Function parseTextCoordinate

source/MRMesh/MRIOParsing.cpp:130–182

template <typename T>
Expected<void> parseTextCoordinate( const std::string_view& str, Vector3<T>& v, Vector3<T>* n, Color* c )
{
    using namespace boost::spirit::x3;

    int vi = 0;
    const auto coord = [&] ( auto& ctx ) { v[vi++] = _attr( ctx ); };
    int ni = 0;
    const auto normal = [&] ( auto& ctx ) { if ( n ) ( *n )[ni++] = _attr( ctx ); };
    int ci = 0;
    const auto color = [&] ( auto& ctx ) { if ( c ) ( *c )[ci++] = uint8_t( _attr( ctx ) ); };

    const auto spaceRule = ( ascii::space | ',' | ';' );
    const auto coordRule = ( floatT[coord] >> floatT[coord] >> floatT[coord] );
    const auto normalRule = ( floatT[normal] >> floatT[normal] >> floatT[normal] );
    const auto colorRule = ( floatT[color] >> floatT[color] >> floatT[color] );

    bool r;
    if ( c != nullptr )
    {
        r = phrase_parse(
            str.begin(),
            str.end(),
            ( coordRule >> -( normalRule >> -colorRule ) ),
            spaceRule
        );
    }
    else if ( n != nullptr )
    {
        r = phrase_parse(
            str.begin(),
            str.end(),
            ( coordRule >> -normalRule ),
            spaceRule
        );
    }
    else
    {
        r = phrase_parse(
            str.begin(),
            str.end(),
            coordRule,
            spaceRule
        );
    }
    if ( !r )
        return unexpected( "Failed to parse coord" );

    // explicitly set alpha value if color is present
    if ( c != nullptr && ci == 3 )
        c->a = 255;

    return {};
}

template <typename T>
Expected<void> parseObjCoordinate( const std::string_view& str, Vector3<T>& v, Vector3<T>* c )