Masked set overwrites values not covered by the mask

[GiovaGa]

Consider the following snippet:

	for(size_t i = 0; i < n ; ++i ){
		rc = rc ? rc :  grb::setElement( y, i, i );
	}

	rc = rc ? rc : grb::setElement( mask, 1, 2 );
	rc = rc ? rc : grb::setElement( mask, 1, 3 );
	rc = rc ? rc : grb::setElement( mask, 1, 5 );
	rc = rc ? rc : grb::setElement( mask, 1, 7 );

	rc = rc ? rc : grb::setElement( x, 1, 4 );
	rc = rc ? rc : grb::setElement( x, 2, 1 );

	std::cerr << "x before:\t";
	for(const auto& a : x){
		std::cerr << a.first << ", " << a.second << " | ";
	}	std::cerr << std::endl;

	rc = rc ? rc : grb::set( x, mask, y );

	std::cerr << "x after:\t";
	for(const auto& a : x){
		std::cerr << a.first << ", " << a.second << " | ";
	}	std::cerr << std::endl;
	assert( rc == grb::SUCCESS );

The output is:

x before:	4, 1 | 1, 2 | 
x after:	2, 2 | 3, 3 | 5, 5 | 7, 7 | 

But I would expect the values in x not covered by the mask to be kept as before, so the expected output would be something like:

x before:	4, 1 | 1, 2 | 
x after:	4, 1 | 1, 2 | 2, 2 | 3, 3 | 5, 5 | 7, 7 | 

The documentation is unclear about this, as it does not specify what happens to the elements in x where the mask is false

[GiovaGa]

I guess the result I wanted is achievable by doing:

const grb::operators::right_assign< int > right_assignOp;
rc = rc ? rc : grb::foldl( x, mask, y, right_assignOp );