feat(tools-react-native): add additional platform helpers

.changeset/short-singers-doubt.md

@@ -0,0 +1,6 @@
+---
+"@rnx-kit/tools-react-native": patch
+---
+
+Add additional platform helpers for react-native related to platform names and
+suffixes

packages/tools-react-native/src/index.ts

@@ -13,7 +13,12 @@ export {
   expandPlatformExtensions,
   getAvailablePlatforms,
   getAvailablePlatformsUncached,
+  getModuleSuffixes,
+  getPlatformPackageName,
+  getPlatformsForPackage,
   parsePlatform,
+  parsePlatformValue,
   platformExtensions,
+  platformValues,
 } from "./platform";
 export type { AllPlatforms } from "./platform";

packages/tools-react-native/src/platform.ts

@@ -8,6 +8,15 @@ import { readReactNativeConfig } from "./context";
  */
 export type AllPlatforms = "android" | "ios" | "macos" | "win32" | "windows";
 
+// Possible values for AllPlatforms
+const allValues: AllPlatforms[] = [
+  "android",
+  "ios",
+  "macos",
+  "win32",
+  "windows",
+];
+
 /**
  * Returns a list of extensions that should be tried for the target platform in
  * prioritized order.
@@ -30,6 +39,25 @@ export function expandPlatformExtensions(
   return expanded;
 }
 
+/**
+ * Get the module suffixes array for a given platform, suitable for use with TypeScript's moduleSuffixes setting
+ * in the form of ['.ios', '.native', ''] or ['.windows', '.win', '.native', ''] or similar
+ *
+ * @param platform platform to get module suffixes for
+ * @param appendEmpty finish the suffixes with an empty entry, required for typescript usage
+ * @returns an array of suffixes to try to match a module to in order of priority
+ */
+export function getModuleSuffixes(
+  platform: AllPlatforms,
+  appendEmpty = true
+): string[] {
+  const extensions = platformExtensions(platform).map((ext) => `.${ext}`);
+  if (appendEmpty) {
+    extensions.push("");
+  }
+  return extensions;
+}
+
 /**
  * Returns a map of available React Native platforms. The result is NOT cached.
  * @param startDir The directory to look for react-native platforms from
@@ -134,22 +162,57 @@ export function platformExtensions(platform: string): string[] {
   }
 }
 
+/**
+ * @returns the given string as a platform value or undefined if it is not a valid platform.
+ */
+export function parsePlatformValue(val: string): AllPlatforms | undefined {
+  return allValues.includes(val as AllPlatforms)
+    ? (val as AllPlatforms)
+    : undefined;
+}
+
 /**
  * Parse a string to ensure it maps to a valid react-native platform.
  *
  * @param val Input string
  * @returns React-native platform name. Throws `Error` on failure.
  */
 export function parsePlatform(val: string): AllPlatforms {
-  switch (val) {
-    case "android":
-    case "ios":
-    case "macos":
-    case "win32":
-    case "windows":
-      return val;
-
-    default:
-      throw new Error("Invalid platform '" + val + "'");
+  const platform = parsePlatformValue(val);
+  if (!platform) {
+    throw new Error(`Invalid platform '${val}'`);
   }
+  return platform;
+}
+
+/**
+ * @returns List of all supported react-native platforms.
+ */
+export function platformValues(): readonly AllPlatforms[] {
+  return allValues;
+}
+
+// Map of platform to npm package name
+const platformToPackage: Record<AllPlatforms, string> = {
+  android: "react-native",
+  ios: "react-native",
+  macos: "react-native-macos",
+  win32: "@office-iss/react-native-win32",
+  windows: "react-native-windows",
+};
+
+/**
+ * @returns The react-native package name for the given platform
+ */
+export function getPlatformPackageName(platform: AllPlatforms): string {
+  return platformToPackage[platform];
+}
+
+/**
+ * @returns The list of packages supported by the given react-native package name
+ */
+export function getPlatformsForPackage(packageName: string): AllPlatforms[] {
+  return Object.entries(platformToPackage)
+    .filter(([, pkg]) => pkg === packageName)
+    .map(([platform]) => platform as AllPlatforms);
 }