Simplify code base.

- In ResMap, drop concept of internal Id to Resource
   map.  The ResMap is now (just) a list, allowing only
   very particular edits.

 - Resources should now be maintained in the order
   loaded.  A later PR can adjust tests to remove the
   internal legacy sorting, and confirm order-out is
   predictable from order-in.  The PR would suppress
   the sort in tests, and reorder the output to make
   all tests pass again, and confirm that the new order
   matched depth-first input traversal.  The FromMap
   fixture function was removed from all test inputs to
   establish a predictable input order.

 - Resources now have two 'Ids', OriginalId and
   CurrentId.  The former is fixed as
   GVK-name-namespace at load time, the latter changes
   during transformations.  The latter can be used to
   narrow name references when the former maps to
   multiple resources.  We allow bases to be loaded
   more than once in a build (a diamond pattern), so
   the OriginalId is not unique across the resources
   set.  The CurrentId is (and must be) unique, but is
   constantly mutating.  Failing to make this
   distinction clear, and attempting to maintain a
   mapping from a single mutating Id to a resource was
   making the code too complex.

 - Drop prefix/suffix from ResId - the ResId is now
   immutable.  A later PR can remove the distinction
   with ItemId.

 - This PR increases coverage of ResMap is since this
   is a large refactor.  Higher level tests didn't need
   much change outside reordering of results at the
   resource level.

pkg/transformers/namereference.go

@@ -7,8 +7,9 @@ import (
 	"fmt"
 	"log"
 
+	"sigs.k8s.io/kustomize/pkg/resource"
+
 	"sigs.k8s.io/kustomize/pkg/gvk"
-	"sigs.k8s.io/kustomize/pkg/resid"
 	"sigs.k8s.io/kustomize/pkg/resmap"
 	"sigs.k8s.io/kustomize/pkg/transformers/config"
 )
@@ -44,14 +45,15 @@ func NewNameReferenceTransformer(br []config.NameBackReferences) Transformer {
 //
 //   - kind: Deployment
 //     fieldSpecs:
-//     - path: spec/scaleTargetRef/name
-//       kind: HorizontalPodAutoscaler
+//     - kind: HorizontalPodAutoscaler
+//       path: spec/scaleTargetRef/name
 //
-// saying that an HPA, via its 'spec/scaleTargetRef/name'
-// field, may refer to a Deployment.  This match to HPA
-// means we may need to modify the value in its
-// 'spec/scaleTargetRef/name' field, by searching for
-// the thing it refers to, and getting its new name.
+// This entry says that an HPA, via its
+// 'spec/scaleTargetRef/name' field, may refer to a
+// Deployment.  This match to HPA means we may need to
+// modify the value in its 'spec/scaleTargetRef/name'
+// field, by searching for the thing it refers to,
+// and getting its new name.
 //
 // As a filter, and search optimization, we compute a
 // subset of all resources that the HPA could refer to,
@@ -76,19 +78,23 @@ func NewNameReferenceTransformer(br []config.NameBackReferences) Transformer {
 //
 func (o *nameReferenceTransformer) Transform(m resmap.ResMap) error {
 	// TODO: Too much looping, here and in transitive calls.
-	for referrer, res := range m.AsMap() {
+	for _, referrer := range m.Resources() {
 		var candidates resmap.ResMap
 		for _, target := range o.backRefs {
 			for _, fSpec := range target.FieldSpecs {
-				if referrer.Gvk().IsSelected(&fSpec.Gvk) {
+				if referrer.OrgId().IsSelected(&fSpec.Gvk) {
 					if candidates == nil {
-						candidates = m.SubsetThatCouldBeReferencedById(referrer)
+						candidates = m.SubsetThatCouldBeReferencedByResource(referrer)
 					}
 					err := MutateField(
-						res.Map(),
+						referrer.Map(),
 						fSpec.PathSlice(),
 						fSpec.CreateIfNotPresent,
-						o.getNewName(
+						o.getNewNameFunc(
+							// referrer could be an HPA instance,
+							// target could be Gvk for Deployment,
+							// candidate a list of resources "reachable"
+							// from the HPA.
 							referrer, target.Gvk, candidates))
 					if err != nil {
 						return err
@@ -100,26 +106,28 @@ func (o *nameReferenceTransformer) Transform(m resmap.ResMap) error {
 	return nil
 }
 
-func (o *nameReferenceTransformer) getNewName(
-	referrer resid.ResId,
+func (o *nameReferenceTransformer) getNewNameFunc(
+	referrer *resource.Resource,
 	target gvk.Gvk,
 	referralCandidates resmap.ResMap) func(in interface{}) (interface{}, error) {
 	return func(in interface{}) (interface{}, error) {
 		switch in.(type) {
 		case string:
 			oldName, _ := in.(string)
-			for id, res := range referralCandidates.AsMap() {
-				if id.Gvk().IsSelected(&target) && id.Name() == oldName {
-					matchedIds := referralCandidates.GetMatchingIds(id.GvknEquals)
+			for _, res := range referralCandidates.Resources() {
+				id := res.OrgId()
+				if id.IsSelected(&target) && res.GetOriginalName() == oldName {
+					matches := referralCandidates.GetMatchingResourcesByOriginalId(id.GvknEquals)
 					// If there's more than one match, there's no way
 					// to know which one to pick, so emit error.
-					if len(matchedIds) > 1 {
+					if len(matches) > 1 {
 						return nil, fmt.Errorf(
-							"Multiple matches for name %s:\n  %v", id, matchedIds)
+							"string case - multiple matches for %s:\n  %v",
+							id, getIds(matches))
 					}
 					// In the resource, note that it is referenced
 					// by the referrer.
-					res.AppendRefBy(referrer)
+					res.AppendRefBy(referrer.CurId())
 					// Return transformed name of the object,
 					// complete with prefixes, hashes, etc.
 					return res.GetName(), nil
@@ -137,18 +145,20 @@ func (o *nameReferenceTransformer) getNewName(
 				}
 				names = append(names, name)
 			}
-			for id, res := range referralCandidates.AsMap() {
-				indexes := indexOf(id.Name(), names)
-				if id.Gvk().IsSelected(&target) && len(indexes) > 0 {
-					matchedIds := referralCandidates.GetMatchingIds(id.GvknEquals)
-					if len(matchedIds) > 1 {
+			for _, res := range referralCandidates.Resources() {
+				indexes := indexOf(res.GetOriginalName(), names)
+				id := res.OrgId()
+				if id.IsSelected(&target) && len(indexes) > 0 {
+					matches := referralCandidates.GetMatchingResourcesByOriginalId(id.GvknEquals)
+					if len(matches) > 1 {
 						return nil, fmt.Errorf(
-							"Multiple matches for name %s:\n %v", id, matchedIds)
+							"slice case - multiple matches for %s:\n %v",
+							id, getIds(matches))
 					}
 					for _, index := range indexes {
 						l[index] = res.GetName()
 					}
-					res.AppendRefBy(referrer)
+					res.AppendRefBy(referrer.CurId())
 					return l, nil
 				}
 			}
@@ -169,3 +179,11 @@ func indexOf(s string, slice []string) []int {
 	}
 	return index
 }
+
+func getIds(rs []*resource.Resource) []string {
+	var result []string
+	for _, r := range rs {
+		result = append(result, r.CurId().String()+"\n")
+	}
+	return result
+}