add resource handling before printing

Resources are currently filtered (in order to prevent printing) at print
time in their HumanReadablePrinter handlers. This design makes it not
possible to filter objects when they are printed using any other
printer, such as YAML, JSON, or the NamePrinter.

This patch removes any filters previously added at the printer level for
pods and adds a way to define resource-specific filters before they are
sent to a printer handler. A woking filter handler for pods has also
been
implemented.

Filters affect resources being printed through the HumanReadablePrinter,
YAML, JSON, and `--template` printers.

pkg/kubectl/cmd/util/helpers.go

@@ -28,6 +28,7 @@ import (
 	"strings"
 	"time"
 
+	"k8s.io/kubernetes/pkg/api"
 	kerrors "k8s.io/kubernetes/pkg/api/errors"
 	"k8s.io/kubernetes/pkg/api/meta"
 	"k8s.io/kubernetes/pkg/api/unversioned"
@@ -43,7 +44,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/sets"
 	"k8s.io/kubernetes/pkg/util/strategicpatch"
 
-	"github.com/evanphx/json-patch"
+	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
 )
@@ -59,7 +60,7 @@ type debugError interface {
 
 // AddSourceToErr adds handleResourcePrefix and source string to error message.
 // verb is the string like "creating", "deleting" etc.
-// souce is the filename or URL to the template file(*.json or *.yaml), or stdin to use to handle the resource.
+// source is the filename or URL to the template file(*.json or *.yaml), or stdin to use to handle the resource.
 func AddSourceToErr(verb string, source string, err error) error {
 	if source != "" {
 		if statusError, ok := err.(kerrors.APIStatus); ok {
@@ -626,3 +627,78 @@ func MaybeConvertObject(obj runtime.Object, gv unversioned.GroupVersion, convert
 		return converter.ConvertToVersion(obj, gv)
 	}
 }
+
+// MustPrintWithKinds determines if printer is dealing
+// with multiple resource kinds, in which case it will
+// return true, indicating resource kind will be
+// included as part of printer output
+func MustPrintWithKinds(objs []runtime.Object, infos []*resource.Info, sorter *kubectl.RuntimeSort, printAll bool) bool {
+	var lastMap *meta.RESTMapping
+
+	if len(infos) == 1 && printAll {
+		return true
+	}
+
+	for ix := range objs {
+		var mapping *meta.RESTMapping
+		if sorter != nil {
+			mapping = infos[sorter.OriginalPosition(ix)].Mapping
+		} else {
+			mapping = infos[ix].Mapping
+		}
+
+		// display "kind" only if we have mixed resources
+		if lastMap != nil && mapping.Resource != lastMap.Resource {
+			return true
+		}
+		lastMap = mapping
+	}
+
+	return false
+}
+
+// FilterResourceList receives a list of runtime objects.
+// If any objects are filtered, that number is returned along with a modified list.
+func FilterResourceList(obj runtime.Object, filterFuncs kubectl.Filters, filterOpts *kubectl.PrintOptions) (int, []runtime.Object, error) {
+	items, err := meta.ExtractList(obj)
+	if err != nil {
+		return 0, []runtime.Object{obj}, utilerrors.NewAggregate([]error{err})
+	}
+	if errs := runtime.DecodeList(items, api.Codecs.UniversalDecoder(), runtime.UnstructuredJSONScheme); len(errs) > 0 {
+		return 0, []runtime.Object{obj}, utilerrors.NewAggregate(errs)
+	}
+
+	filterCount := 0
+	list := make([]runtime.Object, 0, len(items))
+	for _, obj := range items {
+		if isFiltered, err := filterFuncs.Filter(obj, filterOpts); !isFiltered {
+			if err != nil {
+				glog.V(2).Infof("Unable to filter resource: %v", err)
+				continue
+			}
+			list = append(list, obj)
+		} else if isFiltered {
+			filterCount++
+		}
+	}
+	return filterCount, list, nil
+}
+
+func PrintFilterCount(hiddenObjNum int, resource string, out io.Writer, options *kubectl.PrintOptions) error {
+	if !options.NoHeaders && !options.ShowAll && hiddenObjNum > 0 {
+		_, err := fmt.Fprintf(out, "  info: %d completed object(s) was(were) not shown in %s list. Pass --show-all to see all objects.\n\n", hiddenObjNum, resource)
+		return err
+	}
+	return nil
+}
+
+// ObjectListToVersionedObject receives a list of api objects and a group version
+// and squashes the list's items into a single versioned runtime.Object.
+func ObjectListToVersionedObject(objects []runtime.Object, version unversioned.GroupVersion) (runtime.Object, error) {
+	objectList := &api.List{Items: objects}
+	converted, err := resource.TryConvert(api.Scheme, objectList, version, registered.GroupOrDie(api.GroupName).GroupVersion)
+	if err != nil {
+		return nil, err
+	}
+	return converted, nil
+}