add function to find all matched patch targets

pkg/resmap/resmap.go

@@ -8,6 +8,8 @@ package resmap
 import (
 	"bytes"
 	"fmt"
+	"regexp"
+
 	"github.com/pkg/errors"
 
 	"sigs.k8s.io/kustomize/v3/pkg/resid"
@@ -158,6 +160,10 @@ type ResMap interface {
 
 	// Debug prints the ResMap.
 	Debug(title string)
+
+	// Select returns a list of resources that
+	// are selected by a Selector
+	Select(types.Selector) ([]*resource.Resource, error)
 }
 
 // resWrangler holds the content manipulated by kustomize.
@@ -587,3 +593,66 @@ func (m *resWrangler) appendReplaceOrMerge(
 	}
 	return nil
 }
+
+// Select returns a list of resources that
+// are selected by a Selector
+func (m *resWrangler) Select(s types.Selector) ([]*resource.Resource, error) {
+	ns := regexp.MustCompile(s.Namespace)
+	nm := regexp.MustCompile(s.Name)
+	var result []*resource.Resource
+	for _, r := range m.Resources() {
+		curId := r.CurId()
+		orgId := r.OrgId()
+
+		// matches the namespace when namespace is not empty in the selector
+		// It first tries to match with the original namespace
+		// then matches with the current namespace
+		if r.GetNamespace() != "" {
+			matched := ns.MatchString(orgId.EffectiveNamespace())
+			if !matched {
+				matched = ns.MatchString(curId.EffectiveNamespace())
+				if !matched {
+					continue
+				}
+			}
+		}
+
+		// matches the name when name is not empty in the selector
+		// It first tries to match with the original name
+		// then matches with the current name
+		if r.GetName() != "" {
+			matched := nm.MatchString(orgId.Name)
+			if !matched {
+				matched = nm.MatchString(curId.Name)
+				if !matched {
+					continue
+				}
+			}
+		}
+
+		// matches the GVK
+		if !r.GetGvk().IsSelected(&s.Gvk) {
+			continue
+		}
+
+		// matches the label selector
+		matched, err := r.MatchesLabelSelector(s.LabelSelector)
+		if err != nil {
+			return nil, err
+		}
+		if !matched {
+			continue
+		}
+
+		// matches the annotation selector
+		matched, err = r.MatchesAnnotationSelector(s.AnnotationSelector)
+		if err != nil {
+			return nil, err
+		}
+		if !matched {
+			continue
+		}
+		result = append(result, r)
+	}
+	return result, nil
+}

pkg/resmap/selector_test.go

@@ -0,0 +1,130 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.
+
+package resmap_test
+
+import (
+	"testing"
+
+	"sigs.k8s.io/kustomize/v3/pkg/gvk"
+	"sigs.k8s.io/kustomize/v3/pkg/resmap"
+	"sigs.k8s.io/kustomize/v3/pkg/types"
+)
+
+func setupRMForPatchTargets(t *testing.T) resmap.ResMap {
+	result, err := rmF.NewResMapFromBytes([]byte(`
+apiVersion: group1/v1
+kind: Kind1
+metadata:
+  name: name1
+  namespace: ns1
+  labels:
+    app: name1
+  annotations:
+    foo: bar
+---
+apiVersion: group1/v1
+kind: Kind1
+metadata:
+  name: name2
+  namespace: default
+  labels:
+    app: name2
+  annotations:
+    foo: bar
+---
+apiVersion: group1/v1
+kind: Kind2
+metadata:
+  name: name3
+  labels:
+    app: name3
+  annotations:
+    bar: baz
+`))
+	if err != nil {
+		t.Fatalf("unexpected error %v", err)
+	}
+	return result
+}
+
+func TestFindPatchTargets(t *testing.T) {
+	rm := setupRMForPatchTargets(t)
+	testcases := []struct {
+		target types.Selector
+		count  int
+	}{
+		{
+			target: types.Selector{
+				Name: "name*",
+			},
+			count: 3,
+		},
+		{
+			target: types.Selector{
+				Name:               "name*",
+				AnnotationSelector: "foo=bar",
+			},
+			count: 2,
+		},
+		{
+			target: types.Selector{
+				LabelSelector: "app=name1",
+			},
+			count: 1,
+		},
+		{
+			target: types.Selector{
+				Gvk: gvk.Gvk{
+					Kind: "Kind1",
+				},
+				Name: "name*",
+			},
+			count: 2,
+		},
+		{
+			target: types.Selector{
+				Name: "NotMatched",
+			},
+			count: 0,
+		},
+		{
+			target: types.Selector{
+				Name: "",
+			},
+			count: 3,
+		},
+		{
+			target: types.Selector{
+				Namespace: "default",
+			},
+			count: 2,
+		},
+		{
+			target: types.Selector{
+				Namespace: "",
+			},
+			count: 3,
+		},
+		{
+			target: types.Selector{
+				Namespace: "default",
+				Name:      "name*",
+				Gvk: gvk.Gvk{
+					Kind: "Kind1",
+				},
+			},
+			count: 1,
+		},
+	}
+	for _, testcase := range testcases {
+		actual, err := rm.Select(testcase.target)
+		if err != nil {
+			t.Errorf("unexpected error %v", err)
+		}
+		if len(actual) != testcase.count {
+			t.Errorf("expected %d objects, but got %d:\n%v", testcase.count, len(actual), actual)
+		}
+	}
+
+}