def assign(self, name, value):
# Check that variable exists
if self.scopeAbove:
if not name.lexeme in self.values:
self.scopeAbove.assign(name, value)
return
else: # At the global level, if not here than var does not exist
if not name.lexeme in self.values:
raise exceptions.RuntimeException(
"Line %d Undefined variable %s" % (name.line, name.lexeme))
# Variable is in this scope
# Check type
vtype = self.types[name.lexeme]
if vtype == "num":
if not (isinstance(value, int) or isinstance(value, float)):
raise exceptions.RuntimeException(
"Line %d Type error: not num" % name.line)
if vtype == "str":
if not isinstance(value, str):
raise exceptions.RuntimeException(
"Line %d Type error: not str" % name.line)
if vtype == "bool":
if not isinstance(value, bool):
raise exceptions.RuntimeException(
"Line %d Type error: not bool" % name.line)
self.values[name.lexeme] = value
def define(self, name, type, value):
typetok = type
type = typetok.type
# Check that value type and vartype match
# Uninitialized strs are nil, nums are 0 and bools are false
if value is not None:
if type.lower() == "str":
if not isinstance(value, str):
raise exceptions.RuntimeException(
"Line %d Type error: not str" % typetok.line)
if type.lower() == "num":
if not (isinstance(value, int) or isinstance(value, float)):
raise exceptions.RuntimeException(
"Line %d Type error: not a num" % typetok.line)
if type.lower() == "bool":
if not isinstance(value, bool):
raise exceptions.RuntimeException(
"Line %d Type error not a bool" % typetok.line)
else:
if type.lower() == "num":
value = 0
elif type.lower() == "bool":
value = False
# Save variable type and value
self.types[name] = type.lower()
self.values[name] = value
def get(self, name):
# Look for the variable in our scope/env
if name.lexeme in self.values:
# nums and bools can be accessed before being initialized
# nothing else can
varval = self.values[name.lexeme]
vartype = self.types[name.lexeme]
if (vartype != "num" or vartype != "bool") and \
(varval is None):
raise exceptions.RuntimeException(
"Line %d Cannot access uninitialized variable" % name.line)
return self.values[name.lexeme]
# Did not find the variable in our scope so go up the chain
if self.scopeAbove:
return self.scopeAbove.get(name)
# Variable is not defined in any scope
raise exceptions.RuntimeException("Undefined variable " + name.lexeme)
def visitBinary(self, expr):
""" Evaluate the expressions on the left and right of
the operator, then perform the operation on them."""
left = self._evaluate(expr.left)
right = self._evaluate(expr.right)
op = str(expr.operator.type)
# Math operator
if op == "MINUS":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) - float(right)
if op == "PLUS":
if isinstance(right, str) and isinstance(left, str):
return str(left) + str(right)
if isinstance(right, float) and isinstance(left, float):
return float(left) + float(right)
raise exceptions.RuntimeException("Operands must be two numbers"
" or two strings", expr.operator)
if op == "STAR":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) * float(right)
if op == "SLASH":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) / float(right)
# Comparison operator
if op == "GREATER":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) > float(right)
if op == "GREATER_EQUAL":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) >= float(right)
if op == "LESS":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) < float(right)
if op == "LESS_EQUAL":
self._checkNumbersOperand(expr.operator, left, right)
return float(left) <= float(right)
# Equality operators
if op == "BANG_EQUAL":
return not self._isEqual(left, right)
if op == "EQUAL_EQUAL":
return self._isEqual(left, right)
def _checkNumbersOperand(self, op, operand1, operand2):
if isinstance(operand1, float) and isinstance(operand2, float):
return
raise exceptions.RuntimeException("Operands must be numbers!", op)
def _checkNumberOperand(self, op, operand):
if isinstance(operand, float):
return
raise exceptions.RuntimeException("Operand must be a number!", op)