[tcgc] add namespace flag

.chronus/changes/tcgc-namespaceFlag-2025-1-3-14-58-27.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+Add support for `namespace` flag in tspconfig.yaml

packages/typespec-client-generator-core/README.md

@@ -67,6 +67,10 @@ options:
 
 **Type:** `string`
 
+### `namespace`
+
+**Type:** `string`
+
 ## Decorators
 
 ### Azure.ClientGenerator.Core

packages/typespec-client-generator-core/src/context.ts

@@ -79,6 +79,7 @@ export async function createSdkContext<
     decoratorsAllowList: [...defaultDecoratorsAllowList, ...(options?.additionalDecorators ?? [])],
     previewStringRegex: options?.versioning?.previewStringRegex || tcgcContext.previewStringRegex,
     disableUsageAccessPropagationToBase: options?.disableUsageAccessPropagationToBase ?? false,
+    namespace: context.options["namespace"],
   };
   sdkContext.sdkPackage = diagnostics.pipe(getSdkPackage(sdkContext));
   for (const client of sdkContext.sdkPackage.clients) {

packages/typespec-client-generator-core/src/decorators.ts

@@ -60,6 +60,7 @@ import {
   AllScopes,
   clientNameKey,
   clientNamespaceKey,
+  getRootUserDefinedNamespaceName,
   getValidApiVersion,
   isAzureCoreTspModel,
   negationScopesKey,
@@ -1211,9 +1212,13 @@ export function getClientNamespace(
   entity: Namespace | Interface | Model | Enum | Union,
 ): string {
   const override = getScopedDecoratorData(context, clientNamespaceKey, entity);
-  if (override) return override;
+  if (override) {
+    const rootNamespaceName = getRootUserDefinedNamespaceName(context);
+    // if you've defined a namespace flag, we replace the root name with the flag
+    return override.replace(rootNamespaceName, context.namespace || rootNamespaceName);
+  }
   if (!entity.namespace) {
-    return "";
+    return context.namespace || "";
   }
   if (entity.kind === "Namespace") {
     return getNamespaceFullNameWithOverride(context, entity);
@@ -1233,6 +1238,12 @@ function getNamespaceFullNameWithOverride(context: TCGCContext, namespace: Names
     segments.unshift(current.name);
     current = current.namespace;
   }
+  if (context.namespace) {
+    const rootNamespaceName = getRootUserDefinedNamespaceName(context);
+
+    return segments.join(".").replace(rootNamespaceName, context.namespace);
+  }
+
   return segments.join(".");
 }
 

packages/typespec-client-generator-core/src/interfaces.ts

@@ -57,6 +57,7 @@ export interface TCGCContext {
   previewStringRegex: RegExp;
   disableUsageAccessPropagationToBase: boolean;
   __pagedResultSet: Set<SdkType>;
+  namespace?: string;
 }
 
 export interface SdkContext<
@@ -79,6 +80,7 @@ export interface SdkEmitterOptions {
   "examples-directory"?: string;
   "examples-dir"?: string;
   "emitter-name"?: string;
+  namespace?: string;
 }
 
 // Types for TCGC customization decorators
@@ -848,6 +850,9 @@ export type SdkMethod<TServiceOperation extends SdkServiceOperation> =
 
 export interface SdkPackage<TServiceOperation extends SdkServiceOperation> {
   name: string;
+  /**
+   * @deprecated Look at `.namespaces` instead
+   */
   rootNamespace: string;
   clients: SdkClientType<TServiceOperation>[];
   models: SdkModelType[];

packages/typespec-client-generator-core/src/internal-utils.ts

@@ -27,7 +27,7 @@ import {
   HttpOperationResponseContent,
 } from "@typespec/http";
 import { getAddedOnVersions, getRemovedOnVersions, getVersions } from "@typespec/versioning";
-import { getParamAlias } from "./decorators.js";
+import { getParamAlias, listClients } from "./decorators.js";
 import {
   DecoratorInfo,
   SdkBuiltInType,
@@ -83,6 +83,8 @@ export function parseEmitterName(
 }
 
 /**
+ *
+ * @deprecated Use `.namespaces` from sdkContext.sdkPackage instead
  *
  * @param context
  * @param namespace If we know explicitly the namespace of the client, pass this in
@@ -593,3 +595,25 @@ export function getValueTypeValue(
       return undefined;
   }
 }
+
+/**
+ * Get all of the root user-defined namespaces in a TypeSpec definition if they're tied to a client
+ * @param context
+ * @returns
+ */
+export function getRootUserDefinedNamespaceName(context: TCGCContext): string {
+  const rootNamespaces = [...context.program.getGlobalNamespaceType().namespaces.values()];
+
+  // We explicitly want namespaces that are used to define a client, not namespaces that define the service of a client
+  const clientNamespaces = listClients(context).map((x) =>
+    x.type.kind === "Namespace" ? x.type : x.type.namespace,
+  );
+  const globalNamespaces = rootNamespaces.filter((x) => clientNamespaces.includes(x));
+  // if we override with namespace flag, we should override the global namespace to the namespace flag
+  if (globalNamespaces.length !== 1) {
+    throw new Error(
+      "You can only use the `--namespace` flag in conjunction with a single namespace.",
+    );
+  }
+  return globalNamespaces[0].name;
+}

packages/typespec-client-generator-core/src/lib.ts

@@ -13,6 +13,7 @@ const EmitterOptionsSchema: JSONSchemaType<SdkEmitterOptions> = {
     "examples-directory": { type: "string", nullable: true },
     "examples-dir": { type: "string", nullable: true },
     "emitter-name": { type: "string", nullable: true },
+    namespace: { type: "string", nullable: true },
   },
 };
 

packages/typespec-client-generator-core/src/package.ts

@@ -33,6 +33,8 @@ import {
   SdkClient,
   SdkClientInitializationType,
   SdkClientType,
+  SdkContext,
+  SdkEmitterOptions,
   SdkEndpointParameter,
   SdkEndpointType,
   SdkEnumType,
@@ -886,7 +888,7 @@ function createSdkClientType<TServiceOperation extends SdkServiceOperation>(
     summary: getSummary(context.program, client.type),
     methods: [],
     apiVersions: context.__tspTypeToApiVersions.get(client.type)!,
-    nameSpace: getClientNamespaceStringHelper(context, client.service)!,
+    nameSpace: getClientNamespaceStringHelper(context, client.service)!, // eslint-disable-line @typescript-eslint/no-deprecated
     clientNamespace: getClientNamespace(context, client.type),
     initialization: diagnostics.pipe(getSdkInitializationType(context, client)),
     clientInitialization: diagnostics.pipe(createSdkClientInitializationType(context, client)),
@@ -985,17 +987,20 @@ function populateApiVersionInformation(context: TCGCContext): void {
   }
 }
 
-export function getSdkPackage<TServiceOperation extends SdkServiceOperation>(
-  context: TCGCContext,
+export function getSdkPackage<
+  TOptions extends Record<string, any> = SdkEmitterOptions,
+  TServiceOperation extends SdkServiceOperation = SdkHttpOperation,
+>(
+  context: SdkContext<TOptions, TServiceOperation>,
 ): [SdkPackage<TServiceOperation>, readonly Diagnostic[]] {
   const diagnostics = createDiagnosticCollector();
   populateApiVersionInformation(context);
   diagnostics.pipe(handleAllTypes(context));
   const crossLanguagePackageId = diagnostics.pipe(getCrossLanguagePackageId(context));
   const allReferencedTypes = getAllReferencedTypes(context);
   const sdkPackage: SdkPackage<TServiceOperation> = {
-    name: getClientNamespaceString(context)!,
-    rootNamespace: getClientNamespaceString(context)!,
+    name: getClientNamespaceString(context)!, // eslint-disable-line @typescript-eslint/no-deprecated
+    rootNamespace: getClientNamespaceString(context)!, // eslint-disable-line @typescript-eslint/no-deprecated
     clients: listClients(context).map((c) => diagnostics.pipe(createSdkClientType(context, c))),
     models: allReferencedTypes.filter((x): x is SdkModelType => x.kind === "model"),
     enums: allReferencedTypes.filter((x): x is SdkEnumType => x.kind === "enum"),
@@ -1005,13 +1010,14 @@ export function getSdkPackage<TServiceOperation extends SdkServiceOperation>(
     crossLanguagePackageId,
     namespaces: [],
   };
-  organizeNamespaces(sdkPackage);
+  organizeNamespaces(context, sdkPackage);
   return diagnostics.wrap(sdkPackage);
 }
 
-function organizeNamespaces<TServiceOperation extends SdkServiceOperation>(
-  sdkPackage: SdkPackage<TServiceOperation>,
-) {
+function organizeNamespaces<
+  TOptions extends Record<string, any> = SdkEmitterOptions,
+  TServiceOperation extends SdkServiceOperation = SdkHttpOperation,
+>(context: SdkContext<TOptions, TServiceOperation>, sdkPackage: SdkPackage<TServiceOperation>) {
   const clients = [...sdkPackage.clients];
   while (clients.length > 0) {
     const client = clients.shift()!;
@@ -1032,7 +1038,7 @@ function organizeNamespaces<TServiceOperation extends SdkServiceOperation>(
   }
 }
 
-function getSdkNamespace<TServiceOperation extends SdkServiceOperation>(
+function getSdkNamespace<TServiceOperation extends SdkServiceOperation = SdkHttpOperation>(
   sdkPackage: SdkPackage<TServiceOperation>,
   namespace: string,
 ) {

packages/typespec-client-generator-core/src/public-utils.ts

@@ -103,12 +103,15 @@ export function isApiVersion(context: TCGCContext, type: { name: string }): bool
 /**
  * Get the client's namespace for generation. If package-name is passed in config, we return
  * that value as our namespace. Otherwise, we default to the TypeSpec service namespace.
+ *
+ * @deprecated Access namespace information by iterating through `sdkPackage.namespaces` instead
+ *
  * @param program
  * @param context
  * @returns
  */
 export function getClientNamespaceString(context: TCGCContext): string | undefined {
-  return getClientNamespaceStringHelper(context, listServices(context.program)[0]?.type);
+  return getClientNamespaceStringHelper(context, listServices(context.program)[0]?.type); // eslint-disable-line @typescript-eslint/no-deprecated
 }
 
 /**