port rust cataloger to new generic cataloger pattern (#1323)

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

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

syft/pkg/cataloger/rust/package.go

@@ -0,0 +1,74 @@
+package rust
+
+import (
+	"github.com/microsoft/go-rustaudit"
+
+	"github.com/anchore/packageurl-go"
+	"github.com/anchore/syft/syft/pkg"
+	"github.com/anchore/syft/syft/source"
+)
+
+// Pkg returns the standard `pkg.Package` representation of the package referenced within the Cargo.lock metadata.
+func newPackageFromCargoMetadata(m pkg.CargoPackageMetadata, locations ...source.Location) pkg.Package {
+	p := pkg.Package{
+		Name:         m.Name,
+		Version:      m.Version,
+		Locations:    source.NewLocationSet(locations...),
+		PURL:         packageURL(m.Name, m.Version),
+		Language:     pkg.Rust,
+		Type:         pkg.RustPkg,
+		MetadataType: pkg.RustCargoPackageMetadataType,
+		Metadata:     m,
+	}
+
+	p.SetID()
+
+	return p
+}
+
+func newPackagesFromAudit(location source.Location, versionInfo rustaudit.VersionInfo) []pkg.Package {
+	var pkgs []pkg.Package
+
+	for _, dep := range versionInfo.Packages {
+		dep := dep
+		p := newPackageFromAudit(&dep, location)
+		if pkg.IsValid(&p) && dep.Kind == rustaudit.Runtime {
+			pkgs = append(pkgs, p)
+		}
+	}
+
+	return pkgs
+}
+
+func newPackageFromAudit(dep *rustaudit.Package, locations ...source.Location) pkg.Package {
+	p := pkg.Package{
+		Name:         dep.Name,
+		Version:      dep.Version,
+		PURL:         packageURL(dep.Name, dep.Version),
+		Language:     pkg.Rust,
+		Type:         pkg.RustPkg,
+		Locations:    source.NewLocationSet(locations...),
+		MetadataType: pkg.RustCargoPackageMetadataType,
+		Metadata: pkg.CargoPackageMetadata{
+			Name:    dep.Name,
+			Version: dep.Version,
+			Source:  dep.Source,
+		},
+	}
+
+	p.SetID()
+
+	return p
+}
+
+// packageURL returns the PURL for the specific rust package (see https://github.com/package-url/purl-spec)
+func packageURL(name, version string) string {
+	return packageurl.NewPackageURL(
+		packageurl.TypeCargo,
+		"",
+		name,
+		version,
+		nil,
+		"",
+	).ToString()
+}