From dfa05cbcd48e81baf4dd2a9af6e98d02d9690d60 Mon Sep 17 00:00:00 2001
From: Peter van der Zee <kuvos@fb.com>
Date: Tue, 5 Dec 2017 01:26:02 -0800
Subject: [PATCH] Enable flow type for a file and fix a related typo/bug

Reviewed By: rafeca

Differential Revision: D6473575

fbshipit-source-id: 7b96b6bfb2aff96e6d4697ad29fd96fb85d1ceda
---
 packages/metro/src/Bundler/index.js             |  2 +-
 packages/metro/src/lib/createModuleIdFactory.js | 12 +++++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/packages/metro/src/Bundler/index.js b/packages/metro/src/Bundler/index.js
index 86e029a1..de5b659f 100644
--- a/packages/metro/src/Bundler/index.js
+++ b/packages/metro/src/Bundler/index.js
@@ -120,7 +120,7 @@ type Options = {|
 
 class Bundler {
   _opts: Options;
-  _getModuleId: ({path: string}) => number;
+  _getModuleId: (path: string) => number;
   _transformer: Transformer;
   _resolverPromise: Promise<Resolver>;
   _projectRoots: $ReadOnlyArray<string>;
diff --git a/packages/metro/src/lib/createModuleIdFactory.js b/packages/metro/src/lib/createModuleIdFactory.js
index 76c5dbb7..5e57f79b 100644
--- a/packages/metro/src/lib/createModuleIdFactory.js
+++ b/packages/metro/src/lib/createModuleIdFactory.js
@@ -6,20 +6,22 @@
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
  *
+ * @flow
  * @format
  */
 
 'use strict';
 
 function createModuleIdFactory(): (path: string) => number {
-  const fileToIdMap = new Map();
+  const fileToIdMap: Map<string, number> = new Map();
   let nextId = 0;
   return (path: string) => {
-    if (!fileToIdMap.has(path)) {
-      fileToIdMap.set(path, nextId);
-      nextId += 1;
+    let id = fileToIdMap.get(path);
+    if (typeof id !== 'number') {
+      id = nextId++;
+      fileToIdMap.set(path, id);
     }
-    return fileToIdMap.get(path);
+    return id;
   };
 }