1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // <valarray>
10 
11 // template<class T> class valarray;
12 
13 // valarray operator[](const valarray<size_t>& vs) const;
14 
15 #include <valarray>
16 #include <cassert>
17 
18 int main(int, char**)
19 {
20     {
21         int a[] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11,
22                    12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
23                    24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
24                    36, 37, 38, 39, 40};
25         const std::size_t N1 = sizeof(a)/sizeof(a[0]);
26         std::size_t s[] = { 3,  4,  5,  7,  8,  9, 11, 12, 13, 15, 16, 17,
27                            22, 23, 24, 26, 27, 28, 30, 31, 32, 34, 35, 36};
28         const std::size_t S = sizeof(s)/sizeof(s[0]);
29         const std::valarray<int> v1(a, N1);
30         std::valarray<std::size_t> ia(s, S);
31         std::valarray<int> v = v1[ia];
32         assert(v.size() == 24);
33         assert(v[ 0] ==  3);
34         assert(v[ 1] ==  4);
35         assert(v[ 2] ==  5);
36         assert(v[ 3] ==  7);
37         assert(v[ 4] ==  8);
38         assert(v[ 5] ==  9);
39         assert(v[ 6] == 11);
40         assert(v[ 7] == 12);
41         assert(v[ 8] == 13);
42         assert(v[ 9] == 15);
43         assert(v[10] == 16);
44         assert(v[11] == 17);
45         assert(v[12] == 22);
46         assert(v[13] == 23);
47         assert(v[14] == 24);
48         assert(v[15] == 26);
49         assert(v[16] == 27);
50         assert(v[17] == 28);
51         assert(v[18] == 30);
52         assert(v[19] == 31);
53         assert(v[20] == 32);
54         assert(v[21] == 34);
55         assert(v[22] == 35);
56         assert(v[23] == 36);
57     }
58     {
59         int raw_data[] = {0,1,2,3,4,5,6,7,8,9};
60         std::size_t idx_data[] = {0,2,4,6,8};
61         const std::valarray<int> data(raw_data, sizeof(raw_data)/sizeof(raw_data[0]));
62         std::valarray<std::size_t> idx(idx_data, sizeof(idx_data)/sizeof(idx_data[0]));
63         std::valarray<int> result = (data + 0)[idx];
64         assert(result.size() == 5);
65         assert(result[0] == data[idx[0]]);
66         assert(result[1] == data[idx[1]]);
67         assert(result[2] == data[idx[2]]);
68         assert(result[3] == data[idx[3]]);
69         assert(result[4] == data[idx[4]]);
70     }
71   return 0;
72 }
73