command line flag parser

flagparse.py

##
# Flag Parse
#
# Command line flag/switch parsing
##

import sys

class ParserError(Exception):
    def __init__(self, m):
        self.message = "ParserError: "+m

class FlagParser(object):
    _SETFLAGS = []
    _POSFLAGS = []
    _USAGEMSGS = {}
    _DELIMETER = ''

    def __init__(self, flags=None, delim='-'):
        if flags is not None:
            self._POSFLAGS = flags
        self._DELIMETER = delim

    def setFlags(self, flags):
        # make sure they're string type for later
        for flag in flags:
            if len(flag) > 1: raise ParserError("Invalid Flag Set")
            self._POSFLAGS.append(str(flag))

    def flagSet(self, flag):
        return flag in self._SETFLAGS

    def setUsage(self, flag, message):
        # disallow messages for flags that don't exist
        if not self.flagSet(flag): raise ParserError("Flag "+flag+" does not exist.")

        self._USAGEMSGS[flag] = message

    def showUsage(self,flag):
        if flag in self._USAGEMSGS:
            print "Usage", flag, self._USAGEMSGS[flag]
        else:
            print "No usage information available."

    def dumpSetFlags(self):
        print self._SETFLAGS

    def dumpPosFlags(self):
        print self._POSFLAGS

    def parse(self, rawArgs=None):
        # Check if we've actually got args if not then get them
        if rawArgs==None: rawArgs = sys.argv

        # TODO: Support Flags with parameters
        for arg in rawArgs[1::]:
            # check if correct delimeter used
            if arg[0] is not self._DELIMETER:
                raise ParserError("Invalid delimeter \'"+arg[0]+'\'')
            elif len(arg) <= 1:
                raise ParserError("Unknown option \'"+arg[0]+'\'')
            else:
                # loop through flags add to setFlags
                for flag in arg[1::]:
                    # make sure it's a valid flag or none are specefied
                    if flag in self._POSFLAGS or not self._POSFLAGS:
                        self._SETFLAGS.append(flag)
                    else: raise ParserError("Unknown flag \'"+flag+'\'')