2 files changed, 24 insertions, 19 deletions
diff --git a/lib/models/fs.js b/lib/models/fs.js
index 12aee53..20c13ef 100644
--- a/lib/models/fs.js
+++ b/lib/models/fs.js
@@ -198,23 +198,29 @@ FS.prototype.listFiles = function(dirname) {
 /**
     List all files in a directory
 
-    @param {String} dirname
+    @param {String} dirName
+    @param {Function(dirName)} filterFn: call it for each file/directory to test if it should stop iterating
     @return {Promise<List<String>>}
 */
-FS.prototype.listAllFiles = function(folder) {
+FS.prototype.listAllFiles = function(dirName, filterFn) {
     var that = this;
-    folder = folder || '.';
+    dirName = dirName || '.';
 
-    return this.readDir(folder)
+    return this.readDir(dirName)
     .then(function(files) {
         return Promise.reduce(files, function(out, file) {
             var isDirectory = pathIsFolder(file);
+            var newDirName = path.join(dirName, file);
+
+            if (filterFn && filterFn(newDirName) === false) {
+                return out;
+            }
 
             if (!isDirectory) {
-                return out.push(path.join(folder, file));
+                return out.push(newDirName);
             }
 
-            return that.listAllFiles(path.join(folder, file))
+            return that.listAllFiles(newDirName, filterFn)
             .then(function(inner) {
                 return out.concat(inner);
             });
diff --git a/lib/parse/listAssets.js b/lib/parse/listAssets.js
index b2e141c..d83d8fd 100644
--- a/lib/parse/listAssets.js
+++ b/lib/parse/listAssets.js
@@ -23,21 +23,20 @@ function listAssets(book, pages) {
     var config = book.getConfig();
     var configFile = config.getFile().getPath();
 
+    function filterFile(file) {
+        return !(
+            file === summaryFile ||
+            file === glossaryFile ||
+            file === langsFile ||
+            file === configFile ||
+            book.isContentFileIgnored(file) ||
+            pages.has(file)
+        );
+    }
+
     return timing.measure(
         'parse.listAssets',
-        fs.listAllFiles()
-        .then(function(files) {
-            return files.filterNot(function(file) {
-                return (
-                    file === summaryFile ||
-                    file === glossaryFile ||
-                    file === langsFile ||
-                    file === configFile ||
-                    book.isContentFileIgnored(file) ||
-                    pages.has(file)
-                );
-            });
-        })
+        fs.listAllFiles('.', filterFile)
     );
 }