Class Template `filter`

Description
Headers
Reference

Description

The class templates filter, wfilter, multichar_filter, multichar_wfilter and their specializations are provided by the Iostreams library for use as base classes for user-defined Filters. These base classes supply the member types char_type and category used internally by the Iostreams library to classify filters.

The supplied category member is convertible to closable_tag and to localizable_tag. This allows users to define models of the concepts Closable and Localizable simply by providing definitions of member functions close and imbue.

Headers

<boost/iostreams/concepts.hpp>

Reference

Synopsis

namespace boost{ namespace iostreams {

template<typename Mode, typename Ch = char>
struct filter;

template<typename Mode, typename Ch = wchar_t>
struct wfilter : filter<Mode, Ch> { };

typedef filter<input>      input_filter;
typedef wfilter<input>     input_wfilter;
typedef filter<output>     output_filter;
typedef wfilter<output>    output_wfilter;
typedef filter<seekable>   seekable_filter;
typedef wfilter<seekable>  seekable_wfilter;
typedef filter<dual_use>   dual_use_filter;
typedef wfilter<dual_use>  dual_use_wfilter;

template<typename Mode, typename Ch = char>
struct multichar_filter : filter<Mode, Ch> {
    typedef see below  category;
};

template<typename Mode, typename Ch = wchar_t>
struct multichar_wfilter : multichar_filter<Mode, Ch> { };

typedef multichar_filter<input>     multichar_input_filter;
typedef multichar_filter<input>     multichar_input_wfilter;
typedef multichar_filter<output>    multichar_output_filter;
typedef multichar_filter<output>    multichar_output_wfilter;
typedef multichar_filter<dual_use>  multichar_dual_use_filter;
typedef multichar_filter<dual_use>  multichar_dual_use_wfilter;

template<typename Mode, typename Ch = char>
struct filter {
    typedef Ch         char_type;
    typedef see below  category;

    template<typename Device>
    void close(Device&);

    template<typename Device>
    void close(Device&, std::ios_base::openmode);

    void imbue(const std::locale&);
};

} } // End namespace boost::io