class Context():
def __init__(self, text: str):
self.__tokenizer = Tokenizer(text)
self.__currentToken = None
self.nextToken()
def nextToken(self) -> str:
if self.__tokenizer.hasMoreTokens():
self.__currentToken = self.__tokenizer.nextToken()
else:
self.__currentToken = None
return self.__currentToken
def currentToken(self) -> str:
return self.__currentToken
def skipToken(self, token: str) -> None:
if not token == self.__currentToken:
raise ParseException(
"Warning {} is expected, but {} is found".format(
token, self.__currentToken))
self.nextToken()
def currentNumber(self) -> int:
number: int = 0
try:
number = int(self.__currentToken)
except ValueError as e:
raise ParseException("Warning: " + str(e))
return number
class Parser():
def __init__(self, Filebuffer):
self.File = Filebuffer
self.Tokenizer = Tokenizer(Filebuffer)
self.operand = Operands()
def parse(self):
statements = []
while 1:
Token = self.Tokenizer.nextToken()
if Token.Get_Token_Type() == TokenType.EOF:
break
if Token.Get_Token_Type() == TokenType.Mnemonic:
# statement -> mnemonic (%register | $decimal) , %register
operands = []
opcode = Token.Get_Token_value()
Token = self.Tokenizer.nextToken()
# source have adress displacement , in this case Mnemonic means label
if Token.Get_Token_Type(
) == TokenType.Disp or Token.Get_Token_Type(
) == TokenType.Mnemonic:
disp = Token.Get_Token_value()
Token = self.Tokenizer.nextToken()
Token.match(TokenType.LPAREN)
Token = self.Tokenizer.nextToken()
operand = self.operand.MakeOperand(Token.Get_Token_Type(),
Token.Get_Token_value())
operands.append(Address(operand, disp, None, None))
Token = self.Tokenizer.nextToken()
Token.match(TokenType.RPAREN)
elif Token.Get_Token_Type() == TokenType.LPAREN:
Token = self.Tokenizer.nextToken()
operand = self.operand.MakeOperand(Token.Get_Token_Type(),
Token.Get_Token_value())
print(self.Tokenizer.look2ahead().Get_Token_Type())
if self.Tokenizer.look2ahead().Get_Token_Type(
) == TokenType.Register:
basereg = operand
Token = self.Tokenizer.nextToken()
Token.match(TokenType.Comma)
Token = self.Tokenizer.nextToken()
indexreg = self.operand.MakeOperand(
Token.Get_Token_Type(), Token.Get_Token_value())
Token = self.Tokenizer.nextToken()
Token.match(TokenType.Comma)
Token = self.Tokenizer.nextToken()
scale = self.operand.MakeOperand(
Token.Get_Token_Type(), Token.Get_Token_value())
operands.append(Address(operand, None, indexreg,
scale))
Token = self.Tokenizer.nextToken()
Token.match(TokenType.RPAREN)
else:
operands.append(Address(operand, None, None, None))
Token = self.Tokenizer.nextToken()
Token.match(TokenType.RPAREN)
elif Token.Get_Token_Type(
) == TokenType.Register or Token.Get_Token_Type(
) == TokenType.Number:
Token.match(TokenType.Register, TokenType.Number)
operands.append(
self.operand.MakeOperand(Token.Get_Token_Type(),
Token.Get_Token_value()))
if self.Tokenizer.lookahead().Get_Token_Type(
) == TokenType.NewLine:
statements.append(Intruction(opcode, operands))
self.Tokenizer.nextToken()
continue
if self.Tokenizer.lookahead().Get_Token_Type(
) == TokenType.EOF:
statements.append(Intruction(opcode, operands))
self.Tokenizer.nextToken()
break
Token = self.Tokenizer.nextToken()
Token.match(TokenType.Comma)
Token = self.Tokenizer.nextToken()
Token.match(TokenType.Register)
operands.append(
self.operand.MakeOperand(Token.Get_Token_Type(),
Token.Get_Token_value()))
Token = self.Tokenizer.nextToken()
statements.append(Intruction(opcode, operands))
if Token.Get_Token_Type() == TokenType.EOF:
break
Token.match(TokenType.NewLine)
return statements
