boost::xpressive::mark_tag Struct Reference

Sub-match placeholder type, used to create named captures in static regexes. More...

#include <regex_primitives.hpp>

Inheritance diagram for boost::xpressive::mark_tag:

Collaboration diagram for boost::xpressive::mark_tag:

Public Member Functions
	mark_tag (int mark_nbr)
	Initialize a mark_tag placeholder. More...
	operator detail::basic_mark_tag const & () const
	INTERNAL ONLY. More...

Detailed Description

Sub-match placeholder type, used to create named captures in static regexes.

mark_tag is the type of the global sub-match placeholders s0, s1, etc.. You can use the mark_tag type to create your own sub-match placeholders with more meaningful names. This is roughly equivalent to the "named capture" feature of dynamic regular expressions.

To create a named sub-match placeholder, initialize it with a unique integer. The integer must only be unique within the regex in which the placeholder is used. Then you can use it within static regexes to created sub-matches by assigning a sub-expression to it, or to refer back to already created sub-matches.

mark_tag number(1); // "number" is now equivalent to "s1"
// Match a number, followed by a space and the same number again
sregex rx = (number = +_d) >> ' ' >> number;

After a successful regex_match() or regex_search(), the sub-match placeholder can be used to index into the match_results<> object to retrieve the corresponding sub-match.

Constructor & Destructor Documentation

boost::xpressive::mark_tag::mark_tag ( int  mark_nbr )

inline

Initialize a mark_tag placeholder.

Parameters

mark_nbr

An integer that uniquely identifies this mark_tag within the static regexes in which this mark_tag will be used.

Precondition

mark_nbr > 0

References BOOST_ASSERT.

Member Function Documentation

boost::xpressive::mark_tag::operator detail::basic_mark_tag const & ( ) const

inline

INTERNAL ONLY.

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The documentation for this struct was generated from the following file:

• boost_1_57_0/boost/xpressive/regex_primitives.hpp