Boost C++ Libraries

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Struct template local

boost::xpressive::local — local<> is a lazy wrapper for a reference to a value that is stored within the local itself. It is for use within xpressive semantic actions.

Synopsis

// In header: <boost/xpressive/xpressive_fwd.hpp>

template<typename T> 
struct local : public proto::terminal::type< reference_wrapper< T > > {
  // construct/copy/destruct
  local();
  explicit local(T const &);

  // public member functions
  T & get();
  T const  & get() const;
};

Description

Below is an example of how to use local<> in semantic actions.

using namespace boost::xpressive;
local<int> i(0);
std::string str("1!2!3?");
// count the exciting digits, but not the
// questionable ones.
sregex rex = +( _d [ ++i ] >> '!' );
regex_search(str, rex);
assert( i.get() == 2 );

	Note
	As the name "local" suggests, `local<>` objects and the regexes that refer to them should never leave the local scope. The value stored within the local object will be destroyed at the end of the `local<>'s` lifetime, and any regex objects still holding the `local<>` will be left with a dangling reference.

Template Parameters

```
typename T
```
The type of the local variable.

`local` public construct/copy/destruct

```
local();
```
Store a default-constructed value of type T.
```
explicit local(T const & t);
```
Store a default-constructed value of type T.

Parameters:

t

The initial value.

`local` public member functions

```
T & get();
```
Fetch the wrapped value.
```
T const  & get() const;
```
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.