Add option for manifest file

README.md

@@ -92,6 +92,12 @@ filerev: {
 }
 ```
 
+### Manifest file
+
+Type: `file`
+
+JSON file to add additional files to `grunt.filerev.summary`. Useful for hash generated fils from other tools (for example WebPack).
+
 #### Summary
 
 The task keeps track of all files created and its sources in a summary that is

tasks/filerev.js

@@ -15,6 +15,20 @@ module.exports = function (grunt) {
       length: 8
     });
 
+    if (options.manifestFile) {
+      if (grunt.file.isFile(options.manifestFile)) {
+        var manifest = grunt.file.readJSON(options.manifestFile);
+        for (var file in manifest) {
+          if (!filerev.summary[file]) {
+            filerev.summary[file] = manifest[file];
+          }
+        }
+        grunt.verbose.writeln(chalk.green('✔ ') + 'Files from ' + options.manifestFile + ' are' + chalk.gray(' added ') + 'to summary.');
+      } else {
+        grunt.fail.warn('Could not find manifest feil ' + options.manifestFile);
+      }
+    }
+
     eachAsync(this.files, function (el, i, next) {
       var move = true;