enable source.Location to be identifiable

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

syft/artifact/id.go

@@ -1,8 +1,26 @@
 package artifact
 
+import (
+	"fmt"
+
+	"github.com/mitchellh/hashstructure/v2"
+)
+
 // ID represents a unique value for each package added to a package catalog.
 type ID string
 
 type Identifiable interface {
 	ID() ID
 }
+
+func DeriveID(obj interface{}) (ID, error) {
+	f, err := hashstructure.Hash(obj, hashstructure.FormatV2, &hashstructure.HashOptions{
+		ZeroNil:      true,
+		SlicesAsSets: true,
+	})
+	if err != nil {
+		return "", fmt.Errorf("could not build ID for object=%+v: %+v", obj, err)
+	}
+
+	return ID(fmt.Sprint(f)), nil
+}

syft/pkg/package.go

@@ -9,7 +9,6 @@ import (
 	"github.com/anchore/syft/internal/log"
 	"github.com/anchore/syft/syft/artifact"
 	"github.com/anchore/syft/syft/source"
-	"github.com/mitchellh/hashstructure/v2"
 )
 
 // Package represents an application or library that has been bundled into a distributable format.
@@ -29,29 +28,17 @@ type Package struct {
 }
 
 func (p Package) ID() artifact.ID {
-	f, err := p.Fingerprint()
+	f, err := artifact.DeriveID(p)
 	if err != nil {
 		// TODO: what to do in this case?
 		log.Warnf("unable to get fingerprint of package=%s@%s: %+v", p.Name, p.Version, err)
 		return ""
 	}
 
-	return artifact.ID(f)
+	return f
 }
 
 // Stringer to represent a package.
 func (p Package) String() string {
 	return fmt.Sprintf("Pkg(type=%s, name=%s, version=%s)", p.Type, p.Name, p.Version)
 }
-
-func (p Package) Fingerprint() (string, error) {
-	f, err := hashstructure.Hash(p, hashstructure.FormatV2, &hashstructure.HashOptions{
-		ZeroNil:      true,
-		SlicesAsSets: true,
-	})
-	if err != nil {
-		return "", fmt.Errorf("could not build package fingerprint for: %s version: %s", p.Name, p.Version)
-	}
-
-	return fmt.Sprint(f), nil
-}

syft/source/location.go

@@ -3,10 +3,10 @@ package source
 import (
 	"fmt"
 
-	"github.com/anchore/syft/internal/log"
-
 	"github.com/anchore/stereoscope/pkg/file"
 	"github.com/anchore/stereoscope/pkg/image"
+	"github.com/anchore/syft/internal/log"
+	"github.com/anchore/syft/syft/artifact"
 )
 
 // Location represents a path relative to a particular filesystem resolved to a specific file.Reference. This struct is used as a key
@@ -73,3 +73,14 @@ func (l Location) String() string {
 	}
 	return fmt.Sprintf("Location<%s>", str)
 }
+
+func (l Location) ID() artifact.ID {
+	f, err := artifact.DeriveID(l)
+	if err != nil {
+		// TODO: what to do in this case?
+		log.Warnf("unable to get fingerprint of location=%+v: %+v", l, err)
+		return ""
+	}
+
+	return f
+}