forked from golang/hotime
126 lines
3.4 KiB
Go
126 lines
3.4 KiB
Go
// deepcopy makes deep copies of things. A standard copy will copy the
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// pointers: deep copy copies the values pointed to. Unexported field
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// values are not copied.
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//
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// Copyright (c)2014-2016, Joel Scoble (github.com/mohae), all rights reserved.
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// License: MIT, for more details check the included LICENSE file.
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package deepcopy
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import (
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"reflect"
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"time"
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)
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// Interface for delegating copy process to type
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type Interface interface {
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DeepCopy() interface{}
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}
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// Iface is an alias to Copy; this exists for backwards compatibility reasons.
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func Iface(iface interface{}) interface{} {
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return Copy(iface)
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}
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// Copy creates a deep copy of whatever is passed to it and returns the copy
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// in an interface{}. The returned value will need to be asserted to the
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// correct type.
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func Copy(src interface{}) interface{} {
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if src == nil {
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return nil
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}
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// Make the interface a reflect.Value
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original := reflect.ValueOf(src)
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// Make a copy of the same type as the original.
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cpy := reflect.New(original.Type()).Elem()
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// Recursively copy the original.
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copyRecursive(original, cpy)
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// Return the copy as an interface.
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return cpy.Interface()
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}
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// copyRecursive does the actual copying of the interface. It currently has
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// limited support for what it can handle. Add as needed.
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func copyRecursive(original, cpy reflect.Value) {
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// check for implement deepcopy.Interface
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if original.CanInterface() {
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if copier, ok := original.Interface().(Interface); ok {
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cpy.Set(reflect.ValueOf(copier.DeepCopy()))
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return
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}
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}
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// handle according to original's Kind
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switch original.Kind() {
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case reflect.Ptr:
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// Get the actual value being pointed to.
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originalValue := original.Elem()
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// if it isn't valid, return.
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if !originalValue.IsValid() {
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return
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}
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cpy.Set(reflect.New(originalValue.Type()))
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copyRecursive(originalValue, cpy.Elem())
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case reflect.Interface:
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// If this is a nil, don't do anything
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if original.IsNil() {
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return
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}
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// Get the value for the interface, not the pointer.
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originalValue := original.Elem()
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// Get the value by calling Elem().
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copyValue := reflect.New(originalValue.Type()).Elem()
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copyRecursive(originalValue, copyValue)
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cpy.Set(copyValue)
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case reflect.Struct:
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t, ok := original.Interface().(time.Time)
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if ok {
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cpy.Set(reflect.ValueOf(t))
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return
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}
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// Go through each field of the struct and copy it.
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for i := 0; i < original.NumField(); i++ {
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// The Type's StructField for a given field is checked to see if StructField.PkgPath
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// is set to determine if the field is exported or not because CanSet() returns false
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// for settable fields. I'm not sure why. -mohae
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if original.Type().Field(i).PkgPath != "" {
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continue
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}
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copyRecursive(original.Field(i), cpy.Field(i))
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}
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case reflect.Slice:
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if original.IsNil() {
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return
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}
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// Make a new slice and copy each element.
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cpy.Set(reflect.MakeSlice(original.Type(), original.Len(), original.Cap()))
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for i := 0; i < original.Len(); i++ {
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copyRecursive(original.Index(i), cpy.Index(i))
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}
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case reflect.Map:
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if original.IsNil() {
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return
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}
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cpy.Set(reflect.MakeMap(original.Type()))
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for _, key := range original.MapKeys() {
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originalValue := original.MapIndex(key)
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copyValue := reflect.New(originalValue.Type()).Elem()
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copyRecursive(originalValue, copyValue)
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copyKey := Copy(key.Interface())
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cpy.SetMapIndex(reflect.ValueOf(copyKey), copyValue)
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}
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default:
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cpy.Set(original)
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}
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}
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