Пример #1
0
 def matching_primitive_op(
         self,
         candidates: List[OpDescription],
         args: List[Value],
         line: int,
         result_type: Optional[RType] = None) -> Optional[Value]:
     # Find the highest-priority primitive op that matches.
     matching = None  # type: Optional[OpDescription]
     for desc in candidates:
         if len(desc.arg_types) != len(args):
             continue
         if all(
                 is_subtype(actual.type, formal)
                 for actual, formal in zip(args, desc.arg_types)):
             if matching:
                 assert matching.priority != desc.priority, 'Ambiguous:\n1) %s\n2) %s' % (
                     matching, desc)
                 if desc.priority > matching.priority:
                     matching = desc
             else:
                 matching = desc
     if matching:
         target = self.primitive_op(matching, args, line)
         if result_type and not is_runtime_subtype(target.type,
                                                   result_type):
             if is_none_rprimitive(result_type):
                 # Special case None return. The actual result may actually be a bool
                 # and so we can't just coerce it.
                 target = self.none()
             else:
                 target = self.coerce(target, result_type, line)
         return target
     return None
Пример #2
0
    def emit_box(self,
                 src: str,
                 dest: str,
                 typ: RType,
                 declare_dest: bool = False,
                 can_borrow: bool = False) -> None:
        """Emit code for boxing a value of given type.

        Generate a simple assignment if no boxing is needed.

        The source reference count is stolen for the result (no need to decref afterwards).
        """
        # TODO: Always generate a new reference (if a reference type)
        if declare_dest:
            declaration = 'PyObject *'
        else:
            declaration = ''
        if is_int_rprimitive(typ) or is_short_int_rprimitive(typ):
            # Steal the existing reference if it exists.
            self.emit_line('{}{} = CPyTagged_StealAsObject({});'.format(
                declaration, dest, src))
        elif is_bool_rprimitive(typ):
            # N.B: bool is special cased to produce a borrowed value
            # after boxing, so we don't need to increment the refcount
            # when this comes directly from a Box op.
            self.emit_lines('{}{} = {} ? Py_True : Py_False;'.format(
                declaration, dest, src))
            if not can_borrow:
                self.emit_inc_ref(dest, object_rprimitive)
        elif is_none_rprimitive(typ):
            # N.B: None is special cased to produce a borrowed value
            # after boxing, so we don't need to increment the refcount
            # when this comes directly from a Box op.
            self.emit_lines('{}{} = Py_None;'.format(declaration, dest))
            if not can_borrow:
                self.emit_inc_ref(dest, object_rprimitive)
        elif isinstance(typ, RTuple):
            self.declare_tuple_struct(typ)
            self.emit_line('{}{} = PyTuple_New({});'.format(
                declaration, dest, len(typ.types)))
            self.emit_line('if (unlikely({} == NULL))'.format(dest))
            self.emit_line('    CPyError_OutOfMemory();')
            # TODO: Fail if dest is None
            for i in range(0, len(typ.types)):
                if not typ.is_unboxed:
                    self.emit_line('PyTuple_SET_ITEM({}, {}, {}.f{}'.format(
                        dest, i, src, i))
                else:
                    inner_name = self.temp_name()
                    self.emit_box('{}.f{}'.format(src, i),
                                  inner_name,
                                  typ.types[i],
                                  declare_dest=True)
                    self.emit_line('PyTuple_SET_ITEM({}, {}, {});'.format(
                        dest, i, inner_name))
        else:
            assert not typ.is_unboxed
            # Type is boxed -- trivially just assign.
            self.emit_line('{}{} = {};'.format(declaration, dest, src))
Пример #3
0
    def visit_name_expr(self, expr: NameExpr) -> Value:
        assert expr.node, "RefExpr not resolved"
        fullname = expr.node.fullname
        if fullname in name_ref_ops:
            # Use special access op for this particular name.
            desc = name_ref_ops[fullname]
            assert desc.result_type is not None
            return self.builder.add(PrimitiveOp([], desc, expr.line))

        if isinstance(expr.node, Var) and expr.node.is_final:
            value = self.builder.emit_load_final(
                expr.node,
                fullname,
                expr.name,
                self.builder.is_native_ref_expr(expr),
                self.builder.types[expr],
                expr.line,
            )
            if value is not None:
                return value

        if isinstance(expr.node,
                      MypyFile) and expr.node.fullname in self.builder.imports:
            return self.builder.load_module(expr.node.fullname)

        # If the expression is locally defined, then read the result from the corresponding
        # assignment target and return it. Otherwise if the expression is a global, load it from
        # the globals dictionary.
        # Except for imports, that currently always happens in the global namespace.
        if expr.kind == LDEF and not (isinstance(expr.node, Var)
                                      and expr.node.is_suppressed_import):
            # Try to detect and error when we hit the irritating mypy bug
            # where a local variable is cast to None. (#5423)
            if (isinstance(expr.node, Var)
                    and is_none_rprimitive(self.builder.node_type(expr))
                    and expr.node.is_inferred):
                self.builder.error(
                    "Local variable '{}' has inferred type None; add an annotation"
                    .format(expr.node.name), expr.node.line)

            # TODO: Behavior currently only defined for Var and FuncDef node types.
            return self.builder.read(self.builder.get_assignment_target(expr),
                                     expr.line)

        return self.builder.load_global(expr)
Пример #4
0
    def emit_cast(self,
                  src: str,
                  dest: str,
                  typ: RType,
                  declare_dest: bool = False,
                  custom_message: Optional[str] = None,
                  optional: bool = False,
                  src_type: Optional[RType] = None) -> None:
        """Emit code for casting a value of given type.

        Somewhat strangely, this supports unboxed types but only
        operates on boxed versions.  This is necessary to properly
        handle types such as Optional[int] in compatability glue.

        Assign NULL (error value) to dest if the value has an incompatible type.

        Always copy/steal the reference in src.

        Args:
            src: Name of source C variable
            dest: Name of target C variable
            typ: Type of value
            declare_dest: If True, also declare the variable 'dest'

        """
        if custom_message is not None:
            err = custom_message
        else:
            err = 'PyErr_SetString(PyExc_TypeError, "{} object expected");'.format(
                self.pretty_name(typ))

        # Special case casting *from* optional
        if src_type and is_optional_type(
                src_type) and not is_object_rprimitive(typ):
            value_type = optional_value_type(src_type)
            assert value_type is not None
            if is_same_type(value_type, typ):
                if declare_dest:
                    self.emit_line('PyObject *{};'.format(dest))
                self.emit_arg_check(src, dest, typ,
                                    '({} != Py_None)'.format(src), optional)
                self.emit_lines('    {} = {};'.format(dest, src), 'else {',
                                err, '{} = NULL;'.format(dest), '}')
                return

        # TODO: Verify refcount handling.
        if (is_list_rprimitive(typ) or is_dict_rprimitive(typ)
                or is_set_rprimitive(typ) or is_float_rprimitive(typ)
                or is_str_rprimitive(typ) or is_int_rprimitive(typ)
                or is_bool_rprimitive(typ)):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            if is_list_rprimitive(typ):
                prefix = 'PyList'
            elif is_dict_rprimitive(typ):
                prefix = 'PyDict'
            elif is_set_rprimitive(typ):
                prefix = 'PySet'
            elif is_float_rprimitive(typ):
                prefix = 'CPyFloat'
            elif is_str_rprimitive(typ):
                prefix = 'PyUnicode'
            elif is_int_rprimitive(typ):
                prefix = 'PyLong'
            elif is_bool_rprimitive(typ):
                prefix = 'PyBool'
            else:
                assert False, prefix
            self.emit_arg_check(src, dest, typ,
                                '({}_Check({}))'.format(prefix, src), optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_tuple_rprimitive(typ):
            if declare_dest:
                self.emit_line('{} {};'.format(self.ctype(typ), dest))
            self.emit_arg_check(src, dest, typ,
                                '(PyTuple_Check({}))'.format(src), optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif isinstance(typ, RInstance):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            if typ.class_ir.children:
                check = '(PyObject_TypeCheck({}, {}))'.format(
                    src, self.type_struct_name(typ.class_ir))
            else:
                # If the class has no children, just check the type directly
                check = '(Py_TYPE({}) == {})'.format(
                    src, self.type_struct_name(typ.class_ir))
            self.emit_arg_check(src, dest, typ, check, optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_none_rprimitive(typ):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_arg_check(src, dest, typ, '({} == Py_None)'.format(src),
                                optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_object_rprimitive(typ):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_arg_check(src, dest, typ, '', optional)
            self.emit_line('{} = {};'.format(dest, src))
            if optional:
                self.emit_line('}')
        elif isinstance(typ, RUnion):
            self.emit_union_cast(src, dest, typ, declare_dest, err, optional,
                                 src_type)
        elif isinstance(typ, RTuple):
            assert not optional
            self.emit_tuple_cast(src, dest, typ, declare_dest, err, src_type)
        else:
            assert False, 'Cast not implemented: %s' % typ
Пример #5
0
    def emit_unbox(self,
                   src: str,
                   dest: str,
                   typ: RType,
                   custom_failure: Optional[str] = None,
                   declare_dest: bool = False,
                   borrow: bool = False,
                   optional: bool = False) -> None:
        """Emit code for unboxing a value of given type (from PyObject *).

        Evaluate C code in 'failure' if the value has an incompatible type.

        Always generate a new reference.

        Args:
            src: Name of source C variable
            dest: Name of target C variable
            typ: Type of value
            failure: What happens on error
            declare_dest: If True, also declare the variable 'dest'
            borrow: If True, create a borrowed reference
        """
        # TODO: Verify refcount handling.
        raise_exc = 'CPy_TypeError("{}", {});'.format(self.pretty_name(typ),
                                                      src)
        if custom_failure is not None:
            failure = [raise_exc, custom_failure]
        else:
            failure = [raise_exc, '%s = %s;' % (dest, self.c_error_value(typ))]
        if is_int_rprimitive(typ) or is_short_int_rprimitive(typ):
            if declare_dest:
                self.emit_line('CPyTagged {};'.format(dest))
            self.emit_arg_check(src, dest, typ,
                                '(likely(PyLong_Check({})))'.format(src),
                                optional)
            if borrow:
                self.emit_line(
                    '    {} = CPyTagged_BorrowFromObject({});'.format(
                        dest, src))
            else:
                self.emit_line('    {} = CPyTagged_FromObject({});'.format(
                    dest, src))
            self.emit_line('else {')
            self.emit_lines(*failure)
            self.emit_line('}')
        elif is_bool_rprimitive(typ):
            # Whether we are borrowing or not makes no difference.
            if declare_dest:
                self.emit_line('char {};'.format(dest))
            self.emit_arg_check(src, dest, typ,
                                '(unlikely(!PyBool_Check({}))) {{'.format(src),
                                optional)
            self.emit_lines(*failure)
            self.emit_line('} else')
            conversion = '{} == Py_True'.format(src)
            self.emit_line('    {} = {};'.format(dest, conversion))
        elif is_none_rprimitive(typ):
            # Whether we are borrowing or not makes no difference.
            if declare_dest:
                self.emit_line('char {};'.format(dest))
            self.emit_arg_check(src, dest, typ,
                                '(unlikely({} != Py_None)) {{'.format(src),
                                optional)
            self.emit_lines(*failure)
            self.emit_line('} else')
            self.emit_line('    {} = 1;'.format(dest))
        elif isinstance(typ, RTuple):
            self.declare_tuple_struct(typ)
            if declare_dest:
                self.emit_line('{} {};'.format(self.ctype(typ), dest))
            # HACK: The error handling for unboxing tuples is busted
            # and instead of fixing it I am just wrapping it in the
            # cast code which I think is right. This is not good.
            if optional:
                self.emit_line('if ({} == NULL) {{'.format(src))
                self.emit_line('{} = {};'.format(dest,
                                                 self.c_error_value(typ)))
                self.emit_line('} else {')

            cast_temp = self.temp_name()
            self.emit_tuple_cast(src,
                                 cast_temp,
                                 typ,
                                 declare_dest=True,
                                 err='',
                                 src_type=None)
            self.emit_line('if (unlikely({} == NULL)) {{'.format(cast_temp))

            # self.emit_arg_check(src, dest, typ,
            #     '(!PyTuple_Check({}) || PyTuple_Size({}) != {}) {{'.format(
            #         src, src, len(typ.types)), optional)
            self.emit_lines(*failure)  # TODO: Decrease refcount?
            self.emit_line('} else {')
            if not typ.types:
                self.emit_line('{}.empty_struct_error_flag = 0;'.format(dest))
            for i, item_type in enumerate(typ.types):
                temp = self.temp_name()
                # emit_tuple_cast above checks the size, so this should not fail
                self.emit_line(
                    'PyObject *{} = PyTuple_GET_ITEM({}, {});'.format(
                        temp, src, i))
                temp2 = self.temp_name()
                # Unbox or check the item.
                if item_type.is_unboxed:
                    self.emit_unbox(temp,
                                    temp2,
                                    item_type,
                                    custom_failure,
                                    declare_dest=True,
                                    borrow=borrow)
                else:
                    if not borrow:
                        self.emit_inc_ref(temp, object_rprimitive)
                    self.emit_cast(temp, temp2, item_type, declare_dest=True)
                self.emit_line('{}.f{} = {};'.format(dest, i, temp2))
            self.emit_line('}')
            if optional:
                self.emit_line('}')

        else:
            assert False, 'Unboxing not implemented: %s' % typ
Пример #6
0
    def emit_cast(self,
                  src: str,
                  dest: str,
                  typ: RType,
                  declare_dest: bool = False,
                  custom_message: Optional[str] = None,
                  optional: bool = False,
                  src_type: Optional[RType] = None,
                  likely: bool = True) -> None:
        """Emit code for casting a value of given type.

        Somewhat strangely, this supports unboxed types but only
        operates on boxed versions.  This is necessary to properly
        handle types such as Optional[int] in compatibility glue.

        Assign NULL (error value) to dest if the value has an incompatible type.

        Always copy/steal the reference in src.

        Args:
            src: Name of source C variable
            dest: Name of target C variable
            typ: Type of value
            declare_dest: If True, also declare the variable 'dest'
            likely: If the cast is likely to succeed (can be False for unions)
        """
        if custom_message is not None:
            err = custom_message
        else:
            err = 'CPy_TypeError("{}", {});'.format(self.pretty_name(typ), src)

        # Special case casting *from* optional
        if src_type and is_optional_type(
                src_type) and not is_object_rprimitive(typ):
            value_type = optional_value_type(src_type)
            assert value_type is not None
            if is_same_type(value_type, typ):
                if declare_dest:
                    self.emit_line('PyObject *{};'.format(dest))
                check = '({} != Py_None)'
                if likely:
                    check = '(likely{})'.format(check)
                self.emit_arg_check(src, dest, typ, check.format(src),
                                    optional)
                self.emit_lines('    {} = {};'.format(dest, src), 'else {',
                                err, '{} = NULL;'.format(dest), '}')
                return

        # TODO: Verify refcount handling.
        if (is_list_rprimitive(typ) or is_dict_rprimitive(typ)
                or is_set_rprimitive(typ) or is_float_rprimitive(typ)
                or is_str_rprimitive(typ) or is_int_rprimitive(typ)
                or is_bool_rprimitive(typ)):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            if is_list_rprimitive(typ):
                prefix = 'PyList'
            elif is_dict_rprimitive(typ):
                prefix = 'PyDict'
            elif is_set_rprimitive(typ):
                prefix = 'PySet'
            elif is_float_rprimitive(typ):
                prefix = 'CPyFloat'
            elif is_str_rprimitive(typ):
                prefix = 'PyUnicode'
            elif is_int_rprimitive(typ):
                prefix = 'PyLong'
            elif is_bool_rprimitive(typ):
                prefix = 'PyBool'
            else:
                assert False, 'unexpected primitive type'
            check = '({}_Check({}))'
            if likely:
                check = '(likely{})'.format(check)
            self.emit_arg_check(src, dest, typ, check.format(prefix, src),
                                optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_tuple_rprimitive(typ):
            if declare_dest:
                self.emit_line('{} {};'.format(self.ctype(typ), dest))
            check = '(PyTuple_Check({}))'
            if likely:
                check = '(likely{})'.format(check)
            self.emit_arg_check(src, dest, typ, check.format(src), optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif isinstance(typ, RInstance):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            concrete = all_concrete_classes(typ.class_ir)
            n_types = len(concrete)
            # If there are too many concrete subclasses or we can't find any
            # (meaning the code ought to be dead), fall back to a normal typecheck.
            # Otherwise check all the subclasses.
            if n_types == 0 or n_types > FAST_ISINSTANCE_MAX_SUBCLASSES + 1:
                check = '(PyObject_TypeCheck({}, {}))'.format(
                    src, self.type_struct_name(typ.class_ir))
            else:
                full_str = '(Py_TYPE({src}) == {targets[0]})'
                for i in range(1, n_types):
                    full_str += ' || (Py_TYPE({src}) == {targets[%d]})' % i
                if n_types > 1:
                    full_str = '(%s)' % full_str
                check = full_str.format(
                    src=src,
                    targets=[self.type_struct_name(ir) for ir in concrete])
            if likely:
                check = '(likely{})'.format(check)
            self.emit_arg_check(src, dest, typ, check, optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_none_rprimitive(typ):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            check = '({} == Py_None)'
            if likely:
                check = '(likely{})'.format(check)
            self.emit_arg_check(src, dest, typ, check.format(src), optional)
            self.emit_lines('    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_object_rprimitive(typ):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_arg_check(src, dest, typ, '', optional)
            self.emit_line('{} = {};'.format(dest, src))
            if optional:
                self.emit_line('}')
        elif isinstance(typ, RUnion):
            self.emit_union_cast(src, dest, typ, declare_dest, err, optional,
                                 src_type)
        elif isinstance(typ, RTuple):
            assert not optional
            self.emit_tuple_cast(src, dest, typ, declare_dest, err, src_type)
        else:
            assert False, 'Cast not implemented: %s' % typ
Пример #7
0
    def generate_attr_defaults(self, cdef: ClassDef) -> None:
        """Generate an initialization method for default attr values (from class vars)"""
        cls = self.mapper.type_to_ir[cdef.info]
        if cls.builtin_base:
            return

        # Pull out all assignments in classes in the mro so we can initialize them
        # TODO: Support nested statements
        default_assignments = []
        for info in reversed(cdef.info.mro):
            if info not in self.mapper.type_to_ir:
                continue
            for stmt in info.defn.defs.body:
                if (isinstance(stmt, AssignmentStmt)
                        and isinstance(stmt.lvalues[0], NameExpr)
                        and not is_class_var(stmt.lvalues[0])
                        and not isinstance(stmt.rvalue, TempNode)):
                    if stmt.lvalues[0].name == '__slots__':
                        continue

                    # Skip type annotated assignments in dataclasses
                    if is_dataclass(cdef) and stmt.type:
                        continue

                    default_assignments.append(stmt)

        if not default_assignments:
            return

        self.builder.enter()
        self.builder.ret_types[-1] = bool_rprimitive

        rt_args = (RuntimeArg(SELF_NAME, RInstance(cls)),)
        self_var = self.builder.read(add_self_to_env(self.builder.environment, cls), -1)

        for stmt in default_assignments:
            lvalue = stmt.lvalues[0]
            assert isinstance(lvalue, NameExpr)
            if not stmt.is_final_def and not is_constant(stmt.rvalue):
                self.builder.warning('Unsupported default attribute value', stmt.rvalue.line)

            # If the attribute is initialized to None and type isn't optional,
            # don't initialize it to anything.
            attr_type = cls.attr_type(lvalue.name)
            if isinstance(stmt.rvalue, RefExpr) and stmt.rvalue.fullname == 'builtins.None':
                if (not is_optional_type(attr_type) and not is_object_rprimitive(attr_type)
                        and not is_none_rprimitive(attr_type)):
                    continue
            val = self.builder.coerce(self.accept(stmt.rvalue), attr_type, stmt.line)
            self.add(SetAttr(self_var, lvalue.name, val, -1))

        self.add(Return(self.primitive_op(true_op, [], -1)))

        blocks, env, ret_type, _ = self.builder.leave()
        ir = FuncIR(
            FuncDecl('__mypyc_defaults_setup',
                     cls.name, self.module_name,
                     FuncSignature(rt_args, ret_type)),
            blocks, env)
        self.builder.functions.append(ir)
        cls.methods[ir.name] = ir
Пример #8
0
    def emit_cast(self,
                  src: str,
                  dest: str,
                  typ: RType,
                  declare_dest: bool = False,
                  custom_message: Optional[str] = None) -> None:
        """Emit code for casting a value of given type.

        Somewhat strangely, this supports unboxed types but only
        operates on boxed versions.  This is necessary to properly
        handle types such as Optional[int] in compatability glue.

        Assign NULL (error value) to dest if the value has an incompatible type.

        Always copy/steal the reference in src.

        Args:
            src: Name of source C variable
            dest: Name of target C variable
            typ: Type of value
            declare_dest: If True, also declare the variable 'dest'

        """
        if custom_message is not None:
            err = custom_message
        else:
            err = 'PyErr_SetString(PyExc_TypeError, "{} object expected");'.format(
                self.pretty_name(typ))
        # TODO: Verify refcount handling.
        if (is_list_rprimitive(typ) or is_dict_rprimitive(typ)
                or is_set_rprimitive(typ) or is_float_rprimitive(typ)
                or is_str_rprimitive(typ) or is_int_rprimitive(typ)
                or is_bool_rprimitive(typ)):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            if is_list_rprimitive(typ):
                prefix = 'PyList'
            elif is_dict_rprimitive(typ):
                prefix = 'PyDict'
            elif is_set_rprimitive(typ):
                prefix = 'PySet'
            elif is_float_rprimitive(typ):
                prefix = 'PyFloat'
            elif is_str_rprimitive(typ):
                prefix = 'PyUnicode'
            elif is_int_rprimitive(typ):
                prefix = 'PyLong'
            elif is_bool_rprimitive(typ):
                prefix = 'PyBool'
            else:
                assert False, prefix
            self.emit_lines('if ({}_Check({}))'.format(prefix, src),
                            '    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_tuple_rprimitive(typ):
            if declare_dest:
                self.emit_line('{} {};'.format(self.ctype(typ), dest))
            self.emit_lines('if (PyTuple_Check({}))'.format(src),
                            '    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif isinstance(typ, RInstance):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_lines(
                'if (PyObject_TypeCheck({}, &{}))'.format(
                    src, self.type_struct_name(typ.class_ir)),
                '    {} = {};'.format(dest, src), 'else {', err,
                '{} = NULL;'.format(dest), '}')
        elif is_none_rprimitive(typ):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_lines('if ({} == Py_None)'.format(src),
                            '    {} = {};'.format(dest, src), 'else {', err,
                            '{} = NULL;'.format(dest), '}')
        elif is_object_rprimitive(typ):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_line('{} = {};'.format(dest, src))
        elif isinstance(typ, ROptional):
            if declare_dest:
                self.emit_line('PyObject *{};'.format(dest))
            self.emit_lines('if ({} == Py_None)'.format(src),
                            '    {} = {};'.format(dest, src), 'else {')
            self.emit_cast(src, dest, typ.value_type, custom_message=err)
            self.emit_line('}')
        else:
            assert False, 'Cast not implemented: %s' % typ