types: make Result an interface and move existing Result to separate package

version/version.go

@@ -14,6 +14,13 @@
 
 package version
 
+import (
+	"fmt"
+
+	"github.com/containernetworking/cni/pkg/types"
+	"github.com/containernetworking/cni/pkg/types/current"
+)
+
 // Current reports the version of the CNI spec implemented by this library
 func Current() string {
 	return "0.2.0"
@@ -27,3 +34,25 @@ func Current() string {
 // Any future CNI spec versions which meet this definition should be added to
 // this list.
 var Legacy = PluginSupports("0.1.0", "0.2.0")
+
+var resultFactories = []struct {
+	supportedVersions []string
+	newResult         types.ResultFactoryFunc
+}{
+	{current.SupportedVersions, current.NewResult},
+}
+
+// Finds a Result object matching the requested version (if any) and asks
+// that object to parse the plugin result, returning an error if parsing failed.
+func NewResult(version string, resultBytes []byte) (types.Result, error) {
+	reconciler := &Reconciler{}
+	for _, resultFactory := range resultFactories {
+		err := reconciler.CheckRaw(version, resultFactory.supportedVersions)
+		if err == nil {
+			// Result supports this version
+			return resultFactory.newResult(resultBytes)
+		}
+	}
+
+	return nil, fmt.Errorf("unsupported CNI result version %q", version)
+}