checking data availability before calling std::getline

I would like to read some data from a stream I have using std::getline. Below a sample using the std::cin.

std::string line;
std::getline( std::cin, line );

This is a blocking function i.e. if there is no data or line to read it blocks execution.

Do you know if exists a function for checking data availability before calling std::getline? I don't want to block.

How can I check whether the stream buffer is full of data valid for a successful call to std::getline?

Whatever looks like the code below

if( dataAvailableInStream() )
{
     std::string line;
     std::getline( std::cin, line );
}