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/*
* Copyright Andrey Semashev 2007 - 2015.
* 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)
*/
#include <cstddef>
#include <string>
#include <utility>
#include <iostream>
#include <boost/mpl/vector.hpp>
#include <boost/log/attributes/value_extraction.hpp>
#include <boost/log/attributes/attribute_value_impl.hpp>
#include <boost/log/utility/value_ref.hpp>
namespace logging = boost::log;
namespace attrs = boost::log::attributes;
//[ example_attr_value_extraction
void print_value(logging::attribute_value const& attr)
{
// Extract a reference to the stored value
logging::value_ref< int > val = logging::extract< int >(attr);
// Check the result
if (val)
std::cout << "Extraction succeeded: " << val.get() << std::endl;
else
std::cout << "Extraction failed" << std::endl;
}
//]
//[ example_attr_value_extraction_multiple_types
void print_value_multiple_types(logging::attribute_value const& attr)
{
// Define the set of expected types of the stored value
typedef boost::mpl::vector< int, std::string > types;
// Extract a reference to the stored value
logging::value_ref< types > val = logging::extract< types >(attr);
// Check the result
if (val)
{
std::cout << "Extraction succeeded" << std::endl;
switch (val.which())
{
case 0:
std::cout << "int: " << val.get< int >() << std::endl;
break;
case 1:
std::cout << "string: " << val.get< std::string >() << std::endl;
break;
}
}
else
std::cout << "Extraction failed" << std::endl;
}
//]
//[ example_attr_value_extraction_visitor
struct hash_visitor
{
typedef std::size_t result_type;
result_type operator() (int val) const
{
std::size_t h = val;
h = (h << 15) + h;
h ^= (h >> 6) + (h << 7);
return h;
}
result_type operator() (std::string const& val) const
{
std::size_t h = 0;
for (std::string::const_iterator it = val.begin(), end = val.end(); it != end; ++it)
h += *it;
h = (h << 15) + h;
h ^= (h >> 6) + (h << 7);
return h;
}
};
void hash_value(logging::attribute_value const& attr)
{
// Define the set of expected types of the stored value
typedef boost::mpl::vector< int, std::string > types;
// Extract the stored value
logging::value_ref< types > val = logging::extract< types >(attr);
// Check the result
if (val)
std::cout << "Extraction succeeded, hash value: " << val.apply_visitor(hash_visitor()) << std::endl;
else
std::cout << "Extraction failed" << std::endl;
}
//]
#if 0
//[ example_attr_value_extraction_visitor_rec
void hash_value(logging::record_view const& rec, logging::attribute_name name)
{
// Define the set of expected types of the stored value
typedef boost::mpl::vector< int, std::string > types;
// Extract the stored value
logging::value_ref< types > val = logging::extract< types >(name, rec);
// Check the result
if (val)
std::cout << "Extraction succeeded, hash value: " << val.apply_visitor(hash_visitor()) << std::endl;
else
std::cout << "Extraction failed" << std::endl;
}
//]
#endif
int main(int, char*[])
{
print_value(attrs::make_attribute_value(10));
print_value_multiple_types(attrs::make_attribute_value(10));
print_value_multiple_types(attrs::make_attribute_value(std::string("Hello")));
hash_value(attrs::make_attribute_value(10));
hash_value(attrs::make_attribute_value(std::string("Hello")));
return 0;
}
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