60 lines
1.5 KiB
Go
60 lines
1.5 KiB
Go
package config
|
|
|
|
import (
|
|
"fmt"
|
|
"reflect"
|
|
)
|
|
|
|
// Merge recursively combines a set of config file structures into a single structure
|
|
// according to the following rules:
|
|
//
|
|
// * only values of type struct, slice, map and pointer to simple types are allowed. Other types panic.
|
|
// * when merging two structs the result is the recursive merge of all fields according to the rules below
|
|
// * when merging two slices the result is the second slice appended to the first
|
|
// * when merging two maps the result is the second map if it is not empty, otherwise the first
|
|
// * when merging two pointer values the result is the second value if it is not nil, otherwise the first
|
|
func Merge(files ...Config) Config {
|
|
var a Config
|
|
for _, b := range files {
|
|
a = merge(a, b).(Config)
|
|
}
|
|
return a
|
|
}
|
|
|
|
func merge(a, b interface{}) interface{} {
|
|
return mergeValue(reflect.ValueOf(a), reflect.ValueOf(b)).Interface()
|
|
}
|
|
|
|
func mergeValue(a, b reflect.Value) reflect.Value {
|
|
switch a.Kind() {
|
|
case reflect.Map:
|
|
if b.Len() > 0 {
|
|
return b
|
|
}
|
|
return a
|
|
|
|
case reflect.Ptr:
|
|
if !b.IsNil() {
|
|
return b
|
|
}
|
|
return a
|
|
|
|
case reflect.Slice:
|
|
if !a.IsValid() {
|
|
a = reflect.Zero(a.Type())
|
|
}
|
|
return reflect.AppendSlice(a, b)
|
|
|
|
case reflect.Struct:
|
|
r := reflect.New(a.Type()) // &struct{}
|
|
for i := 0; i < a.NumField(); i++ {
|
|
v := mergeValue(a.Field(i), b.Field(i))
|
|
r.Elem().Field(i).Set(v)
|
|
}
|
|
return r.Elem() // *struct
|
|
|
|
default:
|
|
panic(fmt.Sprintf("unsupported element type: %v", a.Type()))
|
|
}
|
|
}
|