opentofu/vendor/github.com/dustin/go-humanize/si.go
James Bardin cfa299d2ee Update deps in unknown state and rever nomad
Nomad was manually updated, so revert that to the version in master,
remove it from vendor.json and add it to the ignore list.

Update all packages that were in an unknown state to their latest master
commits.
2017-01-19 20:10:17 -05:00

114 lines
2.4 KiB
Go

package humanize
import (
"errors"
"math"
"regexp"
"strconv"
)
var siPrefixTable = map[float64]string{
-24: "y", // yocto
-21: "z", // zepto
-18: "a", // atto
-15: "f", // femto
-12: "p", // pico
-9: "n", // nano
-6: "µ", // micro
-3: "m", // milli
0: "",
3: "k", // kilo
6: "M", // mega
9: "G", // giga
12: "T", // tera
15: "P", // peta
18: "E", // exa
21: "Z", // zetta
24: "Y", // yotta
}
var revSIPrefixTable = revfmap(siPrefixTable)
// revfmap reverses the map and precomputes the power multiplier
func revfmap(in map[float64]string) map[string]float64 {
rv := map[string]float64{}
for k, v := range in {
rv[v] = math.Pow(10, k)
}
return rv
}
var riParseRegex *regexp.Regexp
func init() {
ri := `^([\-0-9.]+)\s?([`
for _, v := range siPrefixTable {
ri += v
}
ri += `]?)(.*)`
riParseRegex = regexp.MustCompile(ri)
}
// ComputeSI finds the most appropriate SI prefix for the given number
// and returns the prefix along with the value adjusted to be within
// that prefix.
//
// See also: SI, ParseSI.
//
// e.g. ComputeSI(2.2345e-12) -> (2.2345, "p")
func ComputeSI(input float64) (float64, string) {
if input == 0 {
return 0, ""
}
mag := math.Abs(input)
exponent := math.Floor(logn(mag, 10))
exponent = math.Floor(exponent/3) * 3
value := mag / math.Pow(10, exponent)
// Handle special case where value is exactly 1000.0
// Should return 1M instead of 1000k
if value == 1000.0 {
exponent += 3
value = mag / math.Pow(10, exponent)
}
value = math.Copysign(value, input)
prefix := siPrefixTable[exponent]
return value, prefix
}
// SI returns a string with default formatting.
//
// SI uses Ftoa to format float value, removing trailing zeros.
//
// See also: ComputeSI, ParseSI.
//
// e.g. SI(1000000, B) -> 1MB
// e.g. SI(2.2345e-12, "F") -> 2.2345pF
func SI(input float64, unit string) string {
value, prefix := ComputeSI(input)
return Ftoa(value) + " " + prefix + unit
}
var errInvalid = errors.New("invalid input")
// ParseSI parses an SI string back into the number and unit.
//
// See also: SI, ComputeSI.
//
// e.g. ParseSI(2.2345pF) -> (2.2345e-12, "F", nil)
func ParseSI(input string) (float64, string, error) {
found := riParseRegex.FindStringSubmatch(input)
if len(found) != 4 {
return 0, "", errInvalid
}
mag := revSIPrefixTable[found[2]]
unit := found[3]
base, err := strconv.ParseFloat(found[1], 64)
return base * mag, unit, err
}