does flush have built-in ... while?

ruby resources saving constructs, including if/unless, while/until etc.

the while retard c:

while (condition) {
    ...
}

can directly translated ruby:

while condition 
    ...
end

however, i can't seem built-in homogeneous flush c-like do ... while retard block essence executed during slightest once:

do { 
    ... 
} while (condition);

any suggestions?