BUGFIX: Indenter was in corrupt state when parse failed (Issue #316)

lark/indenter.py

@@ -27,7 +27,9 @@ class Indenter:
 
             assert indent == self.indent_level[-1], '%s != %s' % (indent, self.indent_level[-1])
 
-    def process(self, stream):
+    def _process(self, stream):
+        self.paren_level = 0
+        self.indent_level = [0]
         for token in stream:
             if token.type == self.NL_type:
                 for t in self.handle_NL(token):
@@ -47,6 +49,11 @@ class Indenter:
 
         assert self.indent_level == [0], self.indent_level
 
+    def process(self, stream):
+        self.paren_level = 0
+        self.indent_level = [0]
+        return self._process(stream)
+
     # XXX Hack for ContextualLexer. Maybe there's a more elegant solution?
     @property
     def always_accept(self):