Function Template `get`

Overview
Example
Headers
Reference

Overview

The function template get provides a uniform interface for reading a character from a Source, for use in the definitions of new Filter types (see Example).

Example

The following code illustrates the use of the function get in the definition of an InputFilter.

    #include <ctype.h>                        // tolower    
    #include <boost/iostreams/concepts.hpp>   // input_filter 
    #include <boost/iostreams/operations.hpp> // get, EOF, WOULD_BLOCK

    using namespace std;
    using namespace boost::io;

    struct tolower_filter : public input_filter {
        template<typename Source>
        int get(Source& src)
        {
            int c;
            return (c == boost::iostreams::get(src)) != EOF && 
                    c != WOULD_BLOCK 
                        ?
                tolower((unsigned char) c) :
                c;
        }
    };

Headers

<boost/iostreams/get.hpp>
<boost/iostreams/operations.hpp>

Reference

Description

Attemps to extract a character from a given instance of the template parameter Source, returning the extracted character or one of the special values traits_type::eof or traits_type::would_block, where traits_type is an appropriate specialization of boost::iostreams::char_traits

Synopsis

namespace boost { namespace iostreams {
              
    template<typename Source>     
    typename int_type_of<Source>::type
    get(Source& src);

} } // End namespace boost::io

Template Parameters

Source

A model of Source.

Function Parameters

src - An instance of Source

Semantics

    template<typename Source>     
    typename int_type_of<Source>::type
    get(Source& src);

The semantics of get depends on the category of Source as follows:

`category_of<Source>::type`	semantics
convertible to `direct_tag`	compile-time error
convertible to `istream_tag`	returns `src.get()`
convertible to `streambuf_tag` but not to `istream_tag`	returns `src.sbumpc()`
otherwise	attempts to extract a single character using `src.read()`, returning the extracted character if successful and one of the special values `traits_type::eof` or `traits_type::would_block` otherwise, where `traits_type` is `boost::iostreams::char_traits<Source>`

Revised 20 May, 2004

Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

Function Template get