Experimental lexer generator: Code generator skeleton.

tools/lexer_generator/dfa.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 35 matching lines @@
   def actions(self):
     return self.__actions
 
   def add_transition(self, key, state):
     assert not self.__transitions.has_key(key)
     self.__transitions[key] = state
 
   def transitions(self):
     return self.__transitions
 
+  def to_code(self):
+    # FIXME: add different check types (if, switch, lookup table)
+    # FIXME: add action + break / continue
+    # FIXME: add default action
+    code = '''
+code_%s:
+fprintf(stderr, "state %s, char at hand is %%c\\n", c);
+''' % (self.node_number(), self.node_number())
+
+    for key, state in self.__transitions.items():
+      code += key.to_code()
+      code += ''' {
+  c = *(++cursor);
+  goto code_%s;
+}''' % state.node_number()
+    return code
+
 class Dfa(Automaton):
 
   def __init__(self, start_name, mapping):
     super(Dfa, self).__init__()
     self.__terminal_set = set()
-    name_map = {}
+    self.__name_map = {}
     for i, (name, node_data) in enumerate(mapping.items()):
       node = DfaState(name, i, node_data['actions'])
-      name_map[name] = node
+      self.__name_map[name] = node
       if node_data['terminal']:
         self.__terminal_set.add(node)
     for name, node_data in mapping.items():
-      node = name_map[name]
+      node = self.__name_map[name]
       inversion = {}
       for key, state in node_data['transitions'].items():
         if not state in inversion:
           inversion[state] = []
         inversion[state].append(key)
       for state, keys in inversion.items():
         merged_key = TransitionKey.merged_key(keys)
-        node.add_transition(merged_key, name_map[state])
-    self.__start = name_map[start_name]
+        node.add_transition(merged_key, self.__name_map[state])
+    self.__start = self.__name_map[start_name]
     assert self.__terminal_set
 
   @staticmethod
   def __match_char(state, char):
     match = [s for k, s in state.transitions().items() if k.matches_char(char)]
     if not match: return None
     assert len(match) == 1
     return match[0]
 
   def collect_actions(self, string):
@@ skipping 32 matching lines @@
 
   def __visit_all_edges(self, visitor, state):
     edge = set([self.__start])
     next_edge = lambda node: set(node.transitions().values())
     return self.visit_edges(edge, next_edge, visitor, state)
 
   def to_dot(self):
     iterator = lambda visitor, state: self.__visit_all_edges(visitor, state)
     state_iterator = lambda x : [x]
     return self.generate_dot(self.__start, self.__terminal_set, iterator, state_iterator)
+
+  def to_code(self):
+    code = '''
+char c = *cursor;
+goto code_%s;
+''' % (self.__start.node_number())
+    for n in self.__name_map.values():
+      code += n.to_code()
+    return code