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 IF(Statement):
def __init__(self, tokens):
self.t = TokenHandler(tokens)
def execute(self, skip):
self.t.match("if", self.t.tokens)
currenttoken = self.t.getCurrentToken()
if(skip):
while(currenttoken != "else"):
self.t.match(currenttoken, self.t.tokens)
currenttoken = self.t.getCurrentToken()
self.t.match("else", self.t.tokens)
copytokens = list(self.t.tokens)
s = self.createStatement(copytokens)
tokensexecuted = s.execute(skip)
self.moveAhead(tokensexecuted)
if(self.t.ConditionIsTrue(self.t.tokens, outcondition = [])):
self.t.match("then", self.t.tokens)
copytokens = list(self.t.tokens)
s = self.createStatement(copytokens)
tokensexecuted = s.execute(skip)
self.t.moveAhead(tokensexecuted)
self.t.match("else", self.t.tokens)
copytokens = list(self.t.tokens)
s = self.createStatement(copytokens)
tokensexecuted = s.execute(True)
self.t.moveAhead(tokensexecuted)
else:
currenttoken = self.t.getCurrentToken()
while(currenttoken != "else"):
self.t.match(currenttoken, self.t.tokens)
currenttoken = self.t.getCurrentToken()
self.t.match("else", self.t.tokens)
copytokens = list(self.t.tokens)
s = self.createStatement(copytokens)
tokensexecuted = s.execute(skip)
self.t.moveAhead(tokensexecuted)
return self.t.resetTokens()
class Print(Statement):
def __init__(self, tokens):
self.t = TokenHandler(tokens)
def execute(self, skip):
self.t.match("print", self.t.tokens)
nexttoken = self.t.getCurrentToken()
if not skip:
print(self.t.readTokenValue(nexttoken))
self.t.match(nexttoken, self.t.tokens)
return self.t.resetTokens()
class CompoundStatement(Statement):
def __init__(self, tokens):
self.t = TokenHandler(tokens)
def execute(self, skip):
self.t.match("begin", self.t.tokens)
currenttoken = self.t.getCurrentToken()
condition = True
while condition == True:
copytokens = list(self.t.tokens)
currentstatement = self.createStatement(copytokens)
tokensexecuted = currentstatement.execute(skip)
self.t.moveAhead(tokensexecuted)
currenttoken = self.t.getCurrentToken()
if currenttoken == ";":
condition = True
self.t.match(";", self.t.tokens)
else:
condition = False
self.t.match("end", self.t.tokens)
return self.t.resetTokens()
class ProgramStatement(Statement):
programName = None
def __init__(self, tokens):
self.t = TokenHandler(tokens)
def execute(self, skip):
self.t.match("program", self.t.tokens)
currentToken = self.t.getCurrentToken()
if not skip:
self.programName = currentToken
self.t.match(currentToken, self.t.tokens)
copytokens = list(self.t.tokens)
c = CompoundStatement(copytokens)
tokensExecuted = c.execute(skip)
self.t.moveAhead(tokensExecuted)
return self.t.resetTokens()
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()
