84 lines
2.9 KiB
C++
84 lines
2.9 KiB
C++
// Copyright (c) 2001-2010 Hartmut Kaiser
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// The purpose of this example is to show how to parse arbitrary key/value
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// pairs delimited by some separator into a std::vector. The difference to
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// the example 'key_value_sequence.cpp' is that we preserve the order of the
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// elements in the parsed sequence as well as possibly existing duplicates.
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// In addition to the example 'key_value_sequence_ordered.cpp' we allow for
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// empty values, i.e. the grammar allows to distinguish between 'key=;' and
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// 'key;", where the first stores an empty string as the value, while the
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// second does not initialize the optional holding the value.
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//
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// For a more elaborate explanation see here: http://spirit.sourceforge.net/home/?p=371
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#include <boost/spirit/include/qi.hpp>
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#include <boost/fusion/include/std_pair.hpp>
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#include <iostream>
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#include <map>
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namespace client
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{
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namespace qi = boost::spirit::qi;
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typedef std::pair<std::string, boost::optional<std::string> > pair_type;
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typedef std::vector<pair_type> pairs_type;
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template <typename Iterator>
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struct key_value_sequence_empty_value
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: qi::grammar<Iterator, pairs_type()>
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{
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key_value_sequence_empty_value()
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: key_value_sequence_empty_value::base_type(query)
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{
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query = pair >> *((qi::lit(';') | '&') >> pair);
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pair = key >> -('=' >> -value);
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key = qi::char_("a-zA-Z_") >> *qi::char_("a-zA-Z_0-9");
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value = +qi::char_("a-zA-Z_0-9");
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}
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qi::rule<Iterator, pairs_type()> query;
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qi::rule<Iterator, pair_type()> pair;
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qi::rule<Iterator, std::string()> key, value;
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};
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}
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///////////////////////////////////////////////////////////////////////////////
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int main()
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{
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namespace qi = boost::spirit::qi;
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std::string input("key1=value1;key2;key3=value3;key4=");
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std::string::iterator begin = input.begin();
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std::string::iterator end = input.end();
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client::key_value_sequence_empty_value<std::string::iterator> p;
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client::pairs_type m;
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if (!qi::parse(begin, end, p, m))
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{
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std::cout << "-------------------------------- \n";
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std::cout << "Parsing failed\n";
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std::cout << "-------------------------------- \n";
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}
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else
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{
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std::cout << "-------------------------------- \n";
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std::cout << "Parsing succeeded, found entries:\n";
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client::pairs_type::iterator end = m.end();
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for (client::pairs_type::iterator it = m.begin(); it != end; ++it)
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{
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std::cout << (*it).first;
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if ((*it).second)
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std::cout << "=" << boost::get<std::string>((*it).second);
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std::cout << std::endl;
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}
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std::cout << "---------------------------------\n";
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}
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return 0;
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}
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