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deep_copy.go
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deep_copy.go
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package amino
import (
"fmt"
"reflect"
)
//----------------------------------------
// DeepCopy
// Deeply copies an object.
// If anything implements `.DeepCopy() <any>` along the way,
// the result of that function will be used.
// Otherwise, if it implements `.MarshalAmino() (<any>, error)` and
// `.UnmarshalAmino(<any>) error`, the pair will be used to copy.
// If .MarshalAmino() or .UnmarshalAmino() returns an error, this
// function will panic.
func DeepCopy(o interface{}) (r interface{}) {
if o == nil {
return nil
}
src := reflect.ValueOf(o)
dst := reflect.New(src.Type()).Elem()
deepCopy(src, dst)
return dst.Interface()
}
// Like DeepCopy, but returns a pointer to the copy.
func DeepCopyToPtr(o interface{}) (ptr interface{}) {
if o == nil {
return nil
}
src := reflect.ValueOf(o)
dst := reflect.New(src.Type())
elm := dst.Elem()
deepCopy(src, elm)
return dst.Interface()
}
func deepCopy(src, dst reflect.Value) {
if isNil(src) {
return
}
if callDeepCopy(src, dst) {
return
}
if callAminoCopy(src, dst) {
return
}
_deepCopy(src, dst)
}
func _deepCopy(src, dst reflect.Value) {
switch src.Kind() {
case reflect.Ptr:
cpy := reflect.New(src.Type().Elem())
_deepCopy(src.Elem(), cpy.Elem())
dst.Set(cpy)
return
case reflect.Interface:
cpy := reflect.New(src.Elem().Type())
deepCopy(src.Elem(), cpy.Elem())
dst.Set(cpy.Elem())
return
case reflect.Array:
switch src.Type().Elem().Kind() {
case reflect.Int64, reflect.Int32, reflect.Int16,
reflect.Int8, reflect.Int, reflect.Uint64,
reflect.Uint32, reflect.Uint16, reflect.Uint8,
reflect.Uint, reflect.Bool, reflect.Float64,
reflect.Float32, reflect.String:
reflect.Copy(dst, src)
return
default:
for i := 0; i < src.Type().Len(); i++ {
esrc := src.Index(i)
edst := dst.Index(i)
deepCopy(esrc, edst)
}
return
}
case reflect.Slice:
switch src.Type().Elem().Kind() {
case reflect.Int64, reflect.Int32, reflect.Int16,
reflect.Int8, reflect.Int, reflect.Uint64,
reflect.Uint32, reflect.Uint16, reflect.Uint8,
reflect.Uint, reflect.Bool, reflect.Float64,
reflect.Float32, reflect.String:
cpy := reflect.MakeSlice(
src.Type(), src.Len(), src.Len())
reflect.Copy(cpy, src)
dst.Set(src)
return
default:
cpy := reflect.MakeSlice(
src.Type(), src.Len(), src.Len())
for i := 0; i < src.Len(); i++ {
esrc := src.Index(i)
ecpy := cpy.Index(i)
deepCopy(esrc, ecpy)
}
dst.Set(src)
return
}
case reflect.Struct:
switch src.Type() {
case timeType:
dst.Set(src)
return
default:
for i := 0; i < src.NumField(); i++ {
if !isExported(src.Type().Field(i)) {
continue // field is unexported
}
srcf := src.Field(i)
dstf := dst.Field(i)
deepCopy(srcf, dstf)
}
return
}
case reflect.Map:
cpy := reflect.MakeMapWithSize(src.Type(), src.Len())
keys := src.MapKeys()
for _, key := range keys {
val := src.MapIndex(key)
cpy.SetMapIndex(key, val)
}
dst.Set(cpy)
return
// Primitive types
case reflect.Int64, reflect.Int32, reflect.Int16,
reflect.Int8, reflect.Int:
dst.SetInt(src.Int())
case reflect.Uint64, reflect.Uint32, reflect.Uint16,
reflect.Uint8, reflect.Uint:
dst.SetUint(src.Uint())
case reflect.Bool:
dst.SetBool(src.Bool())
case reflect.Float64, reflect.Float32:
dst.SetFloat(src.Float())
case reflect.String:
dst.SetString(src.String())
default:
panic(fmt.Sprintf("unsupported type %v", src.Kind()))
}
}
//----------------------------------------
// misc.
// Call .DeepCopy() method if possible.
func callDeepCopy(src, dst reflect.Value) bool {
dc := src.MethodByName("DeepCopy")
if !dc.IsValid() {
return false
}
if dc.Type().NumIn() != 0 {
return false
}
if dc.Type().NumOut() != 1 {
return false
}
otype := dc.Type().Out(0)
if dst.Kind() == reflect.Ptr &&
dst.Type().Elem() == otype {
cpy := reflect.New(dst.Type().Elem())
out := dc.Call(nil)[0]
cpy.Elem().Set(out)
dst.Set(cpy)
return true
}
if dst.Type() == otype {
out := dc.Call(nil)[0]
dst.Set(out)
return true
}
return false
}
// Call .MarshalAmino() and .UnmarshalAmino to copy if possible.
// Panics if .MarshalAmino() or .UnmarshalAmino() return an error.
// CONTRACT: src and dst are of equal types.
func callAminoCopy(src, dst reflect.Value) bool {
if src.Type() != dst.Type() {
panic("should not happen")
}
switch {
case src.Kind() == reflect.Ptr:
cpy := reflect.New(src.Type().Elem())
dst.Set(cpy)
case src.CanAddr():
if !dst.CanAddr() {
panic("should not happen")
}
src = src.Addr()
dst = dst.Addr()
default:
return false
}
if !canAminoCopy(src) {
return false
}
ma := src.MethodByName("MarshalAmino")
ua := dst.MethodByName("UnmarshalAmino")
outs := ma.Call(nil)
repr, err := outs[0], outs[1]
if !err.IsNil() {
panic(err.Interface())
}
outs = ua.Call([]reflect.Value{repr})
err = outs[0]
if !err.IsNil() {
panic(err.Interface())
}
return true
}
func canAminoCopy(rv reflect.Value) bool {
if !rv.MethodByName("UnmarshalAmino").IsValid() {
return false
}
ua := rv.MethodByName("UnmarshalAmino")
if !ua.IsValid() {
return false
}
if ua.Type().NumIn() != 1 {
return false
}
if ua.Type().NumOut() != 1 {
return false
}
if ua.Type().Out(0) != errorType {
return false
}
ma := rv.MethodByName("MarshalAmino")
if !ma.IsValid() {
return false
}
if ma.Type().NumIn() != 0 {
return false
}
if ma.Type().NumOut() != 2 {
return false
}
if ma.Type().Out(1) != errorType {
return false
}
if ua.Type().In(0) != ma.Type().Out(0) {
return false
}
return true
}