refactor(generator): use annotations for the model

generator/internal/api/model.go

@@ -59,6 +59,8 @@ type API struct {
 	Messages []*Message
 	// Enums
 	Enums []*Enum
+	// Language specific annotations
+	Codec any
 
 	// State contains helpful information that can be used when generating
 	// clients.
@@ -92,6 +94,9 @@ type Service struct {
 	DefaultHost string
 	// The Protobuf package this service belongs to.
 	Package string
+	// The model this service belongs to, mustache templates use this field to
+	// navigate the data structure.
+	Model *API
 	// Language specific annotations
 	Codec any
 }
@@ -121,6 +126,12 @@ type Method struct {
 	ServerSideStreaming bool
 	// For methods returning long-running operations
 	OperationInfo *OperationInfo
+	// The model this method belongs to, mustache templates use this field to
+	// navigate the data structure.
+	Model *API
+	// The service this method belongs to, mustache templates use this field to
+	// navigate the data structure.
+	Service *Service
 	// Language specific annotations
 	Codec any
 }

generator/internal/api/xref.go

@@ -50,5 +50,12 @@ func CrossReference(model *API) error {
 			m.OperationInfo.Method = m
 		}
 	}
+	for _, s := range model.State.ServiceByID {
+		s.Model = model
+		for _, m := range s.Methods {
+			m.Model = model
+			m.Service = s
+		}
+	}
 	return nil
 }

generator/internal/api/xref_test.go

@@ -104,3 +104,26 @@ func TestCrossReferenceMethod(t *testing.T) {
 		t.Errorf("mismatched output type, got=%v, want=%v", method.OutputType, response)
 	}
 }
+
+func TestCrossReferenceService(t *testing.T) {
+	service := &Service{
+		Name: "Service",
+		ID:   ".test.Service",
+	}
+	mixin := &Service{
+		Name: "Mixin",
+		ID:   ".external.Mixin",
+	}
+
+	model := NewTestAPI([]*Message{}, []*Enum{}, []*Service{service})
+	model.State.ServiceByID[mixin.ID] = mixin
+	if err := CrossReference(model); err != nil {
+		t.Fatal(err)
+	}
+	if service.Model != model {
+		t.Errorf("mismatched model, got=%v, want=%v", service.Model, model)
+	}
+	if mixin.Model != model {
+		t.Errorf("mismatched model, got=%v, want=%v", mixin.Model, model)
+	}
+}

generator/internal/golang/golang.go

@@ -35,12 +35,12 @@ type goImport struct {
 }
 
 func Generate(model *api.API, outdir string, options map[string]string) error {
-	data, err := newTemplateData(model, options)
+	_, err := annotateModel(model, options)
 	if err != nil {
 		return err
 	}
 	provider := templatesProvider()
-	return language.GenerateFromRoot(outdir, data, provider, generatedFiles())
+	return language.GenerateFromRoot(outdir, model, provider, generatedFiles())
 }
 
 func generatedFiles() []language.GeneratedFile {

generator/internal/golang/gotemplate.go

@@ -24,20 +24,14 @@ import (
 	"github.com/iancoleman/strcase"
 )
 
-type templateData struct {
-	Name              string
-	Title             string
-	Description       string
+type modelAnnotations struct {
 	PackageName       string
 	SourcePackageName string
 	HasServices       bool
 	CopyrightYear     string
 	BoilerPlate       []string
 	Imports           []string
 	DefaultHost       string
-	Services          []*api.Service
-	Messages          []*api.Message
-	Enums             []*api.Enum
 	GoPackage         string
 }
 
@@ -105,11 +99,11 @@ type enumValueAnnotation struct {
 	EnumType string
 }
 
-// newTemplateData creates a struct used as input for Mustache templates.
+// annotateModel creates a struct used as input for Mustache templates.
 // Fields and methods defined in this struct directly correspond to Mustache
 // tags. For example, the Mustache tag {{#Services}} uses the
 // [Template.Services] field.
-func newTemplateData(model *api.API, options map[string]string) (*templateData, error) {
+func annotateModel(model *api.API, options map[string]string) (*modelAnnotations, error) {
 	var (
 		sourceSpecificationPackageName string
 		packageNameOverride            string
@@ -153,10 +147,7 @@ func newTemplateData(model *api.API, options map[string]string) (*templateData,
 	for _, s := range model.Services {
 		annotateService(s, model.State)
 	}
-	data := &templateData{
-		Name:              model.Name,
-		Title:             model.Title,
-		Description:       model.Description,
+	ann := &modelAnnotations{
 		PackageName:       modelPackageName(model, packageNameOverride),
 		SourcePackageName: sourceSpecificationPackageName,
 		HasServices:       len(model.Services) > 0,
@@ -171,20 +162,11 @@ func newTemplateData(model *api.API, options map[string]string) (*templateData,
 			}
 			return ""
 		}(),
-		Services:  model.Services,
-		Messages:  model.Messages,
-		Enums:     model.Enums,
 		GoPackage: packageName,
 	}
 
-	for _, s := range data.Services {
-		for _, method := range s.Methods {
-			if m, ok := model.State.MessageByID[method.InputTypeID]; ok {
-				method.InputType = m
-			}
-		}
-	}
-	return data, nil
+	model.Codec = ann
+	return ann, nil
 }
 
 func annotateService(s *api.Service, state *api.APIState) {

generator/internal/golang/gotemplate_test.go

@@ -47,7 +47,7 @@ func Test_GoEnumAnnotations(t *testing.T) {
 
 	model := api.NewTestAPI(
 		[]*api.Message{}, []*api.Enum{enum}, []*api.Service{})
-	_, err := newTemplateData(model, map[string]string{})
+	_, err := annotateModel(model, map[string]string{})
 	if err != nil {
 		t.Fatal(err)
 	}

generator/internal/golang/templates/client.go.mustache

@@ -13,12 +13,12 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 }}
-// Copyright {{CopyrightYear}} Google LLC
-{{#BoilerPlate}}
+// Copyright {{Codec.CopyrightYear}} Google LLC
+{{#Codec.BoilerPlate}}
 //{{{.}}}
-{{/BoilerPlate}}
+{{/Codec.BoilerPlate}}
 
-package {{GoPackage}}
+package {{Codec.GoPackage}}
 
 import (
     "bytes"
@@ -31,13 +31,13 @@ import (
 	"time"
 
     "cloud.google.com/go/auth"
-    {{#Imports}}
+    {{#Codec.Imports}}
     {{{.}}}
-    {{/Imports}}
+    {{/Codec.Imports}}
 )
 
-{{#HasServices}}
-const defaultHost = "https://{{DefaultHost}}"
+{{#Codec.HasServices}}
+const defaultHost = "https://{{Codec.DefaultHost}}"
 
 type Options struct {
     Credentials *auth.Credentials
@@ -145,7 +145,7 @@ func doRequest(client *http.Client, req *http.Request) ([]byte, error){
     }
     return b, nil
 }
-{{/HasServices}}
+{{/Codec.HasServices}}
 {{#Messages}}
 {{> message}}
 {{/Messages}}

generator/internal/golang/templates/go.mod.mustache

@@ -13,6 +13,6 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 }}
-module {{PackageName}}
+module {{Codec.PackageName}}
 
 go 1.23.2

generator/internal/rust/rust.go

@@ -61,14 +61,13 @@ func Generate(model *api.API, outdir string, options map[string]string) error {
 	if err != nil {
 		return err
 	}
-	data, err := newTemplateData(model, codec, outdir)
-	if err != nil {
+	if _, err := annotateModel(model, codec, outdir); err != nil {
 		return err
 	}
 	provider := templatesProvider()
 	hasServices := len(model.State.ServiceByID) > 0
 	generatedFiles := generatedFiles(codec.generateModule, hasServices)
-	return language.GenerateFromRoot(outdir, data, provider, generatedFiles)
+	return language.GenerateFromRoot(outdir, model, provider, generatedFiles)
 }
 
 func newCodec(options map[string]string) (*codec, error) {
@@ -1552,7 +1551,7 @@ func hasStreamingRPC(model *api.API) bool {
 	return false
 }
 
-func addStreamingFeature(data *templateData, api *api.API, extraPackages []*packagez) {
+func addStreamingFeature(ann *modelAnnotations, api *api.API, extraPackages []*packagez) {
 	hasStreamingRPC := hasStreamingRPC(api)
 	if !hasStreamingRPC {
 		return
@@ -1575,8 +1574,8 @@ func addStreamingFeature(data *templateData, api *api.API, extraPackages []*pack
 	}
 	sort.Strings(deps)
 	features := fmt.Sprintf("unstable-stream = [%s]", strings.Join(deps, ", "))
-	data.HasFeatures = true
-	data.Features = append(data.Features, features)
+	ann.HasFeatures = true
+	ann.Features = append(ann.Features, features)
 }
 
 func generateMethod(m *api.Method) bool {

generator/internal/rust/rust_test.go

@@ -402,7 +402,7 @@ func TestRust_NoStreamingFeature(t *testing.T) {
 		{Name: "CreateResource", IsPageableResponse: false},
 	}, []*api.Enum{}, []*api.Service{})
 	loadWellKnownTypes(model.State)
-	data := &templateData{}
+	data := &modelAnnotations{}
 	addStreamingFeature(data, model, c.extraPackages)
 	if data.HasFeatures {
 		t.Errorf("mismatch in data.HasFeatures, expected `HasFeatures: false`, got=%v", data)
@@ -471,7 +471,7 @@ func checkRustContext(t *testing.T, codec *codec, wantFeatures string) {
 		{Name: "ListResources", IsPageableResponse: true},
 	}, []*api.Enum{}, []*api.Service{})
 	loadWellKnownTypes(model.State)
-	data := &templateData{}
+	data := &modelAnnotations{}
 	addStreamingFeature(data, model, codec.extraPackages)
 	want := []string{wantFeatures}
 	if !data.HasFeatures {