std::regex_traits
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                    | Defined in header  <regex> | ||
| template< class CharT > class regex_traits; | (since C++11) | |
The type trait template regex_traits supplies std::basic_regex with the set of types and functions necessary to operate on the type CharT.
Since many of regex operations are locale-sensitive (when std::regex_constants::collate flag is set), the regex_traits class typically holds an instance of a std::locale as a private member.
[edit] Standard specializations
Two specializations of std::regex_traits are defined by the standard library:
| std::regex_traits<char> | |
| std::regex_traits<wchar_t> | 
These specializations make it possible to use std::basic_regex<char> (aka std::regex) and std::basic_regex<wchar_t> (aka std::wregex). To use std::basic_regex with other character types (for example, char32_t), a user-provided trait class must be used.
[edit] Member types
| Type | Definition | 
| char_type | CharT | 
| string_type | std::basic_string<CharT> | 
| locale_type | The locale used for localized behavior in the regular expression. Must be CopyConstructible | 
| char_class_type | Represents a character classification and is capable of holding an implementation specific set returned by lookup_classname. Must be aBitmaskType. | 
[edit] Member functions
| constructs the regex_traits object (public member function) | |
| [static] | calculates the length of a null-terminated character string (public static member function) | 
| determines the equivalence key for a character (public member function) | |
| determines the case-insensitive equivalence key for a character (public member function) | |
| determines the sort key for the given string, used to provide collation order (public member function) | |
| determines the primary sort key for the character sequence, used to determine equivalence class (public member function) | |
| gets a collation element by name (public member function) | |
| gets a character class by name (public member function) | |
| indicates membership in a localized character class (public member function) | |
| translates the character representing a numeric digit into an integral value (public member function) | |
| sets the locale (public member function) | |
| gets the locale (public member function) | 


