class Statement(object):
def __init__(self, tokens):
self.t = TokenHandler(tokens)
def createStatement(self, tokens):
currenttoken = self.t.getCurrentToken()
if currenttoken == "begin":
s = CompoundStatement(tokens)
return s
elif self.t.isVariable(currenttoken):
a = Assignment(tokens)
return a
elif currenttoken == "print":
p = Print(tokens)
return p
elif currenttoken == "if":
i = IF(tokens)
return i
elif currenttoken == "while":
w = While(tokens)
return w
else:
raise ParserException('\';\' expected. Got \'' + currenttoken + '\' instead.')
def execute(self, skip):
raise NotImplementedError("Subclass must implement abstract method")
class Assignment(Statement):
def __init__(self, tokens):
self.t = TokenHandler(tokens)
def execute(self, skip):
currenttoken = self.t.getCurrentToken()
if not self.t.isVariable(currenttoken):
raise VariableException("Not a variable: " + currenttoken)
variablebeingassigned = currenttoken
self.t.match(currenttoken, self.t.tokens)
self.t.match(":=", self.t.tokens)
currenttoken = self.t.getCurrentToken()
variablevalue = None
if not skip:
variablevalue = self.t.readTokenValue(currenttoken)
TokenHandler.variables[variablebeingassigned] = variablevalue
self.t.match(currenttoken, self.t.tokens)
currenttoken = self.t.getCurrentToken()
while(self.t.isMathOperator(currenttoken)):
if currenttoken == "+":
self.t.match("+", self.t.tokens)
currenttoken = self.t.getCurrentToken()
if not skip:
operand = self.t.readTokenValue(currenttoken)
variablevalue += operand
TokenHandler.variables[variablebeingassigned] = variablevalue
self.t.match(currenttoken, self.t.tokens)
elif currenttoken == "-":
self.t.match("-", self.t.tokens)
currenttoken = self.t.getCurrentToken()
if not skip:
operand = self.t.readTokenValue(currenttoken)
variablevalue -= operand
TokenHandler.variables[variablebeingassigned] = variablevalue
self.t.match(currenttoken, self.t.tokens)
elif currenttoken == "*":
self.t.match("*", self.t.tokens)
currenttoken = self.t.getCurrentToken()
if not skip:
operand = self.t.readTokenValue(currenttoken)
variablevalue *= operand
TokenHandler.variables[variablebeingassigned] = variablevalue
self.t.match(currenttoken, self.t.tokens)
elif currenttoken == "/":
self.t.match("/", self.t.tokens)
currenttoken = self.t.getCurrentToken()
if not skip:
operand = self.t.readTokenValue(currenttoken)
if operand == 0:
raise ParserException("Can't divide by zero.")
variablevalue /= operand
TokenHandler.variables[variablebeingassigned] = variablevalue
self.t.match(currenttoken, self.t.tokens)
currenttoken = self.t.getCurrentToken()
return self.t.resetTokens()
