Experimental Parser: move key functions to TransitionKey class

tools/lexer_generator/transition_keys.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
+#       with the distribution.
+#     * Neither the name of Google Inc. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+class TransitionKey:
+
+  __single_char_type = 0
+  __epsilon_type = 1
+  __any_type = 2
+  __class_type = 3
+
+  @staticmethod
+  def __create(key_type, value):
+    key = TransitionKey()
+    key.__type = key_type
+    key.__value = value
+    return key
+
+  @staticmethod
+  def epsilon():
+    return TransitionKey.__create(TransitionKey.__epsilon_type, None)
+
+  @staticmethod
+  def any():
+    return TransitionKey.__create(TransitionKey.__any_type, None)
+
+  @staticmethod
+  def single_char(char):
+    return TransitionKey.__create(TransitionKey.__single_char_type, char)
+
+  @staticmethod
+  def character_class(invert, graph):
+    # TODO
+    return TransitionKey.__create(TransitionKey.__class_type, (invert, graph))
+
+  @staticmethod
+  def __class_match(class_graph, char):
+    assert False
+
+  __char_matchers = {
+    __single_char_type: (lambda x, y : x == y),
+    __epsilon_type: (lambda x, y : False),
+    __any_type: (lambda x, y : True),
+    __class_type: __class_match,
+  }
+
+  def matches_char(self, char):
+    return TransitionKey.__char_matchers[self.__type](self.__value, char)
+
+  def matches_key(self, key):
+    assert key != TransitionKey.epsilon()
+    assert self != TransitionKey.epsilon()
+    if (key == self): return True
+    # TODO need to test intersection/symmetric diff
+    assert self != TransitionKey.any()
+    return False
+
+  def __hash__(self):
+    if self.__value == None:
+      return hash(self.__type)
+    return hash(self.__type) ^ hash(self.__value)
+
+  def __eq__(self, other):
+    return (
+      isinstance(other, self.__class__) and
+      self.__type == other.__type and
+      self.__value == other.__value)
+
+  def __str__(self):
+    if self.__type == self.__single_char_type:
+      return "'%s'" % self.__value
+    if self.__type == self.__epsilon_type:
+      return "epsilon"
+    if self.__type == self.__any_type:
+      return "any"
+    # TODO
+    return "class"
+
+  @staticmethod
+  def merge_key_set(key_set):
+    key_set -= set([TransitionKey.epsilon()])
+    # TODO need intersections and symmetric differences
+    return key_set