diff --git a/lark/load_grammar.py b/lark/load_grammar.py
index 9a0bb00..453ed45 100644
--- a/lark/load_grammar.py
+++ b/lark/load_grammar.py
@@ -219,7 +219,6 @@ class SimplifyTree(InlineTransformer):
         return tokenmods + [value]
 
 def get_tokens(tree, token_set):
-    tokens = []
     for t in tree.find_data('token'):
         x = t.children
         name = x[0].value
@@ -266,10 +265,13 @@ class ExtractAnonTokens(InlineTransformer):
         else:
             assert False, token
 
+        if value in self.token_reverse: # Kind of a wierd placement
+            token_name = self.token_reverse[value]
+
         if token_name not in self.token_set:
             self.token_set.add(token_name)
             self.tokens.append((token_name, token, []))
-            assert value not in self.token_reverse
+            assert value not in self.token_reverse, value
             self.token_reverse[value] = token_name
 
         return Token('TOKEN', token_name, -1)
diff --git a/tools/nearley.py b/tools/nearley.py
index b45ca53..b78d3b8 100644
--- a/tools/nearley.py
+++ b/tools/nearley.py
@@ -1,22 +1,32 @@
 "Converts between Lark and Nearley grammars. Work in progress!"
 
+import os.path
+import sys
+
 from lark import Lark, InlineTransformer
 
 nearley_grammar = r"""
     start: (ruledef|directive)+
 
-    directive: "@" NAME STRING
+    directive: "@" NAME (STRING|NAME)
+             | "@" _JS  -> js_code
     ruledef: NAME "->" expansions
+           | NAME REGEXP "->" expansions -> macro
     expansions: expansion ("|" expansion)*
 
-    expansion: (rule|string|regexp)+ _JS?
+    expansion: expr+ _JS?
+
+    ?expr: item [":" /[+*?]/]
+
+    ?item: rule|string|regexp
+         | "(" expansions ")"
 
     rule: NAME
     string: STRING
     regexp: REGEXP
     _JS: /(?s){%.*?%}/
 
-    NAME: /[a-zA-Z_]\w*/
+    NAME: /[a-zA-Z_$]\w*/
     WS.ignore: /[\t \f\n]+/
     COMMENT.ignore: /\#[^\n]*/
     REGEXP: /\[.*?\]/
@@ -27,13 +37,20 @@ nearley_grammar = r"""
 
 
 class NearleyToLark(InlineTransformer):
+    def __init__(self, builtin_path):
+        self.builtin_path = builtin_path
 
     def rule(self, name):
-        return {'_': '_WS?', '__':'_WS'}.get(name, name)
+        # return {'_': '_WS?', '__':'_WS'}.get(name, name)
+        return {'_': '_ws_maybe', '__':'_ws'}.get(name, name)
 
     def ruledef(self, name, exps):
+        name = {'_': '_ws_maybe', '__':'_ws'}.get(name, name)
         return '%s: %s' % (name, exps)
 
+    def expr(self, item, op):
+        return '(%s)%s' % (item, op)
+
     def regexp(self, r):
         return '/%s/' % r
 
@@ -45,35 +62,32 @@ class NearleyToLark(InlineTransformer):
         return ' '.join(x)
 
     def expansions(self, *x):
-        return '\n    |'.join(x)
+        return '(%s)' % ('\n    |'.join(x))
+
+    def js_code(self):
+        return ''
+
+    def macro(self, *args):
+        return ''   # TODO support macros?!
 
     def directive(self, name, *args):
         if name == 'builtin':
             arg = args[0][1:-1]
-            if arg == 'whitespace.ne':
-                return r'_WS: /[ \t\n\v\f]/'
-            elif arg == 'number.ne':
-                return ('unsigned_int: DIGIT+\n'
-                        'DIGIT: /\d/\n'
-                        'decimal: "-"? DIGIT+ [/\./ DIGIT+] \n'
-                        'percentage: decimal "%"\n'
-                        )
-                # TODO
-            elif arg == 'postprocessors.ne':
-                pass
-            else:
-                assert False, arg
-        else:
-            assert False
-        pass
+            with open(os.path.join(self.builtin_path, arg)) as f:
+                text = f.read()
+            return nearley_to_lark(text, self.builtin_path)
+        elif name == 'preprocessor':
+            return ''
+
+        raise Exception('Unknown directive: %s' % name)
 
     def start(self, *rules):
         return '\n'.join(filter(None, rules))
 
-def nearley_to_lark(g):
+def nearley_to_lark(g, builtin_path):
     parser = Lark(nearley_grammar)
     tree = parser.parse(g)
-    return NearleyToLark().transform(tree)
+    return NearleyToLark(builtin_path).transform(tree)
 
 
 def test():
@@ -112,7 +126,7 @@ def test():
         function(d) {return Math.floor(d[0]*255); }
     %}
     """
-    converted_grammar = nearley_to_lark(css_example_grammar)
+    converted_grammar = nearley_to_lark(css_example_grammar, '/home/erez/nearley/builtin')
     print(converted_grammar)
 
     l = Lark(converted_grammar, start='csscolor', parser='earley_nolex')
@@ -120,5 +134,17 @@ def test():
     print(l.parse('rgb(255, 70%, 3)').pretty())
 
 
+def main():
+    try:
+        nearley_lib = sys.argv[1]
+    except IndexError:
+        print("Reads Nearley grammar from stdin and outputs a lark grammar.")
+        print("Usage: %s <nearley_lib_path>" % sys.argv[0])
+        return
+
+    grammar = sys.stdin.read()
+    print(nearley_to_lark(grammar, os.path.join(nearley_lib, 'builtin')))
+
+
 if __name__ == '__main__':
-    test()
+    main()