // namespace arrow