Delete newly orphaned code.

api/internal/target/kusttarget.go

@@ -17,7 +17,6 @@ import (
 	"sigs.k8s.io/kustomize/api/internal/plugins/loader"
 	"sigs.k8s.io/kustomize/api/konfig"
 	"sigs.k8s.io/kustomize/api/resmap"
-	"sigs.k8s.io/kustomize/api/transform"
 	"sigs.k8s.io/kustomize/api/types"
 	"sigs.k8s.io/yaml"
 )
@@ -258,8 +257,7 @@ func (kt *KustTarget) runTransformers(ra *accumulator.ResAccumulator) error {
 		return err
 	}
 	r = append(r, lts...)
-	t := transform.NewMultiTransformer(r)
-	return ra.Transform(t)
+	return ra.Transform(newMultiTransformer(r))
 }
 
 func (kt *KustTarget) configureExternalTransformers(transformers []string) ([]resmap.Transformer, error) {
@@ -294,7 +292,6 @@ func (kt *KustTarget) runValidators(ra *accumulator.ResAccumulator) error {
 }
 
 func (kt *KustTarget) removeValidatedByLabel(rm resmap.ResMap) {
-
 	resources := rm.Resources()
 	for _, r := range resources {
 		labels := r.GetLabels()

api/internal/target/multitransformer.go

@@ -0,0 +1,71 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package target
+
+import (
+	"fmt"
+
+	"sigs.k8s.io/kustomize/api/resmap"
+)
+
+// multiTransformer contains a list of transformers.
+type multiTransformer struct {
+	transformers         []resmap.Transformer
+	checkConflictEnabled bool
+}
+
+var _ resmap.Transformer = &multiTransformer{}
+
+// newMultiTransformer constructs a multiTransformer.
+func newMultiTransformer(t []resmap.Transformer) resmap.Transformer {
+	r := &multiTransformer{
+		transformers:         make([]resmap.Transformer, len(t)),
+		checkConflictEnabled: false}
+	copy(r.transformers, t)
+	return r
+}
+
+// Transform prepends the name prefix.
+func (o *multiTransformer) Transform(m resmap.ResMap) error {
+	if o.checkConflictEnabled {
+		return o.transformWithCheckConflict(m)
+	}
+	return o.transform(m)
+}
+func (o *multiTransformer) transform(m resmap.ResMap) error {
+	for _, t := range o.transformers {
+		err := t.Transform(m)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Of the len(o.transformers)! possible transformer orderings, compare to a reversed order.
+// A spot check to perform when the transformations are supposed to be commutative.
+// Fail if there's a difference in the result.
+func (o *multiTransformer) transformWithCheckConflict(m resmap.ResMap) error {
+	mcopy := m.DeepCopy()
+	err := o.transform(m)
+	if err != nil {
+		return err
+	}
+	o.reverseTransformers()
+	err = o.transform(mcopy)
+	if err != nil {
+		return err
+	}
+	err = m.ErrorIfNotEqualSets(mcopy)
+	if err != nil {
+		return fmt.Errorf("found conflict between different patches\n%v", err)
+	}
+	return nil
+}
+
+func (o *multiTransformer) reverseTransformers() {
+	for i, j := 0, len(o.transformers)-1; i < j; i, j = i+1, j-1 {
+		o.transformers[i], o.transformers[j] = o.transformers[j], o.transformers[i]
+	}
+}