def validate_modification(self, node: Union[vy_ast.Assign, vy_ast.AugAssign]) -> None:
"""
Validate an attempt to modify this value.
Raises if the value is a constant or involves an invalid operation.
Arguments
---------
node : Assign | AugAssign
Vyper ast node of the modifying action.
"""
if self.location == DataLocation.CALLDATA:
raise ImmutableViolation("Cannot write to calldata", node)
if self.is_constant:
raise ImmutableViolation("Constant value cannot be written to", node)
if self.is_immutable:
if node.get_ancestor(vy_ast.FunctionDef).get("name") != "__init__":
raise ImmutableViolation("Immutable value cannot be written to", node)
if self._modification_count:
raise ImmutableViolation(
"Immutable value cannot be modified after assignment", node
)
self._modification_count += 1
if isinstance(node, vy_ast.AugAssign):
self.validate_numeric_op(node)
def validate_modification(self, node: Union[vy_ast.Assign, vy_ast.AugAssign]) -> None:
"""
Validate an attempt to modify this value.
Raises if the value is a constant or involves an invalid operation.
Arguments
---------
node : Assign | AugAssign
Vyper ast node of the modifying action.
"""
if self.location == DataLocation.CALLDATA:
raise ImmutableViolation("Cannot write to calldata", node)
if self.is_immutable:
raise ImmutableViolation("Immutable value cannot be written to", node)
if isinstance(node, vy_ast.AugAssign):
self.validate_numeric_op(node)
def validate_modification(
self,
node: Union[vy_ast.Assign, vy_ast.AugAssign, vy_ast.Call],
mutability: Any, # should be StateMutability, import cycle
) -> None:
"""
Validate an attempt to modify this value.
Raises if the value is a constant or involves an invalid operation.
Arguments
---------
node : Assign | AugAssign | Call
Vyper ast node of the modifying action.
mutability: StateMutability
The mutability of the context (e.g., pure function) we are currently in
"""
# TODO: break this cycle, probably by moving this to validation module
from vyper.semantics.types.function import StateMutability
if mutability <= StateMutability.VIEW and self.location == DataLocation.STORAGE:
raise StateAccessViolation(
f"Cannot modify storage in a {mutability.value} function",
node)
if self.location == DataLocation.CALLDATA:
raise ImmutableViolation("Cannot write to calldata", node)
if self.is_constant:
raise ImmutableViolation("Constant value cannot be written to",
node)
if self.is_immutable:
if node.get_ancestor(vy_ast.FunctionDef).get("name") != "__init__":
raise ImmutableViolation(
"Immutable value cannot be written to", node)
if self._modification_count:
raise ImmutableViolation(
"Immutable value cannot be modified after assignment",
node)
self._modification_count += 1
if isinstance(node, vy_ast.AugAssign):
self.validate_numeric_op(node)
def visit_For(self, node):
if isinstance(node.iter, vy_ast.Subscript):
raise StructureException("Cannot iterate over a nested list", node.iter)
if isinstance(node.iter, vy_ast.Call):
# iteration via range()
if node.iter.get("func.id") != "range":
raise IteratorException(
"Cannot iterate over the result of a function call", node.iter
)
validate_call_args(node.iter, (1, 2))
args = node.iter.args
if len(args) == 1:
# range(CONSTANT)
if not isinstance(args[0], vy_ast.Num):
raise StateAccessViolation("Value must be a literal", node)
if args[0].value <= 0:
raise StructureException("For loop must have at least 1 iteration", args[0])
validate_expected_type(args[0], Uint256Definition())
type_list = get_possible_types_from_node(args[0])
else:
validate_expected_type(args[0], IntegerAbstractType())
type_list = get_common_types(*args)
if not isinstance(args[0], vy_ast.Constant):
# range(x, x + CONSTANT)
if not isinstance(args[1], vy_ast.BinOp) or not isinstance(
args[1].op, vy_ast.Add
):
raise StructureException(
"Second element must be the first element plus a literal value",
args[0],
)
if not vy_ast.compare_nodes(args[0], args[1].left):
raise StructureException(
"First and second variable must be the same", args[1].left
)
if not isinstance(args[1].right, vy_ast.Int):
raise InvalidLiteral("Literal must be an integer", args[1].right)
if args[1].right.value < 1:
raise StructureException(
f"For loop has invalid number of iterations ({args[1].right.value}),"
" the value must be greater than zero",
args[1].right,
)
else:
# range(CONSTANT, CONSTANT)
if not isinstance(args[1], vy_ast.Int):
raise InvalidType("Value must be a literal integer", args[1])
validate_expected_type(args[1], IntegerAbstractType())
if args[0].value >= args[1].value:
raise StructureException("Second value must be > first value", args[1])
else:
# iteration over a variable or literal list
type_list = [
i.value_type
for i in get_possible_types_from_node(node.iter)
if isinstance(i, ArrayDefinition)
]
if not type_list:
raise InvalidType("Not an iterable type", node.iter)
if next((i for i in type_list if isinstance(i, ArrayDefinition)), False):
raise StructureException("Cannot iterate over a nested list", node.iter)
if isinstance(node.iter, (vy_ast.Name, vy_ast.Attribute)):
# check for references to the iterated value within the body of the loop
assign = _check_iterator_assign(node.iter, node)
if assign:
raise ImmutableViolation("Cannot modify array during iteration", assign)
if node.iter.get("value.id") == "self":
# check if iterated value may be modified by function calls inside the loop
iter_name = node.iter.attr
for call_node in node.get_descendants(vy_ast.Call, {"func.value.id": "self"}):
fn_name = call_node.func.attr
fn_node = self.vyper_module.get_children(vy_ast.FunctionDef, {"name": fn_name})[0]
if _check_iterator_assign(node.iter, fn_node):
# check for direct modification
raise ImmutableViolation(
f"Cannot call '{fn_name}' inside for loop, it potentially "
f"modifies iterated storage variable '{iter_name}'",
call_node,
)
for name in self.namespace["self"].members[fn_name].recursive_calls:
# check for indirect modification
fn_node = self.vyper_module.get_children(vy_ast.FunctionDef, {"name": name})[0]
if _check_iterator_assign(node.iter, fn_node):
raise ImmutableViolation(
f"Cannot call '{fn_name}' inside for loop, it may call to '{name}' "
f"which potentially modifies iterated storage variable '{iter_name}'",
call_node,
)
for_loop_exceptions = []
iter_name = node.target.id
for type_ in type_list:
# type check the for loop body using each possible type for iterator value
type_ = copy.deepcopy(type_)
type_.is_immutable = True
with self.namespace.enter_scope():
try:
self.namespace[iter_name] = type_
except VyperException as exc:
raise exc.with_annotation(node) from None
try:
for n in node.body:
self.visit(n)
return
except TypeMismatch as exc:
for_loop_exceptions.append(exc)
if len(set(str(i) for i in for_loop_exceptions)) == 1:
# if every attempt at type checking raised the same exception
raise for_loop_exceptions[0]
# return an aggregate TypeMismatch that shows all possible exceptions
# depending on which type is used
types_str = [str(i) for i in type_list]
given_str = f"{', '.join(types_str[:1])} or {types_str[-1]}"
raise TypeMismatch(
f"Iterator value '{iter_name}' may be cast as {given_str}, "
"but type checking fails with all possible types:",
node,
*(
(f"Casting '{iter_name}' as {type_}: {exc.message}", exc.annotations[0])
for type_, exc in zip(type_list, for_loop_exceptions)
),
)