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std::regex_traits(3) Library Functions Manual std::regex_traits(3)

NAME

std::regex_traits -

Describes aspects of a regular expression.

SYNOPSIS

Public Types


typedef std::ctype_base::mask char_class_type
typedef _Ch_type char_type
typedef std::locale locale_type
typedef std::basic_string< char_type > string_type

Public Member Functions


locale_type getloc () const
locale_type imbue (locale_type __loc)
bool isctype (_Ch_type __c, char_class_type __f) const
template<typename _Fwd_iter > char_class_type lookup_classname (_Fwd_iter __first, _Fwd_iter __last) const
template<typename _Fwd_iter > string_type lookup_collatename (_Fwd_iter __first, _Fwd_iter __last) const
regex_traits ()
template<typename _Fwd_iter > string_type transform (_Fwd_iter __first, _Fwd_iter __last) const
template<typename _Fwd_iter > string_type transform_primary (_Fwd_iter __first, _Fwd_iter __last) const
char_type translate (char_type __c) const
char_type translate_nocase (char_type __c) const
int value (_Ch_type __ch, int __radix) const

Static Public Member Functions


static std::size_t length (const char_type *__p)

Protected Attributes


locale_type _M_locale

Detailed Description

template<typename _Ch_type> struct std::regex_traits< _Ch_type >

Describes aspects of a regular expression.

A regular expression traits class that satisfies the requirements of tr1 section [7.2].

The class regex is parameterized around a set of related types and functions used to complete the definition of its semantics. This class satisfies the requirements of such a traits class.

Definition at line 432 of file tr1_impl/regex.

Constructor & Destructor Documentation

template<typename _Ch_type > std::regex_traits< _Ch_type >::regex_traits () [inline]

Constructs a default traits object.

Definition at line 444 of file tr1_impl/regex.

Member Function Documentation

template<typename _Ch_type > locale_type std::regex_traits< _Ch_type >::getloc () const [inline]

Gets a copy of the current locale in use by the regex_traits object.

Definition at line 644 of file tr1_impl/regex.

template<typename _Ch_type > locale_type std::regex_traits< _Ch_type >::imbue (locale_type __loc) [inline]

Imbues the regex_traits object with a copy of a new locale. Parameters:

loc A locale.

Returns:

a copy of the previous locale in use by the regex_traits object.

Note:

Calling imbue with a different locale than the one currently in use invalidates all cached data held by *this.

Definition at line 633 of file tr1_impl/regex.

template<typename _Ch_type > static std::size_t std::regex_traits< _Ch_type >::length (const char_type * __p) [inline, static]

Gives the length of a C-style string starting at __p. Parameters:

__p a pointer to the start of a character sequence.

Returns:

the number of characters between *__p and the first default-initialized value of type char_type. In other words, uses the C-string algorithm for determining the length of a sequence of characters.

Definition at line 458 of file tr1_impl/regex.

References std::basic_string< _CharT, _Traits, _Alloc >::length().

template<typename _Ch_type > template<typename _Fwd_iter > char_class_type std::regex_traits< _Ch_type >::lookup_classname (_Fwd_iter __first, _Fwd_iter __last) const [inline]

Maps one or more characters to a named character classification. Parameters:

first beginning of the character sequence.
last one-past-the-end of the character sequence.

Returns:

an unspecified value that represents the character classification named by the character sequence designated by the iterator range [first, last). The value returned shall be independent of the case of the characters in the character sequence. If the name is not recognized then returns a value that compares equal to 0.

At least the following names (or their wide-character equivalent) are supported.

  • d
  • w
  • s
  • alnum
  • alpha
  • blank
  • cntrl
  • digit
  • graph
  • lower
  • print
  • punct
  • space
  • upper
  • xdigit

Todo

Implement this function.

Referenced by std::regex_traits< _Ch_type >::isctype().

template<typename _Ch_type > template<typename _Fwd_iter > string_type std::regex_traits< _Ch_type >::lookup_collatename (_Fwd_iter __first, _Fwd_iter __last) const [inline]

Gets a collation element by name. Parameters:

first beginning of the collation element name.
last one-past-the-end of the collation element name.

Returns:

a sequence of one or more characters that represents the collating element consisting of the character sequence designated by the iterator range [first, last). Returns an empty string if the character sequence is not a valid collating element.

Todo

Implement this function.

template<typename _Ch_type > template<typename _Fwd_iter > string_type std::regex_traits< _Ch_type >::transform (_Fwd_iter __first, _Fwd_iter __last) const [inline]

Gets a sort key for a character sequence. Parameters:

first beginning of the character sequence.
last one-past-the-end of the character sequence.

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).

What this really does is provide a more efficient way to compare a string to multiple other strings in locales with fancy collation rules and equivalence classes.

Returns:

a locale-specific sort key equivalent to the input range.

Exceptions:

std::bad_cast if the current locale does not have a collate facet.

Definition at line 511 of file tr1_impl/regex.

References std::basic_string< _CharT, _Traits, _Alloc >::data(), std::basic_string< _CharT, _Traits, _Alloc >::size(), std::collate< _CharT >::transform(), and std::use_facet().

template<typename _Ch_type > template<typename _Fwd_iter > string_type std::regex_traits< _Ch_type >::transform_primary (_Fwd_iter __first, _Fwd_iter __last) const [inline]

Dunno. Parameters:

first beginning of the character sequence.
last one-past-the-end of the character sequence.

Effects: if typeid(use_facet<collate<_Ch_type> >) == typeid(collate_byname<_Ch_type>) and the form of the sort key returned by collate_byname<_Ch_type>::transform(first, last) is known and can be converted into a primary sort key then returns that key, otherwise returns an empty string. WTF??

Todo

Implement this function.

template<typename _Ch_type > char_type std::regex_traits< _Ch_type >::translate (char_type __c) const [inline]

Performs the identity translation. Parameters:

c A character to the locale-specific character set.

Returns:

c.

Definition at line 469 of file tr1_impl/regex.

template<typename _Ch_type > char_type std::regex_traits< _Ch_type >::translate_nocase (char_type __c) const [inline]

Translates a character into a case-insensitive equivalent. Parameters:

c A character to the locale-specific character set.

Returns:

the locale-specific lower-case equivalent of c.

Exceptions:

std::bad_cast if the imbued locale does not support the ctype facet.

Definition at line 482 of file tr1_impl/regex.

References std::tolower(), and std::use_facet().

Author

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19 Jun 2018 libstdc++