Experimental parser: fixup unit tests

tools/lexer_generator/regex_parser.py

Index: tools/lexer_generator/regex_parser.py
diff --git a/tools/lexer_generator/regex_parser.py b/tools/lexer_generator/regex_parser.py
index 1d2ff388670e35273700daf53151cf583124bc94..c508cb35f5ab636ac23ee97c9adb10306c9e8fa9 100644
--- a/tools/lexer_generator/regex_parser.py
+++ b/tools/lexer_generator/regex_parser.py
@@ -135,7 +135,7 @@ class RegexParser:
     'empty :'
 
   def p_error(self, p):
-    raise Exception("Syntax error in input '%s'" % p)
+    raise Exception("Syntax error in input '%s'" % str(p))
 
   @staticmethod
   def __cat(left, right):
@@ -156,4 +156,8 @@ class RegexParser:
       parser = RegexParser()
       parser.build()
       RegexParser.__static_instance = parser
-    return parser.parser.parse(data, lexer=parser.lexer.lexer)
+    try:
+      return parser.parser.parse(data, lexer=parser.lexer.lexer)
+    except Exception as e:
+      RegexParser.__static_instance = None
+      raise e