BaseTools/Source/Python/Common/Expression.py

   1 ## @file
   2 # This file is used to parse and evaluate expression in directive or PCD value.
   3 #
   4 # Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>
   5 # This program and the accompanying materials
   6 # are licensed and made available under the terms and conditions of the BSD License
   7 # which accompanies this distribution.    The full text of the license may be found at
   8 # http://opensource.org/licenses/bsd-license.php
   9 #
  10 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 ## Import Modules
  14 #
  15 from Common.GlobalData import *
  16 from CommonDataClass.Exceptions import BadExpression
  17 from CommonDataClass.Exceptions import WrnExpression
  18 from Misc import GuidStringToGuidStructureString
  19
  20 ERR_STRING_EXPR         = 'This operator cannot be used in string expression: [%s].'
  21 ERR_SNYTAX              = 'Syntax error, the rest of expression cannot be evaluated: [%s].'
  22 ERR_MATCH               = 'No matching right parenthesis.'
  23 ERR_STRING_TOKEN        = 'Bad string token: [%s].'
  24 ERR_MACRO_TOKEN         = 'Bad macro token: [%s].'
  25 ERR_EMPTY_TOKEN         = 'Empty token is not allowed.'
  26 ERR_PCD_RESOLVE         = 'PCD token cannot be resolved: [%s].'
  27 ERR_VALID_TOKEN         = 'No more valid token found from rest of string: [%s].'
  28 ERR_EXPR_TYPE           = 'Different types found in expression.'
  29 ERR_OPERATOR_UNSUPPORT  = 'Unsupported operator: [%s]'
  30 ERR_REL_NOT_IN          = 'Expect "IN" after "not" operator.'
  31 WRN_BOOL_EXPR           = 'Operand of boolean type cannot be used in arithmetic expression.'
  32 WRN_EQCMP_STR_OTHERS    = '== Comparison between Operand of string type and Boolean/Number Type always return False.'
  33 WRN_NECMP_STR_OTHERS    = '!= Comparison between Operand of string type and Boolean/Number Type always return True.'
  34 ERR_RELCMP_STR_OTHERS   = 'Operator taking Operand of string type and Boolean/Number Type is not allowed: [%s].'
  35 ERR_STRING_CMP          = 'Unicode string and general string cannot be compared: [%s %s %s]'
  36 ERR_ARRAY_TOKEN         = 'Bad C array or C format GUID token: [%s].'
  37 ERR_ARRAY_ELE           = 'This must be HEX value for NList or Array: [%s].'
  38 ERR_EMPTY_EXPR          = 'Empty expression is not allowed.'
  39
  40 ## SplitString
  41 #  Split string to list according double quote
  42 #  For example: abc"de\"f"ghi"jkl"mn will be: ['abc', '"de\"f"', 'ghi', '"jkl"', 'mn']
  43 #
  44 def SplitString(String):
  45     # There might be escaped quote: "abc\"def\\\"ghi"
  46     Str = String.replace('\\\\', '//').replace('\\\"', '\\\'')
  47     RetList = []
  48     InQuote = False
  49     Item = ''
  50     for i, ch in enumerate(Str):
  51         if ch == '"':
  52             InQuote = not InQuote
  53             if not InQuote:
  54                 Item += String[i]
  55                 RetList.append(Item)
  56                 Item = ''
  57                 continue
  58             if Item:
  59                 RetList.append(Item)
  60                 Item = ''
  61         Item += String[i]
  62     if InQuote:
  63         raise BadExpression(ERR_STRING_TOKEN % Item)
  64     if Item:
  65         RetList.append(Item)
  66     return RetList
  67
  68 ## ReplaceExprMacro
  69 #
  70 def ReplaceExprMacro(String, Macros, ExceptionList = None):
  71     StrList = SplitString(String)
  72     for i, String in enumerate(StrList):
  73         InQuote = False
  74         if String.startswith('"'):
  75             InQuote = True
  76         MacroStartPos = String.find('$(')
  77         if MacroStartPos < 0:
  78             continue
  79         RetStr = ''
  80         while MacroStartPos >= 0:
  81             RetStr = String[0:MacroStartPos]
  82             MacroEndPos = String.find(')', MacroStartPos)
  83             if MacroEndPos < 0:
  84                 raise BadExpression(ERR_MACRO_TOKEN % String[MacroStartPos:])
  85             Macro = String[MacroStartPos+2:MacroEndPos]
  86             if Macro not in Macros:
  87                 # From C reference manual:
  88                 # If an undefined macro name appears in the constant-expression of
  89                 # !if or !elif, it is replaced by the integer constant 0.
  90                 RetStr += '0'
  91             elif not InQuote and ExceptionList and Macro in ExceptionList:
  92                 # Make sure the macro in exception list is encapsulated by double quote
  93                 # For example: DEFINE ARCH = IA32 X64
  94                 # $(ARCH) is replaced with "IA32 X64"
  95                 RetStr += '"' + Macros[Macro] + '"'
  96             else:
  97                 if Macros[Macro].strip() != "":
  98                     RetStr += Macros[Macro]
  99                 else:
 100                     RetStr += '""'
 101             RetStr += String[MacroEndPos+1:]
 102             String = RetStr
 103             MacroStartPos = String.find('$(')
 104         StrList[i] = RetStr
 105     return ''.join(StrList)
 106
 107 class ValueExpression(object):
 108     # Logical operator mapping
 109     LogicalOperators = {
 110         '&&' : 'and', '||' : 'or',
 111         '!'  : 'not', 'AND': 'and',
 112         'OR' : 'or' , 'NOT': 'not',
 113         'XOR': '^'  , 'xor': '^',
 114         'EQ' : '==' , 'NE' : '!=',
 115         'GT' : '>'  , 'LT' : '<',
 116         'GE' : '>=' , 'LE' : '<=',
 117         'IN' : 'in'
 118     }
 119
 120     NonLetterOpLst = ['+', '-', '&', '|', '^', '!', '=', '>', '<']
 121
 122     PcdPattern = re.compile(r'[_a-zA-Z][0-9A-Za-z_]*\.[_a-zA-Z][0-9A-Za-z_]*$')
 123     HexPattern = re.compile(r'0[xX][0-9a-fA-F]+$')
 124     RegGuidPattern = re.compile(r'[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}')
 125
 126     SymbolPattern = re.compile("("
 127                                  "\$\([A-Z][A-Z0-9_]*\)|\$\(\w+\.\w+\)|\w+\.\w+|"
 128                                  "&&|\|\||!(?!=)|"
 129                                  "(?<=\W)AND(?=\W)|(?<=\W)OR(?=\W)|(?<=\W)NOT(?=\W)|(?<=\W)XOR(?=\W)|"
 130                                  "(?<=\W)EQ(?=\W)|(?<=\W)NE(?=\W)|(?<=\W)GT(?=\W)|(?<=\W)LT(?=\W)|(?<=\W)GE(?=\W)|(?<=\W)LE(?=\W)"
 131                                ")")
 132
 133     @staticmethod
 134     def Eval(Operator, Oprand1, Oprand2 = None):
 135         WrnExp = None
 136
 137         if Operator not in ["==", "!=", ">=", "<=", ">", "<", "in", "not in"] and \
 138             (type(Oprand1) == type('') or type(Oprand2) == type('')):
 139             raise BadExpression(ERR_STRING_EXPR % Operator)
 140
 141         TypeDict = {
 142             type(0)  : 0,
 143             type(0L) : 0,
 144             type('') : 1,
 145             type(True) : 2
 146         }
 147
 148         EvalStr = ''
 149         if Operator in ["!", "NOT", "not"]:
 150             if type(Oprand1) == type(''):
 151                 raise BadExpression(ERR_STRING_EXPR % Operator)
 152             EvalStr = 'not Oprand1'
 153         else:
 154             if Operator in ["+", "-"] and (type(True) in [type(Oprand1), type(Oprand2)]):
 155                 # Boolean in '+'/'-' will be evaluated but raise warning
 156                 WrnExp = WrnExpression(WRN_BOOL_EXPR)
 157             elif type('') in [type(Oprand1), type(Oprand2)] and type(Oprand1)!= type(Oprand2):
 158                 # == between string and number/boolean will always return False, != return True
 159                 if Operator == "==":
 160                     WrnExp = WrnExpression(WRN_EQCMP_STR_OTHERS)
 161                     WrnExp.result = False
 162                     raise WrnExp
 163                 elif Operator == "!=":
 164                     WrnExp = WrnExpression(WRN_NECMP_STR_OTHERS)
 165                     WrnExp.result = True
 166                     raise WrnExp
 167                 else:
 168                     raise BadExpression(ERR_RELCMP_STR_OTHERS % Operator)
 169             elif TypeDict[type(Oprand1)] != TypeDict[type(Oprand2)]:
 170                 if Operator in ["==", "!=", ">=", "<=", ">", "<"] and set((TypeDict[type(Oprand1)], TypeDict[type(Oprand2)])) == set((TypeDict[type(True)], TypeDict[type(0)])):
 171                     # comparison between number and boolean is allowed
 172                     pass
 173                 elif Operator in ['&', '|', '^', "and", "or"] and set((TypeDict[type(Oprand1)], TypeDict[type(Oprand2)])) == set((TypeDict[type(True)], TypeDict[type(0)])):
 174                     # bitwise and logical operation between number and boolean is allowed
 175                     pass
 176                 else:
 177                     raise BadExpression(ERR_EXPR_TYPE)
 178             if type(Oprand1) == type('') and type(Oprand2) == type(''):
 179                 if (Oprand1.startswith('L"') and not Oprand2.startswith('L"')) or \
 180                     (not Oprand1.startswith('L"') and Oprand2.startswith('L"')):
 181                     raise BadExpression(ERR_STRING_CMP % (Oprand1, Operator, Oprand2))
 182             if 'in' in Operator and type(Oprand2) == type(''):
 183                 Oprand2 = Oprand2.split()
 184             EvalStr = 'Oprand1 ' + Operator + ' Oprand2'
 185
 186         # Local symbols used by built in eval function
 187         Dict = {
 188             'Oprand1' : Oprand1,
 189             'Oprand2' : Oprand2
 190         }
 191         try:
 192             Val = eval(EvalStr, {}, Dict)
 193         except Exception, Excpt:
 194             raise BadExpression(str(Excpt))
 195
 196         if Operator in ['and', 'or']:
 197             if Val:
 198                 Val = True
 199             else:
 200                 Val = False
 201
 202         if WrnExp:
 203             WrnExp.result = Val
 204             raise WrnExp
 205         return Val
 206
 207     def __init__(self, Expression, SymbolTable={}):
 208         self._NoProcess = False
 209         if type(Expression) != type(''):
 210             self._Expr = Expression
 211             self._NoProcess = True
 212             return
 213
 214         self._Expr = ReplaceExprMacro(Expression.strip(),
 215                                   SymbolTable,
 216                                   ['TARGET', 'TOOL_CHAIN_TAG', 'ARCH'])
 217
 218         if not self._Expr.strip():
 219             raise BadExpression(ERR_EMPTY_EXPR)
 220
 221         #
 222         # The symbol table including PCD and macro mapping
 223         #
 224         self._Symb = SymbolTable
 225         self._Symb.update(self.LogicalOperators)
 226         self._Idx = 0
 227         self._Len = len(self._Expr)
 228         self._Token = ''
 229         self._WarnExcept = None
 230
 231         # Literal token without any conversion
 232         self._LiteralToken = ''
 233
 234     # Public entry for this class
 235     #   @param RealValue: False: only evaluate if the expression is true or false, used for conditional expression
 236     #                     True : return the evaluated str(value), used for PCD value
 237     #
 238     #   @return: True or False if RealValue is False
 239     #            Evaluated value of string format if RealValue is True
 240     #
 241     def __call__(self, RealValue=False):
 242         if self._NoProcess:
 243             return self._Expr
 244
 245         self._Expr = self._Expr.strip()
 246         if RealValue:
 247             self._Token = self._Expr
 248             if self.__IsNumberToken():
 249                 return self._Expr
 250
 251             Token = self._GetToken()
 252             if type(Token) == type('') and Token.startswith('{') and Token.endswith('}') and self._Idx >= self._Len:
 253                 return self._Expr
 254
 255             self._Idx = 0
 256             self._Token = ''
 257
 258         Val = self._OrExpr()
 259         RealVal = Val
 260         if type(Val) == type(''):
 261             if Val == 'L""':
 262                 Val = False
 263             elif not Val:
 264                 Val = False
 265                 RealVal = '""'
 266             elif not Val.startswith('L"') and not Val.startswith('{'):
 267                 Val = True
 268                 RealVal = '"' + RealVal + '"'
 269
 270         # The expression has been parsed, but the end of expression is not reached
 271         # It means the rest does not comply EBNF of <Expression>
 272         if self._Idx != self._Len:
 273             raise BadExpression(ERR_SNYTAX % self._Expr[self._Idx:])
 274
 275         if RealValue:
 276             RetVal = str(RealVal)
 277         elif Val:
 278             RetVal = True
 279         else:
 280             RetVal = False
 281
 282         if self._WarnExcept:
 283             self._WarnExcept.result = RetVal
 284             raise self._WarnExcept
 285         else:
 286             return RetVal
 287
 288     # Template function to parse binary operators which have same precedence
 289     # Expr [Operator Expr]*
 290     def _ExprFuncTemplate(self, EvalFunc, OpLst):
 291         Val = EvalFunc()
 292         while self._IsOperator(OpLst):
 293             Op = self._Token
 294             try:
 295                 Val = self.Eval(Op, Val, EvalFunc())
 296             except WrnExpression, Warn:
 297                 self._WarnExcept = Warn
 298                 Val = Warn.result
 299         return Val
 300
 301     # A [|| B]*
 302     def _OrExpr(self):
 303         return self._ExprFuncTemplate(self._AndExpr, ["OR", "or", "||"])
 304
 305     # A [&& B]*
 306     def _AndExpr(self):
 307         return self._ExprFuncTemplate(self._BitOr, ["AND", "and", "&&"])
 308
 309     # A [ | B]*
 310     def _BitOr(self):
 311         return self._ExprFuncTemplate(self._BitXor, ["|"])
 312
 313     # A [ ^ B]*
 314     def _BitXor(self):
 315         return self._ExprFuncTemplate(self._BitAnd, ["XOR", "xor", "^"])
 316
 317     # A [ & B]*
 318     def _BitAnd(self):
 319         return self._ExprFuncTemplate(self._EqExpr, ["&"])
 320
 321     # A [ == B]*
 322     def _EqExpr(self):
 323         Val = self._RelExpr()
 324         while self._IsOperator(["==", "!=", "EQ", "NE", "IN", "in", "!", "NOT", "not"]):
 325             Op = self._Token
 326             if Op in ["!", "NOT", "not"]:
 327                 if not self._IsOperator(["IN", "in"]):
 328                     raise BadExpression(ERR_REL_NOT_IN)
 329                 Op += ' ' + self._Token
 330             try:
 331                 Val = self.Eval(Op, Val, self._RelExpr())
 332             except WrnExpression, Warn:
 333                 self._WarnExcept = Warn
 334                 Val = Warn.result
 335         return Val
 336
 337     # A [ > B]*
 338     def _RelExpr(self):
 339         return self._ExprFuncTemplate(self._AddExpr, ["<=", ">=", "<", ">", "LE", "GE", "LT", "GT"])
 340
 341     # A [ + B]*
 342     def _AddExpr(self):
 343         return self._ExprFuncTemplate(self._UnaryExpr, ["+", "-"])
 344
 345     # [!]*A
 346     def _UnaryExpr(self):
 347         if self._IsOperator(["!", "NOT", "not"]):
 348             Val = self._UnaryExpr()
 349             try:
 350                 return self.Eval('not', Val)
 351             except WrnExpression, Warn:
 352                 self._WarnExcept = Warn
 353                 return Warn.result
 354         return self._IdenExpr()
 355
 356     # Parse identifier or encapsulated expression
 357     def _IdenExpr(self):
 358         Tk = self._GetToken()
 359         if Tk == '(':
 360             Val = self._OrExpr()
 361             try:
 362                 # _GetToken may also raise BadExpression
 363                 if self._GetToken() != ')':
 364                     raise BadExpression(ERR_MATCH)
 365             except BadExpression:
 366                 raise BadExpression(ERR_MATCH)
 367             return Val
 368         return Tk
 369
 370     # Skip whitespace or tab
 371     def __SkipWS(self):
 372         for Char in self._Expr[self._Idx:]:
 373             if Char not in ' \t':
 374                 break
 375             self._Idx += 1
 376
 377     # Try to convert string to number
 378     def __IsNumberToken(self):
 379         Radix = 10
 380         if self._Token.lower()[0:2] == '0x' and len(self._Token) > 2:
 381             Radix = 16
 382         try:
 383             self._Token = int(self._Token, Radix)
 384             return True
 385         except ValueError:
 386             return False
 387         except TypeError:
 388             return False
 389
 390     # Parse array: {...}
 391     def __GetArray(self):
 392         Token = '{'
 393         self._Idx += 1
 394         self.__GetNList(True)
 395         Token += self._LiteralToken
 396         if self._Idx >= self._Len or self._Expr[self._Idx] != '}':
 397             raise BadExpression(ERR_ARRAY_TOKEN % Token)
 398         Token += '}'
 399
 400         # All whitespace and tabs in array are already stripped.
 401         IsArray = IsGuid = False
 402         if len(Token.split(',')) == 11 and len(Token.split(',{')) == 2 \
 403             and len(Token.split('},')) == 1:
 404             HexLen = [11,6,6,5,4,4,4,4,4,4,6]
 405             HexList= Token.split(',')
 406             if HexList[3].startswith('{') and \
 407                 not [Index for Index, Hex in enumerate(HexList) if len(Hex) > HexLen[Index]]:
 408                 IsGuid = True
 409         if Token.lstrip('{').rstrip('}').find('{') == -1:
 410             if not [Hex for Hex in Token.lstrip('{').rstrip('}').split(',') if len(Hex) > 4]:
 411                 IsArray = True
 412         if not IsArray and not IsGuid:
 413             raise BadExpression(ERR_ARRAY_TOKEN % Token)
 414         self._Idx += 1
 415         self._Token = self._LiteralToken = Token
 416         return self._Token
 417
 418     # Parse string, the format must be: "..."
 419     def __GetString(self):
 420         Idx = self._Idx
 421
 422         # Skip left quote
 423         self._Idx += 1
 424
 425         # Replace escape \\\", \"
 426         Expr = self._Expr[self._Idx:].replace('\\\\', '//').replace('\\\"', '\\\'')
 427         for Ch in Expr:
 428             self._Idx += 1
 429             if Ch == '"':
 430                 break
 431         self._Token = self._LiteralToken = self._Expr[Idx:self._Idx]
 432         if not self._Token.endswith('"'):
 433             raise BadExpression(ERR_STRING_TOKEN % self._Token)
 434         self._Token = self._Token[1:-1]
 435         return self._Token
 436
 437     # Get token that is comprised by alphanumeric, underscore or dot(used by PCD)
 438     # @param IsAlphaOp: Indicate if parsing general token or script operator(EQ, NE...)
 439     def __GetIdToken(self, IsAlphaOp = False):
 440         IdToken = ''
 441         for Ch in self._Expr[self._Idx:]:
 442             if not self.__IsIdChar(Ch):
 443                 break
 444             self._Idx += 1
 445             IdToken += Ch
 446
 447         self._Token = self._LiteralToken = IdToken
 448         if not IsAlphaOp:
 449             self.__ResolveToken()
 450         return self._Token
 451
 452     # Try to resolve token
 453     def __ResolveToken(self):
 454         if not self._Token:
 455             raise BadExpression(ERR_EMPTY_TOKEN)
 456
 457         # PCD token
 458         if self.PcdPattern.match(self._Token):
 459             if self._Token not in self._Symb:
 460                 raise BadExpression(ERR_PCD_RESOLVE % self._Token)
 461             self._Token = ValueExpression(self._Symb[self._Token], self._Symb)(True)
 462             if type(self._Token) != type(''):
 463                 self._LiteralToken = hex(self._Token)
 464                 return
 465
 466         if self._Token.startswith('"'):
 467             self._Token = self._Token[1:-1]
 468         elif self._Token in ["FALSE", "false", "False"]:
 469             self._Token = False
 470         elif self._Token in ["TRUE", "true", "True"]:
 471             self._Token = True
 472         else:
 473             self.__IsNumberToken()
 474
 475     def __GetNList(self, InArray=False):
 476         self._GetSingleToken()
 477         if not self.__IsHexLiteral():
 478             if InArray:
 479                 raise BadExpression(ERR_ARRAY_ELE % self._Token)
 480             return self._Token
 481
 482         self.__SkipWS()
 483         Expr = self._Expr[self._Idx:]
 484         if not Expr.startswith(','):
 485             return self._Token
 486
 487         NList = self._LiteralToken
 488         while Expr.startswith(','):
 489             NList += ','
 490             self._Idx += 1
 491             self.__SkipWS()
 492             self._GetSingleToken()
 493             if not self.__IsHexLiteral():
 494                 raise BadExpression(ERR_ARRAY_ELE % self._Token)
 495             NList += self._LiteralToken
 496             self.__SkipWS()
 497             Expr = self._Expr[self._Idx:]
 498         self._Token = self._LiteralToken = NList
 499         return self._Token
 500
 501     def __IsHexLiteral(self):
 502         if self._LiteralToken.startswith('{') and \
 503             self._LiteralToken.endswith('}'):
 504             return True
 505
 506         if self.HexPattern.match(self._LiteralToken):
 507             Token = self._LiteralToken[2:]
 508             Token = Token.lstrip('0')
 509             if not Token:
 510                 self._LiteralToken = '0x0'
 511             else:
 512                 self._LiteralToken = '0x' + Token.lower()
 513             return True
 514         return False
 515
 516     def _GetToken(self):
 517         return self.__GetNList()
 518
 519     @staticmethod
 520     def __IsIdChar(Ch):
 521         return Ch in '._/:' or Ch.isalnum()
 522
 523     # Parse operand
 524     def _GetSingleToken(self):
 525         self.__SkipWS()
 526         Expr = self._Expr[self._Idx:]
 527         if Expr.startswith('L"'):
 528             # Skip L
 529             self._Idx += 1
 530             UStr = self.__GetString()
 531             self._Token = 'L"' + UStr + '"'
 532             return self._Token
 533
 534         self._Token = ''
 535         if Expr:
 536             Ch = Expr[0]
 537             Match = self.RegGuidPattern.match(Expr)
 538             if Match and not Expr[Match.end():Match.end()+1].isalnum() \
 539                 and Expr[Match.end():Match.end()+1] != '_':
 540                 self._Idx += Match.end()
 541                 self._Token = ValueExpression(GuidStringToGuidStructureString(Expr[0:Match.end()]))(True)
 542                 return self._Token
 543             elif self.__IsIdChar(Ch):
 544                 return self.__GetIdToken()
 545             elif Ch == '"':
 546                 return self.__GetString()
 547             elif Ch == '{':
 548                 return self.__GetArray()
 549             elif Ch == '(' or Ch == ')':
 550                 self._Idx += 1
 551                 self._Token = Ch
 552                 return self._Token
 553
 554         raise BadExpression(ERR_VALID_TOKEN % Expr)
 555
 556     # Parse operator
 557     def _GetOperator(self):
 558         self.__SkipWS()
 559         LegalOpLst = ['&&', '||', '!=', '==', '>=', '<='] + self.NonLetterOpLst
 560
 561         self._Token = ''
 562         Expr = self._Expr[self._Idx:]
 563
 564         # Reach end of expression
 565         if not Expr:
 566             return ''
 567
 568         # Script operator: LT, GT, LE, GE, EQ, NE, and, or, xor, not
 569         if Expr[0].isalpha():
 570             return self.__GetIdToken(True)
 571
 572         # Start to get regular operator: +, -, <, > ...
 573         if Expr[0] not in self.NonLetterOpLst:
 574             return ''
 575
 576         OpToken = ''
 577         for Ch in Expr:
 578             if Ch in self.NonLetterOpLst:
 579                 if '!' == Ch and OpToken:
 580                     break
 581                 self._Idx += 1
 582                 OpToken += Ch
 583             else:
 584                 break
 585
 586         if OpToken not in LegalOpLst:
 587             raise BadExpression(ERR_OPERATOR_UNSUPPORT % OpToken)
 588         self._Token = OpToken
 589         return OpToken
 590
 591     # Check if current token matches the operators given from OpList
 592     def _IsOperator(self, OpList):
 593         Idx = self._Idx
 594         self._GetOperator()
 595         if self._Token in OpList:
 596             if self._Token in self.LogicalOperators:
 597                 self._Token = self.LogicalOperators[self._Token]
 598             return True
 599         self._Idx = Idx
 600         return False
 601
 602 if __name__ == '__main__':
 603     pass
 604     while True:
 605         input = raw_input('Input expr: ')
 606         if input in 'qQ':
 607             break
 608         try:
 609             print ValueExpression(input)(True)
 610             print ValueExpression(input)(False)
 611         except WrnExpression, Ex:
 612             print Ex.result
 613             print str(Ex)
 614         except Exception, Ex:
 615             print str(Ex)