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|
package opts
import (
"fmt"
"reflect"
"strconv"
"strings"
)
type fieldSpec struct {
name string
inline bool
required bool
positive bool
defaultValue string
}
type Opts map[string]string
func Parse(s string) (string, Opts) {
v := strings.Split(s, ",")
m := map[string]string{}
for _, t := range v[1:] {
kv := strings.SplitN(t, "=", 2)
if len(kv) < 2 {
m[kv[0]] = ""
} else {
m[kv[0]] = kv[1]
}
}
return v[0], m
}
func (opts Opts) Bool(key string) bool {
_, ok := opts[key]
return ok
}
func (opts Opts) Configure(v interface{}) error {
rv := reflect.ValueOf(v)
switch {
case rv.Kind() != reflect.Ptr:
return fmt.Errorf("opts: configure failed: non-pointer %s", rv.Type().String())
case rv.IsNil():
return fmt.Errorf("opts: configure failed: nil %s", rv.Type().String())
case rv.Elem().Kind() != reflect.Struct:
return fmt.Errorf("opts: configure failed: non-struct %s", rv.Elem().Type().String())
}
return opts.configure(rv.Elem())
}
func getFieldSpec(field reflect.StructField) (fs fieldSpec) {
fs.name = strings.ToLower(field.Name)
for _, s := range strings.Split(field.Tag.Get("opts"), ",") {
switch {
case s == "inline":
fs.inline = true
case s == "required":
fs.required = true
case s == "positive":
fs.positive = true
case strings.HasPrefix(s, "default:"):
fs.defaultValue = s[8:]
}
}
return
}
func (opts Opts) setValue(v reflect.Value, fs fieldSpec) error {
s, ok := opts[fs.name]
kind := v.Kind()
if kind == reflect.Bool {
if s != "" {
return fmt.Errorf("%s: boolean option does not need a value", fs.name)
}
if ok {
v.SetBool(true)
}
return nil
}
if s == "" {
if fs.required {
return fmt.Errorf("%s: expect value", fs.name)
}
s = fs.defaultValue
}
if s == "" {
return nil
}
switch kind {
case reflect.String:
v.SetString(s)
case reflect.Int:
n, err := strconv.Atoi(s)
if err != nil {
return fmt.Errorf("%s: %w", fs.name, err)
}
if n <= 0 {
return fmt.Errorf("%s: expect positive", fs.name)
}
v.SetInt(int64(n))
default:
return fmt.Errorf("%s: unsupported type '%s'", fs.name, v.Type().String())
}
return nil
}
func (opts Opts) configure(v reflect.Value) error {
m := map[string]bool{}
for s := range opts {
m[s] = true
}
var visit func(v reflect.Value) error
visit = func(v reflect.Value) error {
t := v.Type()
for n := 0; n < v.NumField(); n++ {
fs := getFieldSpec(t.Field(n))
fv := v.Field(n)
if fs.inline {
if err := visit(fv); err != nil {
return err
}
} else if fv.CanSet() {
if err := opts.setValue(v.Field(n), fs); err != nil {
return err
}
delete(m, fs.name)
}
}
return nil
}
if err := visit(v); err != nil {
return err
}
if len(m) > 0 {
var ss []string
for s := range m {
ss = append(ss, s)
}
return fmt.Errorf("unknown options: %s", strings.Join(ss, ","))
}
return nil
}
|
