filters: remove out filter proc prototype

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)

utils/filters/filter.go

@@ -1,53 +0,0 @@
-package filters
-
-import (
-	"errors"
-	"fmt"
-	"io"
-)
-
-var DefaultFilterProcs = FilterProcSet{}
-
-func Register(name string, fp FilterProc) error {
-	return DefaultFilterProcs.Register(name, fp)
-}
-
-var ErrorFilterExists = errors.New("filter already exists and ")
-var ErrorFilterExistsConflict = errors.New("filter already exists and FilterProc are different")
-
-type FilterProcSet map[string]FilterProc
-
-func (fs FilterProcSet) Process(context string) {
-}
-
-func (fs FilterProcSet) Register(name string, fp FilterProc) error {
-	if v, ok := fs[name]; ok {
-		if v == fp {
-			return ErrorFilterExists
-		} else {
-			return ErrorFilterExistsConflict
-		}
-	}
-	fs[name] = fp
-	return nil
-}
-
-type FilterProc interface {
-	Process(context, key, value string, output io.Writer) error
-}
-
-type UnknownFilterProc struct{}
-
-func (ufp UnknownFilterProc) Process(context, key, value string, output io.Writer) error {
-	if output != nil {
-		fmt.Fprintf(output, "do not know how to process [%s : %s]", key, value)
-	}
-	return nil
-}
-
-type Filter interface {
-	Scope() string
-	Target() string
-	Expressions() []string
-	Match(interface{}) bool
-}