Experimental parser: some tuple removal

tools/lexer_generator/automaton.py

 # Copyright 2013 the V8 project authors. All rights reserved.
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 # modification, are permitted provided that the following conditions are
 # met:
 #
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 #       notice, this list of conditions and the following disclaimer.
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 #       copyright notice, this list of conditions and the following
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 #       with the distribution.
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 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-from types import TupleType, ListType
+from types import TupleType, ListType, StringType
 from itertools import chain
 from transition_keys import TransitionKey
 
+class Term(object):
+  '''A class representing a function and its arguments.
+  f(a,b,c) would be represented as ('f', a, b, c) where
+  a, b, and c are strings or Terms.'''
+
+  @staticmethod
+  def __verify_string(v):
+    assert (not ',' in v) and (not '(' in v)
+
+  def __init__(self, name, *args):
+    assert type(name) == StringType
+    self.__verify_string(name)
+    for v in args:
+      if type(v) == StringType:
+        self.__verify_string(v)
+      else:
+        assert isinstance(v, self.__class__)
+    self.__tuple = tuple([name] + list(args))
+    self.__str = None
+
+  def name(self):
+    return self.__tuple[0]
+
+  def args(self):
+    return self.__tuple[1:]
+
+  def  __hash__(self):
+    return hash(self.__tuple)
+
+  def __eq__(self, other):
+    return (isinstance(other, self.__class__) and
+            self.__tuple == other.__tuple)
+
+  def __str__(self):
+    if self.__str == None:
+      self.__str = '(%s)' % ','.join(map(str, self.__tuple))
+    return self.__str
+
 class Action(object):
 
   @staticmethod
   def dominant_action(state_set):
     action = None
     for state in state_set:
       if not state.action():
         continue
       if not action:
         action = state.action()
         continue
       if state.action().precedence() == action.precedence():
         assert state.action() == action
       elif state.action().precedence() < action.precedence():
         action = state.action()
     return action
 
   def __init__(self, entry_action, match_action, precedence = -1):
     for action in [entry_action, match_action]:
       if action == None:
         continue
-      assert type(action) == TupleType and len(action)
-      assert action[0] != None
+      assert isinstance(action, Term)
     assert entry_action or match_action
     self.__entry_action = entry_action
     self.__match_action = match_action
     self.__precedence = precedence
 
   def entry_action(self):
     return self.__entry_action
 
   def match_action(self):
     return self.__match_action
 
   def precedence(self):
     return self.__precedence
 
   def __hash__(self):
     return hash((self.__entry_action, self.__match_action))
 
   def __eq__(self, other):
     return (isinstance(other, self.__class__) and
             self.__entry_action == other.__entry_action and
             self.__match_action == other.__match_action)
 
   def __str__(self):
     parts = []
     for action in [self.__entry_action, self.__match_action]:
       part = ""
       if action:
-        part += action[0]
-        if action[1]:
-          part += "(%s)" % str(action[1])
+        part += str(action)
       parts.append(part)
     return "action< %s >" % " | ".join(parts)
 
 class AutomatonState(object):
 
   __node_number_counter = 0
 
   def __init__(self):
     self.__node_number = AutomatonState.__node_number_counter
     AutomatonState.__node_number_counter += 1
@@ skipping 152 matching lines @@
   node [shape = doublecircle, style=unfilled]; %s
   node [shape = circle];
 %s
 %s
 }
     ''' % (start_shape,
            start_number,
            " ".join(terminals),
            "\n".join(edge_content),
            "\n".join(node_content))