def evaluate(token):
if token.id == None or token.id == Types.END:
raise Exception("Empty program")
elif token.id == Types.BOOLEAN:
return token.value
elif token.id == Types.NUMBER:
return token.value
elif token.id == "not":
return not evaluate(token.first)
elif token.id == "and":
return evaluate(token.first) and evaluate(token.second)
elif token.id == "or":
return evaluate(token.first) or evaluate(token.second)
elif token.id == "+":
return evaluate(token.first) + evaluate(token.second)
elif token.id == "-":
return evaluate(token.first) - evaluate(token.second)
elif token.id == "*":
return evaluate(token.first) * evaluate(token.second)
elif token.id == "/":
return float(evaluate(token.first)) / evaluate(token.second)
elif token.id == "->":
var = symbol(token.second.id)
var.value = evaluate(token.first)
return token.second.value
elif token.id == "<-":
var = symbol(token.first.id)
var.value = evaluate(token.second)
return token.first.value
elif token.token_type == Types.VARIABLE:
if token.value == None:
raise Exception("Variable %s is not defined" % token.id)
return token.value
def infix(id, bp):
def led(self, left):
self.first = left
self.second = expression(bp)
return self
symbol(id, bp).led = led
symbol(id, bp).token_type = Types.OPERATOR
def parentheses(id, closing, bp):
def nud(self):
expr = expression()
# advance(")")
global token
if token.id != closing:
raise SyntaxError("Expected %r" % closing)
token = next()
return expr
symbol(id, bp).nud = nud
symbol(id, bp).token_type = Types.OPERATOR
def tokenize(program):
spaces, boolean, integer, double_operator, operator, variable = map(re.compile, ('^ +', 'False|True', '^[0-9]+', '^(->|<-|not|and|or)', '^[\+\-\*\/\(\)]', '^[a-zA-Z_]+'))
while program != '':
if spaces.match(program):
mo = spaces.match(program)
program = program[mo.end():]
elif boolean.match(program):
mo = boolean.match(program)
p = program[0:mo.end()]
t = symbol(Types.BOOLEAN)()
if p == "True":
t.value = True
elif p == "False":
t.value = False
else:
raise Exception("This should never happen")
t.string = p
yield t
program = program[mo.end():]
elif integer.match(program):
mo = integer.match(program)
p = program[0:mo.end()]
t = symbol(Types.NUMBER)()
t.value = int(p)
t.string = p
yield t
program = program[mo.end():]
elif double_operator.match(program):
mo = double_operator.match(program)
p = program[0:mo.end()]
t = symbol(p)()
t.string = p
yield t
program = program[mo.end():]
elif operator.match(program):
mo = operator.match(program)
p = program[0:mo.end()]
t = symbol(p)()
t.string = p
yield t
program = program[mo.end():]
elif variable.match(program):
mo = variable.match(program)
p = program[0:mo.end()]
symbol(p).token_type = Types.VARIABLE
t = symbol(p)()
symbol(p).nud = lambda self: self
symbol(p).lbp = 10
t.string = p
yield t
program = program[mo.end():]
else:
raise Exception("Something went wrong while parsing %s"%program)
t = symbol(Types.END)()
t.value = t.string = "END"
yield t
def literal(type, lbp):
symbol(type).token_type = type
symbol(type).nud = lambda self: self
symbol(type).lbp = lbp
def prefix(id, bp):
def nud(self):
self.first = expression(bp)
return self
symbol(id).nud = nud
