[libcxx] basic_regex: add traits_type, string_type

[jasonliu]

Summary

In the synopsis in C++11 subclause 28.8 [re.regex], basic_regex is specified to have member typedefs traits_type and string_type. This change adds them to libc++.

[hubert.reinterpretcast]

This looks straightforward. @mclow.lists, are you okay with me committing this for Jason?

[jasonliu]

Ping?

[hubert.reinterpretcast]

LGTM.

include/regex

 };
 
 template <class charT, class traits = regex_traits<charT>>
 class basic_regex
 {
 public:
     // types:
     typedef charT                               value_type;
+    typedef traits                              traits_type;
+    typedef typename traits::string_type        string_type;
     typedef regex_constants::syntax_option_type flag_type;
     typedef typename traits::locale_type        locale_type;
 
     // constants:
     static constexpr regex_constants::syntax_option_type icase = regex_constants::icase;
     static constexpr regex_constants::syntax_option_type nosubs = regex_constants::nosubs;
     static constexpr regex_constants::syntax_option_type optimize = regex_constants::optimize;
     static constexpr regex_constants::syntax_option_type collate = regex_constants::collate;

 template <class _CharT, class _Traits> class __lookahead;
 
 template <class _CharT, class _Traits = regex_traits<_CharT> >
 class _LIBCPP_TYPE_VIS_ONLY basic_regex
 {
 public:
     // types:
     typedef _CharT                              value_type;
+    typedef _Traits                             traits_type;
+    typedef typename _Traits::string_type       string_type;
     typedef regex_constants::syntax_option_type flag_type;
     typedef typename _Traits::locale_type       locale_type;
 
 private:
     _Traits   __traits_;
     flag_type __flags_;
     unsigned __marked_count_;
     unsigned __loop_count_;

test/std/re/re.regex/types.pass.cpp

 // <regex>
 
 // template <class charT, class traits = regex_traits<charT>>
 // class basic_regex
 // {
 // public:
 //     // types:
 //     typedef charT                               value_type;
+//     typedef traits                              traits_type;
+//     typedef typename traits::string_type        string_type;
 //     typedef regex_constants::syntax_option_type flag_type;
 //     typedef typename traits::locale_type        locale_type;
 
 #include <regex>
 #include <type_traits>
 #include "test_macros.h"
 
 int main()
 {
     static_assert((std::is_same<std::basic_regex<char>::value_type, char>::value), "");
+    static_assert((std::is_same<std::basic_regex<char>::traits_type, std::regex_traits<char> >::value), "");
+    static_assert((std::is_same<std::basic_regex<char>::string_type, std::basic_string<char> >::value), "");
     static_assert((std::is_same<std::basic_regex<char>::flag_type,
                                 std::regex_constants::syntax_option_type>::value), "");
     static_assert((std::is_same<std::basic_regex<char>::locale_type, std::locale>::value), "");
 
     static_assert((std::is_same<std::basic_regex<wchar_t>::value_type, wchar_t>::value), "");
+    static_assert((std::is_same<std::basic_regex<wchar_t>::traits_type, std::regex_traits<wchar_t> >::value), "");
+    static_assert((std::is_same<std::basic_regex<wchar_t>::string_type, std::basic_string<wchar_t> >::value), "");
     static_assert((std::is_same<std::basic_regex<wchar_t>::flag_type,
                                 std::regex_constants::syntax_option_type>::value), "");
     static_assert((std::is_same<std::basic_regex<wchar_t>::locale_type, std::locale>::value), "");
 }