1 #!/usr/bin/env python

     2 #

     3 # Copyright 2007 Google Inc.

     4 #

     5 # Licensed under the Apache License, Version 2.0 (the "License");

     6 # you may not use this file except in compliance with the License.

     7 # You may obtain a copy of the License at

     8 #

     9 #     http://www.apache.org/licenses/LICENSE-2.0

    10 #

    11 # Unless required by applicable law or agreed to in writing, software

    12 # distributed under the License is distributed on an "AS IS" BASIS,

    13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    14 # See the License for the specific language governing permissions and

    15 # limitations under the License.

    16 #

    17 

    18 

    19 """A wrapper around the generated Groc parser and lexer."""

    20 

    21 

    22 import google

    23 

    24 import antlr3

    25 

    26 import GrocLexer

    27 import GrocParser

    28 

    29 

    30 class GrocException(Exception):

    31   """An error occurred while parsing the groc input string."""

    32 

    33 

    34 class GrocLexerWithErrors(GrocLexer.GrocLexer):

    35   """An overridden Lexer that raises exceptions."""

    36 

    37   def emitErrorMessage(self, msg):

    38     """Raise an exception if the input fails to parse correctly.

    39 

    40     Overriding the default, which normally just prints a message to

    41     stderr.

    42 

    43     Arguments:

    44       msg: the error message

    45     Raises:

    46       GrocException: always.

    47     """

    48     raise GrocException(msg)

    49 

    50 

    51 class GrocParserWithErrors(GrocParser.GrocParser):

    52   """An overridden Parser that raises exceptions."""

    53 

    54   def emitErrorMessage(self, msg):

    55     """Raise an exception if the input fails to parse correctly.

    56 

    57     Overriding the default, which normally just prints a message to

    58     stderr.

    59 

    60     Arguments:

    61       msg: the error message

    62     Raises:

    63       GrocException: always.

    64     """

    65     raise GrocException(msg)

    66 

    67 

    68 def CreateParser(parse_string):

    69   """Creates a Groc Parser."""

    70   input_string = antlr3.ANTLRStringStream(parse_string)

    71   lexer = GrocLexerWithErrors(input_string)

    72   tokens = antlr3.CommonTokenStream(lexer)

    73   parser = GrocParserWithErrors(tokens)

    74   return parser