github.com/aclisp/heapster@v0.19.2-0.20160613100040-51756f899a96/Godeps/_workspace/src/k8s.io/kubernetes/pkg/api/meta/help.go (about)

     1  /*
     2  Copyright 2015 The Kubernetes Authors All rights reserved.
     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 meta
    18  
    19  import (
    20  	"fmt"
    21  	"reflect"
    22  
    23  	"k8s.io/kubernetes/pkg/conversion"
    24  	"k8s.io/kubernetes/pkg/runtime"
    25  )
    26  
    27  // IsListType returns true if the provided Object has a slice called Items
    28  func IsListType(obj runtime.Object) bool {
    29  	_, err := GetItemsPtr(obj)
    30  	return err == nil
    31  }
    32  
    33  // GetItemsPtr returns a pointer to the list object's Items member.
    34  // If 'list' doesn't have an Items member, it's not really a list type
    35  // and an error will be returned.
    36  // This function will either return a pointer to a slice, or an error, but not both.
    37  func GetItemsPtr(list runtime.Object) (interface{}, error) {
    38  	v, err := conversion.EnforcePtr(list)
    39  	if err != nil {
    40  		return nil, err
    41  	}
    42  	items := v.FieldByName("Items")
    43  	if !items.IsValid() {
    44  		return nil, fmt.Errorf("no Items field in %#v", list)
    45  	}
    46  	switch items.Kind() {
    47  	case reflect.Interface, reflect.Ptr:
    48  		target := reflect.TypeOf(items.Interface()).Elem()
    49  		if target.Kind() != reflect.Slice {
    50  			return nil, fmt.Errorf("items: Expected slice, got %s", target.Kind())
    51  		}
    52  		return items.Interface(), nil
    53  	case reflect.Slice:
    54  		return items.Addr().Interface(), nil
    55  	default:
    56  		return nil, fmt.Errorf("items: Expected slice, got %s", items.Kind())
    57  	}
    58  }
    59  
    60  // ExtractList returns obj's Items element as an array of runtime.Objects.
    61  // Returns an error if obj is not a List type (does not have an Items member).
    62  func ExtractList(obj runtime.Object) ([]runtime.Object, error) {
    63  	itemsPtr, err := GetItemsPtr(obj)
    64  	if err != nil {
    65  		return nil, err
    66  	}
    67  	items, err := conversion.EnforcePtr(itemsPtr)
    68  	if err != nil {
    69  		return nil, err
    70  	}
    71  	list := make([]runtime.Object, items.Len())
    72  	for i := range list {
    73  		raw := items.Index(i)
    74  		switch item := raw.Interface().(type) {
    75  		case runtime.RawExtension:
    76  			switch {
    77  			case item.Object != nil:
    78  				list[i] = item.Object
    79  			case item.Raw != nil:
    80  				// TODO: Set ContentEncoding and ContentType correctly.
    81  				list[i] = &runtime.Unknown{Raw: item.Raw}
    82  			default:
    83  				list[i] = nil
    84  			}
    85  		case runtime.Object:
    86  			list[i] = item
    87  		default:
    88  			var found bool
    89  			if list[i], found = raw.Addr().Interface().(runtime.Object); !found {
    90  				return nil, fmt.Errorf("%v: item[%v]: Expected object, got %#v(%s)", obj, i, raw.Interface(), raw.Kind())
    91  			}
    92  		}
    93  	}
    94  	return list, nil
    95  }
    96  
    97  // objectSliceType is the type of a slice of Objects
    98  var objectSliceType = reflect.TypeOf([]runtime.Object{})
    99  
   100  // SetList sets the given list object's Items member have the elements given in
   101  // objects.
   102  // Returns an error if list is not a List type (does not have an Items member),
   103  // or if any of the objects are not of the right type.
   104  func SetList(list runtime.Object, objects []runtime.Object) error {
   105  	itemsPtr, err := GetItemsPtr(list)
   106  	if err != nil {
   107  		return err
   108  	}
   109  	items, err := conversion.EnforcePtr(itemsPtr)
   110  	if err != nil {
   111  		return err
   112  	}
   113  	if items.Type() == objectSliceType {
   114  		items.Set(reflect.ValueOf(objects))
   115  		return nil
   116  	}
   117  	slice := reflect.MakeSlice(items.Type(), len(objects), len(objects))
   118  	for i := range objects {
   119  		dest := slice.Index(i)
   120  		src, err := conversion.EnforcePtr(objects[i])
   121  		if err != nil {
   122  			return err
   123  		}
   124  		if src.Type().AssignableTo(dest.Type()) {
   125  			dest.Set(src)
   126  		} else if src.Type().ConvertibleTo(dest.Type()) {
   127  			dest.Set(src.Convert(dest.Type()))
   128  		} else {
   129  			return fmt.Errorf("item[%d]: can't assign or convert %v into %v", i, src.Type(), dest.Type())
   130  		}
   131  	}
   132  	items.Set(slice)
   133  	return nil
   134  }