packager: assetPathUtils: @flow

Reviewed By: cpojer

Differential Revision: D4913888

fbshipit-source-id: 31ddb4b9ede65e1b6caf740a245c3a11326d15d6

local-cli/bundle/assetPathUtils.js

@@ -5,10 +5,19 @@
  * This source code is licensed under the BSD-style license found in the
  * 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
  */
+
 'use strict';
 
-function getAndroidAssetSuffix(scale) {
+import type {PackagerAsset} from '../../Libraries/Image/AssetRegistry';
+
+/**
+ * FIXME: using number to represent discrete scale numbers is fragile in essence because of
+ * floating point numbers imprecision.
+ */
+function getAndroidAssetSuffix(scale: number): string {
   switch (scale) {
     case 0.75: return 'ldpi';
     case 1: return 'mdpi';
@@ -17,9 +26,10 @@ function getAndroidAssetSuffix(scale) {
     case 3: return 'xxhdpi';
     case 4: return 'xxxhdpi';
   }
+  throw new Error('no such scale');
 }
 
-function getAndroidDrawableFolderName(asset, scale) {
+function getAndroidDrawableFolderName(asset: PackagerAsset, scale: number) {
   var suffix = getAndroidAssetSuffix(scale);
   if (!suffix) {
     throw new Error(
@@ -31,7 +41,7 @@ function getAndroidDrawableFolderName(asset, scale) {
   return androidFolder;
 }
 
-function getAndroidResourceIdentifier(asset) {
+function getAndroidResourceIdentifier(asset: PackagerAsset) {
   var folderPath = getBasePath(asset);
   return (folderPath + '/' + asset.name)
     .toLowerCase()
@@ -40,7 +50,7 @@ function getAndroidResourceIdentifier(asset) {
     .replace(/^assets_/, '');      // Remove "assets_" prefix
 }
 
-function getBasePath(asset) {
+function getBasePath(asset: PackagerAsset) {
   var basePath = asset.httpServerLocation;
   if (basePath[0] === '/') {
     basePath = basePath.substr(1);