class TypeCheck(BaseVisitor):
def __init__(self):
self.env = global_env()
def reset(self):
self.env = global_env()
def run(self, statements):
for stmt in statements:
self.visit(stmt)
def visit_block(self, node):
try:
self.env = Environment(enclosing=self.env)
for stmt in node.statements:
self.visit(stmt)
finally:
self.env = self.env.enclosing
def visit_function_def(self, node):
self.env = Environment(enclosing=self.env)
for p in node.parameters:
self.env.declare_var(p.name, p.type)
try:
self.visit(node.body)
except TypeCheck.ReturnType as r:
self.env = self.env.enclosing
return_type = r.type
else:
self.env = self.env.enclosing
return_type = Type.UNIT
param_types = [p.type for p in node.parameters]
fun = Callable() # dummy for uniformity
fun.signature = CallableSignature(param_types, return_type)
self.env.define_fun(node.name, fun)
def visit_print_stmt(self, node):
self.visit(node.expr)
def visit_variable_declaration(self, node):
if node.value:
r_type = self.visit(node.value)
if node.type != r_type:
raise TypeError(
f'Incorrect value for variable {node.name} of type: {node.type}'
)
self.env.declare_var(node.name, node.type)
def visit_assignment(self, node):
l_type = self.env.resolve_var(node.name, level=node.scope_depth)
r_type = self.visit(node.value)
if l_type != r_type:
raise TypeError(
f'Incorrect value for variable {node.name} of type: {l_type}')
def visit_if_stmt(self, node):
if self.visit(node.condition) != Type.BOOL:
raise TypeError(f'Non-boolean condition in "if" statement.')
self.visit(node.body)
def visit_while_stmt(self, node):
if self.visit(node.condition) != Type.BOOL:
raise TypeError(f'Non-boolean condition in "while" statement.')
self.visit(node.body)
def visit_for_stmt(self, node):
self.env = Environment(enclosing=self.env)
self.visit(node.initializer)
if self.visit(node.condition) != Type.BOOL:
raise TypeError(f'Non-boolean condition in "for" statement.')
self.visit(node.body)
self.env = self.env.enclosing
def visit_binary_expr(self, node):
l_type = self.visit(node.left)
r_type = self.visit(node.right)
return self.check_binary(l_type, r_type, node.op)
def visit_unary_expr(self, node):
e_type = self.visit(node.expr)
return self.check_unary(e_type, node.op)
def visit_assert_stmt(self, node):
type = self.visit(node.expr)
assert type == Type.BOOL
class ReturnType(Exception):
def __init__(self, type):
super()
self.type = type
def visit_return_stmt(self, node):
type = self.visit(node.expr)
raise TypeCheck.ReturnType(type)
def visit_call(self, node):
signature = self.env.resolve_fun(node.name,
level=node.scope_depth).signature
arg_types = [self.visit(a) for a in node.args]
return signature.verify(arg_types)
def visit_variable(self, node):
return self.env.resolve_var(node.name, level=node.scope_depth)
@staticmethod
def visit_literal(node):
return node.type
def visit_unknown(self, m_name):
pass
@staticmethod
def check_binary(l_type, r_type, op):
try:
assert (l_type, r_type) in binary_signatures
assert op in binary_signatures[(l_type, r_type)]
return binary_signatures[(l_type, r_type)][op]
except AssertionError:
raise TypeError(
f'Incorrect types for operator: {l_type} {r_type} {op}')
@staticmethod
def check_unary(e_type, op):
try:
assert e_type in unary_signatures
assert op in unary_signatures[e_type]
return unary_signatures[e_type][op]
except AssertionError:
raise TypeError(f'Incorrect type for operator: {e_type} {op}')
class Evaluator(BaseVisitor):
"""Visitor of abstract syntax tree nodes."""
operators = {
'+': operator.add,
'-': operator.sub,
'*': operator.mul,
'/': operator.truediv,
'^': operator.pow,
'%': operator.mod,
'==': operator.eq,
'!=': operator.ne,
'>': operator.gt,
'>=': operator.ge,
'<=': operator.le,
'<': operator.lt,
}
unary_operators = {
'-': operator.neg,
}
def __init__(self):
self.env = global_env()
def reset(self):
self.env = global_env()
def run(self, statements):
for stmt in statements:
self.visit(stmt)
def visit_block(self, node):
try:
self.env = Environment(enclosing=self.env)
for stmt in node.statements:
self.visit(stmt)
finally:
self.env = self.env.enclosing
def visit_function_def(self, node):
try:
self.env.resolve_fun(node.name, level=0)
except:
self.env.define_fun(node.name,
Function(node.parameters, node.body, self.env))
else:
raise Exception(f'Function {node.name} defined twice!')
def visit_print_stmt(self, node):
print(self.visit(node.expr))
def visit_variable_declaration(self, node):
try:
self.env.resolve_var(node.name, level=0)
except:
if node.value:
value = self.visit(node.value)
else:
value = None
self.env.declare_var(node.name, value)
else:
raise Exception(f'Variable {node.name} declared twice!')
def visit_assignment(self, node):
self.env.resolve_var(node.name, level=node.scope_depth)
value = self.visit(node.value)
self.env.define_var(node.name, value)
def visit_if_stmt(self, node):
if self.visit(node.condition):
self.visit(node.body)
def visit_while_stmt(self, node):
while self.visit(node.condition):
self.visit(node.body)
def visit_for_stmt(self, node):
self.env = Environment(enclosing=self.env)
self.visit(node.initializer)
while self.visit(node.condition):
self.visit(node.body)
self.visit(node.increment)
self.env = self.env.enclosing
def visit_binary_expr(self, node):
if hasattr(node, 'common_node'):
return node.common_node.cache
op = self.operators[node.op]
lval = self.visit(node.left)
rval = self.visit(node.right)
value = op(lval, rval)
if hasattr(node, 'cache'):
node.cache = value
return value
def visit_unary_expr(self, node):
if hasattr(node, 'common_node'):
return node.common_node.cache
op = self.unary_operators[node.op]
value = op(self.visit(node.expr))
if hasattr(node, 'cache'):
node.cache = value
return value
def visit_assert_stmt(self, node):
value = self.visit(node.expr)
assert value
class ReturnValue(Exception):
def __init__(self, val):
super()
self.val = val
def visit_return_stmt(self, node):
value = self.visit(node.expr)
raise Evaluator.ReturnValue(value)
def visit_call(self, node):
function = self.env.resolve_fun(node.name, level=node.scope_depth)
return function.call(self, node.args)
def visit_variable(self, node):
return self.env.resolve_var(node.name, level=node.scope_depth)
@staticmethod
def visit_literal(node):
return node.value