libs/spirit/repository/example/qi/advance.cpp
// Copyright (c) 2011 Aaron Graham
//
// 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 demonstrate the use of the advance parser.
//[qi_advance_includes
#include <boost/spirit/include/qi.hpp>
#include <boost/phoenix/operator.hpp>
#include <boost/spirit/repository/include/qi_advance.hpp>
//]
#include <list>
#include <string>
//[qi_advance_namespaces
namespace qi = boost::spirit::qi;
using boost::spirit::repository::qi::advance;
//]
namespace client
{
//[qi_advance_grammar
template <typename Iterator>
struct advance_grammar : qi::grammar<Iterator, qi::locals<int> >
{
advance_grammar() : advance_grammar::base_type(start)
{
using qi::byte_;
using qi::eoi;
using namespace qi::labels;
start
= byte_ [_a = _1]
>> advance(_a)
>> "boost"
>> byte_ [_a = _1]
>> (advance(_a) | "qi") // note alternative when advance fails
>> eoi
;
}
qi::rule<Iterator, qi::locals<int> > start;
};
//]
}
int main()
{
// This parser is tested with both random access iterators (std::string)
// and bidirectional iterators (std::list).
char const* result;
//[qi_advance_example1
unsigned char const alt1[] =
{
5, // number of bytes to advance
1, 2, 3, 4, 5, // data to advance through
'b', 'o', 'o', 's', 't', // word to parse
2, // number of bytes to advance
11, 12 // more data to advance through
// eoi
};
std::string const alt1_string(alt1, alt1 + sizeof alt1);
std::list<unsigned char> const alt1_list(alt1, alt1 + sizeof alt1);
result =
qi::parse(alt1_string.begin(), alt1_string.end()
, client::advance_grammar<std::string::const_iterator>())
? "succeeded" : "failed";
std::cout << "Parsing alt1 using random access iterator " << result << std::endl;
result =
qi::parse(alt1_list.begin(), alt1_list.end()
, client::advance_grammar<std::list<unsigned char>::const_iterator>())
? "succeeded" : "failed";
std::cout << "Parsing alt1 using bidirectional iterator " << result << std::endl;
//]
//[qi_advance_example2
unsigned char const alt2[] =
{
2, // number of bytes to advance
1, 2, // data to advance through
'b', 'o', 'o', 's', 't', // word to parse
4, // number of bytes to advance
'q', 'i' // alternative (advance won't work)
// eoi
};
std::string const alt2_string(alt2, alt2 + sizeof alt2);
std::list<unsigned char> const alt2_list(alt2, alt2 + sizeof alt2);
result =
qi::parse(alt2_string.begin(), alt2_string.end()
, client::advance_grammar<std::string::const_iterator>())
? "succeeded" : "failed";
std::cout << "Parsing alt2 using random access iterator " << result << std::endl;
result =
qi::parse(alt2_list.begin(), alt2_list.end()
, client::advance_grammar<std::list<unsigned char>::const_iterator>())
? "succeeded" : "failed";
std::cout << "Parsing alt2 using bidirectional iterator " << result << std::endl;
//]
return 0;
}