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

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

C++ named requirements

Basic DefaultConstructible MoveConstructible (C++11) CopyConstructible CopyAssignable MoveAssignable (C++11) Destructible Type properties ScalarType PODType TriviallyCopyable (C++11) TrivialType (C++11) StandardLayoutType (C++11)   ImplicitLifetimeType Library-wide BooleanTestable EqualityComparable LessThanComparable Swappable ValueSwappable (C++11) NullablePointer (C++11) Hash (C++11) Allocator FunctionObject Callable Predicate BinaryPredicate Compare

Container Container ReversibleContainer AllocatorAwareContainer SequenceContainer ContiguousContainer (C++17) AssociativeContainer UnorderedAssociativeContainer (C++11)   Container element DefaultInsertable (C++11) CopyInsertable (C++11) MoveInsertable (C++11) EmplaceConstructible (C++11) Erasable (C++11) Iterator LegacyIterator LegacyInputIterator LegacyOutputIterator LegacyForwardIterator LegacyBidirectionalIterator LegacyRandomAccessIterator LegacyContiguousIterator (C++17) ConstexprIterator (C++20) Stream I/O FormattedInputFunction UnformattedInputFunction FormattedOutputFunction UnformattedOutputFunction Formatters BasicFormatter (C++20) Formatter (C++20)

Random Numbers SeedSequence (C++11) RandomNumberEngine (C++11) RandomNumberDistribution (C++11) UniformRandomBitGenerator (C++11) RandomNumberEngineAdaptor (C++11) Concurrency BasicLockable (C++11) Lockable (C++11) TimedLockable (C++11) SharedLockable (C++14) SharedTimedLockable (C++14) Mutex (C++11) TimedMutex (C++11) SharedMutex (C++17) SharedTimedMutex (C++14) Ranges RangeAdaptorObject (C++20) RangeAdaptorClosureObject (C++20) Multidimensional View LayoutMapping (C++23) LayoutMappingPolicy (C++23) AccessorPolicy (C++23) Other CharTraits RegexTraits (C++11)   BitmaskType LiteralType (C++11) NumericType UnaryTypeTrait (C++11) BinaryTypeTrait (C++11) TransformationTrait (C++11) Clock (C++11) TrivialClock (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 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>; template<> class regex_traits<wchar_t>;		(since C++11) (since C++11)