Experimental parser: remove match actions

tools/lexer_generator/nfa.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 19 matching lines @@
 
 class NfaState(AutomatonState):
 
   def __init__(self):
     super(NfaState, self).__init__()
     self.__transitions = {}
     self.__unclosed = set()
     self.__epsilon_closure = None
     self.__action = Action.empty_action()
 
-  def epsilon_closure_iter(self):
-    return iter(self.__epsilon_closure)
-
-  def set_epsilon_closure(self, closure):
-    assert self.is_closed()
-    assert self.__epsilon_closure == None
-    self.__epsilon_closure = frozenset(closure)
-
   def action(self):
-    assert self.is_closed()
+    assert self.__is_closed()
     return self.__action
 
   def set_action(self, action):
-    assert not self.is_closed()
+    assert not self.__is_closed()
     assert not self.__action
     assert isinstance(action, Action)
     self.__action = action
 
-  def state_iter_for_key(self, key):
-    assert self.is_closed()
-    if not key in self.__transitions:
-      return iter([])
-    return iter(self.__transitions[key])
-
-  def swap_key(self, old_key, new_key):
-    'this is one of the few mutations allowed after closing'
-    assert self.is_closed()
-    assert not new_key == TransitionKey.epsilon(), "changes epsilon closure"
-    value = self.__transitions[old_key]
-    del self.__transitions[old_key]
-    self.__transitions[new_key] = value
-
   def __add_transition(self, key, next_state):
     assert key != None
     if next_state == None:
-      assert not self.is_closed(), "already closed"
+      assert not self.__is_closed(), "already closed"
       self.__unclosed.add(key)
       return
     if not key in self.__transitions:
       self.__transitions[key] = set()
+    else:
+      assert key == TransitionKey.epsilon()
     self.__transitions[key].add(next_state)
 
   def add_unclosed_transition(self, key):
     assert key != TransitionKey.epsilon()
     self.__add_transition(key, None)
 
+  def add_transition(self, key, state):
+    assert not self.__is_closed(), "already closed"
+    assert state != None
+    self.__add_transition(key, state)
+
   def add_epsilon_transition(self, state):
-    assert state != None
-    self.__add_transition(TransitionKey.epsilon(), state)
+    self.add_transition(TransitionKey.epsilon(), state)
 
-  def is_closed(self):
+  def __is_closed(self):
     return self.__unclosed == None
 
   def close(self, end):
-    assert not self.is_closed()
+    assert not self.__is_closed()
     unclosed, self.__unclosed = self.__unclosed, None
     if end == None:
       assert not unclosed
       return
     for key in unclosed:
       self.__add_transition(key, end)
     if not unclosed:
       self.__add_transition(TransitionKey.epsilon(), end)
 
+  def post_creation_verify(self):
+    assert self.__is_closed()
+    assert self.__epsilon_closure != None
+
+  def state_iter_for_key(self, key):
+    assert self.__is_closed()
+    if not key in self.__transitions:
+      return iter([])
+    return iter(self.__transitions[key])
+
   def key_state_iter(
     self,
     key_filter = lambda x: True,
     state_filter = lambda x: True,
     match_func = lambda x, y: True,
     yield_func = lambda x, y: (x, y)):
-    assert self.is_closed()
+    assert self.__is_closed()
     for key, states in self.__transitions.items():
       if key_filter(key):
         for state in states:
           if state_filter(state) and match_func(key, state):
             yield yield_func(key, state)
 
+  def epsilon_closure_iter(self):
+    return iter(self.__epsilon_closure)
+
+  def set_epsilon_closure(self, closure):
+    assert self.__is_closed()
+    assert self.__epsilon_closure == None
+    self.__epsilon_closure = frozenset(closure)
+
+  def swap_key(self, old_key, new_key):
+    'this is one of the few mutations allowed after closing'
+    self.post_creation_verify()
+    assert not old_key == TransitionKey.epsilon(), "changes epsilon closure"
+    assert not new_key == TransitionKey.epsilon(), "changes epsilon closure"
+    value = self.__transitions[old_key]
+    del self.__transitions[old_key]
+    self.__transitions[new_key] = value
+
 class Nfa(Automaton):
 
   def __init__(self, encoding, start, end, nodes_created):
     super(Nfa, self).__init__(encoding)
     self.__start = start
     self.__end = end
     self.__verify(nodes_created)
 
   def start_state(self):
     return self.__start
 
   def terminal_set(self):
     return set([self.__end])
 
   def __verify(self, nodes_created):
     def f(node, count):
-      assert node.is_closed()
+      node.post_creation_verify()
       return count + 1
     count = self.visit_all_states(f, 0)
     assert count == nodes_created
 
   @staticmethod
   def __gather_transition_keys(encoding, state_set):
     keys = set(chain(*map(lambda state: state.key_iter(), state_set)))
     keys.discard(TransitionKey.epsilon())
     return TransitionKey.disjoint_keys(encoding, keys)
 
   def __to_dfa(self, nfa_state_set, dfa_nodes):
     nfa_state_set = Automaton.epsilon_closure(nfa_state_set)
     # nfa_state_set will be a state in the dfa.
     assert nfa_state_set
     name = ".".join(str(x.node_number()) for x in sorted(nfa_state_set))
     if name in dfa_nodes:
       return name
     dfa_nodes[name] = {
       'transitions': {},
       'terminal': self.__end in nfa_state_set,
-      'action' : Action.dominant_action(nfa_state_set)}
+      'action' : self.dominant_action(nfa_state_set)}
     # Gather the set of transition keys for which the dfa state will have
     # transitions (the disjoint set of all the transition keys from all the
     # states combined). For example, if a state in the state set has a
     # transition for key [a-c], and another state for [b-d], the dfa state will
     # have transitions with keys ([a], [b-c], [d]).
     for key in Nfa.__gather_transition_keys(self.encoding(), nfa_state_set):
       # Find out which states we can reach with "key", starting from any of the
       # states in "nfa_state_set". The corresponding dfa state will have a
       # transition with "key" to a state which corresponds to the set of the
       # states ("match_states") (more accurately, its epsilon closure).
       f = lambda state: state.transition_state_iter_for_key(key)
       match_states = set(chain(*map(f, nfa_state_set)))
       transition_state = self.__to_dfa(match_states, dfa_nodes)
       dfa_nodes[name]['transitions'][key] = transition_state
     return name
 
   def compute_dfa(self):
     dfa_nodes = {}
     start_name = self.__to_dfa(set([self.__start]), dfa_nodes)
     return (start_name, dfa_nodes)