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Type Dispatcher

Files

file  type_dispatcher.hpp
 Defines the mapping between cudf::type_id runtime type information and concrete C++ types.
 

Classes

struct  cudf::dispatch_storage_type< Id >
 Use this specialization on type_dispatcher whenever you only need to operate on the underlying stored type. More...
 

Macros

#define CUDF_TYPE_MAPPING(Type, Id)
 Macro used to define a mapping between a concrete C++ type and a cudf::type_id enum. More...
 
#define MAP_NUMERIC_SCALAR(Type)
 Macro used to define scalar type and scalar device type for cudf::numeric_scalar template class for numeric C++ types. More...
 
#define MAP_TIMESTAMP_SCALAR(Type)
 Macro used to define scalar type and scalar device type for cudf::timestamp_scalar template class for timestamp C++ types. More...
 
#define MAP_DURATION_SCALAR(Type)
 Macro used to define scalar type and scalar device type for cudf::duration_scalar template class for duration C++ types. More...
 

Typedefs

template<cudf::type_id Id>
using cudf::id_to_type = typename id_to_type_impl< Id >::type
 Maps a cudf::type_id to its corresponding concrete C++ type. More...
 
template<typename T >
using cudf::device_storage_type_t = std::conditional_t< std::is_same_v< numeric::decimal32, T >, int32_t, std::conditional_t< std::is_same_v< numeric::decimal64, T >, int64_t, std::conditional_t< std::is_same_v< numeric::decimal128, T >, __int128_t, T > >>
 "Returns" the corresponding type that is stored on the device when using cudf::column More...
 
template<typename T >
using cudf::scalar_type_t = typename type_to_scalar_type_impl< T >::ScalarType
 Maps a C++ type to the scalar type required to hold its value. More...
 
template<typename T >
using cudf::scalar_device_type_t = typename type_to_scalar_type_impl< T >::ScalarDeviceType
 Maps a C++ type to the scalar device type required to hold its value. More...
 

Functions

template<typename T >
constexpr type_id cudf::type_to_id ()
 Maps a C++ type to its corresponding cudf::type_id More...
 
template<typename T >
constexpr bool cudf::type_id_matches_device_storage_type (type_id id)
 Checks if fixed_point-like types have template type T matching the column's stored type id. More...
 
template<>
constexpr type_id cudf::type_to_id< char > ()
 Specialization to map 'char' type to type_id::INT8. More...
 
template<template< cudf::type_id > typename IdTypeMap = id_to_type_impl, typename Functor , typename... Ts>
CUDF_HOST_DEVICE constexpr decltype(auto) __forceinline__ cudf::type_dispatcher (cudf::data_type dtype, Functor f, Ts &&... args)
 Invokes an operator() template with the type instantiation based on the specified cudf::data_type's id(). More...
 
template<template< cudf::type_id > typename IdTypeMap = id_to_type_impl, typename F , typename... Ts>
CUDF_HOST_DEVICE constexpr decltype(auto) __forceinline__ cudf::double_type_dispatcher (cudf::data_type type1, cudf::data_type type2, F &&f, Ts &&... args)
 Dispatches two type template parameters to a callable. More...
 
std::string cudf::type_to_name (data_type type)
 Return a name for a given type. More...
 

Detailed Description

Macro Definition Documentation

◆ CUDF_TYPE_MAPPING

#define CUDF_TYPE_MAPPING (   Type,
  Id 
)
Value:
template <> \
constexpr inline type_id type_to_id<Type>() \
{ \
return Id; \
} \
template <> \
inline std::string type_to_name_impl::operator()<Type>() \
{ \
return CUDF_STRINGIFY(Type); \
} \
template <> \
struct id_to_type_impl<Id> { \
using type = Type; \
};
#define CUDF_STRINGIFY(x)
Stringify a macro argument.
Definition: error.hpp:147
type_id
Identifies a column's logical element type.
Definition: types.hpp:203

Macro used to define a mapping between a concrete C++ type and a cudf::type_id enum.

Parameters
TypeThe concrete C++ type
IdThe cudf::type_id enum

Definition at line 142 of file type_dispatcher.hpp.

◆ MAP_DURATION_SCALAR

#define MAP_DURATION_SCALAR (   Type)
Value:
template <> \
struct type_to_scalar_type_impl<Type> { \
using ScalarType = cudf::duration_scalar<Type>; \
using ScalarDeviceType = cudf::duration_scalar_device_view<Type>; \
};
A type of scalar_device_view that stores a pointer to a duration value.
An owning class to represent a duration value in device memory.
Definition: scalar.hpp:682

Macro used to define scalar type and scalar device type for cudf::duration_scalar template class for duration C++ types.

Parameters
TypeThe duration C++ type

Definition at line 326 of file type_dispatcher.hpp.

◆ MAP_NUMERIC_SCALAR

#define MAP_NUMERIC_SCALAR (   Type)
Value:
template <> \
struct type_to_scalar_type_impl<Type> { \
using ScalarType = cudf::numeric_scalar<Type>; \
using ScalarDeviceType = cudf::numeric_scalar_device_view<Type>; \
};
A type of scalar_device_view that stores a pointer to a numerical value.
An owning class to represent a numerical value in device memory.
Definition: scalar.hpp:244

Macro used to define scalar type and scalar device type for cudf::numeric_scalar template class for numeric C++ types.

Parameters
TypeThe numeric C++ type

Definition at line 228 of file type_dispatcher.hpp.

◆ MAP_TIMESTAMP_SCALAR

#define MAP_TIMESTAMP_SCALAR (   Type)
Value:
template <> \
struct type_to_scalar_type_impl<Type> { \
using ScalarType = cudf::timestamp_scalar<Type>; \
using ScalarDeviceType = cudf::timestamp_scalar_device_view<Type>; \
};
A type of scalar_device_view that stores a pointer to a timestamp value.
An owning class to represent a timestamp value in device memory.
Definition: scalar.hpp:626

Macro used to define scalar type and scalar device type for cudf::timestamp_scalar template class for timestamp C++ types.

Parameters
TypeThe timestamp C++ type

Definition at line 305 of file type_dispatcher.hpp.

Typedef Documentation

◆ device_storage_type_t

template<typename T >
using cudf::device_storage_type_t = typedef std::conditional_t<std::is_same_v<numeric::decimal32, T>, int32_t, std::conditional_t<std::is_same_v<numeric::decimal64, T>, int64_t, std::conditional_t<std::is_same_v<numeric::decimal128, T>, __int128_t, T> >>

"Returns" the corresponding type that is stored on the device when using cudf::column

For decimal32, the storage type is an int32_t. For decimal64, the storage type is an int64_t. For decimal128, the storage type is an __int128_t.

Use this "type function" with the using type alias:

using Type = device_storage_type_t<Element>;
Template Parameters
TThe literal type that is stored on the host

Definition at line 111 of file type_dispatcher.hpp.

◆ id_to_type

template<cudf::type_id Id>
using cudf::id_to_type = typedef typename id_to_type_impl<Id>::type

Maps a cudf::type_id to its corresponding concrete C++ type.

Example:

static_assert(std::is_same<int32_t, id_to_type<id_type::INT32>);
Template Parameters
tThe cudf::type_id to map

Definition at line 93 of file type_dispatcher.hpp.

◆ scalar_device_type_t

template<typename T >
using cudf::scalar_device_type_t = typedef typename type_to_scalar_type_impl<T>::ScalarDeviceType

Maps a C++ type to the scalar device type required to hold its value.

Template Parameters
TThe concrete C++ type to map

Definition at line 354 of file type_dispatcher.hpp.

◆ scalar_type_t

template<typename T >
using cudf::scalar_type_t = typedef typename type_to_scalar_type_impl<T>::ScalarType

Maps a C++ type to the scalar type required to hold its value.

Template Parameters
TThe concrete C++ type to map

Definition at line 346 of file type_dispatcher.hpp.

Function Documentation

◆ double_type_dispatcher()

template<template< cudf::type_id > typename IdTypeMap = id_to_type_impl, typename F , typename... Ts>
CUDF_HOST_DEVICE constexpr decltype(auto) __forceinline__ cudf::double_type_dispatcher ( cudf::data_type  type1,
cudf::data_type  type2,
F &&  f,
Ts &&...  args 
)
constexpr

Dispatches two type template parameters to a callable.

This function expects a callable f with an operator() template accepting two typename template parameters T1 and T2.

Parameters
type1The data_type used to dispatch a type for the first template parameter of the callable F
type2The data_type used to dispatch a type for the second template parameter of the callable F
fThe callable whose operator() template is invoked
argsParameter pack forwarded to the operator() invocation F.
Returns
The result of invoking f.template operator<T1, T2>(args)

Definition at line 607 of file type_dispatcher.hpp.

◆ type_dispatcher()

template<template< cudf::type_id > typename IdTypeMap = id_to_type_impl, typename Functor , typename... Ts>
CUDF_HOST_DEVICE constexpr decltype(auto) __forceinline__ cudf::type_dispatcher ( cudf::data_type  dtype,
Functor  f,
Ts &&...  args 
)
constexpr

Invokes an operator() template with the type instantiation based on the specified cudf::data_type's id().

Example usage with a functor that returns the size of the dispatched type:

struct size_of_functor{
template <typename T>
int operator()(){
return sizeof(T);
}
};
cudf::data_type t{INT32};
cudf::type_dispatcher(t, size_of_functor{}); // returns 4
Indicator for the logical data type of an element in a column.
Definition: types.hpp:243
CUDF_HOST_DEVICE constexpr decltype(auto) __forceinline__ type_dispatcher(cudf::data_type dtype, Functor f, Ts &&... args)
Invokes an operator() template with the type instantiation based on the specified cudf::data_type's i...

The type_dispatcher uses cudf::type_to_id<t> to provide a default mapping of cudf::type_ids to dispatched C++ types. However, this mapping may be customized by explicitly specifying a user-defined trait struct for the IdTypeMap. For example, to always dispatch int32_t

template<cudf::type_id t> struct always_int{ using type = int32_t; }
// This will always invoke operator()<int32_t>
cudf::type_dispatcher<always_int>(data_type, f);

It is sometimes necessary to customize the dispatched functor's operator() for different types. This can be done in several ways.

The first method is to use explicit template specialization. This is useful for specializing behavior for single types. For example, a functor that prints int32_t or double when invoked with either of those types, else it prints unhandled type:

struct type_printer {
template <typename ColumnType>
void operator()() { std::cout << "unhandled type\n"; }
};
// Due to a bug in g++, explicit member function specializations need to be
// defined outside of the class definition
template <>
void type_printer::operator()<int32_t>() { std::cout << "int32_t\n"; }
template <>
void type_printer::operator()<double>() { std::cout << "double\n"; }

A second method is to use SFINAE with std::enable_if_t. This is useful for specializing for a set of types that share some property. For example, a functor that prints integral or floating point for integral or floating point types:

struct integral_or_floating_point {
template <typename ColumnType,
std::enable_if_t<not std::is_integral_v<ColumnType> and
not std::is_floating_point_v<ColumnType> >* = nullptr>
void operator()() {
std::cout << "neither integral nor floating point\n "; }
template <typename ColumnType,
std::enable_if_t<std::is_integral_v<ColumnType> >* = nullptr>
void operator()() { std::cout << "integral\n"; }
template <typename ColumnType,
std::enable_if_t<std::is_floating_point_v<ColumnType> >* = nullptr>
void operator()() { std::cout << "floating point\n"; }
};

For more info on SFINAE and std::enable_if, see https://eli.thegreenplace.net/2014/sfinae-and-enable_if/

The return type for all template instantiations of the functor's "operator()" lambda must be the same, else there will be a compiler error as you would be trying to return different types from the same function.

Template Parameters
id_to_type_implMaps a cudf::type_id its dispatched C++ type
FunctorThe callable object's type
TsVariadic parameter pack type
Parameters
dtypeThe cudf::data_type whose id() determines which template instantiation is invoked
fThe callable whose operator() template is invoked
argsParameter pack of arguments forwarded to the operator() invocation
Returns
Whatever is returned by the callable's operator()

Definition at line 456 of file type_dispatcher.hpp.

◆ type_id_matches_device_storage_type()

template<typename T >
constexpr bool cudf::type_id_matches_device_storage_type ( type_id  id)
constexpr

Checks if fixed_point-like types have template type T matching the column's stored type id.

Template Parameters
TThe type that is stored on the device
Parameters
idThe data_type::id of the column
Returns
true If T matches the stored column type_id
false If T does not match the stored column type_id

Definition at line 127 of file type_dispatcher.hpp.

◆ type_to_id()

template<typename T >
constexpr type_id cudf::type_to_id ( )
inlineconstexpr

Maps a C++ type to its corresponding cudf::type_id

When explicitly passed a template argument of a given type, returns the appropriate type_id enum for the specified C++ type.

For example:

return cudf::type_to_id<int32_t>(); // Returns INT32
Template Parameters
TThe type to map to a cudf::type_id
Returns
The cudf::type_id corresponding to the specified type

Definition at line 57 of file type_dispatcher.hpp.

◆ type_to_id< char >()

template<>
constexpr type_id cudf::type_to_id< char > ( )
inlineconstexpr

Specialization to map 'char' type to type_id::INT8.

Required when passing device_uvector<char> to column constructor. Possibly can be removed when PR 14202 is merged.

Returns
id for 'char' type

Definition at line 198 of file type_dispatcher.hpp.

◆ type_to_name()

std::string cudf::type_to_name ( data_type  type)

Return a name for a given type.

The returned type names are intended for error messages and are not guaranteed to be stable.

Parameters
typeThe data_type
Returns
Name of the type