github.com/kubernetes/utils@v0.0.0-20190308190857-21c4ce38f2a7/pointer/pointer.go (about)

     1  /*
     2  Copyright 2018 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 pointer
    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  // Int32Ptr returns a pointer to an int32
    50  func Int32Ptr(i int32) *int32 {
    51  	return &i
    52  }
    53  
    54  // Int64Ptr returns a pointer to an int64
    55  func Int64Ptr(i int64) *int64 {
    56  	return &i
    57  }
    58  
    59  // Int32PtrDerefOr dereference the int32 ptr and returns it i not nil,
    60  // else returns def.
    61  func Int32PtrDerefOr(ptr *int32, def int32) int32 {
    62  	if ptr != nil {
    63  		return *ptr
    64  	}
    65  	return def
    66  }
    67  
    68  // BoolPtr returns a pointer to a bool
    69  func BoolPtr(b bool) *bool {
    70  	return &b
    71  }
    72  
    73  // StringPtr returns a pointer to the passed string.
    74  func StringPtr(s string) *string {
    75  	return &s
    76  }
    77  
    78  // Float32Ptr returns a pointer to the passed float32.
    79  func Float32Ptr(i float32) *float32 {
    80  	return &i
    81  }
    82  
    83  // Float64Ptr returns a pointer to the passed float64.
    84  func Float64Ptr(i float64) *float64 {
    85  	return &i
    86  }