boost::xpressive::value< T > Struct Template Reference

value<> is a lazy wrapper for a value that can be used in xpressive semantic actions. More...

#include <xpressive_fwd.hpp>

Inheritance diagram for boost::xpressive::value< T >:

Collaboration diagram for boost::xpressive::value< T >:

Public Types
typedef proto::extends < typename proto::terminal< T > ::type, value< T > >	base_type
	INTERNAL ONLY. More...

Public Member Functions
	value ()
	Store a default-constructed T. More...
	value (T const &t)
	Store a copy of t. More...
T &	get ()
T const &	get () const
	Fetch the stored value. More...

Detailed Description

template<typename T>
struct boost::xpressive::value< T >

value<> is a lazy wrapper for a value that can be used in xpressive semantic actions.

Template Parameters

T	The type of the value to store.

Below is an example that shows where value<> is useful.

sregex good_voodoo(boost::shared_ptr<int> pi)
{
    using namespace boost::xpressive;
    // Use val() to hold the shared_ptr by value:
    sregex rex = +( _d [ ++*val(pi) ] >> '!' );
    // OK, rex holds a reference count to the integer.
    return rex;
}

In the above code, xpressive::val() is a function that returns a value<> object. Had val() not been used here, the operation ++*pi would have been evaluated eagerly once, instead of lazily when the regex match happens.

Member Typedef Documentation

template<typename T >

typedef proto::extends<typename proto::terminal<T>::type, value<T> > boost::xpressive::value< T >::base_type

INTERNAL ONLY.

Constructor & Destructor Documentation

template<typename T >

boost::xpressive::value< T >::value ( )

inline

Store a default-constructed T.

template<typename T >

boost::xpressive::value< T >::value ( T const &  t )

inlineexplicit

Store a copy of t.

Parameters

t	The initial value.

Member Function Documentation

template<typename T >

T& boost::xpressive::value< T >::get ( )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

References boost::proto::value().

template<typename T >

T const& boost::xpressive::value< T >::get ( ) const

inline

Fetch the stored value.

References boost::proto::value().

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

• boost_1_57_0/boost/xpressive/regex_actions.hpp