kubernetes/pkg/runtime/jsonbase.go

/*
Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package runtime

import (
	"fmt"
	"reflect"
)

// NewJSONBaseResourceVersioner returns a ResourceVersioner that can set or
// retrieve ResourceVersion on objects derived from JSONBase.
func NewJSONBaseResourceVersioner() ResourceVersioner {
	return jsonBaseModifier{}
}

// jsonBaseModifier implements ResourceVersioner and SelfLinker.
type jsonBaseModifier struct{}

func (v jsonBaseModifier) ResourceVersion(obj Object) (uint64, error) {
	json, err := FindJSONBase(obj)
	if err != nil {
		return 0, err
	}
	return json.ResourceVersion(), nil
}

func (v jsonBaseModifier) SetResourceVersion(obj Object, version uint64) error {
	json, err := FindJSONBase(obj)
	if err != nil {
		return err
	}
	json.SetResourceVersion(version)
	return nil
}

func (v jsonBaseModifier) ID(obj Object) (string, error) {
	json, err := FindJSONBase(obj)
	if err != nil {
		return "", err
	}
	return json.ID(), nil
}

func (v jsonBaseModifier) SelfLink(obj Object) (string, error) {
	json, err := FindJSONBase(obj)
	if err != nil {
		return "", err
	}
	return json.SelfLink(), nil
}

func (v jsonBaseModifier) SetSelfLink(obj Object, selfLink string) error {
	json, err := FindJSONBase(obj)
	if err != nil {
		return err
	}
	json.SetSelfLink(selfLink)
	return nil
}

// NewJSONBaseSelfLinker returns a SelfLinker that works on all JSONBase SelfLink fields.
func NewJSONBaseSelfLinker() SelfLinker {
	return jsonBaseModifier{}
}

// JSONBaseInterface lets you work with a JSONBase from any of the versioned or
// internal APIObjects.
type JSONBaseInterface interface {
	ID() string
	SetID(ID string)
	APIVersion() string
	SetAPIVersion(version string)
	Kind() string
	SetKind(kind string)
	ResourceVersion() uint64
	SetResourceVersion(version uint64)
	SelfLink() string
	SetSelfLink(selfLink string)
}

type genericJSONBase struct {
	id              *string
	apiVersion      *string
	kind            *string
	resourceVersion *uint64
	selfLink        *string
}

func (g genericJSONBase) ID() string {
	return *g.id
}

func (g genericJSONBase) SetID(id string) {
	*g.id = id
}

func (g genericJSONBase) APIVersion() string {
	return *g.apiVersion
}

func (g genericJSONBase) SetAPIVersion(version string) {
	*g.apiVersion = version
}

func (g genericJSONBase) Kind() string {
	return *g.kind
}

func (g genericJSONBase) SetKind(kind string) {
	*g.kind = kind
}

func (g genericJSONBase) ResourceVersion() uint64 {
	return *g.resourceVersion
}

func (g genericJSONBase) SetResourceVersion(version uint64) {
	*g.resourceVersion = version
}

func (g genericJSONBase) SelfLink() string {
	return *g.selfLink
}

func (g genericJSONBase) SetSelfLink(selfLink string) {
	*g.selfLink = selfLink
}

// fieldPtr puts the address of fieldName, which must be a member of v,
// into dest, which must be an address of a variable to which this field's
// address can be assigned.
func fieldPtr(v reflect.Value, fieldName string, dest interface{}) error {
	field := v.FieldByName(fieldName)
	if !field.IsValid() {
		return fmt.Errorf("Couldn't find %v field in %#v", fieldName, v.Interface())
	}
	v = reflect.ValueOf(dest)
	if v.Kind() != reflect.Ptr {
		return fmt.Errorf("dest should be ptr")
	}
	v = v.Elem()
	field = field.Addr()
	if field.Type().AssignableTo(v.Type()) {
		v.Set(field)
		return nil
	}
	if field.Type().ConvertibleTo(v.Type()) {
		v.Set(field.Convert(v.Type()))
		return nil
	}
	return fmt.Errorf("Couldn't assign/convert %v to %v", field.Type(), v.Type())
}

// newGenericJSONBase creates a new generic JSONBase from v, which must be an
// addressable/setable reflect.Value having the same fields as api.JSONBase.
// Returns an error if this isn't the case.
func newGenericJSONBase(v reflect.Value) (genericJSONBase, error) {
	g := genericJSONBase{}
	if err := fieldPtr(v, "ID", &g.id); err != nil {
		return g, err
	}
	if err := fieldPtr(v, "APIVersion", &g.apiVersion); err != nil {
		return g, err
	}
	if err := fieldPtr(v, "Kind", &g.kind); err != nil {
		return g, err
	}
	if err := fieldPtr(v, "ResourceVersion", &g.resourceVersion); err != nil {
		return g, err
	}
	if err := fieldPtr(v, "SelfLink", &g.selfLink); err != nil {
		return g, err
	}
	return g, nil
}