def _concat_or_add(operator, left, right):
if isinstance(left, numbers.Number) and isinstance(right, numbers.Number):
return float(left) + float(right)
elif isinstance(left, str) and isinstance(right, str):
return left + right
else:
raise LoxRuntimeError(operator,
"Operands must be two numbers or two strings.")
def get(self, name): # of type Token
"""get name in current scope or outer scope"""
if name.lexeme in self.values.keys():
return self.values.get(name.lexeme)
if self.enclosing is not None:
return self.enclosing.get(name)
raise LoxRuntimeError(name, "Undefined variable " + name.lexeme + ".")
def visit_call(self, expr):
callee = self._evaluate(expr.callee)
arguments = []
for argument in expr.arguments:
arguments.append(self._evaluate(argument))
if not isinstance(callee, LoxCallable):
raise LoxRuntimeError(expr.paren,
"Can only call function and classes.")
function = callee
if len(arguments) != function.arity():
raise LoxRuntimeError(
expr.paren, "Expected" + str(function.arity()) +
"arguments but got {len(arguments)} .")
return function.call(self, arguments)
def assign(self, name, value): # name of type Token
"""The key difference between assignment and definition is that assignment is not allowed to
create a new variable."""
if name.lexeme in self.values:
self.values[name.lexeme] = value
return
if self.enclosing is not None:
self.enclosing.values[name.lexeme] = value
return
raise LoxRuntimeError(name, "Undefined variable " + name.lexeme + ".")
def _check_number_operands(operator, left, right):
if isinstance(left, numbers.Number) and isinstance(right, numbers.Number):
return
raise LoxRuntimeError(operator, "Operands must be numbers.")
def _check_number_operand(operator, operand):
if isinstance(operand, numbers.Number):
return
raise LoxRuntimeError(operator, "Operand must be a number.")