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// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package storage
import (
"reflect"
jsoniter "github.com/json-iterator/go"
)
// Mappable represents an interface that can MapTo another interface
type Mappable interface {
MapTo(v interface{}) error
}
// toConfig will attempt to convert a given configuration cfg into the provided exemplar type.
//
// It will tolerate the cfg being passed as a []byte or string of a json representation of the
// exemplar or the correct type of the exemplar itself
func toConfig(exemplar, cfg interface{}) (interface{}, error) {
json := jsoniter.ConfigCompatibleWithStandardLibrary
// First of all check if we've got the same type as the exemplar - if so it's all fine.
if reflect.TypeOf(cfg).AssignableTo(reflect.TypeOf(exemplar)) {
return cfg, nil
}
// Now if not - does it provide a MapTo function we can try?
if mappable, ok := cfg.(Mappable); ok {
newVal := reflect.New(reflect.TypeOf(exemplar))
if err := mappable.MapTo(newVal.Interface()); err == nil {
return newVal.Elem().Interface(), nil
}
// MapTo has failed us ... let's try the json route ...
}
// OK we've been passed a byte array right?
configBytes, ok := cfg.([]byte)
if !ok {
// oh ... it's a string then?
var configStr string
configStr, ok = cfg.(string)
configBytes = []byte(configStr)
}
if !ok {
// hmm ... can we marshal it to json?
var err error
configBytes, err = json.Marshal(cfg)
ok = err == nil
}
if !ok {
// no ... we've tried hard enough at this point - throw an error!
return nil, ErrInvalidConfiguration{cfg: cfg}
}
// OK unmarshal the byte array into a new copy of the exemplar
newVal := reflect.New(reflect.TypeOf(exemplar))
if err := json.Unmarshal(configBytes, newVal.Interface()); err != nil {
// If we can't unmarshal it then return an error!
return nil, ErrInvalidConfiguration{cfg: cfg, err: err}
}
return newVal.Elem().Interface(), nil
}
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