Experimental parser: unique transition key support

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
@@ skipping 11 matching lines @@
 # 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.
 
 from string import printable
 
 class TransitionKey:
 
+  __class_bounds = {
+    "latin_1" : (0, 255),
+    "whitespace" : (256, 256),
+    "literal" : (257, 257),
+  }
   __lower_bound = 0
-  __latin_1_upper_bound = 255
-  __unicode_whitespace_bounds = (256, 256)
-  __unicode_literal_bounds = (257, 257)
-  __upper_bound = 257
+  __upper_bound = reduce(lambda acc, (k, v): max(acc, v[1]), __class_bounds.items(), 0)
+
+  __cached_keys = {}
+
+  __unique_key_counter = -1
+
+  @staticmethod
+  def __in_latin_1(char):
+    bound = TransitionKey.__class_bounds["latin_1"]
+    return (bound[0] <= char and char <= bound[1])
+
+  @staticmethod
+  def __is_class_range(r):
+    return r[0] == r[1] and not TransitionKey.__in_latin_1(r[0])
+
+  @staticmethod
+  def __is_unique_range(r):
+    return r[0] == r[1] and r[0] < TransitionKey.__lower_bound
 
   @staticmethod
   def __verify_ranges(ranges, check_merged):
     assert ranges
+    if len(ranges) == 1 and TransitionKey.__is_class_range(ranges[0]):
+      return
     last = None
     for r in ranges:
       assert TransitionKey.__lower_bound <= r[0]
       assert r[1] <= TransitionKey.__upper_bound
       assert r[0] <= r[1]
-      r_is_class = (
-        r == TransitionKey.__unicode_whitespace_bounds or
-        r == TransitionKey.__unicode_literal_bounds)
+      r_is_class = TransitionKey.__is_class_range(r)
       if last != None and check_merged:
         assert last[1] + 1 < r[0] or r_is_class
-      if (r[0] > TransitionKey.__latin_1_upper_bound or
-          r[1] > TransitionKey.__latin_1_upper_bound):
+      if not TransitionKey.__in_latin_1(r[0]):
+        assert r_is_class
+      if not TransitionKey.__in_latin_1(r[1]):
         assert r_is_class
       last = r
 
   @staticmethod
-  def __create(ranges):
-    TransitionKey.__verify_ranges(ranges, True)
+  def __create(ranges, name = None):
+    if not ranges:
+      assert name == 'epsilon'
+      assert not name in TransitionKey.__cached_keys
+    else:
+      TransitionKey.__verify_ranges(ranges, True)
     key = TransitionKey()
     key.__ranges = tuple(ranges) # immutable
+    key.__name = name
     key.__cached_hash = None
     return key
 
-  __cached_epsilon = None
+  @staticmethod
+  def __cached_key(name, bounds_getter):
+    if not name in TransitionKey.__cached_keys:
+      bounds = bounds_getter(name)
+      TransitionKey.__cached_keys[name] = TransitionKey.__create(bounds, name)
+    return TransitionKey.__cached_keys[name]
+
   @staticmethod
   def epsilon():
-    if (TransitionKey.__cached_epsilon == None):
-      key = TransitionKey()
-      key.__ranges = tuple([])
-      key.__cached_hash = None
-      TransitionKey.__cached_epsilon = key
-    return TransitionKey.__cached_epsilon
+    return TransitionKey.__cached_key("epsilon", lambda name : [])
 
-  __cached_any = None
   @staticmethod
   def any():
-    if (TransitionKey.__cached_any == None):
-      bounds = [
-        (TransitionKey.__lower_bound, TransitionKey.__latin_1_upper_bound),
-        TransitionKey.__unicode_whitespace_bounds,
-        TransitionKey.__unicode_literal_bounds,
-      ]
-      TransitionKey.__cached_any = TransitionKey.__create(bounds)
-    return TransitionKey.__cached_any
+    return TransitionKey.__cached_key("any",
+      lambda name : TransitionKey.__class_bounds.values())
 
   @staticmethod
   def single_char(char):
     char = ord(char)
-    assert (TransitionKey.__lower_bound <= char and
-            char <= TransitionKey.__latin_1_upper_bound)
+    assert TransitionKey.__in_latin_1(char)
     return TransitionKey.__create([(char, char)])
 
   @staticmethod
+  def unique_key(name):
+    def get_bounds(name):
+      bound = TransitionKey.__unique_key_counter
+      TransitionKey.__unique_key_counter -= 1
+      return [(bound, bound)]
+    name = "__" + name
+    return TransitionKey.__cached_key(name, get_bounds)
+
+  @staticmethod
   def __process_graph(graph, ranges, key_map):
     key = graph[0]
     if key == 'RANGE':
       ranges.append((ord(graph[1]), ord(graph[2])))
     elif key == 'LITERAL':
       ranges.append((ord(graph[1]), ord(graph[1])))
     elif key == 'CAT':
       for x in [graph[1], graph[2]]:
         TransitionKey.__process_graph(x, ranges, key_map)
     elif key == 'CHARACTER_CLASS':
       class_name = graph[1]
       if class_name == 'ws':
-        ranges.append(TransitionKey.__unicode_whitespace_bounds)
+        ranges.append(TransitionKey.__class_bounds["whitespace"])
       elif class_name == 'lit':
-        ranges.append(TransitionKey.__unicode_literal_bounds)
+        ranges.append(TransitionKey.__class_bounds["literal"])
       elif class_name in key_map:
         ranges += key_map[class_name].__ranges
       else:
         raise Exception("unknown character class [%s]" % graph[1])
     else:
       raise Exception("bad key [%s]" % key)
 
   @staticmethod
   def character_class(graph, key_map):
     ranges = []
@@ skipping 29 matching lines @@
   def __eq__(self, other):
     return isinstance(other, self.__class__) and self.__ranges == other.__ranges
 
   __printable_cache = {
     ord('\t') : '\\t',
     ord('\n') : '\\n',
     ord('\r') : '\\r',
   }
 
   @staticmethod
-  def __print_range(r):
+  def __range_str(r):
+    if TransitionKey.__is_class_range(r):
+      for name, v in TransitionKey.__class_bounds.items():
+        if r == v: return name
+      assert False
     def to_str(x):
-      if x <= TransitionKey.__latin_1_upper_bound:
-        if not x in TransitionKey.__printable_cache:
-          res = "'%s'" % chr(x) if chr(x) in printable else str(x)
-          TransitionKey.__printable_cache[x] = res
-        return TransitionKey.__printable_cache[x]
-      if x == TransitionKey.__unicode_literal_bounds[0]:
-        return "literal"
-      if x == TransitionKey.__unicode_whitespace_bounds[0]:
-        return "whitespace"
-      assert False
+      assert TransitionKey.__in_latin_1(x)
+      if not x in TransitionKey.__printable_cache:
+        res = "'%s'" % chr(x) if chr(x) in printable else str(x)
+        TransitionKey.__printable_cache[x] = res
+      return TransitionKey.__printable_cache[x]
     if r[0] == r[1]:
       return "%s" % to_str(r[0])
     else:
       return "[%s-%s]" % (to_str(r[0]), to_str(r[1]))
 
   def __str__(self):
-    if self == self.epsilon():
-      return "epsilon"
-    if self == self.any():
-      return "any"
-    return ", ".join(TransitionKey.__print_range(x) for x in self.__ranges)
+    if self.__name:
+      return self.__name
+    return ", ".join(TransitionKey.__range_str(x) for x in self.__ranges)
 
   @staticmethod
   def __disjoint_keys(range_map):
     sort = lambda x : sorted(set(x))
     range_map = sorted(map(lambda (k, v): (k, sort(v)), range_map.items()))
     ranges = []
     upper_bound = TransitionKey.__upper_bound + 1
     for i in range(len(range_map)):
       (left, left_values) = range_map[i]
       next = range_map[i + 1][0] if i != len(range_map) - 1 else upper_bound
@@ skipping 38 matching lines @@
     ranges = TransitionKey.__merge_ranges(ranges)
     if invert:
       ranges = TransitionKey.__invert_ranges(ranges)
     return TransitionKey.__create(ranges)
 
   @staticmethod
   def __merge_ranges(ranges):
     merged = []
     last = None
     for r in ranges:
+      assert not TransitionKey.__is_unique_range(r)
       if last == None:
         last = r
-      elif (last[1] + 1 == r[0] and
-            r != TransitionKey.__unicode_whitespace_bounds and
-            r != TransitionKey.__unicode_literal_bounds):
+      elif (last[1] + 1 == r[0] and not TransitionKey.__is_class_range(r)):
         last = (last[0], r[1])
       else:
         merged.append(last)
         last = r
     if last != None:
       merged.append(last)
     return merged
 
   @staticmethod
   def merged_key(keys):
     f = lambda acc, key: acc + list(key.__ranges)
     return TransitionKey.__key_from_ranges(False, reduce(f, keys, []))
 
   @staticmethod
   def __invert_ranges(ranges):
     inverted = []
     last = None
-    contains_whitespace = False
-    contains_literal = False
+    classes = set(TransitionKey.__class_bounds.values())
+    classes.remove(TransitionKey.__class_bounds["latin_1"])
     for r in ranges:
-      if r == TransitionKey.__unicode_whitespace_bounds:
-        contains_whitespace = True
-        continue
-      if r == TransitionKey.__unicode_literal_bounds:
-        contains_literal = True
+      assert not TransitionKey.__is_unique_range(r)
+      if TransitionKey.__is_class_range(r):
+        classes.remove(r)
         continue
       if last == None:
         if r[0] != TransitionKey.__lower_bound:
           inverted.append((TransitionKey.__lower_bound, r[0] - 1))
       elif last[1] + 1 < r[0]:
         inverted.append((last[1] + 1, r[0] - 1))
       last = r
-    if last != None and last[1] < TransitionKey.__latin_1_upper_bound:
-      inverted.append((last[1] + 1, TransitionKey.__latin_1_upper_bound))
-    if not contains_whitespace:
-      inverted.append(TransitionKey.__unicode_whitespace_bounds)
-    if not contains_literal:
-      inverted.append(TransitionKey.__unicode_literal_bounds)
+    upper_bound = TransitionKey.__class_bounds["latin_1"][1]
+    if last != None and last[1] < upper_bound:
+      inverted.append((last[1] + 1, upper_bound))
+    inverted += list(classes)
     return inverted