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// Copyright (c) 2001-2010 Hartmut Kaiser
//
// 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)
// The purpose of this example is to show how to parse arbitrary key/value
// pairs delimited by some separator into a std::map. Parsing the URL query
// format is the example we use to demonstrate how this can be done
// (i.e. things like: key1=value1;key2=value2;...;keyN=valueN).
//
// For a more elaborate explanation see here: http://spirit.sourceforge.net/home/?p=371
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/include/std_pair.hpp>
#include <iostream>
#include <map>
namespace client
{
namespace qi = boost::spirit::qi;
typedef std::map<std::string, std::string> pairs_type;
template <typename Iterator>
struct key_value_sequence
: qi::grammar<Iterator, pairs_type()>
{
key_value_sequence()
: key_value_sequence::base_type(query)
{
query = pair >> *((qi::lit(';') | '&') >> pair);
pair = key >> -('=' >> value);
key = qi::char_("a-zA-Z_") >> *qi::char_("a-zA-Z_0-9");
value = +qi::char_("a-zA-Z_0-9");
}
qi::rule<Iterator, pairs_type()> query;
qi::rule<Iterator, std::pair<std::string, std::string>()> pair;
qi::rule<Iterator, std::string()> key, value;
};
}
///////////////////////////////////////////////////////////////////////////////
int main()
{
namespace qi = boost::spirit::qi;
std::string input("key1=value1;key2;key3=value3");
std::string::iterator begin = input.begin();
std::string::iterator end = input.end();
client::key_value_sequence<std::string::iterator> p;
client::pairs_type m;
if (!qi::parse(begin, end, p, m))
{
std::cout << "-------------------------------- \n";
std::cout << "Parsing failed\n";
std::cout << "-------------------------------- \n";
}
else
{
std::cout << "-------------------------------- \n";
std::cout << "Parsing succeeded, found entries:\n";
client::pairs_type::iterator end = m.end();
for (client::pairs_type::iterator it = m.begin(); it != end; ++it)
{
std::cout << (*it).first;
if (!(*it).second.empty())
std::cout << "=" << (*it).second;
std::cout << std::endl;
}
std::cout << "---------------------------------\n";
}
return 0;
}