parser_class

class Parsers(object):

    def parse_verb(self, word_list):
        skip(word_list, 'stop')

        if peek(word_list) == 'verb':
            return match(word_list, 'verb')
        else:
            raise ParserError("Expected a verb next")


    def parse_object(self, word_list):
        skip(word_list, 'stop')
        next = peek(word_list)
        if next == 'noun':
            return match(word_list, 'noun')
        if next == 'direction':
            return match(word_list, 'direction')
        else:
            raise ParserError("Expected a noun or direction next")


    def parse_subject(self, word_list, subj):
        verb = parse_verb(word_list)
        obj = parse_object(word_list)

        return Sentence(subj, verb, obj)


    def parse_sentence(self, word_list):
        skip(word_list, 'stop')

        start = peek(word_list)

        if start == 'noun':
            subj = match(word_list, 'noun')
            return parse_subject(word_list, subj)
        elif start == 'verb':
            # assume the subject is the player then
            return parse_subject(word_list, ('noun', 'player'))
        else:
            raise ParserError("Must start with the subject, object, or verb not: %s" % start)