Python ast.IsNot() Examples

def comp_op_rewrite(op: t.Union[Tokenizer, t.List[Tokenizer]]):
    """
    ('<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not')
    """
    if isinstance(op, list):
        op = tuple(map(lambda it: it.value, op))
    else:
        op = op.value

    return {
        '<': ast.Lt,
        '>': ast.Gt,
        '==': ast.Eq,
        '>=': ast.GtE,
        '<=': ast.LtE,
        '<>': lambda: raise_exp(NotImplemented),
        '!=': ast.NotEq,
        'in': ast.In,
        ('is', ): ast.Is,
        ('is', 'not'): ast.IsNot,
        ('not', 'in'): ast.NotIn,
    }[op]() 

def _process_is_literal(
        tokens: List[Token],
        i: int,
        compare: Union[ast.Is, ast.IsNot],
) -> None:
    while tokens[i].src != 'is':
        i -= 1
    if isinstance(compare, ast.Is):
        tokens[i] = tokens[i]._replace(src='==')
    else:
        tokens[i] = tokens[i]._replace(src='!=')
        # since we iterate backward, the dummy tokens keep the same length
        i += 1
        while tokens[i].src != 'not':
            tokens[i] = Token('DUMMY', '')
            i += 1
        tokens[i] = Token('DUMMY', '') 

def visit_Assert(self, node):
        if is_binary_comparison(node):
            if is_comparison_type(node, ast.Eq):
                return make_call_node(node, assert_equal.__name__)
            elif is_comparison_type(node, ast.NotEq):
                return make_call_node(node, assert_not_equal.__name__)
            elif is_comparison_type(node, ast.In):
                return make_call_node(node, assert_in.__name__)
            elif is_comparison_type(node, ast.NotIn):
                return make_call_node(node, assert_not_in.__name__)
            elif is_comparison_type(node, ast.Is):
                return make_call_node(node, assert_is.__name__)
            elif is_comparison_type(node, ast.IsNot):
                return make_call_node(node, assert_is_not.__name__)
            elif is_comparison_type(node, ast.Lt):
                return make_call_node(node, assert_less_than.__name__)
            elif is_comparison_type(node, ast.LtE):
                return make_call_node(node, assert_less_than_equal_to.__name__)
            elif is_comparison_type(node, ast.Gt):
                return make_call_node(node, assert_greater_than.__name__)
            elif is_comparison_type(node, ast.GtE):
                return make_call_node(node, assert_greater_than_equal_to.__name__)

        return node 

def __init__(self) -> None:
        self.dicts: Dict[Offset, ListCompOrGeneratorExp] = {}
        self.sets: Dict[Offset, ast.expr] = {}
        self.set_empty_literals: Dict[Offset, ListOrTuple] = {}
        self.is_literal: Dict[Offset, Union[ast.Is, ast.IsNot]] = {} 

def visit_Compare(self, node: ast.Compare) -> None:
        left = node.left
        for op, right in zip(node.ops, node.comparators):
            if (
                    isinstance(op, (ast.Is, ast.IsNot)) and
                    (
                        isinstance(left, LITERAL_TYPES) or
                        isinstance(right, LITERAL_TYPES)
                    )
            ):
                self.is_literal[_ast_to_offset(right)] = op
            left = right

        self.generic_visit(node) 

def invert(node):
    """
    Invert the operation in an ast node object (get its negation).

    Args:
        node: An ast node object.

    Returns:
        An ast node object containing the inverse (negation) of the input node.
    """
    inverse = {ast.Eq: ast.NotEq,
               ast.NotEq: ast.Eq,
               ast.Lt: ast.GtE,
               ast.LtE: ast.Gt,
               ast.Gt: ast.LtE,
               ast.GtE: ast.Lt,
               ast.Is: ast.IsNot,
               ast.IsNot: ast.Is,
               ast.In: ast.NotIn,
               ast.NotIn: ast.In}

    if type(node) == ast.Compare:
        op = type(node.ops[0])
        inverse_node = ast.Compare(left=node.left, ops=[inverse[op]()],
                                   comparators=node.comparators)
    elif isinstance(node, ast.BinOp) and type(node.op) in inverse:
        op = type(node.op)
        inverse_node = ast.BinOp(node.left, inverse[op](), node.right)
    elif type(node) == ast.NameConstant and node.value in [True, False]:
        inverse_node = ast.NameConstant(value=not node.value)
    else:
        inverse_node = ast.UnaryOp(op=ast.Not(), operand=node)

    return inverse_node 

def test_correct_comparing(self, node: Any = None) -> None:
        if not node:
            return
        if isinstance(node, Iterable):
            for item in node:
                self.test_correct_comparing(item)
            return

        if isinstance(node, ast.Expr):
            self.test_correct_comparing(node.value)
            return

        if isinstance(node, ast.BinOp):
            self.test_correct_comparing(node.left)
            self.test_correct_comparing(node.right)
            return

        if isinstance(node, ast.BoolOp):
            for val in node.values:
                self.test_correct_comparing(val)
            return

        if isinstance(node, ast.IfExp):
            self.test_correct_comparing(node.body)
            self.test_correct_comparing(node.test)
            self.test_correct_comparing(node.orelse)
            return

        if isinstance(node, ast.Compare):
            if isinstance(node.left, ast.Name):
                comparator = node.comparators[0]
                operation = node.ops[0]
                if isinstance(operation, ast.Is) or isinstance(operation, ast.IsNot):
                    # Is or IsNot are allowed for NameConstant - None - only
                    if isinstance(comparator, ast.NameConstant) and comparator.value is None:
                        return
                    node_text = self.stringify_node(node)
                    self.warnings.append(f'Checking "{node_text}" '
                                         'is unsafe, use "==" operator instead')
                    self.test_correct_comparing(comparator) 

def visit_Compare(self, node: ast.Compare) -> Any:
        """Recursively visit the comparators and apply the operations on them."""
        # pylint: disable=too-many-branches
        left = self.visit(node=node.left)

        comparators = [self.visit(node=comparator) for comparator in node.comparators]

        result = None  # type: Optional[Any]
        for comparator, op in zip(comparators, node.ops):
            if isinstance(op, ast.Eq):
                comparison = left == comparator
            elif isinstance(op, ast.NotEq):
                comparison = left != comparator
            elif isinstance(op, ast.Lt):
                comparison = left < comparator
            elif isinstance(op, ast.LtE):
                comparison = left <= comparator
            elif isinstance(op, ast.Gt):
                comparison = left > comparator
            elif isinstance(op, ast.GtE):
                comparison = left >= comparator
            elif isinstance(op, ast.Is):
                comparison = left is comparator
            elif isinstance(op, ast.IsNot):
                comparison = left is not comparator
            elif isinstance(op, ast.In):
                comparison = left in comparator
            elif isinstance(op, ast.NotIn):
                comparison = left not in comparator
            else:
                raise NotImplementedError("Unhandled op of {}: {}".format(node, op))

            if result is None:
                result = comparison
            else:
                result = result and comparison

            left = comparator

        self.recomputed_values[node] = result
        return result 

def COMPARE(self, node):
        left = node.left
        for op, right in zip(node.ops, node.comparators):
            if (
                    isinstance(op, (ast.Is, ast.IsNot)) and (
                        _is_const_non_singleton(left) or
                        _is_const_non_singleton(right)
                    )
            ):
                self.report(messages.IsLiteral, node)
            left = right

        self.handleChildren(node) 

def p_comp_op_10(p):
    '''comp_op : IS NOT'''
    #             1   2
    p[0] = ast.IsNot(rule=inspect.currentframe().f_code.co_name)

# expr: xor_expr ('|' xor_expr)* 

def _(
    src=each("assert x == y", "assert x is y", "assert x < y", "assert x is not y"),
    node_type=each(ast.Eq, ast.Is, ast.Lt, ast.IsNot),
):
    assert_node = ast.parse(src).body[0]
    assert is_comparison_type(assert_node, node_type) 

def _check_constant(self, op: ast.cmpop, comparator: ast.expr) -> None:
        if not isinstance(op, (ast.Eq, ast.NotEq, ast.Is, ast.IsNot)):
            return
        real = get_assigned_expr(comparator)
        if not isinstance(real, (ast.List, ast.Dict, ast.Tuple)):
            return

        length = len(real.keys) if isinstance(
            real, ast.Dict,
        ) else len(real.elts)

        if not length:
            self.add_violation(FalsyConstantCompareViolation(comparator)) 

def _check_is_constant_comprare(
        self,
        op: ast.cmpop,
        comparator: ast.expr,
    ) -> None:
        if not isinstance(op, (ast.Is, ast.IsNot)):
            return

        unwrapped = operators.unwrap_unary_node(
            get_assigned_expr(comparator),
        )
        if isinstance(unwrapped, self._forbidden_for_is):
            self.add_violation(WrongIsCompareViolation(comparator)) 

def visit_Compare(self, node: ast.Compare) -> ast.AST:
        """Compare nodes are ``==, >=, is, in`` etc. There are multiple Compare categories."""
        self.generic_visit(node)
        log_header = f"visit_Compare: {self.src_file}:"

        # taking only the first operation in the compare node
        # in basic testing, things like (a==b)==1 still end up with lists of 1,
        # but since the AST docs specify a list of operations this seems safer.
        # idx = LocIndex("CompareIs", node.lineno, node.col_offset, type(node.ops[0]))

        cmpop_is_types: Set[type] = {ast.Is, ast.IsNot}
        cmpop_in_types: Set[type] = {ast.In, ast.NotIn}
        op_type = type(node.ops[0])
        node_span = NodeSpan(node)

        locidx_kwargs = {
            "lineno": node_span.lineno,
            "col_offset": node_span.col_offset,
            "op_type": op_type,
            "end_lineno": node_span.end_lineno,
            "end_col_offset": node_span.end_col_offset,
        }

        if op_type in cmpop_is_types:
            idx = LocIndex(ast_class="CompareIs", **locidx_kwargs)  # type: ignore
        elif op_type in cmpop_in_types:
            idx = LocIndex(ast_class="CompareIn", **locidx_kwargs)  # type: ignore
        else:
            idx = LocIndex(ast_class="Compare", **locidx_kwargs)  # type: ignore

        self.locs.add(idx)

        if idx == self.target_idx and self.mutation and not self.readonly:
            LOGGER.debug("%s mutating idx: %s with %s", log_header, self.target_idx, self.mutation)

            # TODO: Determine when/how this case would actually be called
            if len(node.ops) > 1:
                # unlikely test case where the comparison has multiple values
                LOGGER.debug("%s multiple compare ops in node, len: %s", log_header, len(node.ops))
                existing_ops = [i for i in node.ops]
                mutation_ops = [self.mutation()] + existing_ops[1:]

                return ast.copy_location(
                    ast.Compare(left=node.left, ops=mutation_ops, comparators=node.comparators),
                    node,
                )

            else:
                # typical comparison case, will also catch (a==b)==1 as an example.
                LOGGER.debug("%s single comparison node operation", log_header)
                return ast.copy_location(
                    ast.Compare(
                        left=node.left, ops=[self.mutation()], comparators=node.comparators
                    ),
                    node,
                )

        LOGGER.debug("%s (%s, %s): no mutations applied.", log_header, node.lineno, node.col_offset)
        return node