RNode copier

kyaml/yaml/rnode.go

@@ -168,6 +168,16 @@ type RNode struct {
 	Match []string
 }
 
+// Copy returns a distinct copy.
+func (rn *RNode) Copy() *RNode {
+	if rn == nil {
+		return nil
+	}
+	result := *rn
+	result.value = CopyYNode(rn.value)
+	return &result
+}
+
 var ErrMissingMetadata = fmt.Errorf("missing Resource metadata")
 
 // Field names

kyaml/yaml/rnode_test.go

@@ -4,6 +4,7 @@
 package yaml
 
 import (
+	"reflect"
 	"strings"
 	"testing"
 
@@ -206,6 +207,33 @@ func TestIsMissingOrNull(t *testing.T) {
 	}
 }
 
+func TestCopy(t *testing.T) {
+	rn := RNode{
+		fieldPath: []string{"fp1", "fp2"},
+		value: &Node{
+			Kind: 200,
+		},
+		Match: []string{"m1", "m2"},
+	}
+	rnC := rn.Copy()
+	if !reflect.DeepEqual(&rn, rnC) {
+		t.Fatalf("copy %v is not deep equal to %v", rnC, rn)
+	}
+	tmp := rn.value.Kind
+	rn.value.Kind = 666
+	if reflect.DeepEqual(rn, rnC) {
+		t.Fatalf("changing component should break equality")
+	}
+	rn.value.Kind = tmp
+	if !reflect.DeepEqual(&rn, rnC) {
+		t.Fatalf("should be back to normal")
+	}
+	rn.fieldPath[0] = "Different"
+	if reflect.DeepEqual(rn, rnC) {
+		t.Fatalf("changing fieldpath should break equality")
+	}
+}
+
 func TestFieldRNodes(t *testing.T) {
 	testCases := []struct {
 		testName string

kyaml/yaml/types.go

@@ -12,6 +12,23 @@ import (
 	"sigs.k8s.io/kustomize/kyaml/sets"
 )
 
+// CopyYNode returns a distinct copy of its argument.
+// Use https://github.com/jinzhu/copier instead?
+func CopyYNode(n *yaml.Node) *yaml.Node {
+	if n == nil {
+		return nil
+	}
+	c := *n
+	if len(n.Content) > 0 {
+		// Using Go 'copy' here doesn't yield independent slices.
+		c.Content = make([]*Node, len(n.Content))
+		for i, item := range n.Content {
+			c.Content[i] = CopyYNode(item)
+		}
+	}
+	return &c
+}
+
 // IsYNodeTaggedNull returns true if the node is explicitly tagged Null.
 func IsYNodeTaggedNull(n *yaml.Node) bool {
 	return n != nil && n.Tag == NodeTagNull

kyaml/yaml/types_test.go

@@ -4,9 +4,60 @@
 package yaml
 
 import (
+	"reflect"
 	"testing"
 )
 
+func TestCopyYNode(t *testing.T) {
+	ynSub1 := Node{
+		Kind: 100,
+	}
+	ynSub2 := Node{
+		Kind: 200,
+	}
+	ynSub3 := Node{
+		Kind: 300,
+	}
+	yn := Node{
+		Kind:        5000,
+		Style:       6000,
+		Tag:         "red",
+		Value:       "green",
+		Anchor:      "blue",
+		Alias:       &ynSub3,
+		Content:     []*Node{&ynSub1, &ynSub2},
+		HeadComment: "apple",
+		LineComment: "peach",
+		FootComment: "banana",
+		Line:        7000,
+		Column:      8000,
+	}
+	ynAddr := &yn
+	if !reflect.DeepEqual(&yn, ynAddr) {
+		t.Fatalf("truly %v should equal %v", &yn, ynAddr)
+	}
+	ynC := CopyYNode(&yn)
+	if !reflect.DeepEqual(yn.Content, ynC.Content) {
+		t.Fatalf("copy content %v is not deep equal to %v", ynC, yn)
+	}
+	if !reflect.DeepEqual(&yn, ynC) {
+		t.Fatalf("\noriginal: %v\n    copy: %v\nShould be equal.", yn, ynC)
+	}
+	tmp := yn.Content[0].Kind
+	yn.Content[0].Kind = 666
+	if reflect.DeepEqual(&yn, ynC) {
+		t.Fatalf("changing component should break equality")
+	}
+	yn.Content[0].Kind = tmp
+	if !reflect.DeepEqual(&yn, ynC) {
+		t.Fatalf("should be okay now")
+	}
+	yn.Tag = "Different"
+	if yn.Tag == ynC.Tag {
+		t.Fatalf("field aliased!")
+	}
+}
+
 func TestIsYNodeTaggedNull(t *testing.T) {
 	if IsYNodeTaggedNull(nil) {
 		t.Fatalf("nil cannot be tagged null")