Using Iterator parsing with Boost::Spirit Grammars

Question

When I attempt to use the iterator form of parsing for a Spirit grammar I get a argument passing conversion error from the iterator type to const char*. How do I fix this?

There are some restrictions. I'm using an iterator adapter on large inputs, so it is not feasible for me to convert to a C style string.

Here is sample code demonstrating the issue:

#include <boost/spirit/core.hpp>
#include <boost/spirit/iterator/file_iterator.hpp>
#include <vector>
#include <string>
using std;
using boost::spirit;
struct ex : public grammar<route_grammar> {
  template <typename ScannerT> struct defintion {
    definition(ex const& self) {
      expression = real_p; 
    }
    rule<ScannerT> expression;
    rule<ScannerT> const& start() const { return expression; }
};

int main() {
  file_iterator<char> first;
  file_iterator<char> last = first.make_end();
  ex ex_p;
  parse_info<file_iterator<char> > info = parse(first, last, ex_p, space_p);
  return 0;
}

This code breaks with: error: cannot convert const boost::spirit::file_iterator<char_t, boost::spirit::fileiter_impl::mmap_file_iterator<char_t> > to const char* in argument passing

Answer 1

Hard to tell from the code as posted, since it contains a few basic errors. After correction of these, it compiles fine on my machine (with MSVC++7.1):

#include <boost/spirit/core.hpp>
#include <vector>
#include <string>
using namespace std;
using namespace boost::spirit;
struct ex : public grammar<ex> {
template <typename ScannerT> 
struct definition {
    definition(ex const& self)
    {
    expression = real_p; 
    }
    rule<ScannerT> expression;
    rule<ScannerT> const& start() const { return expression; }
};
};

int main() {
vector<char> v;
v.push_back('3'); v.push_back('.'); v.push_back('2');
ex ex_p;
parse_info<vector<char>::iterator> info = parse(v.begin(), v.end(), ex_p, space_p);
return 0;
}