Function Template `restrict`

Description
Headers
Reference

Description

Given a Filter or Device that provides access to a single character sequence, we can construct a second Filter or Device which provides access to contiguous subsequence of the the original sequence. This second Filter or Device is called a restriction of the original device. Restrictions are represented by instances of the class template restriction. The function template resrict is an object generator which returns an appropriate instance of resriction when passed a Filter or Device and a pair of values indicating the endpoints of the restricted subsequence.

The mode of a resriction is the same as that of the underlying component. A resriction is Closable, Flushable, Localizable and OptimallyBuffered.

The function template slice is available as an alias of restrict, for platforms that treat restrict as a keyword.

Headers

<boost/iostreams/restrict.hpp>

Reference

Synopsis

namespace boost { namespace iostreams {

template<typename Component>
class restriction {
public:
    typedef typename char_type_of<Component>::type  char_type;
    typedef implementation-defined                  mode;

    restriction( [const] Component& component,
                 stream_offset off, 
                 stream_offset len = -1 );

    // Filter or Device member functions
};

template<typename Component>
restriction<Component> 
restrict( [const] Component& component,
          stream_offset off, 
          stream_offset len = -1 );

} } // End namespace boost::io

Class Template `restriction`

Template parameters

Component

A model of Filter or Device

`restriction::restriction`

    restriction( [const] Component& component,
                 stream_offset off, 
                 stream_offset len = -1 );

Constructs an instance of restriction based on the given component and offsets. The parameters have the following interpretation:

component	-	The Filter or Device to be restricted. If `Component` is a stream or stream buffer type, the function parameter is a non-`const` reference; otherwise it is a `const` reference.
off	-	The offset of the beginning of the restricted character sequence.
len	-	The length of the restricted character sequence. A value of `-1` indicates that the end of the restricted sequence should be the same as that of the unrestricted sequence.