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merge2.go
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merge2.go
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// Copyright 2019 The Kubernetes Authors.
// SPDX-License-Identifier: Apache-2.0
// Package merge2 contains libraries for merging fields from one RNode to another
// RNode
package merge2
import (
"sigs.k8s.io/kustomize/kyaml/openapi"
"sigs.k8s.io/kustomize/kyaml/yaml"
"sigs.k8s.io/kustomize/kyaml/yaml/walk"
)
// Merge merges fields from src into dest.
func Merge(src, dest *yaml.RNode, mergeOptions yaml.MergeOptions) (*yaml.RNode, error) {
return walk.Walker{
Sources: []*yaml.RNode{dest, src},
Visitor: Merger{},
MergeOptions: mergeOptions,
}.Walk()
}
// MergeStrings parses the arguments, and merges fields from srcStr into destStr.
func MergeStrings(srcStr, destStr string, infer bool, mergeOptions yaml.MergeOptions) (string, error) {
src, err := yaml.Parse(srcStr)
if err != nil {
return "", err
}
dest, err := yaml.Parse(destStr)
if err != nil {
return "", err
}
result, err := walk.Walker{
Sources: []*yaml.RNode{dest, src},
Visitor: Merger{},
InferAssociativeLists: infer,
MergeOptions: mergeOptions,
}.Walk()
if err != nil {
return "", err
}
return result.String()
}
type Merger struct {
}
// for forwards compatibility when new functions are added to the interface
var _ walk.Visitor = Merger{}
func (m Merger) VisitMap(nodes walk.Sources, s *openapi.ResourceSchema) (*yaml.RNode, error) {
if err := m.SetComments(nodes); err != nil {
return nil, err
}
if err := m.SetStyle(nodes); err != nil {
return nil, err
}
if yaml.IsMissingOrNull(nodes.Dest()) {
// Add
ps, _ := determineSmpDirective(nodes.Origin())
if ps == smpDelete {
return walk.ClearNode, nil
}
// If Origin is missing, preserve explicitly set null in Dest ("null", "~", etc)
if nodes.Origin().IsNil() && !nodes.Dest().IsNil() && len(nodes.Dest().YNode().Value) > 0 {
// Return a new node so that it won't have a "!!null" tag and therefore won't be cleared.
return yaml.NewScalarRNode(nodes.Dest().YNode().Value), nil
}
return nodes.Origin(), nil
}
if nodes.Origin().IsTaggedNull() {
// clear the value
return walk.ClearNode, nil
}
ps, err := determineSmpDirective(nodes.Origin())
if err != nil {
return nil, err
}
switch ps {
case smpDelete:
return walk.ClearNode, nil
case smpReplace:
return nodes.Origin(), nil
default:
return nodes.Dest(), nil
}
}
func (m Merger) VisitScalar(nodes walk.Sources, s *openapi.ResourceSchema) (*yaml.RNode, error) {
if err := m.SetComments(nodes); err != nil {
return nil, err
}
if err := m.SetStyle(nodes); err != nil {
return nil, err
}
// Override value
if nodes.Origin() != nil {
return nodes.Origin(), nil
}
// Keep
return nodes.Dest(), nil
}
func (m Merger) VisitList(nodes walk.Sources, s *openapi.ResourceSchema, kind walk.ListKind) (*yaml.RNode, error) {
if err := m.SetComments(nodes); err != nil {
return nil, err
}
if err := m.SetStyle(nodes); err != nil {
return nil, err
}
if kind == walk.NonAssociateList {
// Override value
if nodes.Origin() != nil {
return nodes.Origin(), nil
}
// Keep
return nodes.Dest(), nil
}
// Add
if yaml.IsMissingOrNull(nodes.Dest()) {
return nodes.Origin(), nil
}
// Clear
if nodes.Origin().IsTaggedNull() {
return walk.ClearNode, nil
}
ps, err := determineSmpDirective(nodes.Origin())
if err != nil {
return nil, err
}
switch ps {
case smpDelete:
return walk.ClearNode, nil
case smpReplace:
return nodes.Origin(), nil
default:
return nodes.Dest(), nil
}
}
func (m Merger) SetStyle(sources walk.Sources) error {
source := sources.Origin()
dest := sources.Dest()
if dest == nil || dest.YNode() == nil || source == nil || source.YNode() == nil {
// avoid panic
return nil
}
// copy the style from the source.
// special case: if the dest was an empty map or seq, then it probably had
// folded style applied, but we actually want to keep the style of the origin
// in this case (even if it was the default). otherwise the merged elements
// will get folded even though this probably isn't what is desired.
if dest.YNode().Kind != yaml.ScalarNode && len(dest.YNode().Content) == 0 {
dest.YNode().Style = source.YNode().Style
}
return nil
}
// SetComments copies the dest comments to the source comments if they are present
// on the source.
func (m Merger) SetComments(sources walk.Sources) error {
source := sources.Origin()
dest := sources.Dest()
if dest == nil || dest.YNode() == nil || source == nil || source.YNode() == nil {
// avoid panic
return nil
}
if source.YNode().FootComment != "" {
dest.YNode().FootComment = source.YNode().FootComment
}
if source.YNode().HeadComment != "" {
dest.YNode().HeadComment = source.YNode().HeadComment
}
if source.YNode().LineComment != "" {
dest.YNode().LineComment = source.YNode().LineComment
}
return nil
}