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|
package units
import (
"errors"
"fmt"
"strings"
)
var (
siUnits = []string{"", "K", "M", "G", "T", "P", "E"}
)
func ToString(n int64, scale int64, suffix, baseSuffix string) string {
mn := len(siUnits)
out := make([]string, mn)
for i, m := range siUnits {
if n%scale != 0 || i == 0 && n == 0 {
s := suffix
if i == 0 {
s = baseSuffix
}
out[mn-1-i] = fmt.Sprintf("%d%s%s", n%scale, m, s)
}
n /= scale
if n == 0 {
break
}
}
return strings.Join(out, "")
}
// Below code ripped straight from http://golang.org/src/pkg/time/format.go?s=33392:33438#L1123
var errLeadingInt = errors.New("units: bad [0-9]*") // never printed
// leadingInt consumes the leading [0-9]* from s.
func leadingInt(s string) (x int64, rem string, err error) {
i := 0
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if x >= (1<<63-10)/10 {
// overflow
return 0, "", errLeadingInt
}
x = x*10 + int64(c) - '0'
}
return x, s[i:], nil
}
func ParseUnit(s string, unitMap map[string]float64) (int64, error) {
// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
orig := s
f := float64(0)
neg := false
// Consume [-+]?
if s != "" {
c := s[0]
if c == '-' || c == '+' {
neg = c == '-'
s = s[1:]
}
}
// Special case: if all that is left is "0", this is zero.
if s == "0" {
return 0, nil
}
if s == "" {
return 0, errors.New("units: invalid " + orig)
}
for s != "" {
g := float64(0) // this element of the sequence
var x int64
var err error
// The next character must be [0-9.]
if !(s[0] == '.' || ('0' <= s[0] && s[0] <= '9')) {
return 0, errors.New("units: invalid " + orig)
}
// Consume [0-9]*
pl := len(s)
x, s, err = leadingInt(s)
if err != nil {
return 0, errors.New("units: invalid " + orig)
}
g = float64(x)
pre := pl != len(s) // whether we consumed anything before a period
// Consume (\.[0-9]*)?
post := false
if s != "" && s[0] == '.' {
s = s[1:]
pl := len(s)
x, s, err = leadingInt(s)
if err != nil {
return 0, errors.New("units: invalid " + orig)
}
scale := 1.0
for n := pl - len(s); n > 0; n-- {
scale *= 10
}
g += float64(x) / scale
post = pl != len(s)
}
if !pre && !post {
// no digits (e.g. ".s" or "-.s")
return 0, errors.New("units: invalid " + orig)
}
// Consume unit.
i := 0
for ; i < len(s); i++ {
c := s[i]
if c == '.' || ('0' <= c && c <= '9') {
break
}
}
u := s[:i]
s = s[i:]
unit, ok := unitMap[u]
if !ok {
return 0, errors.New("units: unknown unit " + u + " in " + orig)
}
f += g * unit
}
if neg {
f = -f
}
if f < float64(-1<<63) || f > float64(1<<63-1) {
return 0, errors.New("units: overflow parsing unit")
}
return int64(f), nil
}
|
