Function parseObjFaceInfo

source/MRMesh/MRMeshLoadObj.cpp:234–268

};

Expected<ObjFaceInfo> parseObjFaceInfo( const std::string_view& str )
{
    using namespace boost::spirit::x3;

    ObjFaceInfo res;
    auto v = [&] ( auto& )
    {
        ++res.numVerts;
    };
    auto vt = [&] ( auto& )
    {
        ++res.numTexVerts;
    };
    auto vn = [&] ( auto& )
    {
        // normals are not used currently
    };

    bool r = phrase_parse(
        str.begin(),
        str.end(),
        // NOTE: actions are not being reverted after backtracking
        // https://github.com/boostorg/spirit/issues/378
        ( 'f' >> *( int_[v] >> -( '/' >> ( ( int_[vt] >> -( '/' >> int_[vn] ) ) | ( '/' >> int_[vn] ) ) ) ) ),
        ascii::space
    );
    if ( !r )
        return unexpected( "Failed to parse face in OBJ-file" );

    if ( !res.numVerts )
        return unexpected( "Invalid face vertex count in OBJ-file" );
    if ( res.numTexVerts && res.numVerts != res.numTexVerts )
        return unexpected( "Invalid face texture count in OBJ-file" );
    return res;
}

struct ObjFaces
{