Temp/Parser

#VendingMachineParser.py

import shlex,sys 
from cStringIO import StringIO 
 
class VendingCmd: 
    def __init__(self,cmd,**kwargs): 
        self.cmd = cmd 
        self.__dict__.update(kwargs) 
    def __repr__(self): 
        s = '%s(' % self.cmd 
        for item in self.__dict__.items(): 
            if item[0] != 'cmd': 
                s += ' %s=%s' % item 
        return s + ' )' 
 
class Parser: 
    def __init__(self,aStream=sys.stderr): 
        self.outstream=aStream 
    def next_token(self): 
        tok = self.lexer.get_token() 
        if not tok: 
            self.err('Unexpected end of file') 
        return tok 
    def next_number(self,func=int): 
        tok = self.next_token() 
        if tok: 
            try: tok = func(tok) 
            except ValueError: 
                return self.err('Expected a number, not '+tok) 
        return tok 
    def next_money(self): 
        num=self.next_number() 
        if num not in (10,50,100,500,1000): 
            return self.err('Unexpected money type') 
        return num 
 
    def next_button(self): 
        tok=self.lexer.get_token() 
        if tok not in ('black','white','sugar_black','sugar_white'): 
            return self.err('Unexpected button type') 
        return tok 
 
    def err(self,msg): 
        self.outstream.write(self.lexer.error_leader()+msg+'\n') 
 
    def parse_put(self): 
        money = self.next_money() 
        if money: return VendingCmd('put',arg=money) 
 
    def parse_push(self): 
        button=self.next_button() 
        if button: return VendingCmd('push',arg=button) 
 
    def parse(self,aString=None,aStream=None,aName=None): 
        if aString: 
            aStream=StringIO(aString) 
        lexer=shlex.shlex(aStream,aName) 
        lexer.source = 'include' 
        lexer.wordchars += '.,-' 
        self.lexer=lexer 
        cmds = [] 
        while 1: 
            tok = lexer.get_token() 
            if not tok: 
                break 
            try: 
                parser = getattr(self,'parse_%s'%tok) 
            except: 
                self.err('Unknown command: '+tok) 
                continue 
            cmd=parser() 
            if cmd is None: 
                continue 
            cmds.append(cmd) 
        return cmds 
 
 
if __name__=='__main__': 
    err=StringIO() 
    p=Parser(err) 
    cmds=p.parse("put 30 put 50 put 1000") 
    print cmds 
    print `err.getvalue()`