Allow generic-names hashPrefix option

Author: pascalduez

README.md

@@ -230,6 +230,11 @@ hook({
 });
 ```
 
+### `hashPrefix` string
+
+Short alias for the [generic-names](https://github.com/css-modules/generic-names) helper option.
+Provides additional hash uniqueness. Might be useful for projects with several stylesheets sharing a same name.
+
 ### `mode` string
 
 Short alias for the [postcss-modules-local-by-default](https://github.com/css-modules/postcss-modules-local-by-default) plugin's option.

lib/index.js

@@ -34,6 +34,7 @@ module.exports = function setupHook({
   prepend = [],
   createImportedName,
   generateScopedName,
+  hashPrefix,
   mode,
   use,
   rootDir: context = process.cwd(),
@@ -51,7 +52,7 @@ module.exports = function setupHook({
   let scopedName;
   if (generateScopedName) {
     scopedName = typeof generateScopedName !== 'function'
-      ? genericNames(generateScopedName, {context}) //  for example '[name]__[local]___[hash:base64:5]'
+      ? genericNames(generateScopedName, {context, hashPrefix}) //  for example '[name]__[local]___[hash:base64:5]'
       : generateScopedName;
   } else {
     // small fallback

lib/validate.js

@@ -17,6 +17,7 @@ const rules = {
   use:                'array',
   createImportedName: 'function',
   generateScopedName: 'function|string',
+  hashPrefix:         'string',
   mode:               'string',
   rootDir:            'string',
 };