1 /* 2 Copyright 2023 The Kubernetes Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package ptr 18 19 import ( 20 "fmt" 21 "reflect" 22 ) 23 24 // AllPtrFieldsNil tests whether all pointer fields in a struct are nil. This is useful when, 25 // for example, an API struct is handled by plugins which need to distinguish 26 // "no plugin accepted this spec" from "this spec is empty". 27 // 28 // This function is only valid for structs and pointers to structs. Any other 29 // type will cause a panic. Passing a typed nil pointer will return true. 30 func AllPtrFieldsNil(obj interface{}) bool { 31 v := reflect.ValueOf(obj) 32 if !v.IsValid() { 33 panic(fmt.Sprintf("reflect.ValueOf() produced a non-valid Value for %#v", obj)) 34 } 35 if v.Kind() == reflect.Ptr { 36 if v.IsNil() { 37 return true 38 } 39 v = v.Elem() 40 } 41 for i := 0; i < v.NumField(); i++ { 42 if v.Field(i).Kind() == reflect.Ptr && !v.Field(i).IsNil() { 43 return false 44 } 45 } 46 return true 47 } 48 49 // To returns a pointer to the given value. 50 func To[T any](v T) *T { 51 return &v 52 } 53 54 // Deref dereferences ptr and returns the value it points to if no nil, or else 55 // returns def. 56 func Deref[T any](ptr *T, def T) T { 57 if ptr != nil { 58 return *ptr 59 } 60 return def 61 } 62 63 // Equal returns true if both arguments are nil or both arguments 64 // dereference to the same value. 65 func Equal[T comparable](a, b *T) bool { 66 if (a == nil) != (b == nil) { 67 return false 68 } 69 if a == nil { 70 return true 71 } 72 return *a == *b 73 } 74