Experimental Parser: add lexer generator

tools/lexer_generator/regex_parser.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.
+
+import ply.yacc as yacc
+from regex_lexer import RegexLexer
+from types import ListType, TupleType
+
+class RegexParser:
+
+  tokens = RegexLexer.tokens
+
+  token_map = {
+    '+': 'ONE_OR_MORE',
+    '?': 'ZERO_OR_ONE',
+    '*': 'ZERO_OR_MORE',
+    '|': 'OR',
+    '.': 'ANY',
+  }
+
+  def p_start(self, p):
+    '''start : fragments OR fragments
+             | fragments'''
+    if len(p) == 2:
+      p[0] = p[1]
+    else:
+      p[0] = (self.token_map[p[2]], p[1], p[3])
+
+  def p_fragments(self, p):
+    '''fragments : fragment
+                 | fragment fragments'''
+    if len(p) == 2:
+      p[0] = p[1]
+    else:
+      p[0] = self.__cat(p[1], p[2])
+
+  def p_fragment(self, p):
+    '''fragment : literal maybe_modifier
+                | class maybe_modifier
+                | group maybe_modifier
+                | any maybe_modifier
+    '''
+    if p[2] != None:
+      p[0] = (p[2], p[1])
+    else:
+      p[0] = p[1]
+
+  def p_maybe_modifier(self, p):
+    '''maybe_modifier : ONE_OR_MORE
+                      | ZERO_OR_ONE
+                      | ZERO_OR_MORE
+                      | empty'''
+    p[0] = p[1]
+    if p[1] != None:
+      p[0] = self.token_map[p[1]]
+
+  def p_literal(self, p):
+    '''literal : LITERAL'''
+    p[0] = ('LITERAL', p[1])
+
+  def p_any(self, p):
+    '''any : ANY'''
+    p[0] = (self.token_map[p[1]],)
+
+  def p_class(self, p):
+    '''class : CLASS_BEGIN class_content CLASS_END
+             | CLASS_BEGIN NOT class_content CLASS_END'''
+    if len(p) == 4:
+      p[0] = ("CLASS", p[2])
+    else:
+      p[0] = ("NOT_CLASS", p[3])
+
+  def p_group(self, p):
+    '''group : GROUP_BEGIN start GROUP_END'''
+    p[0] = p[2]
+
+  def p_class_content(self, p):
+    '''class_content : CLASS_LITERAL RANGE CLASS_LITERAL maybe_class_content
+                     | CLASS_LITERAL maybe_class_content
+    '''
+    if len(p) == 5:
+      left = ("RANGE", p[1], p[3])
+    else:
+      left = ('LITERAL', p[1])
+    p[0] = self.__cat(left, p[len(p)-1])
+
+  def p_maybe_class_content(self, p):
+    '''maybe_class_content : class_content
+                           | empty'''
+    p[0] = p[1]
+
+  def p_empty(self, p):
+    'empty :'
+
+  def p_error(self, p):
+    raise Exception("Syntax error in input '%s'" % p)
+
+  @staticmethod
+  def __cat(left, right):
+    if right == None:
+      return left
+    return ('CAT', left, right)
+
+  def build(self, **kwargs):
+    self.parser = yacc.yacc(module=self, **kwargs)
+    self.lexer = RegexLexer()
+    self.lexer.build(**kwargs)
+
+  def parse(self, data):
+    return self.parser.parse(data, lexer=self.lexer.lexer)
+