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package guid
import (
"crypto/rand"
"encoding/json"
"fmt"
"io"
"strconv"
"strings"
)
var _ = (json.Marshaler)(&GUID{})
var _ = (json.Unmarshaler)(&GUID{})
type GUID [16]byte
func New() GUID {
g := GUID{}
_, err := io.ReadFull(rand.Reader, g[:])
if err != nil {
panic(err)
}
return g
}
func (g GUID) String() string {
return fmt.Sprintf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x-%02x", g[3], g[2], g[1], g[0], g[5], g[4], g[7], g[6], g[8:10], g[10:])
}
func FromString(s string) GUID {
if len(s) != 36 {
panic(fmt.Sprintf("invalid GUID length: %d", len(s)))
}
if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
panic("invalid GUID format")
}
indexOrder := [16]int{
0, 2, 4, 6,
9, 11,
14, 16,
19, 21,
24, 26, 28, 30, 32, 34,
}
byteOrder := [16]int{
3, 2, 1, 0,
5, 4,
7, 6,
8, 9,
10, 11, 12, 13, 14, 15,
}
var g GUID
for i, x := range indexOrder {
b, err := strconv.ParseInt(s[x:x+2], 16, 16)
if err != nil {
panic(err)
}
g[byteOrder[i]] = byte(b)
}
return g
}
func (g GUID) MarshalJSON() ([]byte, error) {
return json.Marshal(g.String())
}
func (g *GUID) UnmarshalJSON(data []byte) error {
*g = FromString(strings.Trim(string(data), "\""))
return nil
}
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