Source code for qnet.misc.parser

# coding=utf-8
#This file is part of QNET.
#
#    QNET is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#    QNET is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with QNET.  If not, see <http://www.gnu.org/licenses/>.
#
# Copyright (C) 2012-2013, Nikolas Tezak
#
###########################################################################
"""
Generic Parser class.
"""

from ply import lex, yacc
import os


class ParsingError(SyntaxError):
    """
    Raised for parsing error.
    """
    pass


class Parser(object):
    """
    Base class for a lexer/parser that has the _rules defined as methods
    """
    tokens = ()
    precedence = ()

    def __init__(self, **kw):
        self.debug = kw.get('debug', 0)
        self.names = {}
        try:
            modname = os.path.splitext(os.path.basename(__file__))[0] + "_" + self.__class__.__name__
        except:
            modname = "parser" + "_" + self.__class__.__name__
        self.debugfile = modname + ".dbg"
        self.tabmodule = modname + "_" + "parsetab"
        # print(self.debugfile, self.tabmodule)

        # Build the lexer and parser

        self.lexer = lex.lex(module=self, debug=self.debug)
        self.parser = yacc.yacc(module=self,
            debug=self.debug,
            debugfile=self.debugfile,
            tabmodule=self.tabmodule)

    def parse(self, inputstring):
        return self.parser.parse(inputstring, lexer=self.lexer)

    def parse_file(self, filename):
        with open(filename, 'r') as inputfile:
            filetext = inputfile.read()
        return self.parse(filetext)