C++ named requirements:RegexTraits (since C++11)

RegexTraits is a traits class that abstracts operations needed for a given character type when as template type parameters for std::basic_regex.

Requirements

Given

• CharT, a character type
• X, a RegexTraits type for type CharT
• u, an object of type X
• v, an object of type const X
• p, a value of type const CharT*
• I1, I2, input iterators
• F1, F2, forward iterators
• c, a value of type const CharT
• s, an object of type X::string_type
• cs, an object of type const X::string_type
• b, a value of type bool
• I, a value of type int
• cl, an object of type X::char_class_type
• loc, an object of type X::locale_type

Expression	Return type	Semantics
X::char_type	CharT	Used to refer to the character type.
X::string_type	std::basic_string<CharT>
X::locale_type		A CopyConstructible type that represents the locale used by the traits class.
X::char_class_type		A BitmaskType type that represents a particular character classification.
X::length(p)	std::size_t	Returns: the smallest i such that p[i] == 0. Complexity is linear in i.
v.translate(c)	X::char_type	Returns: a character such that for any character d considered to be equivalent to c, then v.translate(c) == v.translate(d).
v.translate_nocase(c)	X::char_type	Returns: a character such that for any character C considered to be equivalent to c without regard to case, then v.translate_nocase(c) == v.translate_nocase(C).
v.transform(F1, F2)	X::string_type	Returns: a sort key for the character sequence designated by the iterator range [F1, F2) such that if the character sequence [G1, G2) sorts before the character sequence [H1, H2), then v.transform(G1, G2) < v.transform(H1, H2).
v.transform_primary(F1, F2)	X::string_type	Returns: a sort key for the character sequence designated by the iterator range [F1, F2) such that if the character sequence [G1, G2) sorts before the character sequence [H1, H2) without regard to case, then v.transform_primary(G1, G2) < v.transform_primary(H1, H2).
v.lookup_collatename(F1, F2)	X::string_type	Returns:  * An empty string if the character sequence is not a valid collating element  * A sequence of characters that represents the collating element consisting of the character sequence designated by the iterator range [F1, F2) otherwise
v.lookup_classname(F1, F2, b)	X::char_class_type	* Converts the character sequence designated by the iterator range [F1, F2) into a value of a BitmaskType that can subsequently be passed to isctype BitmaskType * Values returned from lookup_classname can be bitwise or'ed together; the resulting value represents membership in either of the corresponding character classes * If b is true, the returned bitmask is suitable for matching characters without regard to their case. * Returns 0 if the character sequence is not the name of a character class recognized by X. * The value returned shall be independent of the case of the characters in the sequence.
v.isctype(c, cl)	bool	Returns: whether c is a member of one of the character classes designated by cl or not.
v.value(c, I)	int	Returns:  * The value represented by the digit c in base I if the character c is a valid digit in base I  * -1 otherwise
u.imbue(loc)	X::locale_type	* Imbues u with the locale loc * Returns: The previous locale used by u if any
v.getloc()	X::locale_type	Returns: The previous locale used by v if any.

Standard library

RegexTraits is satisfied by the following standard library classes:

• template<> class regex_traits<char>; (since C++11)
• template<> class regex_traits<wchar_t>; (since C++11)