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aid.go
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aid.go
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package pttbbs
import (
"errors"
"fmt"
)
var (
ErrInvalidAid = errors.New("invalid aid")
)
const (
aidTable = `0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_`
)
type Aid uint64
func ParseAid(s string) (Aid, error) {
// Not to overflow
if len(s) > 10 {
return Aid(0), ErrInvalidAid
}
var aid Aid
parseLoop:
for _, c := range s {
aid <<= 6
switch {
case c >= '0' && c <= '9':
aid += Aid(c - '0')
case c >= 'A' && c <= 'Z':
aid += Aid(c - 'A' + 10)
case c >= 'a' && c <= 'z':
aid += Aid(c - 'a' + 36)
case c == '-':
aid += 62
case c == '_':
aid += 63
case c == '@':
break parseLoop
default:
return Aid(0), ErrInvalidAid
}
}
return aid, nil
}
func (aid Aid) String() string {
s := make([]rune, 10)
var i int
for i = len(s) - 1; aid > 0 && i >= 0; i-- {
s[i] = rune(aidTable[aid%64])
aid /= 64
}
return string(s[i+1:])
}
func (aid Aid) Filename() string {
tp := uint64((aid >> 44) & 0xF)
v1 := uint64((aid >> 12) & 0xFFFFFFFF)
v2 := uint64(aid & 0xFFF)
var tpc rune
if tp == 0 {
tpc = 'M'
} else {
tpc = 'G'
}
return fmt.Sprintf("%c.%v.A.%03X", tpc, v1, v2)
}