/
cast.go
587 lines (494 loc) · 19.6 KB
/
cast.go
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// 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.
//go:build go1.18
package compute
import (
"context"
"fmt"
"sync"
"github.com/apache/arrow/go/v14/arrow"
"github.com/apache/arrow/go/v14/arrow/array"
"github.com/apache/arrow/go/v14/arrow/bitutil"
"github.com/apache/arrow/go/v14/arrow/compute/exec"
"github.com/apache/arrow/go/v14/arrow/compute/internal/kernels"
)
var (
castTable map[arrow.Type]*castFunction
castInit sync.Once
castDoc = FunctionDoc{
Summary: "cast values to another data type",
Description: "Behavior when values wouldn't fit in the target type\ncan be controlled through CastOptions.",
ArgNames: []string{"input"},
OptionsType: "CastOptions",
OptionsRequired: true,
}
castMetaFunc = NewMetaFunction("cast", Unary(), castDoc,
func(ctx context.Context, fo FunctionOptions, d ...Datum) (Datum, error) {
castOpts := fo.(*CastOptions)
if castOpts == nil || castOpts.ToType == nil {
return nil, fmt.Errorf("%w: cast requires that options be passed with a ToType", arrow.ErrInvalid)
}
if arrow.TypeEqual(d[0].(ArrayLikeDatum).Type(), castOpts.ToType) {
return NewDatum(d[0]), nil
}
fn, err := getCastFunction(castOpts.ToType)
if err != nil {
return nil, fmt.Errorf("%w from %s", err, d[0].(ArrayLikeDatum).Type())
}
return fn.Execute(ctx, fo, d...)
})
)
func RegisterScalarCast(reg FunctionRegistry) {
reg.AddFunction(castMetaFunc, false)
}
type castFunction struct {
ScalarFunction
inIDs []arrow.Type
out arrow.Type
}
func newCastFunction(name string, outType arrow.Type) *castFunction {
return &castFunction{
ScalarFunction: *NewScalarFunction(name, Unary(), EmptyFuncDoc),
out: outType,
inIDs: make([]arrow.Type, 0, 1),
}
}
func (cf *castFunction) AddTypeCast(in arrow.Type, kernel exec.ScalarKernel) error {
kernel.Init = exec.OptionsInit[kernels.CastState]
if err := cf.AddKernel(kernel); err != nil {
return err
}
cf.inIDs = append(cf.inIDs, in)
return nil
}
func (cf *castFunction) AddNewTypeCast(inID arrow.Type, inTypes []exec.InputType, out exec.OutputType,
ex exec.ArrayKernelExec, nullHandle exec.NullHandling, memAlloc exec.MemAlloc) error {
kn := exec.NewScalarKernel(inTypes, out, ex, nil)
kn.NullHandling = nullHandle
kn.MemAlloc = memAlloc
return cf.AddTypeCast(inID, kn)
}
func (cf *castFunction) DispatchExact(vals ...arrow.DataType) (exec.Kernel, error) {
if err := cf.checkArity(len(vals)); err != nil {
return nil, err
}
candidates := make([]*exec.ScalarKernel, 0, 1)
for i := range cf.kernels {
if cf.kernels[i].Signature.MatchesInputs(vals) {
candidates = append(candidates, &cf.kernels[i])
}
}
if len(candidates) == 0 {
return nil, fmt.Errorf("%w: unsupported cast from %s to %s using function %s",
arrow.ErrNotImplemented, vals[0], cf.out, cf.name)
}
if len(candidates) == 1 {
// one match!
return candidates[0], nil
}
// in this situation we may have both an EXACT type and
// a SAME_TYPE_ID match. So we will see if there is an exact
// match among the candidates and if not, we just return the
// first one
for _, k := range candidates {
arg0 := k.Signature.InputTypes[0]
if arg0.Kind == exec.InputExact {
// found one!
return k, nil
}
}
// just return some kernel that matches since we didn't find an exact
return candidates[0], nil
}
func unpackDictionary(ctx *exec.KernelCtx, batch *exec.ExecSpan, out *exec.ExecResult) error {
var (
dictArr = batch.Values[0].Array.MakeArray().(*array.Dictionary)
opts = ctx.State.(kernels.CastState)
dictType = dictArr.DataType().(*arrow.DictionaryType)
toType = opts.ToType
)
defer dictArr.Release()
if !arrow.TypeEqual(toType, dictType) && !CanCast(dictType, toType) {
return fmt.Errorf("%w: cast type %s incompatible with dictionary type %s",
arrow.ErrInvalid, toType, dictType)
}
unpacked, err := TakeArray(ctx.Ctx, dictArr.Dictionary(), dictArr.Indices())
if err != nil {
return err
}
defer unpacked.Release()
if !arrow.TypeEqual(dictType, toType) {
unpacked, err = CastArray(ctx.Ctx, unpacked, &opts)
if err != nil {
return err
}
defer unpacked.Release()
}
out.TakeOwnership(unpacked.Data())
return nil
}
func CastFromExtension(ctx *exec.KernelCtx, batch *exec.ExecSpan, out *exec.ExecResult) error {
opts := ctx.State.(kernels.CastState)
arr := batch.Values[0].Array.MakeArray().(array.ExtensionArray)
defer arr.Release()
castOpts := CastOptions(opts)
result, err := CastArray(ctx.Ctx, arr.Storage(), &castOpts)
if err != nil {
return err
}
defer result.Release()
out.TakeOwnership(result.Data())
return nil
}
func CastList[SrcOffsetT, DestOffsetT int32 | int64](ctx *exec.KernelCtx, batch *exec.ExecSpan, out *exec.ExecResult) error {
var (
opts = ctx.State.(kernels.CastState)
childType = out.Type.(arrow.NestedType).Fields()[0].Type
input = &batch.Values[0].Array
offsets = exec.GetSpanOffsets[SrcOffsetT](input, 1)
isDowncast = kernels.SizeOf[SrcOffsetT]() > kernels.SizeOf[DestOffsetT]()
)
out.Buffers[0] = input.Buffers[0]
out.Buffers[1] = input.Buffers[1]
if input.Offset != 0 && len(input.Buffers[0].Buf) > 0 {
out.Buffers[0].WrapBuffer(ctx.AllocateBitmap(input.Len))
bitutil.CopyBitmap(input.Buffers[0].Buf, int(input.Offset), int(input.Len),
out.Buffers[0].Buf, 0)
}
// Handle list offsets
// Several cases possible:
// - The source offset is non-zero, in which case we slice the
// underlying values and shift the list offsets (regardless of
// their respective types)
// - the source offset is zero but the source and destination types
// have different list offset types, in which case we cast the offsets
// - otherwise we simply keep the original offsets
if isDowncast {
if offsets[input.Len] > SrcOffsetT(kernels.MaxOf[DestOffsetT]()) {
return fmt.Errorf("%w: array of type %s too large to convert to %s",
arrow.ErrInvalid, input.Type, out.Type)
}
}
values := input.Children[0].MakeArray()
defer values.Release()
if input.Offset != 0 {
out.Buffers[1].WrapBuffer(
ctx.Allocate(out.Type.(arrow.OffsetsDataType).
OffsetTypeTraits().BytesRequired(int(input.Len) + 1)))
shiftedOffsets := exec.GetSpanOffsets[DestOffsetT](out, 1)
for i := 0; i < int(input.Len)+1; i++ {
shiftedOffsets[i] = DestOffsetT(offsets[i] - offsets[0])
}
values = array.NewSlice(values, int64(offsets[0]), int64(offsets[input.Len]))
defer values.Release()
} else if kernels.SizeOf[SrcOffsetT]() != kernels.SizeOf[DestOffsetT]() {
out.Buffers[1].WrapBuffer(ctx.Allocate(out.Type.(arrow.OffsetsDataType).
OffsetTypeTraits().BytesRequired(int(input.Len) + 1)))
kernels.DoStaticCast(exec.GetSpanOffsets[SrcOffsetT](input, 1),
exec.GetSpanOffsets[DestOffsetT](out, 1))
}
// handle values
opts.ToType = childType
castedValues, err := CastArray(ctx.Ctx, values, &opts)
if err != nil {
return err
}
defer castedValues.Release()
out.Children = make([]exec.ArraySpan, 1)
out.Children[0].SetMembers(castedValues.Data())
for i, b := range out.Children[0].Buffers {
if b.Owner != nil && b.Owner != values.Data().Buffers()[i] {
b.Owner.Retain()
b.SelfAlloc = true
}
}
return nil
}
func CastStruct(ctx *exec.KernelCtx, batch *exec.ExecSpan, out *exec.ExecResult) error {
var (
opts = ctx.State.(kernels.CastState)
inType = batch.Values[0].Array.Type.(*arrow.StructType)
outType = out.Type.(*arrow.StructType)
inFieldCount = len(inType.Fields())
outFieldCount = len(outType.Fields())
)
fieldsToSelect := make([]int, outFieldCount)
for i := range fieldsToSelect {
fieldsToSelect[i] = -1
}
outFieldIndex := 0
for inFieldIndex := 0; inFieldIndex < inFieldCount && outFieldIndex < outFieldCount; inFieldIndex++ {
inField := inType.Field(inFieldIndex)
outField := outType.Field(outFieldIndex)
if inField.Name == outField.Name {
if inField.Nullable && !outField.Nullable {
return fmt.Errorf("%w: cannot cast nullable field to non-nullable field: %s %s",
arrow.ErrType, inType, outType)
}
fieldsToSelect[outFieldIndex] = inFieldIndex
outFieldIndex++
}
}
if outFieldIndex < outFieldCount {
return fmt.Errorf("%w: struct fields don't match or are in the wrong order: Input: %s Output: %s",
arrow.ErrType, inType, outType)
}
input := &batch.Values[0].Array
if len(input.Buffers[0].Buf) > 0 {
out.Buffers[0].WrapBuffer(ctx.AllocateBitmap(input.Len))
bitutil.CopyBitmap(input.Buffers[0].Buf, int(input.Offset), int(input.Len),
out.Buffers[0].Buf, 0)
}
out.Children = make([]exec.ArraySpan, outFieldCount)
for outFieldIndex, idx := range fieldsToSelect {
values := input.Children[idx].MakeArray()
defer values.Release()
values = array.NewSlice(values, input.Offset, input.Len)
defer values.Release()
opts.ToType = outType.Field(outFieldIndex).Type
castedValues, err := CastArray(ctx.Ctx, values, &opts)
if err != nil {
return err
}
defer castedValues.Release()
out.Children[outFieldIndex].TakeOwnership(castedValues.Data())
}
return nil
}
func addListCast[SrcOffsetT, DestOffsetT int32 | int64](fn *castFunction, inType arrow.Type) error {
kernel := exec.NewScalarKernel([]exec.InputType{exec.NewIDInput(inType)},
kernels.OutputTargetType, CastList[SrcOffsetT, DestOffsetT], nil)
kernel.NullHandling = exec.NullComputedNoPrealloc
kernel.MemAlloc = exec.MemNoPrealloc
return fn.AddTypeCast(inType, kernel)
}
func addStructToStructCast(fn *castFunction) error {
kernel := exec.NewScalarKernel([]exec.InputType{exec.NewIDInput(arrow.STRUCT)},
kernels.OutputTargetType, CastStruct, nil)
kernel.NullHandling = exec.NullComputedNoPrealloc
return fn.AddTypeCast(arrow.STRUCT, kernel)
}
func addCastFuncs(fn []*castFunction) {
for _, f := range fn {
f.AddNewTypeCast(arrow.EXTENSION, []exec.InputType{exec.NewIDInput(arrow.EXTENSION)},
f.kernels[0].Signature.OutType, CastFromExtension,
exec.NullComputedNoPrealloc, exec.MemNoPrealloc)
castTable[f.out] = f
}
}
func initCastTable() {
castTable = make(map[arrow.Type]*castFunction)
addCastFuncs(getBooleanCasts())
addCastFuncs(getNumericCasts())
addCastFuncs(getBinaryLikeCasts())
addCastFuncs(getTemporalCasts())
addCastFuncs(getNestedCasts())
nullToExt := newCastFunction("cast_extension", arrow.EXTENSION)
nullToExt.AddNewTypeCast(arrow.NULL, []exec.InputType{exec.NewExactInput(arrow.Null)},
kernels.OutputTargetType, kernels.CastFromNull, exec.NullComputedNoPrealloc, exec.MemNoPrealloc)
castTable[arrow.EXTENSION] = nullToExt
}
func getCastFunction(to arrow.DataType) (*castFunction, error) {
castInit.Do(initCastTable)
fn, ok := castTable[to.ID()]
if ok {
return fn, nil
}
return nil, fmt.Errorf("%w: unsupported cast to %s", arrow.ErrNotImplemented, to)
}
func getNestedCasts() []*castFunction {
out := make([]*castFunction, 0)
addKernels := func(fn *castFunction, kernels []exec.ScalarKernel) {
for _, k := range kernels {
if err := fn.AddTypeCast(k.Signature.InputTypes[0].MatchID(), k); err != nil {
panic(err)
}
}
}
castLists := newCastFunction("cast_list", arrow.LIST)
addKernels(castLists, kernels.GetCommonCastKernels(arrow.LIST, kernels.OutputTargetType))
if err := addListCast[int32, int32](castLists, arrow.LIST); err != nil {
panic(err)
}
if err := addListCast[int64, int32](castLists, arrow.LARGE_LIST); err != nil {
panic(err)
}
out = append(out, castLists)
castLargeLists := newCastFunction("cast_large_list", arrow.LARGE_LIST)
addKernels(castLargeLists, kernels.GetCommonCastKernels(arrow.LARGE_LIST, kernels.OutputTargetType))
if err := addListCast[int32, int64](castLargeLists, arrow.LIST); err != nil {
panic(err)
}
if err := addListCast[int64, int64](castLargeLists, arrow.LARGE_LIST); err != nil {
panic(err)
}
out = append(out, castLargeLists)
castFsl := newCastFunction("cast_fixed_size_list", arrow.FIXED_SIZE_LIST)
addKernels(castFsl, kernels.GetCommonCastKernels(arrow.FIXED_SIZE_LIST, kernels.OutputTargetType))
out = append(out, castFsl)
castStruct := newCastFunction("cast_struct", arrow.STRUCT)
addKernels(castStruct, kernels.GetCommonCastKernels(arrow.STRUCT, kernels.OutputTargetType))
if err := addStructToStructCast(castStruct); err != nil {
panic(err)
}
out = append(out, castStruct)
return out
}
func getBooleanCasts() []*castFunction {
fn := newCastFunction("cast_boolean", arrow.BOOL)
kns := kernels.GetBooleanCastKernels()
for _, k := range kns {
if err := fn.AddTypeCast(k.Signature.InputTypes[0].Type.ID(), k); err != nil {
panic(err)
}
}
return []*castFunction{fn}
}
func getTemporalCasts() []*castFunction {
output := make([]*castFunction, 0)
addFn := func(name string, id arrow.Type, kernels []exec.ScalarKernel) {
fn := newCastFunction(name, id)
for _, k := range kernels {
if err := fn.AddTypeCast(k.Signature.InputTypes[0].MatchID(), k); err != nil {
panic(err)
}
}
fn.AddNewTypeCast(arrow.DICTIONARY, []exec.InputType{exec.NewIDInput(arrow.DICTIONARY)},
kernels[0].Signature.OutType, unpackDictionary, exec.NullComputedNoPrealloc, exec.MemNoPrealloc)
output = append(output, fn)
}
addFn("cast_timestamp", arrow.TIMESTAMP, kernels.GetTimestampCastKernels())
addFn("cast_date32", arrow.DATE32, kernels.GetDate32CastKernels())
addFn("cast_date64", arrow.DATE64, kernels.GetDate64CastKernels())
addFn("cast_time32", arrow.TIME32, kernels.GetTime32CastKernels())
addFn("cast_time64", arrow.TIME64, kernels.GetTime64CastKernels())
addFn("cast_duration", arrow.DURATION, kernels.GetDurationCastKernels())
addFn("cast_month_day_nano_interval", arrow.INTERVAL_MONTH_DAY_NANO, kernels.GetIntervalCastKernels())
return output
}
func getNumericCasts() []*castFunction {
out := make([]*castFunction, 0)
getFn := func(name string, ty arrow.Type, kns []exec.ScalarKernel) *castFunction {
fn := newCastFunction(name, ty)
for _, k := range kns {
if err := fn.AddTypeCast(k.Signature.InputTypes[0].MatchID(), k); err != nil {
panic(err)
}
}
fn.AddNewTypeCast(arrow.DICTIONARY, []exec.InputType{exec.NewIDInput(arrow.DICTIONARY)},
kns[0].Signature.OutType, unpackDictionary, exec.NullComputedNoPrealloc, exec.MemNoPrealloc)
return fn
}
out = append(out, getFn("cast_int8", arrow.INT8, kernels.GetCastToInteger[int8](arrow.PrimitiveTypes.Int8)))
out = append(out, getFn("cast_int16", arrow.INT16, kernels.GetCastToInteger[int8](arrow.PrimitiveTypes.Int16)))
castInt32 := getFn("cast_int32", arrow.INT32, kernels.GetCastToInteger[int32](arrow.PrimitiveTypes.Int32))
castInt32.AddTypeCast(arrow.DATE32,
kernels.GetZeroCastKernel(arrow.DATE32,
exec.NewExactInput(arrow.FixedWidthTypes.Date32),
exec.NewOutputType(arrow.PrimitiveTypes.Int32)))
castInt32.AddTypeCast(arrow.TIME32,
kernels.GetZeroCastKernel(arrow.TIME32,
exec.NewIDInput(arrow.TIME32), exec.NewOutputType(arrow.PrimitiveTypes.Int32)))
out = append(out, castInt32)
castInt64 := getFn("cast_int64", arrow.INT64, kernels.GetCastToInteger[int64](arrow.PrimitiveTypes.Int64))
castInt64.AddTypeCast(arrow.DATE64,
kernels.GetZeroCastKernel(arrow.DATE64,
exec.NewIDInput(arrow.DATE64),
exec.NewOutputType(arrow.PrimitiveTypes.Int64)))
castInt64.AddTypeCast(arrow.TIME64,
kernels.GetZeroCastKernel(arrow.TIME64,
exec.NewIDInput(arrow.TIME64),
exec.NewOutputType(arrow.PrimitiveTypes.Int64)))
castInt64.AddTypeCast(arrow.DURATION,
kernels.GetZeroCastKernel(arrow.DURATION,
exec.NewIDInput(arrow.DURATION),
exec.NewOutputType(arrow.PrimitiveTypes.Int64)))
castInt64.AddTypeCast(arrow.TIMESTAMP,
kernels.GetZeroCastKernel(arrow.TIMESTAMP,
exec.NewIDInput(arrow.TIMESTAMP),
exec.NewOutputType(arrow.PrimitiveTypes.Int64)))
out = append(out, castInt64)
out = append(out, getFn("cast_uint8", arrow.UINT8, kernels.GetCastToInteger[uint8](arrow.PrimitiveTypes.Uint8)))
out = append(out, getFn("cast_uint16", arrow.UINT16, kernels.GetCastToInteger[uint16](arrow.PrimitiveTypes.Uint16)))
out = append(out, getFn("cast_uint32", arrow.UINT32, kernels.GetCastToInteger[uint32](arrow.PrimitiveTypes.Uint32)))
out = append(out, getFn("cast_uint64", arrow.UINT64, kernels.GetCastToInteger[uint64](arrow.PrimitiveTypes.Uint64)))
out = append(out, getFn("cast_half_float", arrow.FLOAT16, kernels.GetCommonCastKernels(arrow.FLOAT16, exec.NewOutputType(arrow.FixedWidthTypes.Float16))))
out = append(out, getFn("cast_float", arrow.FLOAT32, kernels.GetCastToFloating[float32](arrow.PrimitiveTypes.Float32)))
out = append(out, getFn("cast_double", arrow.FLOAT64, kernels.GetCastToFloating[float64](arrow.PrimitiveTypes.Float64)))
// cast to decimal128
out = append(out, getFn("cast_decimal", arrow.DECIMAL128, kernels.GetCastToDecimal128()))
// cast to decimal256
out = append(out, getFn("cast_decimal256", arrow.DECIMAL256, kernels.GetCastToDecimal256()))
return out
}
func getBinaryLikeCasts() []*castFunction {
out := make([]*castFunction, 0)
addFn := func(name string, ty arrow.Type, kns []exec.ScalarKernel) {
fn := newCastFunction(name, ty)
for _, k := range kns {
if err := fn.AddTypeCast(k.Signature.InputTypes[0].MatchID(), k); err != nil {
panic(err)
}
}
fn.AddNewTypeCast(arrow.DICTIONARY, []exec.InputType{exec.NewIDInput(arrow.DICTIONARY)},
kns[0].Signature.OutType, unpackDictionary, exec.NullComputedNoPrealloc, exec.MemNoPrealloc)
out = append(out, fn)
}
addFn("cast_binary", arrow.BINARY, kernels.GetToBinaryKernels(arrow.BinaryTypes.Binary))
addFn("cast_large_binary", arrow.LARGE_BINARY, kernels.GetToBinaryKernels(arrow.BinaryTypes.LargeBinary))
addFn("cast_string", arrow.STRING, kernels.GetToBinaryKernels(arrow.BinaryTypes.String))
addFn("cast_large_string", arrow.LARGE_STRING, kernels.GetToBinaryKernels(arrow.BinaryTypes.LargeString))
addFn("cast_fixed_sized_binary", arrow.FIXED_SIZE_BINARY, kernels.GetFsbCastKernels())
return out
}
// CastDatum is a convenience function for casting a Datum to another type.
// It is equivalent to calling CallFunction(ctx, "cast", opts, Datum) and
// should work for Scalar, Array or ChunkedArray Datums.
func CastDatum(ctx context.Context, val Datum, opts *CastOptions) (Datum, error) {
return CallFunction(ctx, "cast", opts, val)
}
// CastArray is a convenience function for casting an Array to another type.
// It is equivalent to constructing a Datum for the array and using
// CallFunction(ctx, "cast", ...).
func CastArray(ctx context.Context, val arrow.Array, opts *CastOptions) (arrow.Array, error) {
d := NewDatum(val)
defer d.Release()
out, err := CastDatum(ctx, d, opts)
if err != nil {
return nil, err
}
defer out.Release()
return out.(*ArrayDatum).MakeArray(), nil
}
// CastToType is a convenience function equivalent to calling
// CastArray(ctx, val, compute.SafeCastOptions(toType))
func CastToType(ctx context.Context, val arrow.Array, toType arrow.DataType) (arrow.Array, error) {
return CastArray(ctx, val, SafeCastOptions(toType))
}
// CanCast returns true if there is an implementation for casting an array
// or scalar value from the specified DataType to the other data type.
func CanCast(from, to arrow.DataType) bool {
fn, err := getCastFunction(to)
if err != nil {
return false
}
for _, id := range fn.inIDs {
if from.ID() == id {
return true
}
}
return false
}