Scalars

struct Scalar : public std::enable_shared_from_this<Scalar>, public arrow::util::EqualityComparable<Scalar>

Base class for scalar values.

A Scalar represents a single value with a specific DataType. Scalars are useful for passing single value inputs to compute functions, or for representing individual array elements (with a non-trivial wrapping cost, though).

Subclassed by arrow::BaseListScalar, arrow::ExtensionScalar, arrow::NullScalar, arrow::RunEndEncodedScalar, arrow::StructScalar, arrow::UnionScalar, arrow::internal::PrimitiveScalarBase

Public Functions

Status Validate() const

Perform cheap validation checks.

This is O(k) where k is the number of descendents.

Returns:

Status

Status ValidateFull() const

Perform extensive data validation checks.

This is potentially O(k*n) where k is the number of descendents and n is the length of descendents (if list scalars are involved).

Returns:

Status

Status Accept(ScalarVisitor *visitor) const

Apply the ScalarVisitor::Visit() method specialized to the scalar type.

inline std::shared_ptr<Scalar> GetSharedPtr() const

EXPERIMENTAL Enable obtaining shared_ptr<Scalar> from a const Scalar& context.

Public Members

std::shared_ptr<DataType> type

The type of the scalar value.

bool is_valid = false

Whether the value is valid (not null) or not.

struct Hash

Factory functions

std::shared_ptr<Scalar> MakeNullScalar(std::shared_ptr<DataType> type)

Scalar factory for null scalars.

template<typename Value>
Result<std::shared_ptr<Scalar>> MakeScalar(std::shared_ptr<DataType> type, Value &&value)

Scalar factory for non-null scalars.

template<typename Value, typename Traits = CTypeTraits<typename std::decay<Value>::type>, typename ScalarType = typename Traits::ScalarType, typename Enable = decltype(ScalarType(std::declval<Value>(), Traits::type_singleton()))>
std::shared_ptr<Scalar> MakeScalar(Value value)

Type-inferring scalar factory for non-null scalars.

Construct a Scalar instance with a DataType determined by the input C++ type. (for example Int8Scalar for a int8_t input). Only non-parametric primitive types and String are supported.

inline std::shared_ptr<Scalar> MakeScalar(std::string value)

inline std::shared_ptr<Scalar> MakeScalar(const std::shared_ptr<Scalar> &scalar)

Concrete scalar subclasses

struct NullScalar : public arrow::Scalar

#include <arrow/scalar.h>

A scalar value for NullType. Never valid.

Public Types

using TypeClass = NullType

Public Functions

inline NullScalar()

struct BooleanScalar : public arrow::internal::PrimitiveScalar<BooleanType, bool>

#include <arrow/scalar.h>

Public Types

using Base = internal::PrimitiveScalar<BooleanType, bool>

Public Functions

inline explicit BooleanScalar(bool value)

inline BooleanScalar()

template<typename T>
struct NumericScalar : public arrow::internal::PrimitiveScalar<T>

#include <arrow/scalar.h>

Public Types

using Base = typename internal::PrimitiveScalar<T>

using TypeClass = typename Base::TypeClass

using ValueType = typename Base::ValueType

Public Functions

inline explicit NumericScalar(ValueType value)

inline NumericScalar()

struct Int8Scalar : public arrow::NumericScalar<Int8Type>

#include <arrow/scalar.h>

struct Int16Scalar : public arrow::NumericScalar<Int16Type>

#include <arrow/scalar.h>

struct Int32Scalar : public arrow::NumericScalar<Int32Type>

#include <arrow/scalar.h>

struct Int64Scalar : public arrow::NumericScalar<Int64Type>

#include <arrow/scalar.h>

struct UInt8Scalar : public arrow::NumericScalar<UInt8Type>

#include <arrow/scalar.h>

struct UInt16Scalar : public arrow::NumericScalar<UInt16Type>

#include <arrow/scalar.h>

struct UInt32Scalar : public arrow::NumericScalar<UInt32Type>

#include <arrow/scalar.h>

struct UInt64Scalar : public arrow::NumericScalar<UInt64Type>

#include <arrow/scalar.h>

struct HalfFloatScalar : public arrow::NumericScalar<HalfFloatType>

#include <arrow/scalar.h>

struct FloatScalar : public arrow::NumericScalar<FloatType>

#include <arrow/scalar.h>

struct DoubleScalar : public arrow::NumericScalar<DoubleType>

#include <arrow/scalar.h>

struct BaseBinaryScalar : public arrow::internal::PrimitiveScalarBase, private arrow::internal::ArraySpanFillFromScalarScratchSpace

#include <arrow/scalar.h>

Subclassed by arrow::BinaryScalar, arrow::LargeBinaryScalar

Public Types

using ValueType = std::shared_ptr<Buffer>

Public Functions

inline const void *data() const override

inline void *mutable_data() override

inline std::string_view view() const override

Public Members

std::shared_ptr<Buffer> value

struct BinaryScalar : public arrow::BaseBinaryScalar

#include <arrow/scalar.h>

Subclassed by arrow::FixedSizeBinaryScalar, arrow::StringScalar

Public Types

using TypeClass = BinaryType

Public Functions

inline BinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type)

inline explicit BinaryScalar(std::shared_ptr<Buffer> value)

explicit BinaryScalar(std::string s)

inline BinaryScalar()

inline BaseBinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type)

struct StringScalar : public arrow::BinaryScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = StringType

Public Functions

inline explicit StringScalar(std::shared_ptr<Buffer> value)

explicit StringScalar(std::string s)

inline StringScalar()

inline BinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type)

inline explicit BinaryScalar(std::shared_ptr<Buffer> value)

explicit BinaryScalar(std::string s)

inline BinaryScalar()

struct LargeBinaryScalar : public arrow::BaseBinaryScalar

#include <arrow/scalar.h>

Subclassed by arrow::LargeStringScalar

Public Types

using TypeClass = LargeBinaryType

Public Functions

inline LargeBinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type)

inline explicit LargeBinaryScalar(std::shared_ptr<Buffer> value)

explicit LargeBinaryScalar(std::string s)

inline LargeBinaryScalar()

inline BaseBinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type)

struct LargeStringScalar : public arrow::LargeBinaryScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = LargeStringType

Public Functions

inline explicit LargeStringScalar(std::shared_ptr<Buffer> value)

explicit LargeStringScalar(std::string s)

inline LargeStringScalar()

inline LargeBinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type)

inline explicit LargeBinaryScalar(std::shared_ptr<Buffer> value)

explicit LargeBinaryScalar(std::string s)

inline LargeBinaryScalar()

struct FixedSizeBinaryScalar : public arrow::BinaryScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = FixedSizeBinaryType

Public Functions

FixedSizeBinaryScalar(std::shared_ptr<Buffer> value, std::shared_ptr<DataType> type, bool is_valid = true)

explicit FixedSizeBinaryScalar(const std::shared_ptr<Buffer> &value, bool is_valid = true)

explicit FixedSizeBinaryScalar(std::string s, bool is_valid = true)

template<typename T>
struct TemporalScalar : public arrow::internal::PrimitiveScalar<T>

#include <arrow/scalar.h>

Subclassed by arrow::DateScalar< Date64Type >, arrow::DateScalar< Date32Type >, arrow::IntervalScalar< MonthIntervalType >, arrow::IntervalScalar< DayTimeIntervalType >, arrow::IntervalScalar< MonthDayNanoIntervalType >, arrow::TimeScalar< Time64Type >, arrow::TimeScalar< Time32Type >, arrow::DateScalar< T >, arrow::IntervalScalar< T >, arrow::TimeScalar< T >

Public Types

using ValueType = typename internal::PrimitiveScalar<T>::ValueType

Public Functions

inline TemporalScalar(ValueType value, std::shared_ptr<DataType> type)

template<typename T>
struct DateScalar : public arrow::TemporalScalar<T>

#include <arrow/scalar.h>

Public Types

using ValueType = typename TemporalScalar<T>::ValueType

Public Functions

inline explicit DateScalar(ValueType value)

inline DateScalar()

struct Date32Scalar : public arrow::DateScalar<Date32Type>

#include <arrow/scalar.h>

struct Date64Scalar : public arrow::DateScalar<Date64Type>

#include <arrow/scalar.h>

template<typename T>
struct TimeScalar : public arrow::TemporalScalar<T>

#include <arrow/scalar.h>

Public Functions

inline TimeScalar(typename TemporalScalar<T>::ValueType value, TimeUnit::type unit)

struct Time32Scalar : public arrow::TimeScalar<Time32Type>

#include <arrow/scalar.h>

struct Time64Scalar : public arrow::TimeScalar<Time64Type>

#include <arrow/scalar.h>

struct TimestampScalar : public arrow::TemporalScalar<TimestampType>

#include <arrow/scalar.h>

Public Functions

inline TimestampScalar(typename TemporalScalar<TimestampType>::ValueType value, TimeUnit::type unit, std::string tz = "")

Public Static Functions

static Result<TimestampScalar> FromISO8601(std::string_view iso8601, TimeUnit::type unit)

template<typename T>
struct IntervalScalar : public arrow::TemporalScalar<T>

#include <arrow/scalar.h>

Public Types

using ValueType = typename TemporalScalar<T>::ValueType

Public Functions

inline explicit IntervalScalar(ValueType value)

inline IntervalScalar()

struct MonthIntervalScalar : public arrow::IntervalScalar<MonthIntervalType>

#include <arrow/scalar.h>

struct DayTimeIntervalScalar : public arrow::IntervalScalar<DayTimeIntervalType>

#include <arrow/scalar.h>

struct MonthDayNanoIntervalScalar : public arrow::IntervalScalar<MonthDayNanoIntervalType>

#include <arrow/scalar.h>

struct DurationScalar : public arrow::TemporalScalar<DurationType>

#include <arrow/scalar.h>

Public Functions

inline DurationScalar(typename TemporalScalar<DurationType>::ValueType value, TimeUnit::type unit)

template<template<typename, typename> class StdDuration, typename Rep>
inline explicit DurationScalar(StdDuration<Rep, std::nano> d)

template<template<typename, typename> class StdDuration, typename Rep>
inline explicit DurationScalar(StdDuration<Rep, std::micro> d)

template<template<typename, typename> class StdDuration, typename Rep>
inline explicit DurationScalar(StdDuration<Rep, std::milli> d)

template<template<typename, typename> class StdDuration, typename Rep, intmax_t Num>
inline explicit DurationScalar(StdDuration<Rep, std::ratio<Num, 1>> d)

template<typename TYPE_CLASS, typename VALUE_TYPE>
struct DecimalScalar : public arrow::internal::PrimitiveScalarBase

#include <arrow/scalar.h>

Public Types

using TypeClass = TYPE_CLASS

using ValueType = VALUE_TYPE

Public Functions

inline DecimalScalar(ValueType value, std::shared_ptr<DataType> type)

inline const void *data() const override

inline void *mutable_data() override

inline std::string_view view() const override

Public Members

ValueType value

struct Decimal128Scalar : public arrow::DecimalScalar<Decimal128Type, Decimal128>

#include <arrow/scalar.h>

Public Functions

inline DecimalScalar(ValueType value, std::shared_ptr<DataType> type)

struct Decimal256Scalar : public arrow::DecimalScalar<Decimal256Type, Decimal256>

#include <arrow/scalar.h>

Public Functions

inline DecimalScalar(ValueType value, std::shared_ptr<DataType> type)

struct BaseListScalar : public arrow::Scalar, private arrow::internal::ArraySpanFillFromScalarScratchSpace

#include <arrow/scalar.h>

Subclassed by arrow::FixedSizeListScalar, arrow::LargeListScalar, arrow::ListScalar, arrow::MapScalar

Public Types

using ValueType = std::shared_ptr<Array>

Public Functions

BaseListScalar(std::shared_ptr<Array> value, std::shared_ptr<DataType> type, bool is_valid = true)

inline Scalar(std::shared_ptr<DataType> type, bool is_valid)

Public Members

std::shared_ptr<Array> value

struct ListScalar : public arrow::BaseListScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = ListType

Public Functions

explicit ListScalar(std::shared_ptr<Array> value, bool is_valid = true)

BaseListScalar(std::shared_ptr<Array> value, std::shared_ptr<DataType> type, bool is_valid = true)

struct LargeListScalar : public arrow::BaseListScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = LargeListType

Public Functions

explicit LargeListScalar(std::shared_ptr<Array> value, bool is_valid = true)

BaseListScalar(std::shared_ptr<Array> value, std::shared_ptr<DataType> type, bool is_valid = true)

struct MapScalar : public arrow::BaseListScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = MapType

Public Functions

explicit MapScalar(std::shared_ptr<Array> value, bool is_valid = true)

BaseListScalar(std::shared_ptr<Array> value, std::shared_ptr<DataType> type, bool is_valid = true)

struct FixedSizeListScalar : public arrow::BaseListScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = FixedSizeListType

Public Functions

FixedSizeListScalar(std::shared_ptr<Array> value, std::shared_ptr<DataType> type, bool is_valid = true)

explicit FixedSizeListScalar(std::shared_ptr<Array> value, bool is_valid = true)

struct StructScalar : public arrow::Scalar

#include <arrow/scalar.h>

Public Types

using TypeClass = StructType

using ValueType = std::vector<std::shared_ptr<Scalar>>

Public Functions

Result<std::shared_ptr<Scalar>> field(FieldRef ref) const

inline StructScalar(ValueType value, std::shared_ptr<DataType> type, bool is_valid = true)

Public Members

ScalarVector value

Public Static Functions

static Result<std::shared_ptr<StructScalar>> Make(ValueType value, std::vector<std::string> field_names)

struct UnionScalar : public arrow::Scalar, private arrow::internal::ArraySpanFillFromScalarScratchSpace

#include <arrow/scalar.h>

Subclassed by arrow::DenseUnionScalar, arrow::SparseUnionScalar

Public Functions

virtual const std::shared_ptr<Scalar> &child_value() const = 0

Public Members

int8_t type_code

struct SparseUnionScalar : public arrow::UnionScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = SparseUnionType

using ValueType = std::vector<std::shared_ptr<Scalar>>

Public Functions

SparseUnionScalar(ValueType value, int8_t type_code, std::shared_ptr<DataType> type)

inline virtual const std::shared_ptr<Scalar> &child_value() const override

Public Members

ValueType value

int child_id

Public Static Functions

static std::shared_ptr<Scalar> FromValue(std::shared_ptr<Scalar> value, int field_index, std::shared_ptr<DataType> type)

Construct a SparseUnionScalar from a single value, versus having to construct a vector of scalars.

struct DenseUnionScalar : public arrow::UnionScalar

#include <arrow/scalar.h>

Public Types

using TypeClass = DenseUnionType

using ValueType = std::shared_ptr<Scalar>

Public Functions

inline virtual const std::shared_ptr<Scalar> &child_value() const override

inline DenseUnionScalar(ValueType value, int8_t type_code, std::shared_ptr<DataType> type)

Public Members

ValueType value

struct RunEndEncodedScalar : public arrow::Scalar, private arrow::internal::ArraySpanFillFromScalarScratchSpace

#include <arrow/scalar.h>

Public Types

using TypeClass = RunEndEncodedType

using ValueType = std::shared_ptr<Scalar>

Public Functions

RunEndEncodedScalar(std::shared_ptr<Scalar> value, std::shared_ptr<DataType> type)

explicit RunEndEncodedScalar(const std::shared_ptr<DataType> &type)

Constructs a NULL RunEndEncodedScalar.

~RunEndEncodedScalar() override

inline const std::shared_ptr<DataType> &run_end_type() const

inline const std::shared_ptr<DataType> &value_type() const

Public Members

ValueType value

struct DictionaryScalar : public arrow::internal::PrimitiveScalarBase

#include <arrow/scalar.h>

A Scalar value for DictionaryType.

is_valid denotes the validity of the index, regardless of the corresponding value in the dictionary.

Public Types

using TypeClass = DictionaryType

Public Functions

explicit DictionaryScalar(std::shared_ptr<DataType> type)

inline DictionaryScalar(ValueType value, std::shared_ptr<DataType> type, bool is_valid = true)

Result<std::shared_ptr<Scalar>> GetEncodedValue() const

inline const void *data() const override

inline void *mutable_data() override

inline std::string_view view() const override

Public Members

struct arrow::DictionaryScalar::ValueType value

Public Static Functions

static std::shared_ptr<DictionaryScalar> Make(std::shared_ptr<Scalar> index, std::shared_ptr<Array> dict)

struct ValueType

#include <arrow/scalar.h>

Public Members

std::shared_ptr<Scalar> index

std::shared_ptr<Array> dictionary

struct ExtensionScalar : public arrow::Scalar

#include <arrow/scalar.h>

A Scalar value for ExtensionType.

The value is the underlying storage scalar. is_valid must only be true if value is non-null and value->is_valid is true

Public Types

using TypeClass = ExtensionType

using ValueType = std::shared_ptr<Scalar>

Public Functions

inline ExtensionScalar(std::shared_ptr<Scalar> storage, std::shared_ptr<DataType> type, bool is_valid = true)

template<typename Storage, typename = enable_if_t<std::is_base_of<Scalar, Storage>::value>>
inline ExtensionScalar(Storage &&storage, std::shared_ptr<DataType> type, bool is_valid = true)

Public Members

std::shared_ptr<Scalar> value

Utilities

class ScalarVisitor

Abstract scalar visitor class.

Subclass this to create a visitor that can be used with the Scalar::Accept() method.

Public Functions

virtual ~ScalarVisitor() = default

virtual Status Visit(const NullScalar &scalar)

virtual Status Visit(const BooleanScalar &scalar)

virtual Status Visit(const Int8Scalar &scalar)

virtual Status Visit(const Int16Scalar &scalar)

virtual Status Visit(const Int32Scalar &scalar)

virtual Status Visit(const Int64Scalar &scalar)

virtual Status Visit(const UInt8Scalar &scalar)

virtual Status Visit(const UInt16Scalar &scalar)

virtual Status Visit(const UInt32Scalar &scalar)

virtual Status Visit(const UInt64Scalar &scalar)

virtual Status Visit(const HalfFloatScalar &scalar)

virtual Status Visit(const FloatScalar &scalar)

virtual Status Visit(const DoubleScalar &scalar)

virtual Status Visit(const StringScalar &scalar)

virtual Status Visit(const BinaryScalar &scalar)

virtual Status Visit(const LargeStringScalar &scalar)

virtual Status Visit(const LargeBinaryScalar &scalar)

virtual Status Visit(const FixedSizeBinaryScalar &scalar)

virtual Status Visit(const Date64Scalar &scalar)

virtual Status Visit(const Date32Scalar &scalar)

virtual Status Visit(const Time32Scalar &scalar)

virtual Status Visit(const Time64Scalar &scalar)

virtual Status Visit(const TimestampScalar &scalar)

virtual Status Visit(const DayTimeIntervalScalar &scalar)

virtual Status Visit(const MonthDayNanoIntervalScalar &type)

virtual Status Visit(const MonthIntervalScalar &scalar)

virtual Status Visit(const DurationScalar &scalar)

virtual Status Visit(const Decimal128Scalar &scalar)

virtual Status Visit(const Decimal256Scalar &scalar)

virtual Status Visit(const ListScalar &scalar)

virtual Status Visit(const LargeListScalar &scalar)

virtual Status Visit(const MapScalar &scalar)

virtual Status Visit(const FixedSizeListScalar &scalar)

virtual Status Visit(const StructScalar &scalar)

virtual Status Visit(const DictionaryScalar &scalar)

virtual Status Visit(const SparseUnionScalar &scalar)

virtual Status Visit(const DenseUnionScalar &scalar)

virtual Status Visit(const RunEndEncodedScalar &scalar)

virtual Status Visit(const ExtensionScalar &scalar)