Problems with alternative in X3

Mikael Asplund <[email protected]> Wed, 23 Mar 2016 15:05:52 +0000

Newsgroups	gmane.comp.parsers.spirit.general
Message-ID	<[email protected]>

Hi!

I have an issue with alternatives that I don't understand why it's happening. I've simplified it even down to just x3::attr():s and I still get the problem.

Example here (code also supplied in attachment):

http://coliru.stacked-crooked.com/a/bdf4718cdeb2db4d

Why does the commented out version on line 57 work, and the active one on line 58-59 not work? It's an alternative of two exactly equal sequences, shouldn't that result in them joining to the attribute type as the single sequence?

Regards,
   Mikael

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alt_bug.cpp (text/plain, 1.5 KB)

#include <iostream>
#include <string>
#include <vector>
#include <boost/spirit/home/x3.hpp>
#include <boost/optional.hpp>
#include <boost/fusion/include/std_pair.hpp>
#include <boost/fusion/include/adapt_struct.hpp>

using std::string;
using std::vector;
using std::pair;

namespace x3 = boost::spirit::x3;

int parse_input(vector<string> v);

int main(int argc, const char* argv[]) {
    if (argc > 1) {
      return parse_input(vector<string>(&argv[1], &argv[argc + !argc]));
    }
    return 1;
}

struct Oper {
    int a;
    int b;
};

struct Ident {
    string ns;  
    string name;
};

struct Expr {
    int a;
    vector<Oper> b;
};

struct XXX {
    int a;
    Ident b;
    Expr c;
};

BOOST_FUSION_ADAPT_STRUCT(Oper, a, b)
BOOST_FUSION_ADAPT_STRUCT(Ident, ns, name)
BOOST_FUSION_ADAPT_STRUCT(Expr, a, b)
BOOST_FUSION_ADAPT_STRUCT(XXX, a, b, c)

int parse_input(vector<string> v) {
  std::stringstream ss;
  std::copy(v.begin(), v.end(), std::ostream_iterator<string>(ss, " "));
  string s = ss.str();
  auto iter = s.begin();
  auto end = s.end();
  XXX x;
//bool success = x3::phrase_parse(iter, end, x3::int_ > ((x3::attr(Ident{"",""}) >> x3::attr(Expr{3, {}}))) > ';', x3::space, x);
  bool success = x3::phrase_parse(iter, end, x3::int_ > ((x3::attr(Ident{"",""}) >> x3::attr(Expr{3, {}})) 
                                                        |(x3::attr(Ident{"",""}) >> x3::attr(Expr{3, {}}))) > ';', x3::space, x);
  return !success;
}