ModuleResolver: Narrow arguments, don't require entire ModuleMap

Summary:
The intention here is to make clear what `ModuleResolver` actually needs out of the (Haste) `ModuleMap`, so that we can more easily reason about whether it's safe to pass a snapshot, live object etc in subsequent diffs.

Some "duplication" due to `node-haste.js`, which is only referenced internally by Metro-Buck. I plan to get rid of that and consolidate the implementations, but it's not on the critical path for symlink support right now.

Changelog: Internal

Reviewed By: huntie

Differential Revision: D40837004

fbshipit-source-id: ae305836bc5736359be1de13bc6a361ec4368cc3

packages/metro/src/ModuleGraph/node-haste/node-haste.js

@@ -169,27 +169,32 @@ exports.createResolveFn = function (options: ResolveOptions): ResolveFn {
   const assetExtensions = new Set(assetExts.map(asset => '.' + asset));
   const isAssetFile = (file: string) => assetExtensions.has(path.extname(file));
 
+  const moduleMap = new ModuleMap({
+    duplicates: new Map(),
+    map: createModuleMap({
+      files,
+      moduleCache,
+      sourceExts: new Set(sourceExts),
+      additionalExts: new Set(additionalExts),
+      platforms,
+    }),
+    mocks: new Map(),
+    rootDir: '',
+  });
+
   const moduleResolver = new ModuleResolver({
     dirExists: (filePath: string): boolean => hasteFS.dirExists(filePath),
     disableHierarchicalLookup: options.disableHierarchicalLookup,
     doesFileExist: (filePath: string): boolean => hasteFS.exists(filePath),
     emptyModulePath: options.emptyModulePath,
     extraNodeModules,
+    getHasteModulePath: (name, platform) =>
+      moduleMap.getModule(name, platform, true),
+    getHastePackagePath: (name, platform) =>
+      moduleMap.getPackage(name, platform, true),
     isAssetFile,
     mainFields: options.mainFields,
     moduleCache,
-    moduleMap: new ModuleMap({
-      duplicates: new Map(),
-      map: createModuleMap({
-        files,
-        moduleCache,
-        sourceExts: new Set(sourceExts),
-        additionalExts: new Set(additionalExts),
-        platforms,
-      }),
-      mocks: new Map(),
-      rootDir: '',
-    }),
     nodeModulesPaths: options.nodeModulesPaths,
     preferNativePlatform: true,
     projectRoot: '',

packages/metro/src/node-haste/DependencyGraph.js

@@ -192,10 +192,13 @@ class DependencyGraph extends EventEmitter {
       doesFileExist: this._doesFileExist,
       emptyModulePath: this._config.resolver.emptyModulePath,
       extraNodeModules: this._config.resolver.extraNodeModules,
+      getHasteModulePath: (name, platform) =>
+        this._moduleMap.getModule(name, platform, true),
+      getHastePackagePath: (name, platform) =>
+        this._moduleMap.getPackage(name, platform, true),
       isAssetFile: file => this._assetExtensions.has(path.extname(file)),
       mainFields: this._config.resolver.resolverMainFields,
       moduleCache: this._moduleCache,
-      moduleMap: this._moduleMap,
       nodeModulesPaths: this._config.resolver.nodeModulesPaths,
       preferNativePlatform: true,
       projectRoot: this._config.projectRoot,

packages/metro/src/node-haste/DependencyGraph/ModuleResolution.js

@@ -11,7 +11,6 @@
 
 'use strict';
 
-import type {ModuleMap} from 'metro-file-map';
 import type {
   CustomResolver,
   DoesFileExist,
@@ -55,23 +54,24 @@ export type ModuleishCache<TModule, TPackage> = interface {
   getPackageOf(modulePath: string): ?TPackage,
 };
 
-type Options<TModule, TPackage> = {
-  +dirExists: DirExistsFn,
-  +disableHierarchicalLookup: boolean,
-  +doesFileExist: DoesFileExist,
-  +emptyModulePath: string,
-  +extraNodeModules: ?Object,
-  +isAssetFile: IsAssetFile,
-  +mainFields: $ReadOnlyArray<string>,
-  +moduleCache: ModuleishCache<TModule, TPackage>,
-  +moduleMap: ModuleMap,
-  +nodeModulesPaths: $ReadOnlyArray<string>,
-  +preferNativePlatform: boolean,
-  +projectRoot: string,
-  +resolveAsset: ResolveAsset,
-  +resolveRequest: ?CustomResolver,
-  +sourceExts: $ReadOnlyArray<string>,
-};
+type Options<TModule, TPackage> = $ReadOnly<{
+  dirExists: DirExistsFn,
+  disableHierarchicalLookup: boolean,
+  doesFileExist: DoesFileExist,
+  emptyModulePath: string,
+  extraNodeModules: ?Object,
+  getHasteModulePath: (name: string, platform: ?string) => ?string,
+  getHastePackagePath: (name: string, platform: ?string) => ?string,
+  isAssetFile: IsAssetFile,
+  mainFields: $ReadOnlyArray<string>,
+  moduleCache: ModuleishCache<TModule, TPackage>,
+  nodeModulesPaths: $ReadOnlyArray<string>,
+  preferNativePlatform: boolean,
+  projectRoot: string,
+  resolveAsset: ResolveAsset,
+  resolveRequest: ?CustomResolver,
+  sourceExts: $ReadOnlyArray<string>,
+}>;
 
 class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
   _options: Options<TModule, TPackage>;
@@ -183,9 +183,9 @@ class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
           allowHaste,
           platform,
           resolveHasteModule: (name: string) =>
-            this._options.moduleMap.getModule(name, platform, true),
+            this._options.getHasteModulePath(name, platform),
           resolveHastePackage: (name: string) =>
-            this._options.moduleMap.getPackage(name, platform, true),
+            this._options.getHastePackagePath(name, platform),
           getPackageMainPath: this._getPackageMainPath,
         },
         moduleName,