fix css-modules#32: ensure caches are persisted

Previously, the caches were re-initialized on every plugin
initialization. This caused an incompatibility with other tools like
rebundler or persistify.

This change keeps the original intent of creating caches when the plugin
is initialized, but ensures the process keeps the caches instead of the
plugin instance itself. It’s not really possible to have a cache
conflict since they’re keyed by file.

Author: joeybaker

index.js

@@ -37,6 +37,22 @@ function normalizeManifestPaths (tokensByFile, rootDir) {
 }
 
 var cssExt = /\.css$/;
+
+// caches
+//
+// persist these for as long as the process is running. #32
+
+// keep track of css files visited
+var filenames = [];
+
+// keep track of all tokens so we can avoid duplicates
+var tokensByFile = {};
+
+// keep track of all source files for later builds: when
+// using watchify, not all files will be caught on subsequent
+// bundles
+var sourceByFile = {};
+
 module.exports = function (browserify, options) {
   options = options || {};
 
@@ -91,17 +107,6 @@ module.exports = function (browserify, options) {
     return plugin;
   });
 
-  // keep track of css files visited
-  var filenames = [];
-
-  // keep track of all tokens so we can avoid duplicates
-  var tokensByFile = {};
-
-  // keep track of all source files for later builds: when
-  // using watchify, not all files will be caught on subsequent
-  // bundles
-  var sourceByFile = {};
-
   function transform (filename) {
     // only handle .css files
     if (!cssExt.test(filename)) {