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decimal.go
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decimal.go
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// Copyright 2022 Dolthub, Inc.
//
// Licensed 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.
package types
import (
"fmt"
"math/big"
"reflect"
"strconv"
"github.com/dolthub/vitess/go/sqltypes"
"github.com/dolthub/vitess/go/vt/proto/query"
"github.com/shopspring/decimal"
"gopkg.in/src-d/go-errors.v1"
"github.com/gabereiser/go-mysql-server/sql"
)
const (
// DecimalTypeMaxPrecision returns the maximum precision allowed for the Decimal type.
DecimalTypeMaxPrecision = 65
// DecimalTypeMaxScale returns the maximum scale allowed for the Decimal type, assuming the
// maximum precision is used. For a maximum scale that is relative to the precision of a given
// decimal type, use its MaximumScale function.
DecimalTypeMaxScale = 30
)
var (
ErrConvertingToDecimal = errors.NewKind("value %v is not a valid Decimal")
ErrConvertToDecimalLimit = errors.NewKind("Out of range value for column of Decimal type ")
ErrMarshalNullDecimal = errors.NewKind("Decimal cannot marshal a null value")
decimalValueType = reflect.TypeOf(decimal.Decimal{})
)
type DecimalType_ struct {
exclusiveUpperBound decimal.Decimal
definesColumn bool
precision uint8
scale uint8
}
// InternalDecimalType is a special DecimalType that is used internally for Decimal comparisons. Not intended for usage
// from integrators.
var InternalDecimalType sql.DecimalType = DecimalType_{
exclusiveUpperBound: decimal.New(1, int32(65)),
definesColumn: false,
precision: 95,
scale: 30,
}
// CreateDecimalType creates a DecimalType for NON-TABLE-COLUMN.
func CreateDecimalType(precision uint8, scale uint8) (sql.DecimalType, error) {
return createDecimalType(precision, scale, false)
}
// CreateColumnDecimalType creates a DecimalType for VALID-TABLE-COLUMN. Creating a decimal type for a column ensures that
// when operating on instances of this type, the result will be restricted to the defined precision and scale.
func CreateColumnDecimalType(precision uint8, scale uint8) (sql.DecimalType, error) {
return createDecimalType(precision, scale, true)
}
// createDecimalType creates a DecimalType using given precision, scale
// and whether this type defines a valid table column.
func createDecimalType(precision uint8, scale uint8, definesColumn bool) (sql.DecimalType, error) {
if scale > DecimalTypeMaxScale {
return nil, fmt.Errorf("Too big scale %v specified. Maximum is %v.", scale, DecimalTypeMaxScale)
}
if precision > DecimalTypeMaxPrecision {
return nil, fmt.Errorf("Too big precision %v specified. Maximum is %v.", precision, DecimalTypeMaxPrecision)
}
if scale > precision {
return nil, fmt.Errorf("Scale %v cannot be larger than the precision %v", scale, precision)
}
if precision == 0 {
precision = 10
}
return DecimalType_{
exclusiveUpperBound: decimal.New(1, int32(precision-scale)),
definesColumn: definesColumn,
precision: precision,
scale: scale,
}, nil
}
// MustCreateDecimalType is the same as CreateDecimalType except it panics on errors and for NON-TABLE-COLUMN.
func MustCreateDecimalType(precision uint8, scale uint8) sql.DecimalType {
dt, err := CreateDecimalType(precision, scale)
if err != nil {
panic(err)
}
return dt
}
// MustCreateColumnDecimalType is the same as CreateDecimalType except it panics on errors and for VALID-TABLE-COLUMN.
func MustCreateColumnDecimalType(precision uint8, scale uint8) sql.DecimalType {
dt, err := CreateColumnDecimalType(precision, scale)
if err != nil {
panic(err)
}
return dt
}
// Type implements Type interface.
func (t DecimalType_) Type() query.Type {
return sqltypes.Decimal
}
// Compare implements Type interface.
func (t DecimalType_) Compare(a interface{}, b interface{}) (int, error) {
if hasNulls, res := CompareNulls(a, b); hasNulls {
return res, nil
}
af, err := t.ConvertToNullDecimal(a)
if err != nil {
return 0, err
}
bf, err := t.ConvertToNullDecimal(b)
if err != nil {
return 0, err
}
return af.Decimal.Cmp(bf.Decimal), nil
}
// Convert implements Type interface.
func (t DecimalType_) Convert(v interface{}) (interface{}, error) {
dec, err := t.ConvertToNullDecimal(v)
if err != nil {
return nil, err
}
if !dec.Valid {
return nil, nil
}
return t.BoundsCheck(dec.Decimal)
}
func (t DecimalType_) ConvertNoBoundsCheck(v interface{}) (decimal.Decimal, error) {
dec, err := t.ConvertToNullDecimal(v)
if err != nil {
return decimal.Decimal{}, err
}
if !dec.Valid {
return decimal.Decimal{}, nil
}
return dec.Decimal, nil
}
// ConvertToNullDecimal implements DecimalType interface.
func (t DecimalType_) ConvertToNullDecimal(v interface{}) (decimal.NullDecimal, error) {
if v == nil {
return decimal.NullDecimal{}, nil
}
var res decimal.Decimal
switch value := v.(type) {
case int:
return t.ConvertToNullDecimal(int64(value))
case uint:
return t.ConvertToNullDecimal(uint64(value))
case int8:
return t.ConvertToNullDecimal(int64(value))
case uint8:
return t.ConvertToNullDecimal(uint64(value))
case int16:
return t.ConvertToNullDecimal(int64(value))
case uint16:
return t.ConvertToNullDecimal(uint64(value))
case int32:
res = decimal.NewFromInt32(value)
case uint32:
return t.ConvertToNullDecimal(uint64(value))
case int64:
res = decimal.NewFromInt(value)
case uint64:
res = decimal.NewFromBigInt(new(big.Int).SetUint64(value), 0)
case float32:
res = decimal.NewFromFloat32(value)
case float64:
res = decimal.NewFromFloat(value)
case string:
var err error
res, err = decimal.NewFromString(value)
if err != nil {
// The decimal library cannot handle all of the different formats
bf, _, err := new(big.Float).SetPrec(217).Parse(value, 0)
if err != nil {
return decimal.NullDecimal{}, err
}
res, err = decimal.NewFromString(bf.Text('f', -1))
if err != nil {
return decimal.NullDecimal{}, err
}
}
case *big.Float:
return t.ConvertToNullDecimal(value.Text('f', -1))
case *big.Int:
return t.ConvertToNullDecimal(value.Text(10))
case *big.Rat:
return t.ConvertToNullDecimal(new(big.Float).SetRat(value))
case decimal.Decimal:
res = value
case []uint8:
val, err := strconv.ParseFloat(string(value), 64)
if err != nil {
return decimal.NullDecimal{}, err
}
res = decimal.NewFromFloat(val)
case decimal.NullDecimal:
// This is the equivalent of passing in a nil
if !value.Valid {
return decimal.NullDecimal{}, nil
}
res = value.Decimal
case JSONDocument:
return t.ConvertToNullDecimal(value.Val)
default:
return decimal.NullDecimal{}, ErrConvertingToDecimal.New(v)
}
return decimal.NullDecimal{Decimal: res, Valid: true}, nil
}
func (t DecimalType_) BoundsCheck(v decimal.Decimal) (decimal.Decimal, error) {
if -v.Exponent() > int32(t.scale) {
// TODO : add 'Data truncated' warning
v = v.Round(int32(t.scale))
}
// TODO add shortcut for common case
// ex: certain num of bits fast tracks OK
if !v.Abs().LessThan(t.exclusiveUpperBound) {
return decimal.Decimal{}, ErrConvertToDecimalLimit.New()
}
return v, nil
}
// MustConvert implements the Type interface.
func (t DecimalType_) MustConvert(v interface{}) interface{} {
value, err := t.Convert(v)
if err != nil {
panic(err)
}
return value
}
// Equals implements the Type interface.
func (t DecimalType_) Equals(otherType sql.Type) bool {
if ot, ok := otherType.(DecimalType_); ok {
return t.precision == ot.precision && t.scale == ot.scale
}
return false
}
// MaxTextResponseByteLength implements the Type interface
func (t DecimalType_) MaxTextResponseByteLength() uint32 {
if t.scale == 0 {
// if no digits are reserved for the right-hand side of the decimal point,
// just return precision plus one byte for sign
return uint32(t.precision + 1)
} else {
// otherwise return precision plus one byte for sign plus one byte for the decimal point
return uint32(t.precision + 2)
}
}
// Promote implements the Type interface.
func (t DecimalType_) Promote() sql.Type {
if t.definesColumn {
return MustCreateColumnDecimalType(DecimalTypeMaxPrecision, t.scale)
}
return MustCreateDecimalType(DecimalTypeMaxPrecision, t.scale)
}
// SQL implements Type interface.
func (t DecimalType_) SQL(ctx *sql.Context, dest []byte, v interface{}) (sqltypes.Value, error) {
if v == nil {
return sqltypes.NULL, nil
}
value, err := t.ConvertToNullDecimal(v)
if err != nil {
return sqltypes.Value{}, err
}
// decimal type value for valid table column should use scale defined by the column.
// if the value is not part of valid table column, the result value should used its
// own precision and scale.
var val []byte
if t.definesColumn {
val = AppendAndSliceString(dest, value.Decimal.StringFixed(int32(t.scale)))
} else {
decStr := value.Decimal.StringFixed(value.Decimal.Exponent() * -1)
val = AppendAndSliceString(dest, decStr)
}
return sqltypes.MakeTrusted(sqltypes.Decimal, val), nil
}
// String implements Type interface.
func (t DecimalType_) String() string {
return fmt.Sprintf("decimal(%v,%v)", t.precision, t.scale)
}
// ValueType implements Type interface.
func (t DecimalType_) ValueType() reflect.Type {
return decimalValueType
}
// Zero implements Type interface.
func (t DecimalType_) Zero() interface{} {
return decimal.NewFromInt(0)
}
// ExclusiveUpperBound implements DecimalType interface.
func (t DecimalType_) ExclusiveUpperBound() decimal.Decimal {
return t.exclusiveUpperBound
}
// MaximumScale implements DecimalType interface.
func (t DecimalType_) MaximumScale() uint8 {
if t.precision >= DecimalTypeMaxScale {
return DecimalTypeMaxScale
}
return t.precision
}
// Precision implements DecimalType interface.
func (t DecimalType_) Precision() uint8 {
return t.precision
}
// Scale implements DecimalType interface.
func (t DecimalType_) Scale() uint8 {
return t.scale
}