21     assert(std::regex_match("X", std::regex("[X]")));  in main()
22     assert(std::regex_match("X", std::regex("[XY]")));  in main()
23     assert(!std::regex_match("X", std::regex("[^X]")));  in main()
24     assert(!std::regex_match("X", std::regex("[^XY]")));  in main()
26     assert(std::regex_match("X", std::regex("[\\S]")));  in main()
27     assert(!std::regex_match("X", std::regex("[^\\S]")));  in main()
29     assert(!std::regex_match("X", std::regex("[\\s]")));  in main()
30     assert(std::regex_match("X", std::regex("[^\\s]")));  in main()
32     assert(std::regex_match("X", std::regex("[\\s\\S]")));  in main()
33     assert(std::regex_match("X", std::regex("[^Y\\s]")));  in main()
34     assert(!std::regex_match("X", std::regex("[^X\\s]")));  in main()
36     assert(std::regex_match("X", std::regex("[\\w]")));  in main()
37     assert(std::regex_match("_", std::regex("[\\w]")));  in main()
38     assert(!std::regex_match("X", std::regex("[^\\w]")));  in main()
39     assert(!std::regex_match("_", std::regex("[^\\w]")));  in main()
41     assert(!std::regex_match("X", std::regex("[\\W]")));  in main()
42     assert(!std::regex_match("_", std::regex("[\\W]")));  in main()
43     assert(std::regex_match("X", std::regex("[^\\W]")));  in main()
44     assert(std::regex_match("_", std::regex("[^\\W]")));  in main()
47     assert(std::regex_match("abZcd", std::regex("^ab[\\d\\D]cd")));  in main()
48     assert(std::regex_match("ab5cd", std::regex("^ab[\\d\\D]cd")));  in main()
49     assert(std::regex_match("abZcd", std::regex("^ab[\\D]cd")));  in main()
50     assert(std::regex_match("abZcd", std::regex("^ab\\Dcd")));  in main()
51     assert(std::regex_match("ab5cd", std::regex("^ab[\\d]cd")));  in main()
52     assert(std::regex_match("ab5cd", std::regex("^ab\\dcd")));  in main()
53     assert(!std::regex_match("abZcd", std::regex("^ab\\dcd")));  in main()
54     assert(!std::regex_match("ab5cd", std::regex("^ab\\Dcd")));  in main()
56     assert(std::regex_match("_xyz_", std::regex("_(\\s|\\S)+_")));  in main()
57     assert(std::regex_match("_xyz_", std::regex("_[\\s\\S]+_")));  in main()