update vendor

Signed-off-by: Roland.Ma <rolandma@yunify.com>

vendor/sigs.k8s.io/kustomize/kyaml/yaml/walk/associative_sequence.go

@@ -0,0 +1,385 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"strings"
+
+	"github.com/go-errors/errors"
+	"sigs.k8s.io/kustomize/kyaml/openapi"
+	"sigs.k8s.io/kustomize/kyaml/sets"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// appendListNode will append the nodes from src to dst and return dst.
+// src and dst should be both sequence node. key is used to call ElementSetter.
+// ElementSetter will use key-value pair to find and set the element in sequence
+// node.
+func appendListNode(dst, src *yaml.RNode, keys []string) (*yaml.RNode, error) {
+	var err error
+	for _, elem := range src.Content() {
+		// If key is empty, we know this is a scalar value and we can directly set the
+		// node
+		if keys[0] == "" {
+			_, err = dst.Pipe(yaml.ElementSetter{
+				Element: elem,
+				Keys:    []string{""},
+				Values:  []string{elem.Value},
+			})
+			if err != nil {
+				return nil, err
+			}
+			continue
+		}
+
+		// we need to get the value for key so that we can find the element to set
+		// in sequence.
+		v := []string{}
+		for _, key := range keys {
+			tmpNode := yaml.NewRNode(elem)
+			valueNode, err := tmpNode.Pipe(yaml.Get(key))
+			if err != nil {
+				return nil, err
+			}
+			if valueNode.IsNil() {
+				// no key found, directly append to dst
+				err = dst.PipeE(yaml.Append(elem))
+				if err != nil {
+					return nil, err
+				}
+				continue
+			}
+			v = append(v, valueNode.YNode().Value)
+		}
+
+		// When there are multiple keys, ElementSetter appends the node to dst
+		// even if the output is already in dst. We remove the node from dst to
+		// prevent duplicates.
+		if len(keys) > 1 {
+			_, err = dst.Pipe(yaml.ElementSetter{
+				Keys:   keys,
+				Values: v,
+			})
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		// We use the key and value from elem to find the corresponding element in dst.
+		// Then we will use ElementSetter to replace the element with elem. If we cannot
+		// find the item, the element will be appended.
+		_, err = dst.Pipe(yaml.ElementSetter{
+			Element: elem,
+			Keys:    keys,
+			Values:  v,
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+	return dst, nil
+}
+
+// validateKeys returns a list of valid key-value pairs
+// if secondary merge key values are missing, use only the available merge keys
+func validateKeys(valuesList [][]string, values []string, keys []string) ([]string, []string) {
+	validKeys := make([]string, 0)
+	validValues := make([]string, 0)
+	validKeySet := sets.String{}
+	for _, values := range valuesList {
+		for i, v := range values {
+			if v != "" {
+				validKeySet.Insert(keys[i])
+			}
+		}
+	}
+	if validKeySet.Len() == 0 { // if values missing, fall back to primary keys
+		return keys, values
+	}
+	for _, k := range keys {
+		if validKeySet.Has(k) {
+			validKeys = append(validKeys, k)
+		}
+	}
+	for i, v := range values {
+		if v != "" || validKeySet.Has(keys[i]) {
+			validValues = append(validValues, v)
+		}
+	}
+	return validKeys, validValues
+}
+
+// mergeValues merges values together - e.g. if two containerPorts
+// have the same port and targetPort but one has an empty protocol
+// and the other doesn't, they are treated as the same containerPort
+func mergeValues(valuesList [][]string) [][]string {
+	for i, values1 := range valuesList {
+		for j, values2 := range valuesList {
+			if matched, values := match(values1, values2); matched {
+				valuesList[i] = values
+				valuesList[j] = values
+			}
+		}
+	}
+	return valuesList
+}
+
+// two values match if they have at least one common element and
+// corresponding elements only differ if one is an empty string
+func match(values1 []string, values2 []string) (bool, []string) {
+	if len(values1) != len(values2) {
+		return false, nil
+	}
+	var commonElement bool
+	var res []string
+	for i := range values1 {
+		if values1[i] == values2[i] {
+			commonElement = true
+			res = append(res, values1[i])
+			continue
+		}
+		if values1[i] != "" && values2[i] != "" {
+			return false, nil
+		}
+		if values1[i] != "" {
+			res = append(res, values1[i])
+		} else {
+			res = append(res, values2[i])
+		}
+	}
+	return commonElement, res
+}
+
+// setAssociativeSequenceElements recursively set the elements in the list
+func (l *Walker) setAssociativeSequenceElements(valuesList [][]string, keys []string, dest *yaml.RNode) (*yaml.RNode, error) {
+	// itemsToBeAdded contains the items that will be added to dest
+	itemsToBeAdded := yaml.NewListRNode()
+	var schema *openapi.ResourceSchema
+	if l.Schema != nil {
+		schema = l.Schema.Elements()
+	}
+	if len(keys) > 1 {
+		valuesList = mergeValues(valuesList)
+	}
+
+	// each element in valuesList is a list of values corresponding to the keys
+	// for example, for the following yaml:
+	//        - containerPort: 8080
+	//          protocol: UDP
+	//        - containerPort: 8080
+	//          protocol: TCP
+	// `keys` would be [containerPort, protocol]
+	// and `valuesList` would be [ [8080, UDP], [8080, TCP] ]
+	var validKeys []string
+	var validValues []string
+	for _, values := range valuesList {
+		if len(values) == 0 {
+			continue
+		}
+
+		validKeys, validValues = validateKeys(valuesList, values, keys)
+		val, err := Walker{
+			VisitKeysAsScalars:    l.VisitKeysAsScalars,
+			InferAssociativeLists: l.InferAssociativeLists,
+			Visitor:               l,
+			Schema:                schema,
+			Sources:               l.elementValueList(validKeys, validValues),
+			MergeOptions:          l.MergeOptions,
+		}.Walk()
+		if err != nil {
+			return nil, err
+		}
+
+		exit := false
+		for i, key := range validKeys {
+			// delete the node from **dest** if it's null or empty
+			if yaml.IsMissingOrNull(val) || yaml.IsEmptyMap(val) {
+				_, err = dest.Pipe(yaml.ElementSetter{
+					Keys:   validKeys,
+					Values: validValues,
+				})
+				if err != nil {
+					return nil, err
+				}
+				exit = true
+			} else if val.Field(key) == nil && validValues[i] != "" {
+				// make sure the key is set on the field
+				_, err = val.Pipe(yaml.SetField(key, yaml.NewScalarRNode(validValues[i])))
+				if err != nil {
+					return nil, err
+				}
+			}
+		}
+		if exit {
+			continue
+		}
+
+		// Add the val to the sequence. val will replace the item in the sequence if
+		// there is an item that matches all key-value pairs. Otherwise val will be appended
+		// the the sequence.
+		_, err = itemsToBeAdded.Pipe(yaml.ElementSetter{
+			Element: val.YNode(),
+			Keys:    validKeys,
+			Values:  validValues,
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	var err error
+	if len(valuesList) > 0 {
+		if l.MergeOptions.ListIncreaseDirection == yaml.MergeOptionsListPrepend {
+			// items from patches are needed to be prepended. so we append the
+			// dest to itemsToBeAdded
+			dest, err = appendListNode(itemsToBeAdded, dest, validKeys)
+		} else {
+			// append the items
+			dest, err = appendListNode(dest, itemsToBeAdded, validKeys)
+		}
+	}
+
+	if err != nil {
+		return nil, err
+	}
+	// sequence is empty
+	if yaml.IsMissingOrNull(dest) {
+		return nil, nil
+	}
+	return dest, nil
+}
+
+func (l *Walker) walkAssociativeSequence() (*yaml.RNode, error) {
+	// may require initializing the dest node
+	dest, err := l.Sources.setDestNode(l.VisitList(l.Sources, l.Schema, AssociativeList))
+	if dest == nil || err != nil {
+		return nil, err
+	}
+
+	// get the merge key(s) from schema
+	var strategy string
+	var keys []string
+	if l.Schema != nil {
+		strategy, keys = l.Schema.PatchStrategyAndKeyList()
+	}
+	if strategy == "" && len(keys) == 0 { // neither strategy nor keys present in the schema -- infer the key
+		// find the list of elements we need to recursively walk
+		key, err := l.elementKey()
+		if err != nil {
+			return nil, err
+		}
+		if key != "" {
+			keys = append(keys, key)
+		}
+	}
+
+	// non-primitive associative list -- merge the elements
+	values := l.elementValues(keys)
+	if len(values) != 0 || len(keys) > 0 {
+		return l.setAssociativeSequenceElements(values, keys, dest)
+	}
+
+	// primitive associative list -- merge the values
+	return l.setAssociativeSequenceElements(l.elementPrimitiveValues(), []string{""}, dest)
+}
+
+// elementKey returns the merge key to use for the associative list
+func (l Walker) elementKey() (string, error) {
+	var key string
+	for i := range l.Sources {
+		if l.Sources[i] != nil && len(l.Sources[i].Content()) > 0 {
+			newKey := l.Sources[i].GetAssociativeKey()
+			if key != "" && key != newKey {
+				return "", errors.Errorf(
+					"conflicting merge keys [%s,%s] for field %s",
+					key, newKey, strings.Join(l.Path, "."))
+			}
+			key = newKey
+		}
+	}
+	if key == "" {
+		return "", errors.Errorf("no merge key found for field %s",
+			strings.Join(l.Path, "."))
+	}
+	return key, nil
+}
+
+// elementValues returns a slice containing all values for the field across all elements
+// from all sources.
+// Return value slice is ordered using the original ordering from the elements, where
+// elements missing from earlier sources appear later.
+func (l Walker) elementValues(keys []string) [][]string {
+	// use slice to to keep elements in the original order
+	var returnValues [][]string
+	var seen sets.StringList
+
+	// if we are doing append, dest node should be the first.
+	// otherwise dest node should be the last.
+	beginIdx := 0
+	if l.MergeOptions.ListIncreaseDirection == yaml.MergeOptionsListPrepend {
+		beginIdx = 1
+	}
+	for i := range l.Sources {
+		src := l.Sources[(i+beginIdx)%len(l.Sources)]
+		if src == nil {
+			continue
+		}
+
+		// add the value of the field for each element
+		// don't check error, we know this is a list node
+		values, _ := src.ElementValuesList(keys)
+		for _, s := range values {
+			if len(s) == 0 || seen.Has(s) {
+				continue
+			}
+			returnValues = append(returnValues, s)
+			seen = seen.Insert(s)
+		}
+	}
+	return returnValues
+}
+
+// elementPrimitiveValues returns the primitive values in an associative list -- eg. finalizers
+func (l Walker) elementPrimitiveValues() [][]string {
+	// use slice to to keep elements in the original order
+	var returnValues [][]string
+	seen := sets.String{}
+	// if we are doing append, dest node should be the first.
+	// otherwise dest node should be the last.
+	beginIdx := 0
+	if l.MergeOptions.ListIncreaseDirection == yaml.MergeOptionsListPrepend {
+		beginIdx = 1
+	}
+	for i := range l.Sources {
+		src := l.Sources[(i+beginIdx)%len(l.Sources)]
+		if src == nil {
+			continue
+		}
+
+		// add the value of the field for each element
+		// don't check error, we know this is a list node
+		for _, item := range src.YNode().Content {
+			if seen.Has(item.Value) {
+				continue
+			}
+			returnValues = append(returnValues, []string{item.Value})
+			seen.Insert(item.Value)
+		}
+	}
+	return returnValues
+}
+
+// fieldValue returns a slice containing each source's value for fieldName
+func (l Walker) elementValueList(keys []string, values []string) []*yaml.RNode {
+	keys, values = validateKeys([][]string{values}, values, keys)
+	var fields []*yaml.RNode
+	for i := range l.Sources {
+		if l.Sources[i] == nil {
+			fields = append(fields, nil)
+			continue
+		}
+		fields = append(fields, l.Sources[i].ElementList(keys, values))
+	}
+	return fields
+}

vendor/sigs.k8s.io/kustomize/kyaml/yaml/walk/map.go

@@ -0,0 +1,173 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"sort"
+
+	"sigs.k8s.io/kustomize/kyaml/fieldmeta"
+	"sigs.k8s.io/kustomize/kyaml/openapi"
+	"sigs.k8s.io/kustomize/kyaml/sets"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// walkMap returns the value of VisitMap
+//
+// - call VisitMap
+// - set the return value on l.Dest
+// - walk each source field
+// - set each source field value on l.Dest
+func (l Walker) walkMap() (*yaml.RNode, error) {
+	// get the new map value
+	dest, err := l.Sources.setDestNode(l.VisitMap(l.Sources, l.Schema))
+	if dest == nil || err != nil {
+		return nil, err
+	}
+
+	// recursively set the field values on the map
+	for _, key := range l.fieldNames() {
+		var res *yaml.RNode
+		var keys []*yaml.RNode
+		if l.VisitKeysAsScalars {
+			// visit the map keys as if they were scalars,
+			// this is necessary if doing things such as copying
+			// comments
+			for i := range l.Sources {
+				// construct the sources from the keys
+				if l.Sources[i] == nil {
+					keys = append(keys, nil)
+					continue
+				}
+				field := l.Sources[i].Field(key)
+				if field == nil || yaml.IsMissingOrNull(field.Key) {
+					keys = append(keys, nil)
+					continue
+				}
+				keys = append(keys, field.Key)
+			}
+			// visit the sources as a scalar
+			// keys don't have any schema --pass in nil
+			res, err = l.Visitor.VisitScalar(keys, nil)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		var s *openapi.ResourceSchema
+		if l.Schema != nil {
+			s = l.Schema.Field(key)
+		}
+		fv, commentSch := l.fieldValue(key)
+		if commentSch != nil {
+			s = commentSch
+		}
+		val, err := Walker{
+			VisitKeysAsScalars:    l.VisitKeysAsScalars,
+			InferAssociativeLists: l.InferAssociativeLists,
+			Visitor:               l,
+			Schema:                s,
+			Sources:               fv,
+			MergeOptions:          l.MergeOptions,
+			Path:                  append(l.Path, key)}.Walk()
+		if err != nil {
+			return nil, err
+		}
+
+		// transfer the comments of res to dest node
+		var comments yaml.Comments
+		if !yaml.IsMissingOrNull(res) {
+			comments = yaml.Comments{
+				LineComment: res.YNode().LineComment,
+				HeadComment: res.YNode().HeadComment,
+				FootComment: res.YNode().FootComment,
+			}
+			if len(keys) > 0 && !yaml.IsMissingOrNull(keys[DestIndex]) {
+				keys[DestIndex].YNode().HeadComment = res.YNode().HeadComment
+				keys[DestIndex].YNode().LineComment = res.YNode().LineComment
+				keys[DestIndex].YNode().FootComment = res.YNode().FootComment
+			}
+		}
+
+		// this handles empty and non-empty values
+		_, err = dest.Pipe(yaml.FieldSetter{Name: key, Comments: comments, Value: val})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return dest, nil
+}
+
+// valueIfPresent returns node.Value if node is non-nil, otherwise returns nil
+func (l Walker) valueIfPresent(node *yaml.MapNode) (*yaml.RNode, *openapi.ResourceSchema) {
+	if node == nil {
+		return nil, nil
+	}
+
+	// parse the schema for the field if present
+	var s *openapi.ResourceSchema
+	fm := fieldmeta.FieldMeta{}
+	var err error
+	// check the value for a schema
+	if err = fm.Read(node.Value); err == nil {
+		s = &openapi.ResourceSchema{Schema: &fm.Schema}
+		if fm.Schema.Ref.String() != "" {
+			r, err := openapi.Resolve(&fm.Schema.Ref, openapi.Schema())
+			if err == nil && r != nil {
+				s.Schema = r
+			}
+		}
+	}
+	// check the key for a schema -- this will be used
+	// when the value is a Sequence (comments are attached)
+	// to the key
+	if fm.IsEmpty() {
+		if err = fm.Read(node.Key); err == nil {
+			s = &openapi.ResourceSchema{Schema: &fm.Schema}
+		}
+		if fm.Schema.Ref.String() != "" {
+			r, err := openapi.Resolve(&fm.Schema.Ref, openapi.Schema())
+			if err == nil && r != nil {
+				s.Schema = r
+			}
+		}
+	}
+	return node.Value, s
+}
+
+// fieldNames returns a sorted slice containing the names of all fields that appear in any of
+// the sources
+func (l Walker) fieldNames() []string {
+	fields := sets.String{}
+	for _, s := range l.Sources {
+		if s == nil {
+			continue
+		}
+		// don't check error, we know this is a mapping node
+		sFields, _ := s.Fields()
+		fields.Insert(sFields...)
+	}
+	result := fields.List()
+	sort.Strings(result)
+	return result
+}
+
+// fieldValue returns a slice containing each source's value for fieldName
+func (l Walker) fieldValue(fieldName string) ([]*yaml.RNode, *openapi.ResourceSchema) {
+	var fields []*yaml.RNode
+	var sch *openapi.ResourceSchema
+	for i := range l.Sources {
+		if l.Sources[i] == nil {
+			fields = append(fields, nil)
+			continue
+		}
+		field := l.Sources[i].Field(fieldName)
+		f, s := l.valueIfPresent(field)
+		fields = append(fields, f)
+		if sch == nil && !s.IsMissingOrNull() {
+			sch = s
+		}
+	}
+	return fields, sch
+}

vendor/sigs.k8s.io/kustomize/kyaml/yaml/walk/nonassociative_sequence.go

@@ -0,0 +1,13 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// walkNonAssociativeSequence returns the value of VisitList
+func (l Walker) walkNonAssociativeSequence() (*yaml.RNode, error) {
+	return l.VisitList(l.Sources, l.Schema, NonAssociateList)
+}

vendor/sigs.k8s.io/kustomize/kyaml/yaml/walk/scalar.go

@@ -0,0 +1,11 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import "sigs.k8s.io/kustomize/kyaml/yaml"
+
+// walkScalar returns the value of VisitScalar
+func (l Walker) walkScalar() (*yaml.RNode, error) {
+	return l.VisitScalar(l.Sources, l.Schema)
+}

vendor/sigs.k8s.io/kustomize/kyaml/yaml/walk/visitor.go

@@ -0,0 +1,28 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"sigs.k8s.io/kustomize/kyaml/openapi"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+type ListKind int32
+
+const (
+	AssociativeList ListKind = 1 + iota
+	NonAssociateList
+)
+
+// Visitor is invoked by walk with source and destination node pairs
+type Visitor interface {
+	VisitMap(Sources, *openapi.ResourceSchema) (*yaml.RNode, error)
+
+	VisitScalar(Sources, *openapi.ResourceSchema) (*yaml.RNode, error)
+
+	VisitList(Sources, *openapi.ResourceSchema, ListKind) (*yaml.RNode, error)
+}
+
+// ClearNode is returned if GrepFilter should do nothing after calling Set
+var ClearNode *yaml.RNode

vendor/sigs.k8s.io/kustomize/kyaml/yaml/walk/walk.go

@@ -0,0 +1,186 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"sigs.k8s.io/kustomize/kyaml/fieldmeta"
+	"sigs.k8s.io/kustomize/kyaml/openapi"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+	"sigs.k8s.io/kustomize/kyaml/yaml/schema"
+)
+
+// Walker walks the Source RNode and modifies the RNode provided to GrepFilter.
+type Walker struct {
+	// Visitor is invoked by GrepFilter
+	Visitor
+
+	Schema *openapi.ResourceSchema
+
+	// Source is the RNode to walk.  All Source fields and associative list elements
+	// will be visited.
+	Sources Sources
+
+	// Path is the field path to the current Source Node.
+	Path []string
+
+	// InferAssociativeLists if set to true will infer merge strategies for
+	// fields which it doesn't have the schema based on the fields in the
+	// list elements.
+	InferAssociativeLists bool
+
+	// VisitKeysAsScalars if true will call VisitScalar on map entry keys,
+	// providing nil as the OpenAPI schema.
+	VisitKeysAsScalars bool
+
+	// MergeOptions is a struct to store options for merge
+	MergeOptions yaml.MergeOptions
+}
+
+// Kind returns the kind of the first non-null node in Sources.
+func (l Walker) Kind() yaml.Kind {
+	for _, s := range l.Sources {
+		if !yaml.IsMissingOrNull(s) {
+			return s.YNode().Kind
+		}
+	}
+	return 0
+}
+
+// Walk will recursively traverse every item in the Sources and perform corresponding
+// actions on them
+func (l Walker) Walk() (*yaml.RNode, error) {
+	l.Schema = l.GetSchema()
+
+	// invoke the handler for the corresponding node type
+	switch l.Kind() {
+	case yaml.MappingNode:
+		if err := yaml.ErrorIfAnyInvalidAndNonNull(yaml.MappingNode, l.Sources...); err != nil {
+			return nil, err
+		}
+		return l.walkMap()
+	case yaml.SequenceNode:
+		if err := yaml.ErrorIfAnyInvalidAndNonNull(yaml.SequenceNode, l.Sources...); err != nil {
+			return nil, err
+		}
+		// AssociativeSequence means the items in the sequence are associative. They can be merged
+		// according to merge key.
+		if schema.IsAssociative(l.Schema, l.Sources, l.InferAssociativeLists) {
+			return l.walkAssociativeSequence()
+		}
+		return l.walkNonAssociativeSequence()
+
+	case yaml.ScalarNode:
+		if err := yaml.ErrorIfAnyInvalidAndNonNull(yaml.ScalarNode, l.Sources...); err != nil {
+			return nil, err
+		}
+		return l.walkScalar()
+	case 0:
+		// walk empty nodes as maps
+		return l.walkMap()
+	default:
+		return nil, nil
+	}
+}
+
+func (l Walker) GetSchema() *openapi.ResourceSchema {
+	for i := range l.Sources {
+		r := l.Sources[i]
+		if yaml.IsMissingOrNull(r) {
+			continue
+		}
+
+		fm := fieldmeta.FieldMeta{}
+		if err := fm.Read(r); err == nil && !fm.IsEmpty() {
+			// per-field schema, this is fine
+			if fm.Schema.Ref.String() != "" {
+				// resolve the reference
+				s, err := openapi.Resolve(&fm.Schema.Ref, openapi.Schema())
+				if err == nil && s != nil {
+					fm.Schema = *s
+				}
+			}
+			return &openapi.ResourceSchema{Schema: &fm.Schema}
+		}
+	}
+
+	if l.Schema != nil {
+		return l.Schema
+	}
+	for i := range l.Sources {
+		r := l.Sources[i]
+		if yaml.IsMissingOrNull(r) {
+			continue
+		}
+
+		m, _ := r.GetMeta()
+		if m.Kind == "" || m.APIVersion == "" {
+			continue
+		}
+
+		s := openapi.SchemaForResourceType(yaml.TypeMeta{Kind: m.Kind, APIVersion: m.APIVersion})
+		if s != nil {
+			return s
+		}
+	}
+	return nil
+}
+
+const (
+	DestIndex = iota
+	OriginIndex
+	UpdatedIndex
+)
+
+// Sources are a list of RNodes. First item is the dest node, followed by
+// multiple source nodes.
+type Sources []*yaml.RNode
+
+// Dest returns the destination node
+func (s Sources) Dest() *yaml.RNode {
+	if len(s) <= DestIndex {
+		return nil
+	}
+	return s[DestIndex]
+}
+
+// Origin returns the origin node
+func (s Sources) Origin() *yaml.RNode {
+	if len(s) <= OriginIndex {
+		return nil
+	}
+	return s[OriginIndex]
+}
+
+// Updated returns the updated node
+func (s Sources) Updated() *yaml.RNode {
+	if len(s) <= UpdatedIndex {
+		return nil
+	}
+	return s[UpdatedIndex]
+}
+
+func (s Sources) String() string {
+	var values []string
+	for i := range s {
+		str, err := s[i].String()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "%v\n", err)
+		}
+		values = append(values, str)
+	}
+	return strings.Join(values, "\n")
+}
+
+// setDestNode sets the destination source node
+func (s Sources) setDestNode(node *yaml.RNode, err error) (*yaml.RNode, error) {
+	if err != nil {
+		return nil, err
+	}
+	s[0] = node
+	return node, nil
+}