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// Copyright (C) 2023 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package structutil
import (
"reflect"
"strconv"
"strings"
)
type defaultParser interface {
ParseDefault(string) error
}
// SetDefaults sets default values on a struct, based on the default annotation.
func SetDefaults(data any) {
s := reflect.ValueOf(data).Elem()
t := s.Type()
for i := 0; i < s.NumField(); i++ {
f := s.Field(i)
tag := t.Field(i).Tag
v := tag.Get("default")
if len(v) > 0 {
if f.CanInterface() {
if parser, ok := f.Interface().(defaultParser); ok {
if err := parser.ParseDefault(v); err != nil {
panic(err)
}
continue
}
}
if f.CanAddr() && f.Addr().CanInterface() {
if parser, ok := f.Addr().Interface().(defaultParser); ok {
if err := parser.ParseDefault(v); err != nil {
panic(err)
}
continue
}
}
switch f.Interface().(type) {
case string:
f.SetString(v)
case int, uint32, int32, int64, uint64:
i, err := strconv.ParseInt(v, 10, 64)
if err != nil {
panic(err)
}
f.SetInt(i)
case float64, float32:
i, err := strconv.ParseFloat(v, 64)
if err != nil {
panic(err)
}
f.SetFloat(i)
case bool:
f.SetBool(v == "true")
case []string:
// We don't do anything with string slices here. Any default
// we set will be appended to by the XML decoder, so we fill
// those after decoding.
default:
panic(f.Type())
}
} else if f.CanSet() && f.Kind() == reflect.Struct && f.CanAddr() {
if addr := f.Addr(); addr.CanInterface() {
SetDefaults(addr.Interface())
}
}
}
}
func FillNilExceptDeprecated(data any) {
fillNil(data, true)
}
func FillNil(data any) {
fillNil(data, false)
}
func fillNil(data any, skipDeprecated bool) {
s := reflect.ValueOf(data).Elem()
t := s.Type()
for i := 0; i < s.NumField(); i++ {
if skipDeprecated && strings.HasPrefix(t.Field(i).Name, "Deprecated") {
continue
}
f := s.Field(i)
for f.Kind() == reflect.Ptr && f.IsZero() && f.CanSet() {
newValue := reflect.New(f.Type().Elem())
f.Set(newValue)
f = f.Elem()
}
if f.CanSet() {
if f.IsZero() {
switch f.Kind() {
case reflect.Map:
f.Set(reflect.MakeMap(f.Type()))
case reflect.Slice:
f.Set(reflect.MakeSlice(f.Type(), 0, 0))
case reflect.Chan:
f.Set(reflect.MakeChan(f.Type(), 0))
}
}
switch f.Kind() {
case reflect.Slice:
if f.Type().Elem().Kind() != reflect.Struct {
continue
}
for i := 0; i < f.Len(); i++ {
fillNil(f.Index(i).Addr().Interface(), skipDeprecated)
}
case reflect.Struct:
if f.CanAddr() {
if addr := f.Addr(); addr.CanInterface() {
fillNil(addr.Interface(), skipDeprecated)
}
}
}
}
}
}
// FillNilSlices sets default value on slices that are still nil.
func FillNilSlices(data any) error {
s := reflect.ValueOf(data).Elem()
t := s.Type()
for i := 0; i < s.NumField(); i++ {
f := s.Field(i)
tag := t.Field(i).Tag
v := tag.Get("default")
if len(v) > 0 {
switch f.Interface().(type) {
case []string:
if f.IsNil() {
// Treat the default as a comma separated slice
vs := strings.Split(v, ",")
for i := range vs {
vs[i] = strings.TrimSpace(vs[i])
}
rv := reflect.MakeSlice(reflect.TypeOf([]string{}), len(vs), len(vs))
for i, v := range vs {
rv.Index(i).SetString(v)
}
f.Set(rv)
}
}
}
}
return nil
}
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