Experimental lexer generator: transfer actions across epsilon transitions correctly when constructi…

tools/lexer_generator/rule_parser.py

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 29 matching lines @@
     self.character_classes = {}
     self.current_state = None
     self.rules = {}
 
   def parse(self, string):
     return RuleParser.parse(string, self)
 
 class RuleParser:
 
   tokens = RuleLexer.tokens
+  __rule_precedence_counter = 0
 
   def __init__(self):
     self.__state = None
 
   def p_statements(self, p):
     'statements : aliases rules'
 
   def p_aliases(self, p):
     '''aliases : alias_rule aliases
                | empty'''
@@ skipping 28 matching lines @@
 
   def p_transition_rules(self, p):
     '''transition_rules : transition_rule transition_rules
                         | empty'''
 
   def p_transition_rule(self, p):
     '''transition_rule : composite_regex_or_default code action
                        | composite_regex_or_default empty action
                        | composite_regex_or_default code empty'''
     rules = self.__state.rules[self.__state.current_state]
-    rule = (p[1], p[2], p[3])
+    rule = (p[1], RuleParser.__rule_precedence_counter, p[2], p[3])
+    RuleParser.__rule_precedence_counter += 1
     if p[1] == 'default':
       assert not rules['default']
       rules['default'] = rule
     else:
       rules['regex'].append(rule)
 
   def p_action(self, p):
     'action : ACTION_OPEN IDENTIFIER ACTION_CLOSE'
     p[0] = p[2]
 
@@ skipping 78 matching lines @@
   __static_instance = None
   @staticmethod
   def parse(data, parser_state):
     if not RuleParser.__static_instance:
       RuleParser.__static_instance = RuleParser()
       RuleParser.__static_instance.build()
     parser = RuleParser.__static_instance
     parser.__state = parser_state
     parser.parser.parse(data, lexer=parser.lexer.lexer)
     parser.__state = None