From 5790a4b57f050e4a3f295a34dbddb09138ef1da6 Mon Sep 17 00:00:00 2001
From: Jean Lauliac <jeanlauliac@fb.com>
Date: Tue, 11 Apr 2017 08:05:20 -0700
Subject: [PATCH] packager: Module.js: fix Haste name code

Summary: The original code wasn't very readable. Better with this change, I think.

Reviewed By: davidaurelio

Differential Revision: D4851335

fbshipit-source-id: 210309d4b727aff58bea48d0ab324256234cd941
---
 .../metro-bundler/src/node-haste/Module.js    | 74 ++++++++++---------
 .../src/node-haste/__tests__/Module-test.js   |  1 +
 2 files changed, 39 insertions(+), 36 deletions(-)

diff --git a/packages/metro-bundler/src/node-haste/Module.js b/packages/metro-bundler/src/node-haste/Module.js
index 474d2c36..c3b0a230 100644
--- a/packages/metro-bundler/src/node-haste/Module.js
+++ b/packages/metro-bundler/src/node-haste/Module.js
@@ -210,46 +210,48 @@ class Module {
   }
 
   _getHasteName(): ?string {
-    if (this._hasteNameCache != null) {
-      return this._hasteNameCache.hasteName;
-    }
-    const hasteImpl = this._options.hasteImpl;
-    if (hasteImpl === undefined || hasteImpl.enforceHasteNameMatches) {
-      const moduleDocBlock = this._readDocBlock();
-      const {providesModule} = moduleDocBlock;
-      this._hasteNameCache = {
-        hasteName: providesModule && !this._depGraphHelpers.isNodeModulesDir(this.path)
-          ? /^\S+/.exec(providesModule)[0]
-          : undefined,
-      };
-    }
-    if (hasteImpl !== undefined) {
-      const {enforceHasteNameMatches} = hasteImpl;
-      if (enforceHasteNameMatches) {
-        /* $FlowFixMe: this rely on the above if being executed, that is fragile.
-         * Rework the algo. */
-        enforceHasteNameMatches(this.path, this._hasteNameCache.hasteName);
-      }
-      this._hasteNameCache = {hasteName: hasteImpl.getHasteName(this.path)};
-    } else {
-      // Extract an id for the module if it's using @providesModule syntax
-      // and if it's NOT in node_modules (and not a whitelisted node_module).
-      // This handles the case where a project may have a dep that has @providesModule
-      // docblock comments, but doesn't want it to conflict with whitelisted @providesModule
-      // modules, such as react-haste, fbjs-haste, or react-native or with non-dependency,
-      // project-specific code that is using @providesModule.
-      const moduleDocBlock = this._readDocBlock();
-      const {providesModule} = moduleDocBlock;
-      this._hasteNameCache = {
-        hasteName:
-          providesModule && !this._depGraphHelpers.isNodeModulesDir(this.path)
-            ? /^\S+/.exec(providesModule)[0]
-            : undefined,
-      };
+    if (this._hasteNameCache == null) {
+      this._hasteNameCache = {hasteName: this._readHasteName()};
     }
     return this._hasteNameCache.hasteName;
   }
 
+  /**
+   * If a custom Haste implementation is provided, then we use it to determine
+   * the actual Haste name instead of "@providesModule".
+   * `enforceHasteNameMatches` has been added to that it is easier to
+   * transition from a system using "@providesModule" to a system using another
+   * custom system, by throwing if inconsistencies are detected. For example,
+   * we could verify that the file's basename (ex. "bar/foo.js") is the same as
+   * the "@providesModule" name (ex. "foo").
+   */
+  _readHasteName(): ?string {
+    const hasteImpl = this._options.hasteImpl;
+    if (hasteImpl == null) {
+      return this._readHasteNameFromDocBlock();
+    }
+    const {enforceHasteNameMatches} = hasteImpl;
+    if (enforceHasteNameMatches != null) {
+      const name = this._readHasteNameFromDocBlock();
+      enforceHasteNameMatches(this.path, name || undefined);
+    }
+    return hasteImpl.getHasteName(this.path);
+  }
+
+  /**
+   * We extract the Haste name from the `@providesModule` docbloc field. This is
+   * not allowed for modules living in `node_modules`, except if they are
+   * whitelisted.
+   */
+  _readHasteNameFromDocBlock(): ?string {
+    const moduleDocBlock = this._readDocBlock();
+    const {providesModule} = moduleDocBlock;
+    if (providesModule && !this._depGraphHelpers.isNodeModulesDir(this.path)) {
+      return /^\S+/.exec(providesModule)[0];
+    }
+    return null;
+  }
+
   /**
    * To what we read from the cache or worker, we need to add id and source.
    */
diff --git a/packages/metro-bundler/src/node-haste/__tests__/Module-test.js b/packages/metro-bundler/src/node-haste/__tests__/Module-test.js
index e8d38b3d..5e5e6e88 100644
--- a/packages/metro-bundler/src/node-haste/__tests__/Module-test.js
+++ b/packages/metro-bundler/src/node-haste/__tests__/Module-test.js
@@ -315,6 +315,7 @@ describe('Module', () => {
         arbitrary: 'arbitrary',
         dependencies: ['foo', 'bar'],
         dependencyOffsets: [12, 764],
+        id: null,
         map: {version: 3},
         subObject: {foo: 'bar'},
       };