BaseTools/Source/Python/Common/RangeExpression.py

   1 # # @file
   2 # This file is used to parse and evaluate range expression in Pcd declaration.
   3 #
   4 # Copyright (c) 2015 - 2018, 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 import uuid
  19 from Common.Expression import PcdPattern,BaseExpression
  20 from Common.DataType import *
  21
  22 ERR_STRING_EXPR = 'This operator cannot be used in string expression: [%s].'
  23 ERR_SNYTAX = 'Syntax error, the rest of expression cannot be evaluated: [%s].'
  24 ERR_MATCH = 'No matching right parenthesis.'
  25 ERR_STRING_TOKEN = 'Bad string token: [%s].'
  26 ERR_MACRO_TOKEN = 'Bad macro token: [%s].'
  27 ERR_EMPTY_TOKEN = 'Empty token is not allowed.'
  28 ERR_PCD_RESOLVE = 'PCD token cannot be resolved: [%s].'
  29 ERR_VALID_TOKEN = 'No more valid token found from rest of string: [%s].'
  30 ERR_EXPR_TYPE = 'Different types found in expression.'
  31 ERR_OPERATOR_UNSUPPORT = 'Unsupported operator: [%s]'
  32 ERR_REL_NOT_IN = 'Expect "IN" after "not" operator.'
  33 WRN_BOOL_EXPR = 'Operand of boolean type cannot be used in arithmetic expression.'
  34 WRN_EQCMP_STR_OTHERS = '== Comparison between Operand of string type and Boolean/Number Type always return False.'
  35 WRN_NECMP_STR_OTHERS = '!= Comparison between Operand of string type and Boolean/Number Type always return True.'
  36 ERR_RELCMP_STR_OTHERS = 'Operator taking Operand of string type and Boolean/Number Type is not allowed: [%s].'
  37 ERR_STRING_CMP = 'Unicode string and general string cannot be compared: [%s %s %s]'
  38 ERR_ARRAY_TOKEN = 'Bad C array or C format GUID token: [%s].'
  39 ERR_ARRAY_ELE = 'This must be HEX value for NList or Array: [%s].'
  40 ERR_EMPTY_EXPR = 'Empty expression is not allowed.'
  41 ERR_IN_OPERAND = 'Macro after IN operator can only be: $(FAMILY), $(ARCH), $(TOOL_CHAIN_TAG) and $(TARGET).'
  42
  43 class RangeObject(object):
  44     def __init__(self, start, end, empty = False):
  45
  46         if int(start) < int(end):
  47             self.start = int(start)
  48             self.end = int(end)
  49         else:
  50             self.start = int(end)
  51             self.end = int(start)
  52         self.empty = empty
  53
  54 class RangeContainer(object):
  55     def __init__(self):
  56         self.rangelist = []
  57
  58     def push(self, RangeObject):
  59         self.rangelist.append(RangeObject)
  60         self.rangelist = sorted(self.rangelist, key = lambda rangeobj : rangeobj.start)
  61         self.merge()
  62
  63     def pop(self):
  64         for item in self.rangelist:
  65             yield item
  66
  67     def __clean__(self):
  68         newrangelist = []
  69         for rangeobj in self.rangelist:
  70             if rangeobj.empty == True:
  71                 continue
  72             else:
  73                 newrangelist.append(rangeobj)
  74         self.rangelist = newrangelist
  75     def merge(self):
  76         self.__clean__()
  77         for i in range(0, len(self.rangelist) - 1):
  78             if self.rangelist[i + 1].start > self.rangelist[i].end:
  79                 continue
  80             else:
  81                 self.rangelist[i + 1].start = self.rangelist[i].start
  82                 self.rangelist[i + 1].end = self.rangelist[i + 1].end > self.rangelist[i].end and self.rangelist[i + 1].end or self.rangelist[i].end
  83                 self.rangelist[i].empty = True
  84
  85         self.__clean__()
  86
  87     def dump(self):
  88         print "----------------------"
  89         rangelist = ""
  90         for object in self.rangelist:
  91             rangelist = rangelist + "[%d , %d]" % (object.start, object.end)
  92         print rangelist
  93
  94
  95 class XOROperatorObject(object):
  96     def __init__(self):
  97         pass
  98     def Calculate(self, Operand, DataType, SymbolTable):
  99         if type(Operand) == type('') and not Operand.isalnum():
 100             Expr = "XOR ..."
 101             raise BadExpression(ERR_SNYTAX % Expr)
 102         rangeId = str(uuid.uuid1())
 103         rangeContainer = RangeContainer()
 104         rangeContainer.push(RangeObject(0, int(Operand) - 1))
 105         rangeContainer.push(RangeObject(int(Operand) + 1, MAX_VAL_TYPE[DataType]))
 106         SymbolTable[rangeId] = rangeContainer
 107         return rangeId
 108
 109 class LEOperatorObject(object):
 110     def __init__(self):
 111         pass
 112     def Calculate(self, Operand, DataType, SymbolTable):
 113         if type(Operand) == type('') and not Operand.isalnum():
 114             Expr = "LE ..."
 115             raise BadExpression(ERR_SNYTAX % Expr)
 116         rangeId1 = str(uuid.uuid1())
 117         rangeContainer = RangeContainer()
 118         rangeContainer.push(RangeObject(0, int(Operand)))
 119         SymbolTable[rangeId1] = rangeContainer
 120         return rangeId1
 121 class LTOperatorObject(object):
 122     def __init__(self):
 123         pass
 124     def Calculate(self, Operand, DataType, SymbolTable):
 125         if type(Operand) == type('') and not Operand.isalnum():
 126             Expr = "LT ..."
 127             raise BadExpression(ERR_SNYTAX % Expr)
 128         rangeId1 = str(uuid.uuid1())
 129         rangeContainer = RangeContainer()
 130         rangeContainer.push(RangeObject(0, int(Operand) - 1))
 131         SymbolTable[rangeId1] = rangeContainer
 132         return rangeId1
 133
 134 class GEOperatorObject(object):
 135     def __init__(self):
 136         pass
 137     def Calculate(self, Operand, DataType, SymbolTable):
 138         if type(Operand) == type('') and not Operand.isalnum():
 139             Expr = "GE ..."
 140             raise BadExpression(ERR_SNYTAX % Expr)
 141         rangeId1 = str(uuid.uuid1())
 142         rangeContainer = RangeContainer()
 143         rangeContainer.push(RangeObject(int(Operand), MAX_VAL_TYPE[DataType]))
 144         SymbolTable[rangeId1] = rangeContainer
 145         return rangeId1
 146
 147 class GTOperatorObject(object):
 148     def __init__(self):
 149         pass
 150     def Calculate(self, Operand, DataType, SymbolTable):
 151         if type(Operand) == type('') and not Operand.isalnum():
 152             Expr = "GT ..."
 153             raise BadExpression(ERR_SNYTAX % Expr)
 154         rangeId1 = str(uuid.uuid1())
 155         rangeContainer = RangeContainer()
 156         rangeContainer.push(RangeObject(int(Operand) + 1, MAX_VAL_TYPE[DataType]))
 157         SymbolTable[rangeId1] = rangeContainer
 158         return rangeId1
 159
 160 class EQOperatorObject(object):
 161     def __init__(self):
 162         pass
 163     def Calculate(self, Operand, DataType, SymbolTable):
 164         if type(Operand) == type('') and not Operand.isalnum():
 165             Expr = "EQ ..."
 166             raise BadExpression(ERR_SNYTAX % Expr)
 167         rangeId1 = str(uuid.uuid1())
 168         rangeContainer = RangeContainer()
 169         rangeContainer.push(RangeObject(int(Operand) , int(Operand)))
 170         SymbolTable[rangeId1] = rangeContainer
 171         return rangeId1
 172
 173 def GetOperatorObject(Operator):
 174     if Operator == '>':
 175         return GTOperatorObject()
 176     elif Operator == '>=':
 177         return GEOperatorObject()
 178     elif Operator == '<':
 179         return LTOperatorObject()
 180     elif Operator == '<=':
 181         return LEOperatorObject()
 182     elif Operator == '==':
 183         return EQOperatorObject()
 184     elif Operator == '^':
 185         return XOROperatorObject()
 186     else:
 187         raise BadExpression("Bad Operator")
 188
 189 class RangeExpression(BaseExpression):
 190     # Logical operator mapping
 191     LogicalOperators = {
 192         '&&' : 'and', '||' : 'or',
 193         '!'  : 'not', 'AND': 'and',
 194         'OR' : 'or' , 'NOT': 'not',
 195         'XOR': '^'  , 'xor': '^',
 196         'EQ' : '==' , 'NE' : '!=',
 197         'GT' : '>'  , 'LT' : '<',
 198         'GE' : '>=' , 'LE' : '<=',
 199         'IN' : 'in'
 200     }
 201
 202     NonLetterOpLst = ['+', '-', '&', '|', '^', '!', '=', '>', '<']
 203
 204     RangePattern = re.compile(r'[0-9]+ - [0-9]+')
 205
 206     def preProcessRangeExpr(self, expr):
 207         # convert hex to int
 208         # convert interval to object index. ex. 1 - 10 to a GUID
 209         expr = expr.strip()
 210         NumberDict = {}
 211         for HexNumber in gHexPattern.findall(expr):
 212             Number = str(int(HexNumber, 16))
 213             NumberDict[HexNumber] = Number
 214         for HexNum in NumberDict:
 215             expr = expr.replace(HexNum, NumberDict[HexNum])
 216
 217         rangedict = {}
 218         for validrange in self.RangePattern.findall(expr):
 219             start, end = validrange.split(" - ")
 220             start = start.strip()
 221             end = end.strip()
 222             rangeid = str(uuid.uuid1())
 223             rangeContainer = RangeContainer()
 224             rangeContainer.push(RangeObject(start, end))
 225             self.operanddict[str(rangeid)] = rangeContainer
 226             rangedict[validrange] = str(rangeid)
 227
 228         for validrange in rangedict:
 229             expr = expr.replace(validrange, rangedict[validrange])
 230
 231         self._Expr = expr
 232         return expr
 233
 234
 235     def EvalRange(self, Operator, Oprand):
 236
 237         operatorobj = GetOperatorObject(Operator)
 238         return operatorobj.Calculate(Oprand, self.PcdDataType, self.operanddict)
 239
 240     def Rangeintersection(self, Oprand1, Oprand2):
 241         rangeContainer1 = self.operanddict[Oprand1]
 242         rangeContainer2 = self.operanddict[Oprand2]
 243         rangeContainer = RangeContainer()
 244         for range1 in rangeContainer1.pop():
 245             for range2 in rangeContainer2.pop():
 246                 start1 = range1.start
 247                 end1 = range1.end
 248                 start2 = range2.start
 249                 end2 = range2.end
 250                 if start1 >= start2:
 251                     start1, start2 = start2, start1
 252                     end1, end2 = end2, end1
 253                 if range1.empty:
 254                     rangeid = str(uuid.uuid1())
 255                     rangeContainer.push(RangeObject(0, 0, True))
 256                 if end1 < start2:
 257                     rangeid = str(uuid.uuid1())
 258                     rangeContainer.push(RangeObject(0, 0, True))
 259                 elif end1 == start2:
 260                     rangeid = str(uuid.uuid1())
 261                     rangeContainer.push(RangeObject(end1, end1))
 262                 elif end1 <= end2 and end1 > start2:
 263                     rangeid = str(uuid.uuid1())
 264                     rangeContainer.push(RangeObject(start2, end1))
 265                 elif end1 >= end2:
 266                     rangeid = str(uuid.uuid1())
 267                     rangeContainer.push(RangeObject(start2, end2))
 268
 269         self.operanddict[rangeid] = rangeContainer
 270 #        rangeContainer.dump()
 271         return rangeid
 272
 273     def Rangecollections(self, Oprand1, Oprand2):
 274
 275         rangeContainer1 = self.operanddict[Oprand1]
 276         rangeContainer2 = self.operanddict[Oprand2]
 277         rangeContainer = RangeContainer()
 278
 279         for rangeobj in rangeContainer2.pop():
 280             rangeContainer.push(rangeobj)
 281         for rangeobj in rangeContainer1.pop():
 282             rangeContainer.push(rangeobj)
 283
 284         rangeid = str(uuid.uuid1())
 285         self.operanddict[rangeid] = rangeContainer
 286
 287 #        rangeContainer.dump()
 288         return rangeid
 289
 290
 291     def NegtiveRange(self, Oprand1):
 292         rangeContainer1 = self.operanddict[Oprand1]
 293
 294
 295         rangeids = []
 296
 297         for rangeobj in rangeContainer1.pop():
 298             rangeContainer = RangeContainer()
 299             rangeid = str(uuid.uuid1())
 300             if rangeobj.empty:
 301                 rangeContainer.push(RangeObject(0, MAX_VAL_TYPE[self.PcdDataType]))
 302             else:
 303                 if rangeobj.start > 0:
 304                     rangeContainer.push(RangeObject(0, rangeobj.start - 1))
 305                 if rangeobj.end < MAX_VAL_TYPE[self.PcdDataType]:
 306                     rangeContainer.push(RangeObject(rangeobj.end + 1, MAX_VAL_TYPE[self.PcdDataType]))
 307             self.operanddict[rangeid] = rangeContainer
 308             rangeids.append(rangeid)
 309
 310         if len(rangeids) == 0:
 311             rangeContainer = RangeContainer()
 312             rangeContainer.push(RangeObject(0, MAX_VAL_TYPE[self.PcdDataType]))
 313             rangeid = str(uuid.uuid1())
 314             self.operanddict[rangeid] = rangeContainer
 315             return rangeid
 316
 317         if len(rangeids) == 1:
 318             return rangeids[0]
 319
 320         re = self.Rangeintersection(rangeids[0], rangeids[1])
 321         for i in range(2, len(rangeids)):
 322             re = self.Rangeintersection(re, rangeids[i])
 323
 324         rangeid2 = str(uuid.uuid1())
 325         self.operanddict[rangeid2] = self.operanddict[re]
 326         return rangeid2
 327
 328     def Eval(self, Operator, Oprand1, Oprand2 = None):
 329
 330         if Operator in ["!", "NOT", "not"]:
 331             if not gGuidPattern.match(Oprand1.strip()):
 332                 raise BadExpression(ERR_STRING_EXPR % Operator)
 333             return self.NegtiveRange(Oprand1)
 334         else:
 335             if Operator in ["==", ">=", "<=", ">", "<", '^']:
 336                 return self.EvalRange(Operator, Oprand1)
 337             elif Operator == 'and' :
 338                 if not gGuidPatternEnd.match(Oprand1.strip()) or not gGuidPatternEnd.match(Oprand2.strip()):
 339                     raise BadExpression(ERR_STRING_EXPR % Operator)
 340                 return self.Rangeintersection(Oprand1, Oprand2)
 341             elif Operator == 'or':
 342                 if not gGuidPatternEnd.match(Oprand1.strip()) or not gGuidPatternEnd.match(Oprand2.strip()):
 343                     raise BadExpression(ERR_STRING_EXPR % Operator)
 344                 return self.Rangecollections(Oprand1, Oprand2)
 345             else:
 346                 raise BadExpression(ERR_STRING_EXPR % Operator)
 347
 348
 349     def __init__(self, Expression, PcdDataType, SymbolTable = {}):
 350         super(RangeExpression, self).__init__(self, Expression, PcdDataType, SymbolTable)
 351         self._NoProcess = False
 352         if type(Expression) != type(''):
 353             self._Expr = Expression
 354             self._NoProcess = True
 355             return
 356
 357         self._Expr = Expression.strip()
 358
 359         if not self._Expr.strip():
 360             raise BadExpression(ERR_EMPTY_EXPR)
 361
 362         #
 363         # The symbol table including PCD and macro mapping
 364         #
 365         self._Symb = SymbolTable
 366         self._Symb.update(self.LogicalOperators)
 367         self._Idx = 0
 368         self._Len = len(self._Expr)
 369         self._Token = ''
 370         self._WarnExcept = None
 371
 372
 373         # Literal token without any conversion
 374         self._LiteralToken = ''
 375
 376         # store the operand object
 377         self.operanddict = {}
 378         # The Pcd max value depends on PcdDataType
 379         self.PcdDataType = PcdDataType
 380
 381     # Public entry for this class
 382     #   @param RealValue: False: only evaluate if the expression is true or false, used for conditional expression
 383     #                     True : return the evaluated str(value), used for PCD value
 384     #
 385     #   @return: True or False if RealValue is False
 386     #            Evaluated value of string format if RealValue is True
 387     #
 388     def __call__(self, RealValue = False, Depth = 0):
 389         if self._NoProcess:
 390             return self._Expr
 391
 392         self._Depth = Depth
 393
 394         self._Expr = self._Expr.strip()
 395
 396         self.preProcessRangeExpr(self._Expr)
 397
 398         # check if the expression does not need to evaluate
 399         if RealValue and Depth == 0:
 400             self._Token = self._Expr
 401             if gGuidPatternEnd.match(self._Expr):
 402                 return [self.operanddict[self._Expr] ]
 403
 404             self._Idx = 0
 405             self._Token = ''
 406
 407         Val = self._OrExpr()
 408         RealVal = Val
 409
 410         RangeIdList = RealVal.split("or")
 411         RangeList = []
 412         for rangeid in RangeIdList:
 413             RangeList.append(self.operanddict[rangeid.strip()])
 414
 415         return RangeList
 416
 417     # Template function to parse binary operators which have same precedence
 418     # Expr [Operator Expr]*
 419     def _ExprFuncTemplate(self, EvalFunc, OpSet):
 420         Val = EvalFunc()
 421         while self._IsOperator(OpSet):
 422             Op = self._Token
 423             try:
 424                 Val = self.Eval(Op, Val, EvalFunc())
 425             except WrnExpression, Warn:
 426                 self._WarnExcept = Warn
 427                 Val = Warn.result
 428         return Val
 429
 430     # A [|| B]*
 431     def _OrExpr(self):
 432         return self._ExprFuncTemplate(self._AndExpr, {"OR", "or"})
 433
 434     # A [&& B]*
 435     def _AndExpr(self):
 436         return self._ExprFuncTemplate(self._NeExpr, {"AND", "and"})
 437
 438     def _NeExpr(self):
 439         Val = self._RelExpr()
 440         while self._IsOperator({"!=", "NOT", "not"}):
 441             Op = self._Token
 442             if Op in ["!", "NOT", "not"]:
 443                 if not self._IsOperator({"IN", "in"}):
 444                     raise BadExpression(ERR_REL_NOT_IN)
 445                 Op += ' ' + self._Token
 446             try:
 447                 Val = self.Eval(Op, Val, self._RelExpr())
 448             except WrnExpression, Warn:
 449                 self._WarnExcept = Warn
 450                 Val = Warn.result
 451         return Val
 452
 453     # [!]*A
 454     def _RelExpr(self):
 455         if self._IsOperator({"NOT" , "LE", "GE", "LT", "GT", "EQ", "XOR"}):
 456             Token = self._Token
 457             Val = self._NeExpr()
 458             try:
 459                 return self.Eval(Token, Val)
 460             except WrnExpression, Warn:
 461                 self._WarnExcept = Warn
 462                 return Warn.result
 463         return self._IdenExpr()
 464
 465     # Parse identifier or encapsulated expression
 466     def _IdenExpr(self):
 467         Tk = self._GetToken()
 468         if Tk == '(':
 469             Val = self._OrExpr()
 470             try:
 471                 # _GetToken may also raise BadExpression
 472                 if self._GetToken() != ')':
 473                     raise BadExpression(ERR_MATCH)
 474             except BadExpression:
 475                 raise BadExpression(ERR_MATCH)
 476             return Val
 477         return Tk
 478
 479     # Skip whitespace or tab
 480     def __SkipWS(self):
 481         for Char in self._Expr[self._Idx:]:
 482             if Char not in ' \t':
 483                 break
 484             self._Idx += 1
 485
 486     # Try to convert string to number
 487     def __IsNumberToken(self):
 488         Radix = 10
 489         if self._Token.lower()[0:2] == '0x' and len(self._Token) > 2:
 490             Radix = 16
 491         try:
 492             self._Token = int(self._Token, Radix)
 493             return True
 494         except ValueError:
 495             return False
 496         except TypeError:
 497             return False
 498
 499     # Parse array: {...}
 500     def __GetArray(self):
 501         Token = '{'
 502         self._Idx += 1
 503         self.__GetNList(True)
 504         Token += self._LiteralToken
 505         if self._Idx >= self._Len or self._Expr[self._Idx] != '}':
 506             raise BadExpression(ERR_ARRAY_TOKEN % Token)
 507         Token += '}'
 508
 509         # All whitespace and tabs in array are already stripped.
 510         IsArray = IsGuid = False
 511         if len(Token.split(',')) == 11 and len(Token.split(',{')) == 2 \
 512             and len(Token.split('},')) == 1:
 513             HexLen = [11, 6, 6, 5, 4, 4, 4, 4, 4, 4, 6]
 514             HexList = Token.split(',')
 515             if HexList[3].startswith('{') and \
 516                 not [Index for Index, Hex in enumerate(HexList) if len(Hex) > HexLen[Index]]:
 517                 IsGuid = True
 518         if Token.lstrip('{').rstrip('}').find('{') == -1:
 519             if not [Hex for Hex in Token.lstrip('{').rstrip('}').split(',') if len(Hex) > 4]:
 520                 IsArray = True
 521         if not IsArray and not IsGuid:
 522             raise BadExpression(ERR_ARRAY_TOKEN % Token)
 523         self._Idx += 1
 524         self._Token = self._LiteralToken = Token
 525         return self._Token
 526
 527     # Parse string, the format must be: "..."
 528     def __GetString(self):
 529         Idx = self._Idx
 530
 531         # Skip left quote
 532         self._Idx += 1
 533
 534         # Replace escape \\\", \"
 535         Expr = self._Expr[self._Idx:].replace('\\\\', '//').replace('\\\"', '\\\'')
 536         for Ch in Expr:
 537             self._Idx += 1
 538             if Ch == '"':
 539                 break
 540         self._Token = self._LiteralToken = self._Expr[Idx:self._Idx]
 541         if not self._Token.endswith('"'):
 542             raise BadExpression(ERR_STRING_TOKEN % self._Token)
 543         self._Token = self._Token[1:-1]
 544         return self._Token
 545
 546     # Get token that is comprised by alphanumeric, underscore or dot(used by PCD)
 547     # @param IsAlphaOp: Indicate if parsing general token or script operator(EQ, NE...)
 548     def __GetIdToken(self, IsAlphaOp = False):
 549         IdToken = ''
 550         for Ch in self._Expr[self._Idx:]:
 551             if not self.__IsIdChar(Ch):
 552                 break
 553             self._Idx += 1
 554             IdToken += Ch
 555
 556         self._Token = self._LiteralToken = IdToken
 557         if not IsAlphaOp:
 558             self.__ResolveToken()
 559         return self._Token
 560
 561     # Try to resolve token
 562     def __ResolveToken(self):
 563         if not self._Token:
 564             raise BadExpression(ERR_EMPTY_TOKEN)
 565
 566         # PCD token
 567         if PcdPattern.match(self._Token):
 568             if self._Token not in self._Symb:
 569                 Ex = BadExpression(ERR_PCD_RESOLVE % self._Token)
 570                 Ex.Pcd = self._Token
 571                 raise Ex
 572             self._Token = RangeExpression(self._Symb[self._Token], self._Symb)(True, self._Depth + 1)
 573             if type(self._Token) != type(''):
 574                 self._LiteralToken = hex(self._Token)
 575                 return
 576
 577         if self._Token.startswith('"'):
 578             self._Token = self._Token[1:-1]
 579         elif self._Token in ["FALSE", "false", "False"]:
 580             self._Token = False
 581         elif self._Token in ["TRUE", "true", "True"]:
 582             self._Token = True
 583         else:
 584             self.__IsNumberToken()
 585
 586     def __GetNList(self, InArray = False):
 587         self._GetSingleToken()
 588         if not self.__IsHexLiteral():
 589             if InArray:
 590                 raise BadExpression(ERR_ARRAY_ELE % self._Token)
 591             return self._Token
 592
 593         self.__SkipWS()
 594         Expr = self._Expr[self._Idx:]
 595         if not Expr.startswith(','):
 596             return self._Token
 597
 598         NList = self._LiteralToken
 599         while Expr.startswith(','):
 600             NList += ','
 601             self._Idx += 1
 602             self.__SkipWS()
 603             self._GetSingleToken()
 604             if not self.__IsHexLiteral():
 605                 raise BadExpression(ERR_ARRAY_ELE % self._Token)
 606             NList += self._LiteralToken
 607             self.__SkipWS()
 608             Expr = self._Expr[self._Idx:]
 609         self._Token = self._LiteralToken = NList
 610         return self._Token
 611
 612     def __IsHexLiteral(self):
 613         if self._LiteralToken.startswith('{') and \
 614             self._LiteralToken.endswith('}'):
 615             return True
 616
 617         if gHexPattern.match(self._LiteralToken):
 618             Token = self._LiteralToken[2:]
 619             Token = Token.lstrip('0')
 620             if not Token:
 621                 self._LiteralToken = '0x0'
 622             else:
 623                 self._LiteralToken = '0x' + Token.lower()
 624             return True
 625         return False
 626
 627     def _GetToken(self):
 628         return self.__GetNList()
 629
 630     @staticmethod
 631     def __IsIdChar(Ch):
 632         return Ch in '._/:' or Ch.isalnum()
 633
 634     # Parse operand
 635     def _GetSingleToken(self):
 636         self.__SkipWS()
 637         Expr = self._Expr[self._Idx:]
 638         if Expr.startswith('L"'):
 639             # Skip L
 640             self._Idx += 1
 641             UStr = self.__GetString()
 642             self._Token = 'L"' + UStr + '"'
 643             return self._Token
 644
 645         self._Token = ''
 646         if Expr:
 647             Ch = Expr[0]
 648             Match = gGuidPattern.match(Expr)
 649             if Match and not Expr[Match.end():Match.end() + 1].isalnum() \
 650                 and Expr[Match.end():Match.end() + 1] != '_':
 651                 self._Idx += Match.end()
 652                 self._Token = Expr[0:Match.end()]
 653                 return self._Token
 654             elif self.__IsIdChar(Ch):
 655                 return self.__GetIdToken()
 656             elif Ch == '(' or Ch == ')':
 657                 self._Idx += 1
 658                 self._Token = Ch
 659                 return self._Token
 660
 661         raise BadExpression(ERR_VALID_TOKEN % Expr)
 662
 663     # Parse operator
 664     def _GetOperator(self):
 665         self.__SkipWS()
 666         LegalOpLst = ['&&', '||', '!=', '==', '>=', '<='] + self.NonLetterOpLst
 667
 668         self._Token = ''
 669         Expr = self._Expr[self._Idx:]
 670
 671         # Reach end of expression
 672         if not Expr:
 673             return ''
 674
 675         # Script operator: LT, GT, LE, GE, EQ, NE, and, or, xor, not
 676         if Expr[0].isalpha():
 677             return self.__GetIdToken(True)
 678
 679         # Start to get regular operator: +, -, <, > ...
 680         if Expr[0] not in self.NonLetterOpLst:
 681             return ''
 682
 683         OpToken = ''
 684         for Ch in Expr:
 685             if Ch in self.NonLetterOpLst:
 686                 if '!' == Ch and OpToken:
 687                     break
 688                 self._Idx += 1
 689                 OpToken += Ch
 690             else:
 691                 break
 692
 693         if OpToken not in LegalOpLst:
 694             raise BadExpression(ERR_OPERATOR_UNSUPPORT % OpToken)
 695         self._Token = OpToken
 696         return OpToken