Add support for 'ref' annotation

pkg/annotations/annotations.go

@@ -63,3 +63,17 @@ func GoName(concept concepts.Annotated) string {
 	}
 	return fmt.Sprintf("%s", name)
 }
+
+// Reference checks if the given concept has a `reference` annotation. If it has it then it returns the value
+// of the `path` parameter. It returns an empty string if there is no such annotation or parameter.
+func ReferencePath(concept concepts.Annotated) string {
+	annotation := concept.GetAnnotation("ref")
+	if annotation == nil {
+		return ""
+	}
+	name := annotation.FindParameter("path")
+	if name == nil {
+		return ""
+	}
+	return fmt.Sprintf("%s", name)
+}

pkg/language/reader.go

@@ -30,6 +30,7 @@ import (
 
 	"github.com/antlr/antlr4/runtime/Go/antlr"
 
+	"github.com/openshift-online/ocm-api-metamodel/pkg/annotations"
 	"github.com/openshift-online/ocm-api-metamodel/pkg/concepts"
 	"github.com/openshift-online/ocm-api-metamodel/pkg/names"
 	"github.com/openshift-online/ocm-api-metamodel/pkg/nomenclator"
@@ -737,6 +738,67 @@ func (r *Reader) ExitLocatorDecl(ctx *LocatorDeclContext) {
 	// Add the annotations:
 	r.addAnnotations(locator, ctx.GetAnnotations())
 
+	if path := annotations.ReferencePath(locator); path != "" {
+		if len(r.inputs) > 1 {
+			panic("refernced service with multiple inputs in undefined")
+		}
+
+		if r.service.Versions().Len() > 1 {
+			panic("cannot infer which version to add reference with multiple versions")
+		}
+
+		input := r.inputs[0]
+		currVersion := r.service.Versions()[0]
+		path = strings.TrimPrefix(path, "/")
+		components := strings.Split(path, "/")
+		referencedServiceName := components[0]
+		referencedVersion := components[1]
+		referencedLocator := components[2]
+
+		// Create an ad-hoc reader and model for the specific referenced service.
+		refReader := NewReader().
+			Reporter(r.reporter)
+		refReader.model = concepts.NewModel()
+
+		// Initialize the indexes of undefined concepts:
+		refReader.undefinedTypes = make(map[string]*concepts.Type)
+		refReader.undefinedResources = make(map[string]*concepts.Resource)
+		refReader.undefinedErrors = make(map[string]*concepts.Error)
+
+		// load the ad-hoc service and version referenced and find the correct locator.
+		refReader.loadService(fmt.Sprintf("%s/%s", input, referencedServiceName))
+		refVersion := refReader.service.FindVersion(names.ParseUsingSeparator(referencedVersion, "_"))
+		for _, currLocator := range refVersion.Root().Locators() {
+			if strings.Compare(currLocator.Name().String(), referencedLocator) == 0 {
+				for _, resource := range refVersion.Resources() {
+					if resource.IsRoot() {
+						// We do not need to copy over the root resource.
+						continue
+					}
+
+					// Add any underlying resource to the current version.
+					currVersion.AddResource(resource)
+					// Add underlying methods.
+					for _, method := range resource.Methods() {
+						currVersion.
+							FindResource(resource.Name()).
+							AddMethod(method)
+					}
+
+					// Remove any undefined resources as
+					// This is a no-op except for the reference target added
+					// by the locator as the compiler will attempt to compile it
+					r.removeUndefinedResource(resource)
+				}
+
+				currVersion.AddTypes(refVersion.Types())
+				locator = currLocator
+				ctx.SetResult(locator)
+				return
+			}
+		}
+	}
+
 	// Add the members:
 	membersCtxs := ctx.GetMembers()
 	if len(membersCtxs) > 0 {