1/*
2 * Copyright (c) 2024 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16function is_null(v: Object | null | undefined) {
17    return v instanceof null;
18}
19
20function is_obj(v: Object | null | undefined) {
21    return v instanceof Object;
22}
23
24class Foo { };
25
26type nullish_obj = Object | null | undefined;
27type nullish_int = Int | null | undefined;
28type nullish_foo = Foo | null | undefined;
29
30function is_nullish_obj(v: nullish_obj) {
31    return v instanceof nullish_obj;
32}
33
34function is_nullish_int(v: nullish_int) {
35    return v instanceof nullish_int;
36}
37
38function is_nullish_foo(v: nullish_foo) {
39    return v instanceof nullish_foo;
40}
41
42function is_nullish_foo_erased(v: nullish_obj) {
43    return v instanceof nullish_foo;
44}
45
46function main() {
47    const obj = new Object();
48    const foo = new Foo();
49    const boxint = new Int(3);
50
51    assert(is_null(null) == true);
52    assert(is_null(undefined) == false);
53    assert(is_null(obj) == false);
54
55    assert(is_obj(null) == false);
56    assert(is_obj(undefined) == false);
57    assert(is_obj(obj) == true);
58
59    assert(is_nullish_obj(null) == true);
60    assert(is_nullish_obj(undefined) == true);
61    assert(is_nullish_obj(obj) == true);
62    assert(is_nullish_obj(foo) == true);
63
64    assert(is_nullish_int(null) == true);
65    assert(is_nullish_int(undefined) == true);
66    assert(is_nullish_int(boxint) == true);
67
68    assert(is_nullish_foo(null) == true);
69    assert(is_nullish_foo(undefined) == true);
70    assert(is_nullish_foo(foo) == true);
71
72    assert(is_nullish_foo_erased(null) == true);
73    assert(is_nullish_foo_erased(undefined) == true);
74    assert(is_nullish_foo_erased(obj) == false);
75    assert(is_nullish_foo_erased(boxint) == false);
76    assert(is_nullish_foo_erased(foo) == true);
77}
78