Why doesn't my boost::spirit rule compile for parsing a list of lists?

Question

I'm trying to write a parser for Open Inventor .iv files using boost::spirit.

I have the following struct for VertexProperty nodes:

struct VertexProperty
{
   std::vector<std::vector<float> > vertices;
   std::vector<std::vector<float> > normals;
   std::vector<std::vector<float> > texCoords;
};

BOOST_FUSION_ADAPT_STRUCT(
   VertexProperty,
   (std::vector<std::vector<float> >, vertices)
   (std::vector<std::vector<float> >, normals)
   (std::vector<std::vector<float> >, texCoords)
   )

And the following rule for parsing it (which doesn't compile):

qi::rule<Iterator, VertexProperty(), Skipper> RULE_VertexProperty;
RULE_VertexProperty = lit("VertexProperty")
   >> char_('{')
   >> lit("vertex") >> char_('[')
   >> repeat(3)[qi::float_] >> *(char_(',') >> repeat(3)[qi::float_])
   >> char_(']')
   >> lit("normal") >> char_('[')
   >> repeat(3)[qi::float_] >> *(char_(',') >> repeat(3)[qi::float_])
   >> char_(']')
   >> lit("texCoord") >> char_('[')
   >> repeat(2)[qi::float] >> *(char_(',') >> repeat(2)[qi::float_])
   >> char_(']') >> char_('}');

Based on this rule, the following should result in a valid VertexProperty parse:

VertexProperty {
   vertex [ 0.0 0.0 1.0,
            1.0 1.0 1.0,
            1.0 0.0 1.0]
   normal [1.0 0.0 0.0,
           0.0 1.0 0.0,
           0.0 0.0 1.0]
   texCoord [0.0 0.0,
             1.0 0.0,
             1.0 1.0]
}

My assumption is that the problem is coming from how I'm trying to parse the comma separated tuples into a vector of a vector.

What is the correct way to parse a list of 3-tuples and or 2-tuples of the form:

[float float float, float float float, float float float]

using boost::spirit?

sehe sehe · Accepted Answer · 2016-02-10T23:35:51

EDIT I misread the question. Here's the rewrite:

Live On Coliru

Live On Coliru (with debug output)

struct V2 { float a, b;    } ;
struct V3 { float a, b, c; } ;
struct VertexProperty { 
    std::vector<V3> vertices, normals;
    std::vector<V2> texCoords; 
};

BOOST_FUSION_ADAPT_STRUCT(V2, a,b)
BOOST_FUSION_ADAPT_STRUCT(V3, a,b,c)
BOOST_FUSION_ADAPT_STRUCT(VertexProperty, vertices,normals,texCoords)

template <typename Iterator>
struct Parser : qi::grammar<Iterator, VertexProperty()> {
    Parser() : Parser::base_type(start) {
        v2 = qi::double_ >> qi::double_;
        v3 = qi::double_ >> qi::double_ >> qi::double_;

        vertexproperty = qi::lit("VertexProperty")
            >> '{'
            >> "vertex"   >> '[' >> (v3 % ',') >> ']'
            >> "normal"   >> '[' >> (v3 % ',') >> ']'
            >> "texCoord" >> '[' >> (v2 % ',') >> ']'
            >> '}';

        start = qi::skip(qi::space) [vertexproperty];

        BOOST_SPIRIT_DEBUG_NODES((v2)(v3)(vertexproperty))
    }

  private:
    qi::rule<Iterator, VertexProperty()> start;
    qi::rule<Iterator, VertexProperty(), qi::space_type> vertexproperty;
    qi::rule<Iterator, V2(),             qi::space_type> v2;
    qi::rule<Iterator, V3(),             qi::space_type> v3;
};

Notes:

use a typed element instead of 'just' a vector
use a separate rule for the V3
use literals (qi::lit) instead of qi::char_ because you do not want to expose the matched interpunction
use the list operator (a % b matches a [b a]... already)

UPDATE: Full Live Demo

//#define BOOST_SPIRIT_DEBUG
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/adapted/struct.hpp>

namespace qi = boost::spirit::qi;

struct V2 { float a, b;    } ;
struct V3 { float a, b, c; } ;
struct VertexProperty { 
    std::vector<V3> vertices, normals;
    std::vector<V2> texCoords; 
};

BOOST_FUSION_ADAPT_STRUCT(V2, a,b)
BOOST_FUSION_ADAPT_STRUCT(V3, a,b,c)
BOOST_FUSION_ADAPT_STRUCT(VertexProperty, vertices,normals,texCoords)

template <typename Iterator>
struct Parser : qi::grammar<Iterator, VertexProperty()> {
    Parser() : Parser::base_type(start) {
        v2 = qi::double_ >> qi::double_;
        v3 = qi::double_ >> qi::double_ >> qi::double_;

        vertexproperty = qi::lit("VertexProperty")
            >> '{'
            >> "vertex"   >> '[' >> (v3 % ',') >> ']'
            >> "normal"   >> '[' >> (v3 % ',') >> ']'
            >> "texCoord" >> '[' >> (v2 % ',') >> ']'
            >> '}';

        start = qi::skip(qi::space) [vertexproperty];

        BOOST_SPIRIT_DEBUG_NODES((v2)(v3)(vertexproperty))
    }

  private:
    qi::rule<Iterator, VertexProperty()> start;
    qi::rule<Iterator, VertexProperty(), qi::space_type> vertexproperty;
    qi::rule<Iterator, V2(),             qi::space_type> v2;
    qi::rule<Iterator, V3(),             qi::space_type> v3;
};

int main() {
    using Iterator = std::string::const_iterator;

    std::string const sample = "VertexProperty {\n"
        " vertex [ 0.0 0.0 1.0,\n"
        "     1.0 1.0 1.0,\n"
        "     1.0 0.0 1.0]\n"
        " normal [1.0 0.0 0.0,\n"
        "     0.0 1.0 0.0,\n"
        "     0.0 0.0 1.0]\n"
        " texCoord [0.0 0.0,\n"
        "     1.0 0.0,\n"
        "     1.0 1.0]\n"
        "}";

    auto f = sample.begin(), l = sample.end();
    VertexProperty data;
    bool ok = qi::parse(f, l, Parser<Iterator>(), data);

    if (ok) {
        std::cout << "Parsed: " << data.vertices.size() << ", " << data.normals.size() << ", " << data.texCoords.size() << "\n";
    } else {
        std::cout << "Parse failed\n";
    }

    if (f!=l)
        std::cout << "Remaining input: '" << std::string(f,l) << "'\n";
}

Prints

Parsed: 3, 3, 3

With debug info

<vertexproperty>
  <try>VertexProperty {\n ve</try>
  <v3>
    <try> 0.0 0.0 1.0,\n     1</try>
    <success>,\n     1.0 1.0 1.0,\n</success>
    <attributes>[[0, 0, 1]]</attributes>
  </v3>
  <v3>
    <try>\n     1.0 1.0 1.0,\n </try>
    <success>,\n     1.0 0.0 1.0]\n</success>
    <attributes>[[1, 1, 1]]</attributes>
  </v3>
  <v3>
    <try>\n     1.0 0.0 1.0]\n </try>
    <success>]\n normal [1.0 0.0 0</success>
    <attributes>[[1, 0, 1]]</attributes>
  </v3>
  <v3>
    <try>1.0 0.0 0.0,\n     0.</try>
    <success>,\n     0.0 1.0 0.0,\n</success>
    <attributes>[[1, 0, 0]]</attributes>
  </v3>
  <v3>
    <try>\n     0.0 1.0 0.0,\n </try>
    <success>,\n     0.0 0.0 1.0]\n</success>
    <attributes>[[0, 1, 0]]</attributes>
  </v3>
  <v3>
    <try>\n     0.0 0.0 1.0]\n </try>
    <success>]\n texCoord [0.0 0.0</success>
    <attributes>[[0, 0, 1]]</attributes>
  </v3>
  <v2>
    <try>0.0 0.0,\n     1.0 0.</try>
    <success>,\n     1.0 0.0,\n    </success>
    <attributes>[[0, 0]]</attributes>
  </v2>
  <v2>
    <try>\n     1.0 0.0,\n     </try>
    <success>,\n     1.0 1.0]\n}</success>
    <attributes>[[1, 0]]</attributes>
  </v2>
  <v2>
    <try>\n     1.0 1.0]\n}</try>
    <success>]\n}</success>
    <attributes>[[1, 1]]</attributes>
  </v2>
  <success></success>
  <attributes>[[[[0, 0, 1], [1, 1, 1], [1, 0, 1]], [[1, 0, 0], [0, 1, 0], [0, 0, 1]], [[0, 0], [1, 0], [1, 1]]]]</attributes>
</vertexproperty>

Why doesn't my boost::spirit rule compile for parsing a list of lists?

1 Answers

UPDATE: Full Live Demo