blob: 3e3a2b59158f046934c6ce763f82f7cd3ee73c29 [file] [log] [blame]
package types
import (
"fmt"
"io"
"reflect"
"strings"
)
// An IntMode is a mode for parsing integer values, representing a set of
// accepted bases.
type IntMode uint8
// IntMode values for ParseInt; can be combined using binary or.
const (
Dec IntMode = 1 << iota
Hex
Oct
)
// String returns a string representation of IntMode; e.g. `IntMode(Dec|Hex)`.
func (m IntMode) String() string {
var modes []string
if m&Dec != 0 {
modes = append(modes, "Dec")
}
if m&Hex != 0 {
modes = append(modes, "Hex")
}
if m&Oct != 0 {
modes = append(modes, "Oct")
}
return "IntMode(" + strings.Join(modes, "|") + ")"
}
var errIntAmbig = fmt.Errorf("ambiguous integer value; must include '0' prefix")
func prefix0(val string) bool {
return strings.HasPrefix(val, "0") || strings.HasPrefix(val, "-0")
}
func prefix0x(val string) bool {
return strings.HasPrefix(val, "0x") || strings.HasPrefix(val, "-0x")
}
// ParseInt parses val using mode into intptr, which must be a pointer to an
// integer kind type. Non-decimal value require prefix `0` or `0x` in the cases
// when mode permits ambiguity of base; otherwise the prefix can be omitted.
func ParseInt(intptr interface{}, val string, mode IntMode) error {
val = strings.TrimSpace(val)
verb := byte(0)
switch mode {
case Dec:
verb = 'd'
case Dec + Hex:
if prefix0x(val) {
verb = 'v'
} else {
verb = 'd'
}
case Dec + Oct:
if prefix0(val) && !prefix0x(val) {
verb = 'v'
} else {
verb = 'd'
}
case Dec + Hex + Oct:
verb = 'v'
case Hex:
if prefix0x(val) {
verb = 'v'
} else {
verb = 'x'
}
case Oct:
verb = 'o'
case Hex + Oct:
if prefix0(val) {
verb = 'v'
} else {
return errIntAmbig
}
}
if verb == 0 {
panic("unsupported mode")
}
return scanFully(intptr, val, verb)
}
func scanFully(intptr interface{}, val string, verb byte) error {
t := reflect.ValueOf(intptr).Elem().Type()
var r rune
n, err := fmt.Sscanf(val, "%"+string(verb)+"%c", intptr, &r)
switch {
case n < 1 || n == 1 && err != io.EOF:
return fmt.Errorf("failed to parse %q as %v: %v", val, t, err)
case n > 1:
return fmt.Errorf("failed to parse %q as %v: extra characters", val, t)
}
// n == 1 && err == io.EOF
return nil
}