linker: add getpackages by filter

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/onsi/ginkgo v1.12.0 // indirect
 	github.com/onsi/gomega v1.9.0 // indirect
+	github.com/scylladb/go-set v1.0.2
 	github.com/sirupsen/logrus v1.0.5
 	github.com/spf13/cobra v0.0.2
 	github.com/spf13/pflag v1.0.1 // indirect

go.sum

@@ -2,6 +2,7 @@ github.com/awalterschulze/gographviz v0.0.0-20190522210029-fa59802746ab h1:+cdNq
 github.com/awalterschulze/gographviz v0.0.0-20190522210029-fa59802746ab/go.mod h1:GEV5wmg4YquNw7v1kkyoX9etIk8yVmXj+AkDHuuETHs=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fatih/set v0.2.1/go.mod h1:+RKtMCH+favT2+3YecHGxcc0b4KyVWA1QWWJUs4E0CI=
 github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
@@ -18,6 +19,8 @@ github.com/onsi/gomega v1.9.0 h1:R1uwffexN6Pr340GtYRIdZmAiN4J+iw6WG4wog1DUXg=
 github.com/onsi/gomega v1.9.0/go.mod h1:Ho0h+IUsWyvy1OpqCwxlQ/21gkhVunqlU8fDGcoTdcA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/scylladb/go-set v1.0.2 h1:SkvlMCKhP0wyyct6j+0IHJkBkSZL+TDzZ4E7f7BCcRE=
+github.com/scylladb/go-set v1.0.2/go.mod h1:DkpGd78rljTxKAnTDPFqXSGxvETQnJyuSOQwsHycqfs=
 github.com/sirupsen/logrus v1.0.5 h1:8c8b5uO0zS4X6RPl/sd1ENwSkIc0/H2PaHxE3udaE8I=
 github.com/sirupsen/logrus v1.0.5/go.mod h1:pMByvHTf9Beacp5x1UXfOR9xyW/9antXMhjMPG0dEzc=
 github.com/spf13/cobra v0.0.2 h1:NfkwRbgViGoyjBKsLI0QMDcuMnhM+SBg3T0cGfpvKDE=

linker/linker.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"strings"
 
+	set "github.com/scylladb/go-set"
 	"github.com/sirupsen/logrus"
 )
 
@@ -45,6 +46,47 @@ func SetLinkerLogLevel(lv logrus.Level) {
 	logrus.SetLevel(lv)
 }
 
+type Filter func([]string) []string
+
+type Searcher interface {
+	Filt(...Filter) Searcher
+	List() []string
+	Error() error
+}
+
+type SearchFilter struct {
+	err error
+	src []string
+}
+
+func (sf *SearchFilter) Error() error   { return sf.err }
+func (sf *SearchFilter) List() []string { return sf.src }
+func (sf *SearchFilter) Filt(fs ...Filter) Searcher {
+	for _, f := range fs {
+		sf.src = f(sf.src)
+	}
+	return sf
+}
+
+func (l *Linker) GetPackagesByFilter(allowDup bool, excludeDirs []string) Searcher {
+	sf := new(SearchFilter)
+	pkgsmap, err := l.GetAllPKGNames(allowDup, excludeDirs)
+	if err != nil {
+		sf.err = err
+	}
+	s := set.NewStringSet()
+	for _, pkgs := range pkgsmap {
+		for _, pkg := range pkgs {
+			if s.Has(pkg) {
+				continue
+			}
+			s.Add(pkg)
+		}
+	}
+	sf.src = s.List()
+	return sf
+}
+
 // GetAllPKGNames gets the full layers packages names
 func (l *Linker) GetAllPKGNames(allowDup bool, excludeDirs []string) (map[string][]string, error) {