// ParseQuantity turns str into a Quantity, or returns an error.
func ParseQuantity(str string) (*Quantity, error) {
parts := splitRE.FindStringSubmatch(strings.TrimSpace(str))
// regexp returns are entire match, followed by an entry for each () section.
if len(parts) != 3 {
return nil, ErrFormatWrong
}
amount := new(inf.Dec)
if _, ok := amount.SetString(parts[1]); !ok {
return nil, ErrNumeric
}
base, exponent, format, ok := quantitySuffixer.interpret(suffix(parts[2]))
if !ok {
return nil, ErrSuffix
}
// So that no one but us has to think about suffixes, remove it.
if base == 10 {
amount.SetScale(amount.Scale() + Scale(exponent).infScale())
} else if base == 2 {
// numericSuffix = 2 ** exponent
numericSuffix := big.NewInt(1).Lsh(bigOne, uint(exponent))
ub := amount.UnscaledBig()
amount.SetUnscaledBig(ub.Mul(ub, numericSuffix))
}
// Cap at min/max bounds.
sign := amount.Sign()
if sign == -1 {
amount.Neg(amount)
}
// This rounds non-zero values up to the minimum representable value, under the theory that
// if you want some resources, you should get some resources, even if you asked for way too small
// of an amount. Arguably, this should be inf.RoundHalfUp (normal rounding), but that would have
// the side effect of rounding values < .5n to zero.
if v, ok := amount.Unscaled(); v != int64(0) || !ok {
amount.Round(amount, Nano.infScale(), inf.RoundUp)
}
// The max is just a simple cap.
if amount.Cmp(maxAllowed) > 0 {
amount.Set(maxAllowed)
}
if format == BinarySI && amount.Cmp(decOne) < 0 && amount.Cmp(decZero) > 0 {
// This avoids rounding and hopefully confusion, too.
format = DecimalSI
}
if sign == -1 {
amount.Neg(amount)
}
return &Quantity{amount, format}, nil
}
// ParseQuantity turns str into a Quantity, or returns an error.
func ParseQuantity(str string) (Quantity, error) {
if len(str) == 0 {
return Quantity{}, ErrFormatWrong
}
if str == "0" {
return Quantity{Format: DecimalSI, s: str}, nil
}
positive, value, num, denom, suf, err := parseQuantityString(str)
if err != nil {
return Quantity{}, err
}
base, exponent, format, ok := quantitySuffixer.interpret(suffix(suf))
if !ok {
return Quantity{}, ErrSuffix
}
precision := int32(0)
scale := int32(0)
mantissa := int64(1)
switch format {
case DecimalExponent, DecimalSI:
scale = exponent
precision = maxInt64Factors - int32(len(num)+len(denom))
case BinarySI:
scale = 0
switch {
case exponent >= 0 && len(denom) == 0:
// only handle positive binary numbers with the fast path
mantissa = int64(int64(mantissa) << uint64(exponent))
// 1Mi (2^20) has ~6 digits of decimal precision, so exponent*3/10 -1 is roughly the precision
precision = 15 - int32(len(num)) - int32(float32(exponent)*3/10) - 1
default:
precision = -1
}
}
if precision >= 0 {
// if we have a denominator, shift the entire value to the left by the number of places in the
// denominator
scale -= int32(len(denom))
if scale >= int32(Nano) {
shifted := num + denom
var value int64
value, err := strconv.ParseInt(shifted, 10, 64)
if err != nil {
return Quantity{}, ErrNumeric
}
if result, ok := int64Multiply(value, int64(mantissa)); ok {
if !positive {
result = -result
}
// if the number is in canonical form, reuse the string
switch format {
case BinarySI:
if exponent%10 == 0 && (value&0x07 != 0) {
return Quantity{i: int64Amount{value: result, scale: Scale(scale)}, Format: format, s: str}, nil
}
default:
if scale%3 == 0 && !strings.HasSuffix(shifted, "000") && shifted[0] != '0' {
return Quantity{i: int64Amount{value: result, scale: Scale(scale)}, Format: format, s: str}, nil
}
}
return Quantity{i: int64Amount{value: result, scale: Scale(scale)}, Format: format}, nil
}
}
}
amount := new(inf.Dec)
if _, ok := amount.SetString(value); !ok {
return Quantity{}, ErrNumeric
}
// So that no one but us has to think about suffixes, remove it.
if base == 10 {
amount.SetScale(amount.Scale() + Scale(exponent).infScale())
} else if base == 2 {
// numericSuffix = 2 ** exponent
numericSuffix := big.NewInt(1).Lsh(bigOne, uint(exponent))
ub := amount.UnscaledBig()
amount.SetUnscaledBig(ub.Mul(ub, numericSuffix))
}
// Cap at min/max bounds.
sign := amount.Sign()
if sign == -1 {
amount.Neg(amount)
}
// This rounds non-zero values up to the minimum representable value, under the theory that
// if you want some resources, you should get some resources, even if you asked for way too small
// of an amount. Arguably, this should be inf.RoundHalfUp (normal rounding), but that would have
// the side effect of rounding values < .5n to zero.
if v, ok := amount.Unscaled(); v != int64(0) || !ok {
amount.Round(amount, Nano.infScale(), inf.RoundUp)
}
// The max is just a simple cap.
// TODO: this prevents accumulating quantities greater than int64, for instance quota across a cluster
if format == BinarySI && amount.Cmp(maxAllowed.Dec) > 0 {
amount.Set(maxAllowed.Dec)
}
if format == BinarySI && amount.Cmp(decOne) < 0 && amount.Cmp(decZero) > 0 {
// This avoids rounding and hopefully confusion, too.
format = DecimalSI
}
if sign == -1 {
amount.Neg(amount)
}
return Quantity{d: infDecAmount{amount}, Format: format}, nil
}