Update to github.com/lafriks/xormstore@v1.3.0 (#8317)

vendor/github.com/denisenkom/go-mssqldb/internal/decimal/decimal.go

@@ -0,0 +1,252 @@
+package decimal
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"math"
+	"math/big"
+	"strings"
+)
+
+// Decimal represents decimal type in the Microsoft Open Specifications: http://msdn.microsoft.com/en-us/library/ee780893.aspx
+type Decimal struct {
+	integer  [4]uint32 // Little-endian
+	positive bool
+	prec     uint8
+	scale    uint8
+}
+
+var (
+	scaletblflt64 [39]float64
+	int10         big.Int
+	int1e5        big.Int
+)
+
+func init() {
+	var acc float64 = 1
+	for i := 0; i <= 38; i++ {
+		scaletblflt64[i] = acc
+		acc *= 10
+	}
+
+	int10.SetInt64(10)
+	int1e5.SetInt64(1e5)
+}
+
+const autoScale = 100
+
+// SetInteger sets the ind'th element in the integer array
+func (d *Decimal) SetInteger(integer uint32, ind uint8) {
+	d.integer[ind] = integer
+}
+
+// SetPositive sets the positive member
+func (d *Decimal) SetPositive(positive bool) {
+	d.positive = positive
+}
+
+// SetPrec sets the prec member
+func (d *Decimal) SetPrec(prec uint8) {
+	d.prec = prec
+}
+
+// SetScale sets the scale member
+func (d *Decimal) SetScale(scale uint8) {
+	d.scale = scale
+}
+
+// IsPositive returns true if the Decimal is positive
+func (d *Decimal) IsPositive() bool {
+	return d.positive
+}
+
+// ToFloat64 converts decimal to a float64
+func (d Decimal) ToFloat64() float64 {
+	val := float64(0)
+	for i := 3; i >= 0; i-- {
+		val *= 0x100000000
+		val += float64(d.integer[i])
+	}
+	if !d.positive {
+		val = -val
+	}
+	if d.scale != 0 {
+		val /= scaletblflt64[d.scale]
+	}
+	return val
+}
+
+// BigInt converts decimal to a bigint
+func (d Decimal) BigInt() big.Int {
+	bytes := make([]byte, 16)
+	binary.BigEndian.PutUint32(bytes[0:4], d.integer[3])
+	binary.BigEndian.PutUint32(bytes[4:8], d.integer[2])
+	binary.BigEndian.PutUint32(bytes[8:12], d.integer[1])
+	binary.BigEndian.PutUint32(bytes[12:16], d.integer[0])
+	var x big.Int
+	x.SetBytes(bytes)
+	if !d.positive {
+		x.Neg(&x)
+	}
+	return x
+}
+
+// Bytes converts decimal to a scaled byte slice
+func (d Decimal) Bytes() []byte {
+	x := d.BigInt()
+	return ScaleBytes(x.String(), d.scale)
+}
+
+// UnscaledBytes converts decimal to a unscaled byte slice
+func (d Decimal) UnscaledBytes() []byte {
+	x := d.BigInt()
+	return x.Bytes()
+}
+
+// String converts decimal to a string
+func (d Decimal) String() string {
+	return string(d.Bytes())
+}
+
+// Float64ToDecimal converts float64 to decimal
+func Float64ToDecimal(f float64) (Decimal, error) {
+	return Float64ToDecimalScale(f, autoScale)
+}
+
+// Float64ToDecimalScale converts float64 to decimal; user can specify the scale
+func Float64ToDecimalScale(f float64, scale uint8) (Decimal, error) {
+	var dec Decimal
+	if math.IsNaN(f) {
+		return dec, errors.New("NaN")
+	}
+	if math.IsInf(f, 0) {
+		return dec, errors.New("Infinity can't be converted to decimal")
+	}
+	dec.positive = f >= 0
+	if !dec.positive {
+		f = math.Abs(f)
+	}
+	if f > 3.402823669209385e+38 {
+		return dec, errors.New("Float value is out of range")
+	}
+	dec.prec = 20
+	var integer float64
+	for dec.scale = 0; dec.scale <= scale; dec.scale++ {
+		integer = f * scaletblflt64[dec.scale]
+		_, frac := math.Modf(integer)
+		if frac == 0 && scale == autoScale {
+			break
+		}
+	}
+	for i := 0; i < 4; i++ {
+		mod := math.Mod(integer, 0x100000000)
+		integer -= mod
+		integer /= 0x100000000
+		dec.integer[i] = uint32(mod)
+		if mod-math.Trunc(mod) >= 0.5 {
+			dec.integer[i] = uint32(mod) + 1
+		}
+	}
+	return dec, nil
+}
+
+// Int64ToDecimalScale converts float64 to decimal; user can specify the scale
+func Int64ToDecimalScale(v int64, scale uint8) Decimal {
+	positive := v >= 0
+	if !positive {
+		if v == math.MinInt64 {
+			// Special case - can't negate
+			return Decimal{
+				integer:  [4]uint32{0, 0x80000000, 0, 0},
+				positive: false,
+				prec:     20,
+				scale:    0,
+			}
+		}
+		v = -v
+	}
+	return Decimal{
+		integer:  [4]uint32{uint32(v), uint32(v >> 32), 0, 0},
+		positive: positive,
+		prec:     20,
+		scale:    scale,
+	}
+}
+
+// StringToDecimalScale converts string to decimal
+func StringToDecimalScale(v string, outScale uint8) (Decimal, error) {
+	var r big.Int
+	var unscaled string
+	var inScale int
+
+	point := strings.LastIndexByte(v, '.')
+	if point == -1 {
+		inScale = 0
+		unscaled = v
+	} else {
+		inScale = len(v) - point - 1
+		unscaled = v[:point] + v[point+1:]
+	}
+	if inScale > math.MaxUint8 {
+		return Decimal{}, fmt.Errorf("can't parse %q as a decimal number: scale too large", v)
+	}
+
+	_, ok := r.SetString(unscaled, 10)
+	if !ok {
+		return Decimal{}, fmt.Errorf("can't parse %q as a decimal number", v)
+	}
+
+	if inScale > int(outScale) {
+		return Decimal{}, fmt.Errorf("can't parse %q as a decimal number: scale %d is larger than the scale %d of the target column", v, inScale, outScale)
+	}
+	for inScale < int(outScale) {
+		if int(outScale)-inScale >= 5 {
+			r.Mul(&r, &int1e5)
+			inScale += 5
+		} else {
+			r.Mul(&r, &int10)
+			inScale++
+		}
+	}
+
+	bytes := r.Bytes()
+	if len(bytes) > 16 {
+		return Decimal{}, fmt.Errorf("can't parse %q as a decimal number: precision too large", v)
+	}
+	var out [4]uint32
+	for i, b := range bytes {
+		pos := len(bytes) - i - 1
+		out[pos/4] += uint32(b) << uint(pos%4*8)
+	}
+	return Decimal{
+		integer:  out,
+		positive: r.Sign() >= 0,
+		prec:     20,
+		scale:    uint8(inScale),
+	}, nil
+}
+
+// ScaleBytes converts a stringified decimal to a scaled byte slice
+func ScaleBytes(s string, scale uint8) []byte {
+	z := make([]byte, 0, len(s)+1)
+	if s[0] == '-' || s[0] == '+' {
+		z = append(z, byte(s[0]))
+		s = s[1:]
+	}
+	pos := len(s) - int(scale)
+	if pos <= 0 {
+		z = append(z, byte('0'))
+	} else if pos > 0 {
+		z = append(z, []byte(s[:pos])...)
+	}
+	if scale > 0 {
+		z = append(z, byte('.'))
+		for pos < 0 {
+			z = append(z, byte('0'))
+			pos++
+		}
+		z = append(z, []byte(s[pos:])...)
+	}
+	return z
+}